Journal articles on the topic 'Cane toads'
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1
Webb, Jonathan K., David Pearson, and Richard Shine. "A small dasyurid predator (Sminthopsis virginiae) rapidly learns to avoid a toxic invader." Wildlife Research 38, no. 8 (2011): 726. http://dx.doi.org/10.1071/wr10206.
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Context Invasive species are a leading cause of extinctions, yet predicting their ecological impacts poses a formidable challenge for conservation biologists. When native predators are naïve to invaders, they may lack appropriate behaviours to deal with the invader. In northern Australia, the invasion of the highly toxic cane toad (Rhinella marina) has caused serious population declines of reptilian and mammalian predators that are ill equipped to deal with toad toxins. Cane toads recently invaded the Kimberley region of Western Australia, where they potentially threaten several species of small dasyurid predators. Aims We investigated whether red-cheeked dunnarts (Sminthopsis virginiae) attack cane toads, and if so, whether individuals subsequently learn to avoid toads as prey. Methods We quantified feeding and learning behaviours in toad-naïve red-cheeked dunnarts from the north Kimberley in Western Australia. Key results All toad-naïve dunnarts attacked toads during their first encounter. Most dunnarts bit the toad on the snout, killed it by biting the cranium, and consumed the toad snout-first, thereby initially avoiding the toad’s parotoid glands. Most dunnarts partially consumed toads before discarding them, and only one animal showed visible signs of toad poisoning. All dunnarts rapidly learnt to avoid toads as prey after one or two encounters. Predators rejected toads as prey for the duration of the study (22 days), suggesting long-term retention of the knowledge that toads are noxious. Conclusions Our results show that red-cheeked dunnarts rapidly learn to avoid cane toads as prey. Implications Our study was limited by small sample sizes, but our results suggest that small dasyurids can adapt to the cane toad invasion via taste aversion learning.
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Britton, Adam R. C., Erin K. Britton, and Clive R. McMahon. "Impact of a toxic invasive species on freshwater crocodile (Crocodylus johnstoni) populations in upstream escarpments." Wildlife Research 40, no. 4 (2013): 312. http://dx.doi.org/10.1071/wr12215.
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Context Spread of the invasive cane toad (Rhinella marina) across northern Australia is of concern. Predator species, including the freshwater crocodile (Crocodylus johnstoni), are susceptible to cane toad toxins when ingested. Upstream populations of freshwater crocodiles are smaller than downstream counterparts because of limited resources. We measured the impact of cane toad arrival on densities of these upstream populations. Aims Our aim was to determine whether the influx of cane toads had a negative impact on populations of upstream ‘stunted’ freshwater crocodiles. Methods Population surveys for crocodiles were conducted in three upstream creek systems, using day- and night-based survey methods, before the arrival of cane toads in the area. These surveys were repeated under similar conditions following the arrival of cane toads, to compare the distribution and densities of freshwater crocodiles and, hence, measure the impact of cane toads. Key results There were significant declines in crocodile density at two survey sites following the arrival of cane toads, and we found dead crocodiles and cane toad carcasses with crocodile bite marks. The third site showed no change in density. There was a decline in mean density across all sites from 3.0 crocodiles km–1 to 1.1 crocodiles km–1 following the arrival of cane toads. Conclusions There was an overall decrease in crocodile densities and a reduction in distribution following the arrival of cane toads into the survey area. Dead crocodiles and evidence of their having eaten cane toads strongly suggest that these declines were caused directly by the arrival of cane toads into the area. One site showed no apparent change other than an increase in wariness, which may reflect the distribution of available feeding and shelter resources among the three sites. Implications These results suggest that upstream freshwater crocodile populations are highly susceptible to cane toad toxins, and that impacts on their population can include local extirpation. Considering their morphological and possibly genetic distinctiveness, the loss of these unique populations is of conservation concern.
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Semeniuk, M., F. Lemckert, and R. Shine. "Breeding-site selection by cane toads (Bufo marinus) and native frogs in northern New South Wales, Australia." Wildlife Research 34, no. 1 (2007): 59. http://dx.doi.org/10.1071/wr06112.
