Journal articles on the topic 'Dive behaviour'
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1
Heide-JøRgensen, M. P., and R. Dietz. "Some characteristics of narwhal, Monodon monoceros, diving behaviour in Baffin Bay." Canadian Journal of Zoology 73, no. 11 (November 1, 1995): 2120–32. http://dx.doi.org/10.1139/z95-249.
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Dive data were collected from nine narwhals, Monodon monoceros, instrumented with satellite-linked dive recorders in northwest Greenland in August–September 1993 and 1994. Data were collected for periods ranging from a few weeks to 9 months. The narwhals made daily dives to depths of more than 500 m and frequently dived to 1000 m or more. However, most of the time spent below the surface was in the water column at depths of between 8 and 52 m. For two males that were tracked from September through November the maximum dive depth increased steadily through time. There were no consistent differences in the duration of dives or the number of dives to depths > 8 m during four 6-h periods that were monitored. There were significant differences in dive rates (number of dives per hour) between the large males, the small male, and the females. More than half of the dives lasted less than 5 min and few lasted more than 20 min. These relatively short dive times suggest that narwhals do not exceed their aerobic dive limit. The average time spent in the upper 5 m of the water column was 39.3% (SD = 13.5%; n = 632) for seven whales combined. Speed of vertical movements increased significantly from 1 m∙s−1 for 100-m dives to more than 2 m∙s−1 for dives deeper than 900 m. A female accompanied by a calf had dive parameters and surfacing times that were identical with those of the other females.
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Gales, N. J., and R. H. Mattlin. "Summer diving behaviour of lactating New Zealand sea lions, Phocarctos hookeri." Canadian Journal of Zoology 75, no. 10 (October 1, 1997): 1695–706. http://dx.doi.org/10.1139/z97-796.
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The diving behaviour of 14 female New Zealand sea lions (Phocarctos hookeri) was recorded during early lactation in January and February 1995 on the Auckland Islands, New Zealand. During 73 trips to sea, 19 720 dives were recorded. The average duration of a foraging cycle was 2.9 days (range 1.4–4.8 days), of which 1.7 days (57%) (range 1.1–3.4 days) were spent at sea and 1.2 days (43%) (range 0.8–2.3 days) ashore. At sea the sea lions dived almost continuously at a rate of 7.5 dives/h and spent a mean of 45% of the time submerged (≥ 2 m). Dive behaviour varied among individuals but showed no diel pattern overall. The dive depth for all dives ≥ 6 m was 123 ± 87 m (mean ± SD) (median 124 m, maximum 474 m) and ranged among individuals from 79 ± 85 to 187 ± 166 m. About half of the dives were in the 101- to 180-m range. The duration of all dives was 3.9 ± 1.8 min (median 4.33 min, maximum 11.3 min); about half (51%) of the dive durations were between 4 and 6 min. Surface interval was 4.5 ± 15.8 min (median 1.9 min). Almost half (44%) of all dives exceeded the calculated aerobic dive limit of each sea lion (range 16–73% for individuals). Most dive profiles were flat bottomed and, we believe, are to the benthos. A mean of 51.5% of all dive time was spent in the deepest 85% of the dive. Prey remains found during this study were primarily of benthic and demersal organisms. Phocarctos hookeri is the deepest and longest diving of any of the otariids recorded to date. We suggest that the dive behaviour may reflect either successful physiological adaptation to exploiting benthic prey and (or) a marginal foraging environment in which diving behaviour is close to physiological limits.
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McCafferty, D. J., I. L. Boyd, and R. I. Taylor. "Diving behaviour of Antarctic fur seal (Arctocephalus gazella) pups." Canadian Journal of Zoology 76, no. 3 (March 1, 1998): 513–20. http://dx.doi.org/10.1139/z97-219.
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The diving behaviour of Antarctic fur seal (Arctocephalus gazella) pups on Bird Island, South Georgia (54°S, 38°W), was examined during February-April 1996 using capillary-tube depth gauges (CDGs) and time-depth recorders (TDRs). CDGs were deployed on 6 female and 10 male pups aged 65-101 days. Depths measured by CDGs were within 10% of maximum depths recorded by TDRs. Maximum dive depths averaged 13.8 m and ranged from 4.2 to 28.1 m. Body length alone accounted for 66% of the total variation in maximum dive depth. TDRs were deployed on one female and two male pups aged 89-101 days. In total, 4858 dives were recorded during 173 h at sea. The average dive depth and duration was 4.2 m and 20 s, respectively. Pups made a total of 34 trips and each spent 50% of its time at sea. Not all trips included dives; however, when diving took place trips lasted, on average, 6.8 h and contained 214 dives, most of which took place during daylight. Dives were made at a frequency of 30/h and the vertical distance dived was 124 m · h-1. The number of dives, percentage of time spent submerged, percentage of time spent diving, dive frequency, and dive rate were positively correlated with trip duration. These results show that Antarctic fur seal pups develop diving skills at an early age, and by the time they are close to being weaned they have the diving ability to exploit prey similar to those taken by adults.
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Cox, S. L., P. I. Miller, C. B. Embling, K. L. Scales, A. W. J. Bicknell, P. J. Hosegood, G. Morgan, S. N. Ingram, and S. C. Votier. "Seabird diving behaviour reveals the functional significance of shelf-sea fronts as foraging hotspots." Royal Society Open Science 3, no. 9 (September 2016): 160317. http://dx.doi.org/10.1098/rsos.160317.
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Oceanic fronts are key habitats for a diverse range of marine predators, yet how they influence fine-scale foraging behaviour is poorly understood. Here, we investigated the dive behaviour of northern gannets Morus bassanus in relation to shelf-sea fronts. We GPS (global positioning system) tracked 53 breeding birds and examined the relationship between 1901 foraging dives (from time-depth recorders) and thermal fronts (identified via Earth Observation composite front mapping) in the Celtic Sea, Northeast Atlantic. We (i) used a habitat-use availability analysis to determine whether gannets preferentially dived at fronts, and (ii) compared dive characteristics in relation to fronts to investigate the functional significance of these oceanographic features. We found that relationships between gannet dive probabilities and fronts varied by frontal metric and sex. While both sexes were more likely to dive in the presence of seasonally persistent fronts, links to more ephemeral features were less clear. Here, males were positively correlated with distance to front and cross-front gradient strength, with the reverse for females. Both sexes performed two dive strategies: shallow V-shaped plunge dives with little or no active swim phase (92% of dives) and deeper U-shaped dives with an active pursuit phase of at least 3 s (8% of dives). When foraging around fronts, gannets were half as likely to engage in U-shaped dives compared with V-shaped dives, independent of sex. Moreover, V-shaped dive durations were significantly shortened around fronts. These behavioural responses support the assertion that fronts are important foraging habitats for marine predators, and suggest a possible mechanistic link between the two in terms of dive behaviour. This research also emphasizes the importance of cross-disciplinary research when attempting to understand marine ecosystems.
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Miller, Patrick James O’Malley, Ari Daniel Shapiro, and Volker Bernt Deecke. "The diving behaviour of mammal-eating killer whales (Orcinus orca): variations with ecological not physiological factors." Canadian Journal of Zoology 88, no. 11 (November 2010): 1103–12. http://dx.doi.org/10.1139/z10-080.
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Mammal-eating killer whales ( Orcinus orca (L., 1758)) are a rare example of social predators that hunt together in groups of sexually dimorphic adults and juveniles with diverse physiological diving capacities. Day–night ecological differences should also affect diving as their prey show diel variation in activity and mammal-eating killer whales do not rely on echolocation for prey detection. Our objective was to explore the extent to which physiological aerobic capacities versus ecological factors shape the diving behaviour of this breath-hold diver. We used suction-cup-attached depth recorders (Dtags) to record 7608 dives of 11 animals in southeast Alaska. Analysis of dive sequences revealed a strong bout structure in both dive depth and duration. Day–night comparisons revealed reduced rates of deep dives, longer shallow dives, and shallower long-duration dives at night. In contrast, dive variables did not differ by age–sex class. Estimates of the aerobic dive limit (cADL) suggest that juveniles exceeded their cADL during as much as 15% of long dives, whereas adult males and females never exceeded their cADL. Mammal-eating killer whales in this area appear to employ a strategy of physiological compromise, with smaller group members diving nearer their physiological limits and large-bodied males scaling down their physiological performance.
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Werner, Rodolfo, and Claudio Campagna. "Diving behaviour of lactating southern sea lions (Otaria flavescens) in Patagonia." Canadian Journal of Zoology 73, no. 11 (November 1, 1995): 1975–82. http://dx.doi.org/10.1139/z95-232.
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The diving behaviour of six lactating female southern sea lions (Otaria flavescens) was recorded during 52.4 animal-days at sea. Information was obtained from 18 057 dives. Females spent 52.7 ± 6.2% of the time at sea diving. Median and maximum dive depths ranged from 19 to 62 and from 97 to 175 m, respectively. Dives were short, with median and maximum durations ranging from 2.1 to 3.2 and from 4.4 to 7.7 min, respectively. Dives deeper than 10 m represented 56 – 89% of total dives and involved 93 – 97% of total diving time. Mean dive depth and duration of dives greater than 10 m were 61 m and 3 min, respectively. Most of these dives (69%) had a flat-bottomed U-shaped profile, bottom time constituting about half of the dive duration. Shallow dives, with a modal depth of 2 m, were short (median duration 0.1 –0.8 min), with virtually no time spent at the bottom of the dive. During trips to sea, which ranged from less than 1 day to more than 4 days, females dove continuously. Mean dive frequency was between 11 and 19 per hour. Surface intervals were short (median 0.9–1.2 min) and there was no apparent diel variation in dive depth or frequency. The estimated aerobic dive limit of the females was exceeded on only a few dives (0.7 – 6.2%). Transit to potential foraging areas took 0.2–8.3 h.