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Previous research on cane toads (Bufo marinus) has documented non-random selection of breeding sites by this invasive species. In the wet–dry tropics of the Northern Territory, toads selected spawning sites in open areas with gently sloping banks and shallow water. If consistent, such biases may present opportunities for toad control via waterbody manipulation – but first we need to know whether such criteria for spawning-site selection (1) are consistent across other parts of the toad’s extensive Australian range, and (2) differ from those of native anurans breeding at the same waterbodies. We quantified the attributes of potential and actual spawning-sites in north-eastern New South Wales, in temperate-zone habitat where cane toads have been present for many decades; our study area thus differs in many ways from the previously studied tropical site. We compared habitat and water chemistry variables between 23 cane toad breeding sites and 23 nearby unused sites. To examine habitat use at an even finer scale, we conducted nocturnal surveys of microhabitat use by calling male toads and native anurans. Our results revealed that cane toads in this region were highly selective in their choice of breeding sites, and that the criteria they used in this respect were similar to those used by toads in the Northern Territory. Calling male cane toads also used microhabitats non-randomly within each pond, apparently based on similar criteria to those used when selecting among ponds. Toads differed significantly from native anurans in these respects, suggesting that it may be feasible to manipulate waterbody attributes to impact on invasive toads without disrupting reproduction by native anurans.
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Schwarzkopf, L., and R. A. Alford. "Acoustic attractants enhance trapping success for cane toads." Wildlife Research 34, no. 5 (2007): 366. http://dx.doi.org/10.1071/wr06173.
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Cane toads are an introduced pest in many tropical locations around the world, but, surprisingly, there are few methods available for their control. Highly effective trapping may provide a means of controlling toads, either alone or as part of an integrated pest-management scheme. Existing cane toad trap designs use lights to lure insects to traps, and toads enter the traps to feed. Using a large, outdoor experimental arena and playback of cane toad mating calls, we examined the possibility that cane toads, like many other anurans, are attracted to conspecific mating vocalisations. We found that both male and female toads were attracted to quiet (47dB(A) at 1 m) playbacks, whereas only males responded to loud (67dB(A) at 1 m) playbacks with phonotaxis. We also tested whether playbacks broadcast from traps would be useful attractants to traps in the field. We captured three times more toads in traps with playbacks than in traps without playbacks, suggesting that playbacks can be used to enhance trapping success for toads.
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Freeland, WJ, BLJ Delvinquier, and B. Bonnin. "Decline of Cane Toad, Bufo-Marinus, Populations - Status of Urban Toads." Wildlife Research 13, no. 4 (1986): 597. http://dx.doi.org/10.1071/wr9860597.
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Cane toads from an urban population in Townsville, Qld, exhibit poor body condition and small body size, as do toads in populations around Townsville which have declined in numbers. The small body size and poor condition are associated with a high food intake and a low rate of parasitism. The results suggest that decline of rural populations is not a product of parasitism, or food and or water shortages related to unusually adverse seasonal conditions. Populations of cane toads around Townsville declined more than 3 years before this study.
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Mayer, Martin, Gregory P. Brown, Barbara Zimmermann, Matthew J. Greenlees, and Richard Shine. "Habitat use of the introduced cane toad (Rhinella marina) and native frog species in tropical Australia." Journal of Tropical Ecology 31, no. 6 (September 17, 2015): 531–40. http://dx.doi.org/10.1017/s0266467415000474.
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Abstract:The ecological impacts of introduced species can reveal mechanisms underlying habitat selection and behaviour. We investigated the habitat use of native frog species and the invasive cane toads (Rhinella marina) in tropical northern Australia to measure overlap in habitat use, and to test if the presence of the cane toad influences frog behaviour. Native frog species and the cane toad both preferred habitats close to water and unvegetated holes. However, native frogs were found further from water (on average 19.4 m) than were toads (on average 12.6 m), and preferred areas with higher vegetation (8–50 cm) than did toads, which were more abundant in vegetation lower than 8 cm. For both types of anuran, the next neighbour was more often of the same type (89% in frogs, 52% in toads) than expected by chance (observed ratio: 75% frogs vs 25% toads), reflecting these differences in habitat use. Our counts of frog abundance increased on average 14.5% in areas from which we removed cane toads temporarily. This result suggests that cane toads inhibit the activity of native anurans either by inducing avoidance, or by reducing activity. By modifying the behaviour and spatial distribution of native taxa, invasive cane toads may curtail activities such as feeding and breeding.
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Dall, David. "A Catastrophe of Cane Toads." Outlooks on Pest Management 22, no. 5 (October 1, 2011): 226–29. http://dx.doi.org/10.1564/22oct08.
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Thomas, Julian, Tristram Miall, and Mark Lewis. "Cane Toads: An Unnatural History." American Historical Review 96, no. 4 (October 1991): 1118. http://dx.doi.org/10.2307/2165000.
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N. Reed, Robert, Kristin A. Bakkegard, Glenn E. Desy, and Sheldon M. Plentovich. "Diet composition of the invasive cane toad (Chaunus marinus) on Rota, Northern Mariana Islands." Pacific Conservation Biology 13, no. 3 (2007): 219. http://dx.doi.org/10.1071/pc070219.
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The cane or marine toad (Chaunus marinus, formerly Buto marinus) was introduced to the Northern Mariana Islands starting in the 1930s. The effects of this exotic predator on native vertebrates (especially lizards) are largely unknown. We analysed the stomach contents of 336 cane toads collected from the island of Rota, with the goal of estimating the level of toad predation on native vertebrates. Beetles, ants, millipedes, and grasshoppers/crickets comprised the majority of prey classes consumed by toads. The introduced Brahminy blindsnake (Ramphotyphlops braminus; N = 6) and conspecific cane toads (N = 4) were the vertebrates most commonly found in toad stomachs. Skinks (Emoia; N = 2) were the only native vertebrates represented in our sample. The small numbers of nocturnal terrestrial vertebrates native to Rota likely translates to relatively low rates of predation by cane toads on native vertebrates.
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KELEHEAR, C., J. K. WEBB, and R. SHINE. "Rhabdias pseudosphaerocephala infection in Bufo marinus: lung nematodes reduce viability of metamorph cane toads." Parasitology 136, no. 8 (June 15, 2009): 919–27. http://dx.doi.org/10.1017/s0031182009006325.
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SUMMARYCane toads (Bufo marinus) were introduced to Australia in 1935 and have since spread widely over the continent, generating concern regarding ecological impacts on native predators. Most Australian cane toad populations are infected with lung nematodes Rhabdias pseudosphaerocephala, a parasite endemic to New World (native-range) cane toad populations; presumably introduced to Australia with its toad host. Considering the high intensities and prevalence reached by this parasite in Australian toad populations, and public ardour for developing a control plan for the invasive host species, the lack of experimental studies on this host-parasite system is surprising. To investigate the extent to which this lungworm influences cane toad viability, we experimentally infected metamorph toads (the smallest and presumably most vulnerable terrestrial phase of the anuran life cycle) with the helminth. Infected toads exhibited reduced survival and growth rates, impaired locomotor performance (both speed and endurance), and reduced prey intake. In summary, R. pseudosphaerocephala can substantially reduce the viability of metamorph cane toads.
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Doody, J. S., B. Green, R. Sims, D. Rhind, P. West, and D. Steer. "Indirect impacts of invasive cane toads (Bufo marinus) on nest predation in pig-nosed turtles (Carettochelys insculpta)." Wildlife Research 33, no. 5 (2006): 349. http://dx.doi.org/10.1071/wr05042.