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Mattlin, R. H., N. J. Gales, and D. P. Costa. "Seasonal dive behaviour of lactating New Zealand fur seals (Arctocephalus forsteri)." Canadian Journal of Zoology 76, no. 2 (February 1, 1998): 350–60. http://dx.doi.org/10.1139/z97-187.
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The dive behaviour of 18 female New Zealand fur seals (Arctocephalus forsteri) from Taumaka, Open Bay Islands, New Zealand (43°52'S, 168°53'E), was recorded during early (summer; December-February), mid (autumn; March-May), and late (winter; June-August) lactation. Mean dive depth, dive duration, and bottom time for dives >=6 m in depth increased from summer through winter. Variation in individual seal dive behaviour within a season accounted for approximately 11, 9, and 11% of the observed difference between seasons in dive depth, dive duration, and bottom time, respectively. Seasonal dive data (mean ± 1 SD) were as follows: summer: dive depth 30 ± 37 m, dive duration 1.4 ± 1.1 min, and bottom time 0.5 ± 0.6 min; autumn: dive depth 54 ± 47 m, dive duration 2.4 ± 1.3 min, and bottom time 1.0 ± 0.8 min; winter: dive depth 74 ± 64 m, dive duration 2.9 ± 1.5 min, and bottom time 1.2 ± 1.1 min. Maximum recorded dive depth was 274 m for a 5.67-min dive in autumn. Maximum duration was 11.17 min for a dive to 237+ m in winter. New Zealand fur seals are the deepest diving fur seal species reported thus far. The estimated theoretical aerobic dive limit was exceeded on 18.4% of dives (range of individual values 0.2-57.8%). Females (n = 12) were ashore about 1.8 days at a time during February through November, and this increased to about 4.3 days during December and January. Average time spent away from the rookery ranged from 3 to 15 days.
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Shearer, Jeanne M., Nicola J. Quick, William R. Cioffi, Robin W. Baird, Daniel L. Webster, Heather J. Foley, Zachary T. Swaim, Danielle M. Waples, Joel T. Bell, and Andrew J. Read. "Diving behaviour of Cuvier's beaked whales ( Ziphius cavirostris ) off Cape Hatteras, North Carolina." Royal Society Open Science 6, no. 2 (February 2019): 181728. http://dx.doi.org/10.1098/rsos.181728.
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Cuvier's beaked whales exhibit exceptionally long and deep foraging dives. The species is little studied due to their deep-water, offshore distribution and limited time spent at the surface. We used LIMPET satellite tags to study the diving behaviour of Cuvier's beaked whales off Cape Hatteras, North Carolina from 2014 to 2016. We deployed 11 tags, recording 3242 h of behaviour data, encompassing 5926 dives. Dive types were highly bimodal; deep dives (greater than 800 m, n = 1408) had a median depth of 1456 m and median duration of 58.9 min; shallow dives (50–800 m, n = 4518) were to median depths of 280 m with a median duration of 18.7 min. Most surface intervals were very short (median 2.2 min), but all animals occasionally performed extended surface intervals. We found no diel differences in dive depth or the percentage of time spent deep diving, but whales spent significantly more time near the surface at night. Other populations of this species exhibit similar dive patterns, but with regional differences in depth, duration and inter-dive intervals. Satellite-linked tags allow for the collection of long periods of dive records, including the occurrence of anomalous behaviours, bringing new insights into the lives of these deep divers.
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Germonpré, Peter, Paul Van der Eecken, Elke Van Renterghem, Faye-Lisa Germonpré, and Costantino Balestra. "First impressions: Use of the Azoth Systems O’Dive subclavian bubble monitor on a liveaboard dive vessel." Diving and Hyperbaric Medicine Journal 50, no. 4 (December 20, 2020): 405–12. http://dx.doi.org/10.28920/dhm50.4.405-412.
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Germonpré P, Van der Eecken P, Van Renterghem E, Germonpré F-L, Balestra C. First impressions: Use of the Azoth Systems O’Dive subclavian bubble monitor on a liveaboard dive vessel. Diving and Hyperbaric Medicine. 2020 December 20;50(4):405–412. doi: 10.28920/dhm50.4.405-412. PMID: 33325023.) Introduction: The Azoth Systems O’Dive bubble monitor is marketed at recreational and professional divers as a tool to improve personal diving decompression safety. We report the use of this tool during a 12-day dive trip aboard a liveaboard vessel. Methods: Six divers were consistently monitored according to the user manual of the O’Dive system. Data were synchronised with the Azoth server whenever possible (depending on cell phone data signal). Information regarding ease of use, diver acceptance and influence on dive behaviour were recorded. Results: In total, 157 dives were completely monitored over 11 diving days. Formal evaluations were only available after six days because of internet connection problems. Sixty-one dives resulted in the detection of bubbles, mostly in one diver, none of which produced any symptoms of decompression illness. Conclusions: The O’Dive system may contribute to increasing dive safety by making divers immediately aware of the potential consequences of certain types of diving behaviour. It was noted that bubble monitoring either reinforced divers in their safe diving habits or incited them to modify their dive planning. Whether this is a lasting effect is not known.
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Baechler, J., C. A. Beck, and W. D. Bowen. "Dive shapes reveal temporal changes in the foraging behaviour of different age and sex classes of harbour seals (Phoca vitulina)." Canadian Journal of Zoology 80, no. 9 (September 1, 2002): 1569–77. http://dx.doi.org/10.1139/z02-150.
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Classifying dives into two-dimensional shapes based on time and depth is an attempt to extract additional information about the behaviour of aquatic air-breathing predators. In some species, there is considerable circumstantial evidence that different dive shapes represent different behaviours. However, few studies have provided direct evidence of the relationship between dive shape and function. We classified over 283 000 dives of adults (31 males and 45 females) and suckling (13) and recently weaned (15) harbour seal (Phoca vitulina) pups into seven shapes using supervised discriminant function analysis. Changes in the percentage of U-shaped dives over time within adults and weaned pups were associated with changes in food intake derived from water-flux studies on subsets of the same individuals. The changes in the percentage of U-shaped dives were accompanied by roughly reciprocal changes in V-shaped dives, whereas there was little change in other dive shapes, indicating that V-shaped dives are not generally exhibited during foraging. Video of adult males (from an animal-borne video system) also showed that there was a strong but not exclusive association between foraging and U-shaped dives. Our results indicate that changes in the percentage of U-shaped dives may serve as a reasonable index of changes in foraging behaviour. However, behaviours of suckling pups and adult males during the breeding season cannot be easily inferred from dive shape alone.
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Harcourt, Robert G., Corey J. A. Bradshaw, and Lloyd S. Davis. "Summer foraging behaviour of a generalist predator, the New Zealand fur seal (Arctocephalus forsteri)." Wildlife Research 28, no. 6 (2001): 599. http://dx.doi.org/10.1071/wr01045.
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This study examined the dive behaviour of 20 lactating New Zealand fur seals (Arctocephalus forsteri) breeding at Fuchsia Gully (Ohinepuha, 45˚52S, 170˚44E), Otago Peninsula, New Zealand, over five consecutive austral summers (1993/94–1997/98). We examined annual variation in dive behaviour by classifying series of dives into dive bouts using an iterative statistical technique. We found a non-random pattern of dive bouts and bout classification was relatively insensitive to changes in the clustering parameters used. Minimum bouts consisted of at least three dives 10 m occurring within a 20-min period. Bouts were classified into three bout types (clusters) using a multi-variate clustering procedure. These clusters described bouts of: (1) long duration with many dives of medium depth (LONG); (2) short duration with few, shallow dives (SHALLOW); and (3) short duration consisting of long, deep dives and long surface intervals and bottom times (DEEP). Diving was primarily nocturnal, and bout type varied significantly with time of day. The proportion of LONG bouts was greatest at dusk and least near dawn, SHALLOW bouts predominated during the night, and DEEP bouts were of importance near dawn. Few dives occurred during the day. We detected no annual differences in individual parameters of dive behaviour due to low statistical power. We used randomisation tests to assess whether the proportion of each bout type might vary in years of differing prey consumption, but no significant differences were found. Changes in prey composition were detected in two of these years, which suggests that using the dive behaviour of generalist predators to detect changes in resource availability may be a poor option. The high degree of flexibility in foraging behaviour of the New Zealand fur seal means that, inevitably, analyses of dive behaviour will have low statistical power. Changes in foraging behaviour may only be useful to detect very large changes in resource availability. Alternatively, very large sample sizes may be able to detect more subtle changes.
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Paredes, Rosana, Ian L. Jones, Daryl J. Boness, Yann Tremblay, and Martin Renner. "Sex-specific differences in diving behaviour of two sympatric Alcini species: thick-billed murres and razorbills." Canadian Journal of Zoology 86, no. 7 (July 2008): 610–22. http://dx.doi.org/10.1139/z08-036.