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The cane toad (Bufo marinus) was introduced into Australia in 1935. Because this toxic frog is novel to the Australian fauna, its introduction has impacted native fauna in a variety of ways. We anticipated a severe decline in the yellow-spotted monitor lizard (Varanus panoptes) associated with the arrival of cane toads along the Daly River, Northern Territory, and predicted a simultaneous impact on nest predation in the pig-nosed turtle (Carettochelys insculpta) because the lizard is the chief predator of C. insculpta eggs at the site. We surveyed for monitors and cane toads for five years at two sites before and after the arrival of cane toads, and surveyed for turtle nest predation for three years before, and one year after, the arrival of the toads. Collectively, our data and observations, combined with unpublished reports, indicate that: (1) cane toads arrived at our study sites during the wet seasons of 2003–04 and 2004–05; (2) the lizard V. panoptes readily succumbs to cane toad toxins; (3) . panoptes has experienced a marked decline in relative population numbers coincident with the arrival of the toads at the site; and (4) V. panoptes has been reduced to such low numbers that it is currently no longer a significant predator of pig-nosed turtle eggs.
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Kämper, Wiebke, Jonathan K. Webb, Mathew S. Crowther, Matthew J. Greenlees, and Richard Shine. "Behaviour and survivorship of a dasyurid predator (Antechinus flavipes) in response to encounters with the toxic and invasive cane toad (Rhinella marina)." Australian Mammalogy 35, no. 2 (2013): 136. http://dx.doi.org/10.1071/am12025.
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Australia’s biogeographical isolation has rendered many endemic species vulnerable to invaders. The recent spread of the cane toad (Rhinella marina) has caused serious population declines for some predatory reptile and mammal species. To determine a priori whether or not cane toad poisoning endangers native species, we can test the fates of predators in laboratory trials. We investigated whether an Australian marsupial whose range is increasingly being occupied by cane toads (the yellow-footed antechinus, Antechinus flavipes) is at risk of toad poisoning by testing (1) whether yellow-footed antechinuses approach or attack cane toads and, if so, whether they die as a result; and (2) if they survive, whether they then learn to avoid toads in subsequent encounters. We also investigated the effects of sympatry with toads on the feeding response. In all, 58% of antechinuses from eastern New South Wales approached or attacked a toad (over 4 or 5 opportunities to do so, on successive nights), and none showed ill effects after doing so. Antechinuses that attacked (killed or ingested) toads rapidly learnt to avoid them. Antechinuses from toad-exposed populations ingested more toad flesh, but otherwise reacted in the same ways as did conspecifics from toad-free areas. Hence, the yellow-footed antechinus is unlikely to face population declines via toad poisoning.
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Beckmann, Christa, and Richard Shine. "The power of myth: the (non) impact of invasive cane toads (Bufo marinus) on domestic chickens (Gallus gallus)." Animal Production Science 50, no. 9 (2010): 847. http://dx.doi.org/10.1071/an10084.
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Myths about invasive species are widespread in the general community, even when contrary to scientific evidence. Public revulsion against invasive cane toads (Bufo marinus) in Australia has encouraged the belief that toads pose a significant risk to domestic poultry, by poisoning fowls that eat toads or that drink water contaminated by toads. Although discredited by scientists in 1938, within 2 years of the toads’ introduction to Australia, the myth continues to flourish. We conducted experimental trials to evaluate the vulnerability of chickens to toad-contaminated water, and to toad ingestion. No ill effects were seen, with one chicken consuming 45 small toads without falling ill. Thus, available evidence suggests that cane toads do not imperil domestic poultry.
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Somaweera, Ruchira, Michael R. Crossland, and Richard Shine. "Assessing the potential impact of invasive cane toads on a commercial freshwater fishery in tropical Australia." Wildlife Research 38, no. 5 (2011): 380. http://dx.doi.org/10.1071/wr11026.