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At the Gannet Islands, Labrador, sympatric thick-billed murres ( Uria lomvia (L., 1758)) and razorbills ( Alca torda L., 1758) are slightly sexually dimorphic and have similar intersexual differences in parental roles; females are the main meal providers and males are mostly involved in brooding and chick defence at the breeding site and at sea. The question is whether differences in parental roles influence the foraging behaviour patterns of males and females. Murre females foraged during twilight periods and dived shallower than males. In razorbills, although sex differences were not as clear, females also tended to dive shallower (<10 m) and more often at twilight. Males of both species foraged during daylight hours and tended to dive deeper than females. Females of both species had shorter dive bouts (i.e., duration of a series of dives) even though the number of bouts and dives per day were equal between sexes. In both species, female dives were mostly shallower W-shaped dives, likely for capturing crustaceans at twilight. In contrast, males performed mostly deeper U-shaped dives for capturing mid-water species (e.g., capelin, Mallotus villosus (Müller, 1776)). Altogether, our results show that the two sympatric auks had relatively similar intersexual segregation in feeding time, depth, and prey. Sex differences in nest attendance, driven by differences in parental roles, seem to explain these findings.
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Tremblay, Y., T. R. Cook, and Y. Cherel. "Time budget and diving behaviour of chick-rearing Crozet shags." Canadian Journal of Zoology 83, no. 7 (July 1, 2005): 971–82. http://dx.doi.org/10.1139/z05-085.
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Blue-eyed shags are known to be capable of the deepest dives in the cormorant family. Yet, the way these birds balance their energy and time budgets remains enigmatic. Using ventrally attached time–depth recorders on chick-rearing Crozet shags (Phalacrocorax melanogenis Blyth, 1860), we simultaneously described their time budget and diving behaviour. Crozet shags are diurnal, benthic foragers (mean foraging range 1.7 km) that spend 37% of the daytime at sea. While at sea, they spend 49% of their time on the water, 44% diving, and 7% flying, and consume mainly benthic nototheniid fish. Larger fish (>20 g) were caught at shallower depths during shorter trips. They made, on average, 4.4 trips/day, each including 2.5 diving periods of 14 dives. On average, Crozet shags dove to 28 m (max. 145 m) for 2 min 2 s (max. 6 min 11 s). Descent and ascent rates became less variable at a depth of 40 m, possibly owing to a change in bird relative buoyancy at that depth. Ten percent of dives exceeded the estimated behavioural aerobic dive limit (4 min) and diving depths showed a bimodal distribution at <5 and ~18 m for dives lasting ~1 min. This dive duration corresponded to dives with higher dive duration/postdive interval ratios. The Crozet shags managed their dive cycle to fully exploit their breathing capacities, thus optimizing foraging performance.
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Laidre, Kristin L., Mads Peter Heide-Jørgensen, and Rune Dietz. "Diving behaviour of narwhals (Monodon monoceros) at two coastal localities in the Canadian High Arctic." Canadian Journal of Zoology 80, no. 4 (April 1, 2002): 624–35. http://dx.doi.org/10.1139/z02-041.
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In August 1999 and 2000, four suction-cup-attached timedepth recorders (TDRs) were deployed and retrieved from narwhals (Monodon monoceros) in Tremblay Sound, Baffin Island, and Creswell Bay, Somerset Island, Nunavut, Canada. The TDRs remained on the whales for between 12 and 33 h and collected 64.5 h of dive data. Mean dive depths ranged from 20.8 m (SD = 14.8 m) to 50.8 m (SD = 43.8 m) and mean dive durations ranged from 3.4 min (SD = 1.6 min) to 4.9 min (SD = 4.5 min). There appeared to be individual differences in dive parameters both within a region and between regions. Three of the whales made short, shallow dives, while another whale made dives twice as deep and twice as long. One whale had maximum dive durations (>20 min) that exceeded predicted aerobic dive limits for narwhals. There was a strong relationship between maximum dive depth and duration for all whales (p < 0.0001). Narwhals spent between 30.3 and 52.9% of their time at depths <5 m and the range of correction factors for availability bias was 1.93.3. Satellite-linked TDRs were simultaneously deployed on the whales at both localities. Dive data collected using the two methods were compared and good agreement between the methods was obtained.
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Stephenson, R., P. J. Butler, and A. J. Woakes. "Diving behaviour and heart rate in tufted ducks (Aythya fuligula)." Journal of Experimental Biology 126, no. 1 (November 1, 1986): 341–59. http://dx.doi.org/10.1242/jeb.126.1.341.
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Diving behaviour and heart rate were monitored in tufted ducks diving under circumstances which simulated various environmental conditions such as feeding under ice in winter. When distance to food was increased on a covered outdoor pond, dive duration increased proportionately, but it was calculated that time available for feeding was reduced during the longer-distance ‘extended’ dives. There was a gradual reduction in heart rate to 77.3 +/− 13.8 beats min-1, which is significantly lower than the resting value of 121.1 +/− 14.1 beats min-1, during the course of extended dives, suggesting that the ducks could gradually switch over to a ‘classical’ oxygen-conserving response during these prolonged voluntary dives. The duration of the pre-dive preparatory period was positively correlated with dive distance. When the ducks were briefly unable to resurface during an otherwise normal feeding dive in an indoor tank, a situation which may occur if they become disoriented under ice, there was an immediate switch to a full bradycardia. Reduction in heart rate during these ‘enclosed’ dives occurred only when the ducks were apparently aware of the situation and the rate of onset of bradycardia was very similar to that previously observed during involuntary submersion of tufted ducks. Minimum heart rate was the same at 46 beats min-1 after 15 s of enclosed dives and after 30 s of involuntary submersions, despite the differences in levels of activity in the two situations.
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Boyd, I. L., and J. P. Croxall. "Diving behaviour of lactating Antarctic fur seals." Canadian Journal of Zoology 70, no. 5 (May 1, 1992): 919–28. http://dx.doi.org/10.1139/z92-131.
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The diving behaviour of 11 lactating female Antarctic fur seals (Arctocephalus gazella) was recorded for a total of 254 animal-days at sea. Median and maximum dive depths for individuals varied from 8 to 19 m and from 82 to 181 m, respectively, and median and maximum dive durations from 0.75 to 1.17 min and from 2.8–10.0 min, respectively. Theoretical aerobic diving limits were exceeded on < 1% of dives. Dives were mainly V-shaped. Sixty percent of dives were to less than 20 m depth, and these dives were distinguished from deep dives (> 20 m) by having slower rates of descent and ascent and by being confined to the mixed layer at the ocean surface, as judged by records of sea temperature obtained concurrently with records of depth. Dives were grouped into bouts, defined by inflexion points observed in the cumulative probability distribution of surface interval after probit transformation. Bouts (defined by preceding and succeeding surface intervals lasting 13–24 min) occurred within a diel pattern of diving activity, with 74–85% of dives occurring at night. The pattern of diving, in terms of division into bouts, showed greater differences between individual seals than did dive depth and duration. Dives tended to be shorter and shallower later in lactation. Most variation in diving behaviour between individuals was in terms of the proportion of available time spent foraging, bout frequency, and bout duration. The foraging strategy in the Antarctic fur seal is geared to exploiting prey within the surface mixed layer.
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Pratt, Kirstin L., Hamish A. Campbell, Matthew E. Watts, and Craig E. Franklin. "Environmental and ecological factors influencing dive behaviour in the freshwater snake Acrochordus arafurae: a field-based telemetric study." Marine and Freshwater Research 61, no. 5 (2010): 560. http://dx.doi.org/10.1071/mf09194.
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Acrochordus arafurae is a fully aquatic, freshwater snake distributed throughout tropical Australia. To better understand the ecological factors influencing their behavioural repertoire, we remotely monitored field body temperature and diving in snakes free-ranging within their natural habitat. The body temperatures of A. arafurae exhibited a diel profile similar to the surface water temperature, and reflected the high proportion of time that snakes remained <1 m from the surface. The average dive depth was 0.62 m and 95% of dives had an average depth of 1 m or less. Snakes occasionally ventured into deeper water (>6 m), and there was a positive correlation between dive depth and duration. Average dive duration was 6.6 min and 84% of dives were terminated within 10 min, but all snakes performed dives >50 min during the 14-day observation period. We hypothesise that the dive behaviour was strongly influenced by predation pressure. The snakes partake in short dives within the aerobic dive limit to reduce the amount of time they need to spend at the surface on each breathing bout, reducing the risk of predation by birds. Predation is a strong selective force that might alter the time allocation during dive cycles.
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Hull, Cindy L. "Comparative diving behaviour and segregation of the marine habitat by breeding Royal Penguins, Eudyptes schlegeli, and eastern Rockhopper Penguins, Eudyptes chrysocome filholi, at Macquarie Island." Canadian Journal of Zoology 78, no. 3 (April 1, 2000): 333–45. http://dx.doi.org/10.1139/z99-192.
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Comparative use of the water column by Royal Penguins, Eudyptes schlegeli, and eastern Rockhopper Penguins, Eudyptes chrysocome filholi, was examined by comparing their diving behaviour at Macquarie Island during the 1993-1994, 1994-1995, and 1995-1996 breeding seasons. Fifty-eight deployments of time-depth recorders measured depth and duration of dives, time spent submerged, bottom time, occurrence of wiggles, and descent and ascent rates. Both species dived predominantly during daylight hours (4:00-21:00 local time), with shallower dives around midday. Royal and Rockhopper penguins spent 38.9 ± 8.9 and 36.6 ± 9.3% of a 24-h period under water, respectively, but Rockhopper Penguins performed more dives (14.8 ± 9.4/h) of shorter duration (1.2 ± 0.7 min) than did Royal Penguins (11.1 ± 6.9 dives/h; 1.7 ± 0.6 min). Although both could dive to over 100 m, they rarely did so, with Royal and Rockhopper penguins making 79 ± 0.13 and 91 ± 0.08% of their dives to depths of less than 60 m, respectively. Although the difference was not significant, Royal Penguins dived in deeper water (32.9 ± 25.6 m) than did Rockhopper Penguins (27.3 ± 20.3 m). However, Royal Penguins performed wiggles (assumed foraging activity) in water significantly deeper (47.7 ± 24.3 m) than did Rockhopper Penguins (41.3 ± 19.0 m). Royal Penguins also performed more dives with wiggles than Rockhopper Penguins, suggesting differences in foraging technique. The amount of time both spent at the bottom of dives increased across the breeding season from incubation to chick rearing. As dive durations and ascent and descent rates did not change during this time, dive angles must have changed. There were no interannual differences in the diving behaviour of Royal Penguins, but Rockhopper Penguins exhibited differences in dive depths and durations and in the amount of bottom time. Royal Penguins, unlike Rockhopper Penguins, performed fewer dives on the first day of foraging trips, indicating more travelling and less foraging, which reflects differences in foraging zones between the two. The estimated foraging efficiency of Rockhopper Penguins was lower than that of Royal Penguins, probably making them more vulnerable to changes in prey availability and abundance. The two species exhibited some differences in diving behaviour but overlapped substantially in their use of the water column. Therefore, for minimising competition for resources, segregation in this aspect of their habitat is far less important than differences in diet and foraging zone.
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Warren, VE, PJO Miller, and PL Tyack. "Short-term responses of sperm whales Physeter macrocephalus to the attachment of suction cup tags." Marine Ecology Progress Series 645 (July 9, 2020): 219–34. http://dx.doi.org/10.3354/meps13344.
Full textAbstract:
Animal-mounted data logging devices are used to study the behaviour, physiology, and ecology of free-ranging marine mammals, as well as their reactions to controlled exposures. It is important to consider whether collected data are representative of natural behaviour or biased by responses to tagging. In species with stereotypical diving behaviour, tagging responses can be quantified by identifying anomalous dives. Data from 36 suction cup tag deployments on sperm whales Physeter macrocephalus from 4 locations were analysed to consider whether tagging effects were evident within 5 dive parameters: maximum dive depth, dive duration, descent speed, depth difference between start of clicking and first prey capture attempt, and buzz rate. Linear mixed models were generated for each response parameter and covariates for dive index were added to assess whether model fit improved when the order of dives was taken into account. Time-decaying tagging effects were noted in maximum dive depth (first dives were 25% shallower than average) and buzz rate (first dives contained 34% fewer buzzes per minute than average). In the Azores, the first 3 dives subsequent to tag attachment featured faster descent speeds than average. The whales were likely responding to the cumulative ‘dose’ of research activity at the surface: multiple boat approaches, tag placement, and general disturbance. Disturbance should be minimised during tagging, and the extent and duration of responses should be quantified. Modelling of quantified tagging responses could enable correction of these responses in tag data.
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Krafft, Bjørn A., Christian Lydersen, Kit M. Kovacs, Ian Gjertz, and Tore Haug. "Diving behaviour of lactating bearded seals (Erignathus barbatus) in the Svalbard area." Canadian Journal of Zoology 78, no. 8 (August 1, 2000): 1408–18. http://dx.doi.org/10.1139/z00-088.
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This study documents activity patterns and diving behaviour of four bearded seal (Erignathus barbatus) mothers during the lactation period. The females spent 8 ± 3% (mean ± SD) of their time hauled out on the ice and 92 ± 3% in the water. Approximately half of their time was spent diving. During the study 15 077 dives were recorded. The duration of dives was 2.0 ± 2.3 min and diving depth was 17.2 ± 22.5 m (maximum 18.7 min and 288 m, respectively). Haulout periods occurred 3 ± 2 times per day (duration = 44.0 ± 98.1 min). The overall distance swum per day was 48.1 ± 23.2 km. Three dive types were differentiated using a combination of hierarchical and k-means clustering, one V-shaped grouping and two U-shaped groupings. The most common dive type was U1; these dives were the deepest and longest type (depth = 28 ± 32 m, duration = 185 ± 146 s), and bottom time occupied a significant fraction of the total dive time (120 ± 120 s). These dives are likely foraging dives. Lactation is energetically demanding for bearded seals, and females do forage while they have dependent pups.
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Ries, Edith H., Petra Paffen, Ilona M. Traut, and Paul W. Goedhart. "Diving patterns of harbour seals (Phoca vitulina) in the Wadden Sea, the Netherlands and Germany, as indicated by VHF telemetry." Canadian Journal of Zoology 75, no. 12 (December 1, 1997): 2063–68. http://dx.doi.org/10.1139/z97-840.
Full textAbstract:
The diving behaviour of 25 harbour seals, Phoca vitulina (14 females and 11 males), of various body lengths was monitored by means of VHF telemetry at different locations in the Wadden Sea during late autumn in 1991 and 1992. Median dive durations for individual seals ranged from 46 s to 2.9 min. The maximum dive recorded was 31 min, performed by an adult male, which represents the longest dive reported for harbour seals. Dive endurance increased significantly in relation to body length. Female harbour seals tended to perform fewer short dives and had a more narrow distribution of dive times. We detected no diurnal differences in dive behaviour and only the ambient air temperature was found to influence the duration of surface periods, in that surface intervals tended to be shorter when temperatures were below 9 °C. The overall mean percentage of dive time was 85%, with individuals varying from 76 to 93%, and was in general higher in females.
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Hindell, MA, DJ Slip, and HR Burton. "The Diving Behavior of Adult Male and Female Southern Elephant Seals, Mirounga-Leonina (Pinnipedia, Phocidae)." Australian Journal of Zoology 39, no. 5 (1991): 595. http://dx.doi.org/10.1071/zo9910595.
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Over 50 000 individual dive records collected by time-depth recorders were analysed with respect to sex of the seal, time of year and the approximate geographic location of the dive. Six distinct dive types were described on the basis of parameters such as the amount of time spent at the maximum depth of the dive, the rate of ascent and descent, and the general form of the dive profile. These dive types were 'rest' dives, 'travel' dives, 'surface' dives, 'general non-foraging' dives, 'pelagic foraging' dives and 'benthic foraging' dives. The seals spent 90% of their time at sea submerged. Less than 2% of the time was spent on the surface in intervals of more than 10 min. A further 20-30% of the time was spent on the various non-foraging types of dives. Most females performed only 'pelagic foraging' dives, while males performed both 'pelagic' and 'benthic foraging' dives. All the 'benthic foraging' dives occurred in Area 3 (defined by water-temperature data as lying over the Antarctic Continental Shelf) and were 400-500 m deep. 'Pelagic foraging' dives occurred in all three foraging areas and ranged in depth from 200 to 1100 m. These types of dives also exhibited marked diurnal variations in depth, unlike 'benthic foraging' dives. The seals spent 10-20 min at the bottom of each 'foraging' dive, where they generally displayed a series of small changes in depth (wiggles). The size of these 'wiggles' tended to be larger in 'pelagic foraging' dives than in 'benthic foraging' dives. The diving behaviour of southern elephant seals is related to the possible prey they exploit in the Southern Ocean.
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Elliott, Kyle H., Gail K. Davoren, and Anthony J. Gaston. "The influence of buoyancy and drag on the dive behaviour of an Arctic seabird, the Thick-billed Murre." Canadian Journal of Zoology 85, no. 3 (February 2007): 352–61. http://dx.doi.org/10.1139/z07-012.
Full textAbstract:
We used time–depth recorders to investigate the behaviour of free-ranging Thick-billed Murres ( Uria lomvia L., 1758) after attaching positively (n = 9), negatively (n = 10), or neutrally (n = 9) buoyant handicaps and increasing cross-sectional area by 3% (2.8 cm2; n = 8) or 6% (5.6 cm2; n = 6). When buoyancy was altered or drag increased, murres reduced dive depth and duration, suggesting that murres do not manipulate dive depth to obtain neutral buoyancy during the bottom phase. Ascent rate increased as the bird surfaced and mean ascent rate increased for deeper dives, presumably reflecting steeper dive angles and greater buoyancy during deep dives. For short dives (<150 s), preceding surface pauses were better correlated with dive depth and duration than succeeding surface pauses (surface pauses were “anticipatory”), suggesting that murres control inhalation rates based on anticipated dive depth and duration. Murres reduced ascent rate near the surface, possibly to reduce the risk of decompression sickness. Neutrally buoyant recorders attached to the legs had no effect on chick feeding frequencies or adult mass loss, suggesting that this attachment method may have the least effect on the foraging behaviour of alcids.
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Luna, Beatriz, Carlos Valle Pérez, and Jose Luis Sánchez-Lizaso. "Benthic impacts of recreational divers in a Mediterranean Marine Protected Area." ICES Journal of Marine Science 66, no. 3 (February 17, 2009): 517–23. http://dx.doi.org/10.1093/icesjms/fsp020.