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Context The toxins produced by cane toads (Rhinella marina) are fatal to many Australian predators that ingest these invasive anurans. To date, the potential economic impact of the cane toad invasion has attracted little attention. Toads have recently arrived at a large impoundment (Lake Argyle) in north-eastern Western Australia, that supports a commercial fishery for silver cobbler (shovel-nosed catfish, Arius midgleyi), raising concern that the toads may inflict significant economic damage by killing fish. Aims Our research aimed to clarify the vulnerability of silver cobblers to the eggs and larvae of cane toads by determining (a) whether catfish are adversely affected if they prey on toad eggs or tadpoles, and (b) whether surviving catfish learn to avoid cane toad eggs and tadpoles in subsequent encounters. Methods We conducted laboratory feeding trials to examine feeding responses of catfish to cane toad eggs and tadpoles in early and late developmental stages. Fish that survived exposure to toad eggs and/or tadpoles were re-tested with potential prey of the same sizes and developmental stages four days later. Key results Our laboratory trials confirmed that some catfish eat toad eggs and die; but most catfish avoided the eggs. Catfish readily consumed toad tadpoles at both early and late developmental stages, but without experiencing mortality; and soon learned not to consume this toxic new prey type. Conclusions and implications Despite potential frequent episodes of mortality of small numbers of catfish during the wet season, the overall impacts of cane toads on the Lake Argyle fishery likely will be minimal.
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Kosmala, Georgia, Keith Christian, Gregory Brown, and Richard Shine. "Locomotor performance of cane toads differs between native-range and invasive populations." Royal Society Open Science 4, no. 7 (July 2017): 170517. http://dx.doi.org/10.1098/rsos.170517.
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Invasive species provide a robust opportunity to evaluate how animals deal with novel environmental challenges. Shifts in locomotor performance—and thus the ability to disperse—(and especially, the degree to which it is constrained by thermal and hydric extremes) are of special importance, because they might affect the rate that an invader can spread. We studied cane toads ( Rhinella marina ) across a broad geographical range: two populations within the species' native range in Brazil, two invasive populations on the island of Hawai'i and eight invasive populations encompassing the eastern, western and southern limits of the toad invasion in Australia. A toad's locomotor performance on a circular raceway was strongly affected by both its temperature and its hydration state, but the nature and magnitude of those constraints differed across populations. In their native range, cane toads exhibited relatively low performance (even under optimal test conditions) and a rapid decrease in performance at lower temperatures and hydration levels. At the other extreme, performance was high in toads from southern Australia, and virtually unaffected by desiccation. Hawai'ian toads broadly resembled their Brazilian conspecifics, plausibly reflecting similar climatic conditions. The invasion of Australia has been accompanied by a dramatic enhancement in the toads' locomotor abilities, and (in some populations) by an ability to maintain locomotor performance even when the animal is cold and/or dehydrated. The geographical divergences in performance among cane toad populations graphically attest to the adaptability of invasive species in the face of novel abiotic challenges.
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Pearson, David, Matthew Greenlees, Georgia Ward-Fear, and Richard Shine. "Predicting the ecological impact of cane toads (Bufo marinus) on threatened camaenid land snails in north-western Australia." Wildlife Research 36, no. 6 (2009): 533. http://dx.doi.org/10.1071/wr09060.
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The spread of cane toads (Bufo marinus) through north-western Australia may threaten populations of endemic camaenid land snails because these snails exhibit restricted geographic distributions, low vagility and ‘slow’ life-histories. We conducted laboratory trials to determine whether toads would consume camaenids if they encountered them, and conducted field surveys to evaluate the likelihood of such encounters (on the basis of habitat overlap). In laboratory trials with 13 camaenid species, cane toads were more likely to consume camaenids than were two species of native frogs that we tested (Cyclorana australis, Litoria caerulea). However, field surveys suggested that many camaenids are active on vertical surfaces in limestone outcrops, and cane toads rarely venture into these habitats. Although the preferred habitats and activity patterns of camaenids thus reduce their vulnerability to cane toads, we recommend regular surveys of toad and snail numbers to monitor toad impacts. Given the restricted distributions of threatened saxicoline camaenid species in the Kimberley, localised management of grazing stock and fire is feasible to maintain vine-thicket vegetation cover and snail populations, as well as reducing open habitats favoured by toads.