Full textAbstract:
Abstract Luna, B., Valle Pérez, C., and Sánchez-Lizaso, J. L. 2009. Benthic impacts of recreational divers in a Mediterranean Marine Protected Area. – ICES Journal of Marine Science, 66: 517–523. The features of many Marine Protected Areas (MPAs) have increased scuba diving tourism in these areas. Impacts caused by recreational scuba activity vary widely among different divers with differing underwater behaviour. We studied diver underwater behaviour, the effects on the natural environment, and the characteristics that may influence diver behaviour. In all, 181 recreational divers were followed, and contacts and the effects produced were recorded. Information on diver profile and dive features was recorded. Field sampling revealed that 175 of the divers observed (96.7%) made at least one contact with the seabed, with a mean contact of 41.20 ± 3.55 (mean ± s.e.) per diver per 10 min. Flapping was the most frequent type of contact, and the main damage by this action was to raise sediment. Contact with the seabed was greater for males than for females, inexperienced divers than for experienced divers, camera or lantern (dive light) users than for non-users, and divers unaccompanied by a dive leader or who had not been briefed about avoiding seabed contact before undertaking a dive than for accompanied or briefed divers. A greater understanding of the causes of harmful behaviour may be useful for stricter management, reducing diving damage and assuring the sustainability of this activity in MPAs.
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Elliott, Nicole M., Russel D. Andrews, and David R. Jones. "Pharmacological blockade of the dive response: effects on heart rate and diving behaviour in the harbour seal (Phoca vitulina)." Journal of Experimental Biology 205, no. 23 (December 1, 2002): 3757–65. http://dx.doi.org/10.1242/jeb.205.23.3757.
Full textAbstract:
SUMMARYWhile diving, harbour seals (Phoca vitulina) manage their oxygen stores through cardiovascular adjustments, including bradycardia, a concurrent reduction in cardiac output, and peripheral vasoconstriction. At the surface,post-dive tachycardia facilitates rapid reloading of oxygen stores. Although harbour seals can tolerate >20 min of submergence, the majority of their natural dives are only 2-6 min and are usually followed by surface intervals that are <1 min, so they spend approximately 80% of their time submerged. Given that harbour seals meet their ecological needs through repetitive short aerobic dives, we were interested in the functional role, if any, of the dive response during these short dives. During voluntary diving in an 11 m deep tank, the cardiovascular responses to submergence of five harbour seals were manipulated using specific pharmacological antagonists, and the effects on diving behaviour were observed. Effects of pharmacological blockade on heart rate were also examined to assess the autonomic control of heart rate during voluntary diving. Heart rate was recorded using subcutaneous electrodes and data loggers, while diving behaviour was monitored using a video camera. The muscarinic blocker methoctramine blocked diving bradycardia, theα-adrenergic blocker prazosin blocked diving vasoconstriction, and theβ-adrenergic blocker metoprolol blocked post-dive tachycardia. Heart-rate analysis indicated that diving bradycardia is primarily modulated by the vagus, while post-dive tachycardia results from parasympathetic withdrawal as well as increased sympathetic stimulation of the heart. None of the pharmacological blockers had any effect on average dive or surface interval duration. Seals maintained a high percentage of time spent diving in all treatments. Thus, harbour seals do not appear to need the dive response during short dives in order to maintain an efficient dive strategy.
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Kirkman, S. P., D. P. Costa, A. L. Harrison, P. G. H. Kotze, W. H. Oosthuizen, M. Weise, J. A. Botha, and J. P. Y. Arnould. "Dive behaviour and foraging effort of female Cape fur seals Arctocephalus pusillus pusillus." Royal Society Open Science 6, no. 10 (October 2019): 191369. http://dx.doi.org/10.1098/rsos.191369.
Full textAbstract:
While marine top predators can play a critical role in ecosystem structure and dynamics through their effects on prey populations, how the predators function in this role is often not well understood. In the Benguela region of southern Africa, the Cape fur seal ( Arctocephalus pusillus pusillus ) population constitutes the largest marine top predator biomass, but little is known of its foraging ecology other than its diet and some preliminary dive records. Dive information was obtained from 32 adult females instrumented with dive recorders at the Kleinsee colony (29°34.17′ S, 16°59.80′ E) in South Africa during 2006–2008. Most dives were in the depth range of epipelagic prey species (less than 50 m deep) and at night, reflecting the reliance of Cape fur seals on small, vertically migrating, schooling prey. However, most females also performed benthic dives, and benthic diving was prevalent in some individuals. Benthic diving was significantly associated with the frequency with which females exceeded their aerobic dive limit. The greater putative costs of benthic diving highlight the potential detrimental effects to Cape fur seals of well-documented changes in the availability of epipelagic prey species in the Benguela.
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Baylis, A. M. M., B. Page, K. Peters, R. McIntosh, J. Mckenzie, and S. Goldsworthy. "The ontogeny of diving behaviour in New Zealand fur seal pups (Arctocephalus forsteri)." Canadian Journal of Zoology 83, no. 9 (September 1, 2005): 1149–61. http://dx.doi.org/10.1139/z05-097.
Full textAbstract:
This study investigated the development of diving in 21 New Zealand fur seal pups, Arctocephalus forsteri (Lesson, 1828), prior to weaning at Cape Gantheaume, Kangaroo Island. Diving behaviour was examined using time–depth recorders, which were deployed during two time periods, 5 months prior to weaning (n = 6) and 2 months prior to weaning (n = 15). Scats were also examined to assess whether fur seal pups foraged prior to weaning. The maximum dive depth attained was 44 m, while the maximum dive duration was 3.3 min. Immediately prior to weaning, fur seal pups spent a greater proportion of their time diving at night, and concomitantly several measures of diving performance also increased. In general, pups dived successively deeper (6–44 m between June and September), and the average number of dives per day, dive frequency, and vertical distance travelled increased. Prey remains were present in approximately 30% of scats and indicated that some pups were foraging as early as June (5–6 months of age, approximately 4–5 months prior to weaning). Of the scats that contained prey remains, fish (South American pilchard, Sardinops sagax (Jenyns, 1842); Australian anchovy, Engraulis australis (White, 1790); and redbait, Emmelichthys nitidus Richardson, 1845) accounted for 43% of the prey items found, crustaceans accounted for 36%, and cephalopods (Gould's squid, Nototodarus gouldi (McCoy, 1888)) accounted for 20%.
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Huin, N., and P. A. Prince. "Diving behaviour of the grey-headed albatross." Antarctic Science 9, no. 3 (September 1997): 243–49. http://dx.doi.org/10.1017/s0954102097000321.
Full textAbstract:
Foraging grey-headed albatrosses spent 86% of the night but only 20% of the day sitting on the sea; most diving activity occurred during daylight. During the broad-guard period of nesting, peaks of diving activity occurred at midday and dusk. During the subsequent chick-rearing period, however, diving was mainly at dawn and dusk. Of 485 dives measured, the depth averaged 0.74 m, with maximum depth at 6.5 m. On average grey-headed albatrosses dived 24 times during a five day foraging trip. Dive depths increased towards midday, probably as a function of the birds' visual acuity rather than due to vertical migration of their prey. We estimate that grey-headed albatrosses may obtain 30–45% of their daily food requirements by diving.
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Bowen, W. D., D. J. Boness, and S. J. Iverson. "Diving behaviour of lactating harbour seals and their pups during maternal foraging trips." Canadian Journal of Zoology 77, no. 6 (October 10, 1999): 978–88. http://dx.doi.org/10.1139/z99-065.
Full textAbstract:
Female harbour seals (Phoca vitulina) undertake foraging trips during mid to late lactation. We show that they are accompanied by their pup during many of these foraging trips. Time-depth recorder data were obtained from 20 lactating females and 14 of their pups in 1995 and 1996 at Sable Island, Nova Scotia. Overall, females spent 55.4 ± 4.68% (mean ± SE) of their time at sea compared with 39.8 ± 2.29% for pups. Like those of their mothers, pups' dives occurred in clusters or bouts: 71.4 ± 4.4 dives, 2.5 ± 0.15 h in duration. Bouts of diving by females and pups began 0-3 days post partum. Mean dive duration of pups increased from about 1 to 1.5 min over the course of lactation, but was still shorter than that of adult females (1.5-2.25 min). Both females and pups appeared to dive within their theoretical aerobic dive limits (TADL) of 8.9 and 2.6-3.1 min, respectively. Up to 3.6% of dives by some pups may have exceeded their TADL. Pups appeared to compensate for their lesser diving ability by making more and shorter dives per bout than females, particularly during early lactation.
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Westgate, Andrew J., Andrew J. Head, Per Berggren, Heather N. Koopman, and David E. Gaskin. "Diving behaviour of harbour porpoises, Phocoena phocoena." Canadian Journal of Fisheries and Aquatic Sciences 52, no. 5 (May 1, 1995): 1064–73. http://dx.doi.org/10.1139/f95-104.
Full textAbstract:
The diving behaviour of seven free-ranging harbour porpoises (Phocoena phocoena) was examined using time–depth recorders. In total, 8167 individual dives were recorded over 254 h. The longest period of data collection from an individual was 106.1 h. Mean dive depths and durations ranged from 14 ± 16 to 41 ± 32 m, and from 44 ± 37 to 103 ± 67 s, respectively. The maximum recorded dive depth and duration was 226 m and 321 s. This performance may not represent the maximum capacity of harbour porpoises but rather the maximum depth of the study area. Individual dives had similar rates of descent and ascent, which ranged from 1.1 ± 0.6 to 2.3 ± 1.4 m/s, and from 0.9 ± 0.6 to 2.1 ± 1.4 m/s, respectively. Two porpoises with monitoring periods >2 days demonstrated a diel pattern in their diving, making fewer, but deeper dives at night. Comparison of the diving behaviour of harbour porpoises with data on the depth of 140 porpoises entanglements in groundfish gill nets in the Bay of Fundy showed these seven porpoises made between 22 and 70% of dives to depths (range 20–130 m) where the majority of entanglements were reported.
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Clowater, James S., and Alan E. Burger. "The diving behaviour of Pigeon Guillemots (Cepphus columba) off southern Vancouver Island." Canadian Journal of Zoology 72, no. 5 (May 1, 1994): 863–72. http://dx.doi.org/10.1139/z94-117.
Full textAbstract:
The foraging behaviour of Pigeon Guillemots (Cepphus columba) was observed off southern Vancouver Island, British Columbia. Diving bouts comprised 1–24 dives. Birds returned to the surface with prey in 22 of 248 (9%) dives, and mean handling time for prey was 34.7 s. Dives averaged 87 s (ranging from 37 s in water 14 m deep to 144 s at 34 m) and the mean postdive pause lasted 98 s (range 24–232 s). Birds foraged in water depths from 6 to 45 m. The duration of both dives and pauses increased with water depth. Our model of Pigeon Guillemot diving behaviour predicts foraging time at the bottom to be maximized during dives to depths of 22–24 m, while foraging efficiency, (foraging time)/(dive + recovery time), is maximized at 10 m. Calculated work to resist buoyancy and drag during descent and foraging phases of the dive cycle suggest that energetic savings from reduced buoyancy at depth may not explain how birds increase dive duration with increasing depth. Pigeon Guillemots appear to maximize time spent in the foraging patch. In 82% of transects, the most frequently chosen foraging depth was 15–20 m (mode). Model predictions were supported by observations that 43.6% of Pigeon Guillemots preferred water depths of 15–20 m, while 19% preferred water depths of 10–15 m.
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Harcourt, Robert G., Andrew M. Schulman, Lloyd S. Davis, and Fritz Trillmich. "Summer foraging by lactating female New Zealand fur seals (Arctocephalus forsteri) off Otago Peninsula, New Zealand." Canadian Journal of Zoology 73, no. 4 (April 1, 1995): 678–90. http://dx.doi.org/10.1139/z95-080.
Full textAbstract:
The behaviour of female New Zealand fur seals (Arctocephalus forsteri) at sea and on land at the rookery of Fuchsia Gully, Otago Peninsula, New Zealand (45 °52′S, 170 °44′E), was examined during the early stages of lactation in the 1993 – 1994 breeding season. The attendance patterns of 19 females were investigated using daily observation at the rookery. Trips to sea to forage ranged from 3.4 h up to 8 days (mean 3.26 ± 1.1 days), and attendance periods at the rookery ranged from 1 to 13 days (mean 3.09 ± 1.63 days). At sea, the behaviour of four females was examined by deploying time–depth recorders. Females showed a nocturnal pattern of diving, 88.8–97.3% of dives being made during the hours of darkness. For all females and each night of foraging, the deepest dives were completed around dawn and dusk. The deepest dive recorded was 163 m and all females dove over 100 m deep on at least one dive. The overall median dive depth was considerably less than this, as around 24:00–03:00, females undertook many shallow dives, and during this time the median dive depth ranged from 5 to 10 m for the four females. Dives occurred in bouts, but bout duration varied significantly with time of day. Bouts were short during the day and longer at night, 55% of night bouts lasting throughout the night. Maximum dive durations ranged from 3.17 to 6.17 min and mean dive durations from 0.67 to 1.18 min for individual females. Dive depth was significantly related to dive duration for all four females. Two of the females also carried satellite transmitters, and at sea location was determined on three separate nights of foraging. Females were found to be foraging up to 78 km from the rookery, but always over the continental shelf (in water shallower than the 200 m depth contour).
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Wilson, Kenady, Charles Littnan, Patrick Halpin, and Andrew Read. "Integrating multiple technologies to understand the foraging behaviour of Hawaiian monk seals." Royal Society Open Science 4, no. 3 (March 2017): 160703. http://dx.doi.org/10.1098/rsos.160703.
Full textAbstract:
The objective of this research was to investigate and describe the foraging behaviour of monk seals in the main Hawaiian Islands. Specifically, our goal was to identify a metric to classify foraging behaviour from telemetry instruments. We deployed accelerometers, seal-mounted cameras and GPS tags on six monk seals during 2012–2014 on the islands of Molokai, Kauai and Oahu. We used pitch, calculated from the accelerometer, to identify search events and thus classify foraging dives. A search event and consequent ‘foraging dive’ occurred when the pitch was greater than or equal to 70° at a depth less than or equal to −3 m. By integrating data from the accelerometers with video and GPS, we were able to ground-truth this classification method and identify environmental variables associated with each foraging dive. We used Bayesian logistic regression to identify the variables that influenced search events. Dive depth, body motion (mean overall dynamic body acceleration during the dive) and proximity to the sea floor were the best predictors of search events for these seals. Search events typically occurred on long, deep dives, with more time spent at the bottom (more than 50% bottom time). We can now identify where monk seals are foraging in the main Hawaiian Islands (MHI) and what covariates influence foraging behaviour in this region. This increased understanding will inform management strategies and supplement outreach and recovery efforts.
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Fortune, SME, SH Ferguson, AW Trites, B. LeBlanc, V. LeMay, JM Hudson, and MF Baumgartner. "Seasonal diving and foraging behaviour of Eastern Canada-West Greenland bowhead whales." Marine Ecology Progress Series 643 (June 11, 2020): 197–217. http://dx.doi.org/10.3354/meps13356.
Full textAbstract:
Climate change may affect the foraging success of bowhead whales Balaena mysticetus by altering the diversity and abundance of zooplankton species available as food. However, assessing climate-induced impacts first requires documenting feeding conditions under current environmental conditions. We collected seasonal movement and dive-behaviour data from 25 Eastern Canada-West Greenland bowheads instrumented with time-depth telemetry tags and used state-space models to examine whale movements and dive behaviours. Zooplankton samples were also collected in Cumberland Sound (CS) to determine species composition and biomass. We found that CS was used seasonally by 14 of the 25 tagged whales. Area-restricted movement was the dominant behaviour in CS, suggesting that the tagged whales allocated considerable time to feeding. Prey sampling data suggested that bowheads were exploiting energy-rich Arctic copepods such as Calanus glacialis and C. hyperboreus during summer. Dive behaviour changed seasonally in CS. Most notably, probable feeding dives were substantially shallower during spring and summer compared to fall and winter. These seasonal changes in dive depths likely reflect changes in the vertical distribution of calanoid copepods, which are known to suspend development and overwinter at depth during fall and winter when availability of their phytoplankton prey is presumed to be lower. Overall, CS appears to be an important year-round foraging habitat for bowheads, but is particularly important during the late summer and fall. Whether CS will remain a reliable feeding area for bowhead whales under climate change is not yet known.
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Mitani, Yoko, Russel D. Andrews, Katsufumi Sato, Akiko Kato, Yasuhiko Naito, and Daniel P. Costa. "Three-dimensional resting behaviour of northern elephant seals: drifting like a falling leaf." Biology Letters 6, no. 2 (October 28, 2009): 163–66. http://dx.doi.org/10.1098/rsbl.2009.0719.
Full textAbstract:
During their long migrations through the Pacific, northern elephant seals, Mirounga angustirostris , never haul out on land and they rarely spend more than a few minutes at a time at the surface. They are almost constantly making repetitive, deep dives, raising the question of when do they rest? One type of dive, the drift dive, characterized by a time-depth profile with a phase of lower than average descent speed is believed to be a resting dive. To examine the behaviour of seals during drift dives, we measured body position and three-dimensional diving paths of six juvenile seals. We found that seals rolled over and sank on their backs during the drift phase, wobbling periodically so that they resembled a falling leaf. This enabled seals to drastically slow their descent rate, possibly so that negatively buoyant seals can rest without ending up in the abyss. This reduces the work required to return to the surface to breath, and allows them time to rest, process food or possibly sleep during the descent phase of these dives where they are probably less susceptible to predation.
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Bennett, K. A., B. J. McConnell, and M. A. Fedak. "Diurnal and seasonal variations in the duration and depth of the longest dives in southern elephant seals (Mirounga leonina): possible physiological and behavioural constraints." Journal of Experimental Biology 204, no. 4 (February 15, 2001): 649–62. http://dx.doi.org/10.1242/jeb.204.4.649.
Full textAbstract:
This study seeks to understand how the physiological constraints of diving may change on a daily and seasonal basis. Dive data were obtained from southern elephant seals (Mirounga leonina) from South Georgia using satellite relay data loggers. We analysed the longest (95th percentile) dive durations as proxies for physiological dive limits. A strong, significant relationship existed between the duration of these dives and the time of day and week of year in which they were performed. The depth of the deepest dives also showed a significant, but far less consistent, relationship with local time of day and season. Changes in the duration of the longest dives occurred irrespective of their depth. Dives were longest in the morning (04:00-12:00 h) and shortest in the evening (16:00-00:00 h). The size of the fluctuation varied among animals from 4.0 to 20.0 min. The daily pattern in dive depth was phase-shifted in relation to the diurnal rhythm in dive duration. Dives were deeper at midday and shallower around midnight. Greater daily changes in duration occurred in seals feeding in the open ocean than in those foraging on the continental shelf. The seasonal peak in the duration of the longest dives coincided with austral midwinter. The size of the increase in dive duration from autumn/spring to winter ranged from 11.5 to 30.0 min. Changes in depth of the longest dives were not consistently associated with particular times of year. The substantial diurnal and seasonal fluctuations in maximum dive duration may be a result of changes in the physiological capacity to remain submerged, in addition to temporal changes in the ecological constraints on dive behaviour. We speculate about the role of melatonin as a hormonal mediator of diving capability.