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Webb, Jonathan K., Mike Letnic, Tim S. Jessop, and Tim Dempster. "Behavioural flexibility allows an invasive vertebrate to survive in a semi-arid environment." Biology Letters 10, no. 2 (February 2014): 20131014. http://dx.doi.org/10.1098/rsbl.2013.1014.
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Plasticity or evolution in behavioural responses are key attributes of successful animal invasions. In northern Australia, the invasive cane toad ( Rhinella marina ) recently invaded semi-arid regions. Here, cane toads endure repeated daily bouts of severe desiccation and thermal stress during the long dry season (April–October). We investigated whether cane toads have shifted their ancestral nocturnal rehydration behaviour to one that exploits water resources during the day. Such a shift in hydration behaviour could increase the fitness of individual toads by reducing exposure to desiccation and thermal stress suffered during the day even within terrestrial shelters. We used a novel method (acoustic tags) to monitor the daily hydration behaviour of 20 toads at two artificial reservoirs on Camfield station, Northern Territory. Remarkably, cane toads visited reservoirs to rehydrate during daylight hours, with peaks in activity between 9.00 and 17.00. This diurnal pattern of rehydration activity contrasts with nocturnal rehydration behaviour exhibited by adult toads in their native geographical range and more mesic parts of Australia. Our results demonstrate that cane toads phase shift a key behaviour to survive in a harsh semi-arid landscape. Behavioural phase shifts have rarely been reported in invasive species but could facilitate ongoing invasion success.
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G. Smith, James, and Ben L. Phillips. "Toxic tucker: the potential impact of Cane Toads on Australian reptiles." Pacific Conservation Biology 12, no. 1 (2006): 40. http://dx.doi.org/10.1071/pc060040.
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Cane Toads Bufo marinus are a highly successful invasive species, having invaded more than twenty countries in the last 150 years. In Australia, they currently occupy more than 1 million square kilometres. Toads are highly toxic and Australian predators have no evolutionary history with the cardiac toxins in toad skin. As such, toads constitute a novel and extremely toxic prey for Australia's predators. Australia's reptiles are perhaps the largest group likely to be affected by the invasion of the toad. By examining species distributions, we conclude that 59% of agamids, 85% of the varanids and all of Australia's crocodiles and freshwater turtles are potentially at risk from toads. We then assayed eleven species of reptile; one freshwater turtle (Chelidae), two crocodiles (Crocodylidae), two dragons (Agamidae), one python (Pythonidae) and five species of monitor (Varanidae) for resistance to toad toxin. We found a high level of variation between species in resistance to toad toxin but in all cases (except for one species of crocodile) all species were easily capable of eating a toad large enough to kill them. We conclude that toads pose a real and ongoing threat to the majority of Australian reptile species we examined.
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Alford, Ross A., Gregory P. Brown, Lin Schwarzkopf, Benjamin L. Phillips, and Richard Shine. "Comparisons through time and space suggest rapid evolution of dispersal behaviour in an invasive species." Wildlife Research 36, no. 1 (2009): 23. http://dx.doi.org/10.1071/wr08021.
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During a biological invasion, we expect that the expanding front will increasingly become dominated by individuals with better dispersal abilities. Over many generations, selection at the invasion front thus will favour traits that increase dispersal rates. As a result of this process, cane toads (Bufo marinus) are now spreading through tropical Australia about 5-fold faster than in the early years of toad invasion; but how have toads changed to make this happen? Here we present data from radio-tracking of free-ranging cane toads from three populations (spanning a 15-year period of the toads’ Australian invasion, and across 1800 km). Our data reveal dramatic shifts in behavioural traits (proportion of nights when toads move from their existing retreat-site to a new one, and distance between those successive retreat-sites) associated with the rapid acceleration of toad invasion. Over a maximum period of 70 years (~50 generations), cane toads at the invasion front in Australia apparently have evolved such that populations include a higher proportion of individuals that make long, straight moves.