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Beck, C. A., W. D. Bowen, and S. J. Iverson. "Seasonal changes in buoyancy and diving behaviour of adult grey seals." Journal of Experimental Biology 203, no. 15 (August 1, 2000): 2323–30. http://dx.doi.org/10.1242/jeb.203.15.2323.
Full textAbstract:
Phocid seals go through dramatic seasonal changes in body mass and composition as a result of the spatial and temporal separation of foraging, reproduction and moulting. These changes in body fat content and body mass result in seasonal changes in buoyancy, which in turn may influence diving behaviour. We examined the longitudinal changes in buoyancy and diving behaviour of 14 adult grey seals (Halichoerus grypus) during two periods that represent maximal contrast in body mass and composition. During both the post-moulting (PM) and pre-breeding (PB) periods, grey seals were negatively buoyant. However, buoyancy increased by 47.9 % between the PM and PB periods. Descent rate was significantly faster during the PM period (1.0+/−0.07 m s(−1)) than during the PB period (0.7+/−0.06 m s(−1)), suggesting that seals were aided by negative buoyancy during the downward portion of dives. Ascent rate was also significantly faster during the PM period (0.8+/−0.06 m s(−1)) than during the PB period (0.6+/−0.05 m s(−1)), contradicting the prediction that more buoyant animals should ascend faster. The effects of drag could not account for this discrepancy. Dive depth and surface interval between dives did not differ significantly between the two periods. Similarly, the distribution of dive shapes used by individuals did not differ between the two periods. However, dive duration was significantly longer during the PB period than during the PM period (5.5+/−0.25 min compared with 4.4+/−0.24 min, respectively) as was time spent at the bottom of the dive (3.1+/−0.22 min compared with 2.5+/−0.15 min, respectively).
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BEVAN, R. M., E. KEIJER, and P. J. BUTLER. "A Method for Controlling the Feeding Behaviour of Aquatic Birds: Heart Rate and Oxygen Consumption during Dives of Different Duration." Journal of Experimental Biology 162, no. 1 (January 1, 1992): 91–106. http://dx.doi.org/10.1242/jeb.162.1.91.
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Tufted ducks, Aythya fuligula, were trained to dive for different durations in shallow tanks using a computer-controlled system of lights. The birds were rewarded with food for a correct response, i.e. performing a dive of the required duration. When dive durations (td) elicited by the system were longer than the durations required, the extra time was spent feeding. As the required duration was increased, so the time spent feeding decreased, and the required and actual dive durations approached equality. This occurred at approximately 40 s, although some birds did perform dives of up to 45 s. Heart rate (fH) and oxygen consumption (VOO2) were measured from the birds during voluntary diving using an implanted radiotransmitter and respirometry, respectively. The oxygen consumption during submersion decreased with increasing mean (td, and may reflect a reduction in aerobic metabolism as a dive progressed, possibly as a result of reduced buoyancy or through a gradual switch to anaerobic metabolism. Over a total dive cycle (the time spent submerged plus that spent on the surface between dives), fH proved to be a very good predictor of VOO2, with an error of only +7.9 %. This compares favourably with other methods used to determine the energy expenditures of animals, e.g. the doubly labelled water and the time energy budget methods, and shows that the electronic acquisition of fH could be a useful tool for estimating the energy usage of free-living, aquatic birds.
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Bengtson, John L., Donald A. Croll, and Michael E. Goebel. "Diving behaviour of chinstrap penguins at Seal Island." Antarctic Science 5, no. 1 (March 1993): 9–15. http://dx.doi.org/10.1017/s0954102093000033.
Full textAbstract:
Diving behaviour of chinstrap penguins (Pygoscelis antarctica) was studied in four adults brooding chicks on Seal Island, South Shetland Islands, Antarctica. During foraging trips to sea, chinstrap penguins made shallow, short duration dives almost continuously, for the most part within 50 m of the surface. Diving effort was concentrated during the daylight hours (10h00-15h00), although a second peak in effort was seen around midnight (22h00-02h00). These peaks were possibly due to the constraints of visual location of prey, chick provisioning, or the need to take advantage of diurnal changes in krill swarm densities or behaviour. It was estimated that most effort was concentrated 3-20 km from shore. Dive depth and duration averaged 31.0 m (± 26.3m) and 72s(± 36s), respectively. Maximum dive depth and duration were 121m and 180s, respectively.
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Papastavrou, Vassili, Sean C. Smith, and Hal Whitehead. "Diving behaviour of the sperm whale, Physeter macrocephalus, off the Galapagos Islands." Canadian Journal of Zoology 67, no. 4 (April 1, 1989): 839–46. http://dx.doi.org/10.1139/z89-124.
Full textAbstract:
Sperm whales, Physeter macrocephalus, were tracked by means of a recording depth sounder in the waters off the Galapagos Islands. At depths of less than 300 m the whales generally dived nearly vertically at 60–100 m/min. At greater depths their descents were usually slower. Between February and April 1985, they dived to about 420 m, which is approximately the depth of the oxygen minimum. In 1987, a year of warmer water temperatures, they usually dived about 70 m shallower. There was no apparent diurnal variation in dive depths. None of the whales tracked dived to the ocean floor. Whales dived for about 40 min, followed by 10 min at the surface. Sperm whales usually started to make regular clicks when 150–300 m deep. Young calves appeared not to make prolonged deep dives. Our results are generally consistent with other direct information on the diving behaviour of relatively undisturbed sperm whales, but often conflict with results obtained using sonar for sperm whales being chased by whale catchers.
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Lemieux Lefebvre, S., V. Lesage, R. Michaud, and M. M. Humphries. "Classifying and combining herd surface activities and individual dive profiles to identify summer behaviours of beluga (Delphinapterus leucas) from the St. Lawrence Estuary, Canada." Canadian Journal of Zoology 96, no. 5 (May 2018): 393–410. http://dx.doi.org/10.1139/cjz-2017-0015.
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Studies of the behaviour of diving animals usually focus on either individual dives or surface group activities, but these complementary observations are seldom combined in the same study. We here study the summer (June–October) behaviour of St. Lawrence Estuary belugas (Delphinapterus leucas (Pallas, 1776)) by combining fine-scale individual diving data from 27 time–depth–speed recorder deployments (conducted in 2002–2005) with surface activity data from 1413 focal herd follows (conducted in 1991–2012). We classified 6312 dives into seven dive types based on shape and swim speed. Dives were then combined into five bout types, including three pelagic, one benthic, and one near-surface. We classified surface activities of herds into six clusters, differentiated primarily by their associated movement patterns (milling or directional) and additionally by herd structure and dispersion and occurrence of acrobatic surface events. Finally, we used herd focal follows conducted while tracking an individual beluga to relate dive and bout types to surface activities. Results indicate that milling at the surface was more frequently related to benthic dives, potentially, associated with behaviours such as benthic foraging, resting, socializing, and care of young. Directional surface movements were more frequently associated with pelagic dives likely used during pelagic foraging, exploration, and travelling.
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Thompson, D., and M. A. Fedak. "Cardiac responses of grey seals during diving at sea." Journal of Experimental Biology 174, no. 1 (January 1, 1993): 139–54. http://dx.doi.org/10.1242/jeb.174.1.139.
Full textAbstract:
Heart rate, swimming speed and diving depth data were collected from free-ranging grey seals, Halichoerus grypus, as they foraged and travelled in the sea around the Hebrides Islands off western Scotland. Information was collected on a tracking yacht using a combination of sonic and radio telemetry. Diving heart rate declined as a function of dive duration. In long dives, grey seals employed extreme bradycardia, with heart rates falling to 4 beats min-1 for extended periods, despite the animal being free to breath at will. This extreme dive response is part of the normal foraging behaviour. Seals spent 89% of the time submerged during bouts of long dives; swimming was restricted to ascent and descent. Dive durations exceeded estimated aerobic dive limit, even assuming resting metabolic rates. These results indicate that behavioural, and possibly cellular, energy-sparing mechanisms play an important role in diving behaviour of grey seals. This has implications not only for studies of mammalian energetics but also for our understanding of the foraging tactics and prey selection of marine mammals. If some seals are using energy-sparing mechanisms to reduce metabolic costs while at depth, they may be forced to wait for and ambush prey rather than to search for and chase it.
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Baird, Robin W., M. Bradley Hanson, and Lawrence M. Dill. "Factors influencing the diving behaviour of fish-eating killer whales: sex differences and diel and interannual variation in diving rates." Canadian Journal of Zoology 83, no. 2 (February 1, 2005): 257–67. http://dx.doi.org/10.1139/z05-007.
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Diving behaviour of air-breathing vertebrates may be influenced by a variety of factors including age, body size, and changes in prey behaviour and (or) abundance over both short and long timescales. We studied the diving behaviour of a highly sexually dimorphic odontocete cetacean, the killer whale, Orcinus orca (L., 1758), using suction-cup-attached time-depth recorders (TDRs). We tested the hypotheses that dive rates (no. of dives/h greater than or equal to specific depths) of fish-eating killer whales varied between males and females, with age, between day and night, and among pods and years. Data were used from 34 TDR deployments between 1993 and 2002 in the inshore waters of southern British Columbia, Canada, and Washington, USA. Dive rates did not change with age or differ among pods or between males and females, although analyses restricted to adults showed that adult males dove deep significantly more frequently than adult females during the day. For all whales, dive rates and swim speeds were greater during the day than at night, suggesting decreased activity levels at night. Dive rates to deeper depths during the day decreased over the study, suggesting a long-term change in prey behaviour or abundance, though uncertainty regarding the diet of this population precludes determination of the cause of such changes.
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Webb, Tom, and Richard Thelwell. "“He’s taken a dive”." Sport, Business and Management: An International Journal 5, no. 3 (July 13, 2015): 242–58. http://dx.doi.org/10.1108/sbm-04-2014-0019.
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Purpose – The purpose of this paper is to consider the cultural similarities and differences between elite referees concerning their preparation and performance in dealing with reduced player behaviour. Design/methodology/approach – Semi-structured interviews were employed to collect the data. The 37 participants from England, Spain and Italy were selected through the use of purposive sampling, and all were working in the field of refereeing as current elite-level referees, ex-elite-level referees, referee assessors, referee coaches, or managers and administrators from bodies that manage and train referees. Inductive content analysis was employed to generate themes from the raw data. Findings – Referees have identified particular issues related specifically to player behaviour and also identified specific traits pertaining to players from certain countries. Furthermore, results demonstrate that referees have begun to alter their preparation and performance due to the pressure they perceive exists within association football and, more specifically, from the players themselves. Originality/value – This study is the first to compare cross-cultural elite referee responses regarding their preparation and performance related to player behaviour.
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Hays, GC, S. Hochscheid, AC Broderick, BJ Godley, and JD Metcalfe. "Diving behaviour of green turtles: dive depth, dive duration and activity levels." Marine Ecology Progress Series 208 (2000): 297–98. http://dx.doi.org/10.3354/meps208297.
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Blakeway, Jessica-Anne, John P. Y. Arnould, Andrew J. Hoskins, Patricia Martin-Cabrera, Grace J. Sutton, Luis A. Huckstadt, Daniel P. Costa, Diego Páez-Rosas, and Stella Villegas-Amtmann. "Influence of hunting strategy on foraging efficiency in Galapagos sea lions." PeerJ 9 (April 13, 2021): e11206. http://dx.doi.org/10.7717/peerj.11206.
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The endangered Galapagos sea lion (GSL, Zalophus wollebaeki) exhibits a range of foraging strategies utilising various dive types including benthic, epipelagic and mesopelagic dives. In the present study, potential prey captures (PPC), prey energy consumption and energy expenditure in lactating adult female GSLs (n = 9) were examined to determine their foraging efficiency relative to the foraging strategy used. Individuals displayed four dive types: (a) epipelagic (<100 m; EP); or (b) mesopelagic (>100 m; MP) with a characteristic V-shape or U-shape diving profile; and (c) shallow benthic (<100 m; SB) or (d) deep benthic (>100 m; DB) with square or flat-bottom dive profiles. These dive types varied in the number of PPC, assumed prey types, and the energy expended. Prey items and their energetic value were assumed from previous GSL diet studies in combination with common habitat and depth ranges of the prey. In comparison to pelagic dives occurring at similar depths, when diving benthically, GSLs had both higher prey energy consumption and foraging energy expenditure whereas PPC rate was lower. Foraging efficiency varied across dive types, with benthic dives being more profitable than pelagic dives. Three foraging trip strategies were identified and varied relative to prey energy consumed, energy expended, and dive behaviour. Foraging efficiency did not significantly vary among the foraging trip strategies suggesting that, while individuals may diverge into different foraging habitats, they are optimal within them. These findings indicate that these three strategies will have different sensitivities to habitat-specific fluctuations due to environmental change.
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Davis, Randall W., and Daniel Weihs. "Locomotion in diving elephant seals: physical and physiological constraints." Philosophical Transactions of the Royal Society B: Biological Sciences 362, no. 1487 (May 2007): 2141–50. http://dx.doi.org/10.1098/rstb.2007.2107.
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To better understand how elephant seals ( Mirounga angustirostris ) use negative buoyancy to reduce energy metabolism and prolong dive duration, we modelled the energetic cost of transit and deep foraging dives in an elephant seal. A numerical integration technique was used to model the effects of swim speed, descent and ascent angles, and modes of locomotion (i.e. stroking and gliding) on diving metabolic rate, aerobic dive limit, vertical displacement (maximum dive depth) and horizontal displacement (maximum horizontal distance along a straight line between the beginning and end locations of the dive) for aerobic transit and foraging dives. Realistic values of the various parameters were taken from previous experimental data. Our results indicate that there is little energetic advantage to transit dives with gliding descent compared with horizontal swimming beneath the surface. Other factors such as feeding and predator avoidance may favour diving to depth during migration. Gliding descent showed variable energy savings for foraging dives. Deep mid-water foraging dives showed the greatest energy savings (approx. 18%) as a result of gliding during descent. In contrast, flat-bottom foraging dives with horizontal swimming at a depth of 400 m showed less of an energetic advantage with gliding descent, primarily because more of the dive involved stroking. Additional data are needed before the advantages of gliding descent can be fully understood for male and female elephant seals of different age and body composition. This type of data will require animal-borne instruments that can record the behaviour, three-dimensional movements and locomotory performance of free-ranging animals at depth.
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Southwell, Colin. "Diving behaviour of two Ross seals off east Antarctica." Wildlife Research 32, no. 1 (2005): 63. http://dx.doi.org/10.1071/wr03090.
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The Ross seal (Ommatophoca rossii) is the least frequently sighted and least known of the Antarctic pinnipeds. Current knowledge of foraging and diving behaviour is based on observations of a single seal over <2 days. The current study provides some additional data on the diving behaviour of two Ross seals off east Antarctica over periods of 31 and 12 days during December–January 1999–2000 using satellite-linked dive recorders. Both seals remained over the continental shelf for these times, the female remaining some distance from the coast and the male moving close to the coast approximately half-way through his transmission period. Most dives by the female reached depths >150 m (maximum depth 372 m) and the modal duration was 10–11 min. The male’s dives were slightly shallower (most >100 m) and shorter (mode 6–7 min) when distant from the continental coast, and were truncated to a depth of 180 m when close to the coast, presumably by the sea floor. These dive patterns suggest that their prey species, thought to comprise mostly fish and squid, were relatively unavailable at depths <100 m.
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Southwood, Amanda L., Richard D. Reina, Vivienne S. Jones, and David R. Jones. "Seasonal diving patterns and body temperatures of juvenile green turtles at Heron Island, Australia." Canadian Journal of Zoology 81, no. 6 (June 1, 2003): 1014–24. http://dx.doi.org/10.1139/z03-081.
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This study compared diving patterns of juvenile green turtles, Chelonia mydas, in a coral reef habitat during summer and winter. Dataloggers were deployed on green turtles at Heron Island, Australia, during December 2000 and August 2001 so that dive variables and ambient water temperature (TW) could be monitored. Cloacal temperatures (TB) were recorded from green turtles upon capture to assess their ability to maintain a thermal gradient between TB and TW. Data show that green turtles altered diving behaviour seasonally. Green turtles spent significantly more time in shallow water (<1 m) during winter than during summer. Dive depth for dives that exceeded 1 m was 2.9 ± 0.4 m (mean ± SEM) during summer and 4.4 ± 0.6 m during winter. Dive duration in summer (13.1 ± 1.2 min) was approximately half the dive duration in winter (24.3 ± 1.6 min), and surface interval in summer (0.6 ± 0.1 min) was one-third that of the surface interval in winter (1.8 ± 0.1 min). The observed changes in behaviour may be due to seasonal changes in environmental and physiological factors. There was no statistically significant difference between TB and TW during summer or winter.
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Arnould, John PY, and Mark A. Hindell. "Dive behaviour, foraging locations, and maternal-attendance patterns of Australian fur seals (Arctocephalus pusillus doriferus)." Canadian Journal of Zoology 79, no. 1 (January 1, 2001): 35–48. http://dx.doi.org/10.1139/z00-178.
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The dive behaviour, foraging locations, and colony-attendance patterns of female Australian fur seals (Arctocephalus pusillus doriferus) from Kanowna Island (39°10'S, 146°18'E) in Bass Strait, southeastern Australia, were determined throughout lactation during 19971999. Foraging-trip durations increased as lactation progressed, being shortest in summer (3.71 ± 0.24 days; mean ± 1 SE) and longest in winter (6.77 ± 0.57 days, P < 0.05), but maternal-attendance periods did not differ in duration (1.70 ± 0.10 days, P > 0.5). Individual mean attendance periods and trip durations were positively correlated (r2 = 0.21, P < 0.005). Diving commenced shortly after seals left the colony (2.6 ± 0.4 h), was continuous for long periods (up to 36 h), occurred mostly during daylight hours, and lacked regular diel variation in depth. The majority of dives (78%) were typically U-shaped and reached depths corresponding to the prevailing depths in Bass Strait (6585 m), indicating that these animals forage mostly on the benthos of the shallow continental shelf in this region. Such behaviour is unusual for fur seals but is reminiscent of that of some sea lion species. Mean dive durations varied between 2.0 and 3.7 min (maximum 8.9 min) and the theoretical aerobic dive limit (3.914.26 min) was exceeded on 17.3% of dives. Dive frequency (8.3 ± 0.6/h) and the proportion of time at sea spent diving (40.7 ± 2.1%) were weakly negatively related to the duration of the foraging trip (r2 = 0.07, P < 0.004, and r2 = 0.13, P < 0.0001, respectively). Data from at-sea locations showed that lactating females forage almost exclusively within Bass Strait during all seasons.