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Phillips, K. "COLD CANE TOADS CUT PROTON LEAK." Journal of Experimental Biology 211, no. 12 (June 15, 2008): ii. http://dx.doi.org/10.1242/jeb.020388.
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Milius, Susan. "Life: News briefs: Dam cane toads." Science News 179, no. 7 (March 24, 2011): 15. http://dx.doi.org/10.1002/scin.5591790722.
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Price-Rees, Samantha J., Gregory P. Brown, and Richard Shine. "Predation on toxic cane toads (Bufo marinus) may imperil bluetongue lizards (Tiliqua scincoides intermedia, Scincidae) in tropical Australia." Wildlife Research 37, no. 2 (2010): 166. http://dx.doi.org/10.1071/wr09170.
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Context. Detecting ecological impacts of invasive species can be extremely difficult. Even major population declines may be undetectable without extensive long-term data if the affected taxon is rare and/or difficult to census, and exhibits stochastic variation in abundance as a result of other factors. Our data suggest such a situation in an iconic Australian reptile species, the bluetongue lizard. Originally restricted to Central and South America, cane toads (Bufo marinus) are rapidly spreading through tropical Australia. Most native predators have no evolutionary history of exposure to the toads’ distinctive chemical defences (bufadienolides), and many varanid lizards, elapid snakes, crocodiles and marsupials have been killed when they have attempted to consume toads. Aims. Scincid lizards have not been considered vulnerable to toad invasion; however, one lineage (the bluetongues, genus Tiliqua) consists of large omnivores that may be affected. Our field and laboratory research aimed to elucidate this concern. Methods. Nightly surveys for bluetongue lizards (Tiliqua scincoides intermedia) and cane toads were conducted along two adjacent roadways on the Adelaide River floodplain of the Northern Territory. Scent discrimination trials in the laboratory assessed lizard responses to chemical cues from three food types (native frogs, cane toads and ‘preferred foods’) by counting tongue-flicks and biting elicited by cotton swabs. A subset of lizards was presented with live toads. Key results. Numbers of bluetongues encountered during standardised field surveys in the Darwin region declined soon after toads arrived, and we have not recorded a single lizard for the last 20 months. In the laboratory, foraging responses of bluetongues were as intense to cane-toad scent as to the scent of native frogs, and many of the lizards we tested attempted to consume toads, and were poisoned as a result. Conclusions and implications. The population decline of bluetongues in this region appears to have been the direct result of fatal ingestion of toxic cane toads. Our studies thus add a scincid lizard species to the list of native Australian predators imperilled by cane-toad invasion, and point to the difficulty of detecting invader impact even for an iconic species in a system subject to detailed survey work.
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Crossland, Michael R., Takashi Haramura, Angela A. Salim, Robert J. Capon, and Richard Shine. "Exploiting intraspecific competitive mechanisms to control invasive cane toads ( Rhinella marina )." Proceedings of the Royal Society B: Biological Sciences 279, no. 1742 (June 13, 2012): 3436–42. http://dx.doi.org/10.1098/rspb.2012.0821.
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If invasive species use chemical weapons to suppress the viability of conspecifics, we may be able to exploit those species-specific chemical cues for selective control of the invader. Cane toads ( Rhinella marina ) are spreading through tropical Australia, with negative effects on native species. The tadpoles of cane toads eliminate intraspecific competitors by locating and consuming newly laid eggs. Our laboratory trials show that tadpoles find those eggs by searching for the powerful bufadienolide toxins (especially, bufogenins) that toads use to deter predators. Using those toxins as bait, funnel-traps placed in natural waterbodies achieved near-complete eradication of cane toad tadpoles with minimal collateral damage (because most native (non-target) species are repelled by the toads' toxins). More generally, communication systems that have evolved for intraspecific conflict provide novel opportunities for invasive-species control.
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Catling, P. C., A. Hertog, R. J. Burt, R. I. Forrester, and J. C. Wombey. "The short-term effect of cane toads (Bufo marinus) on native fauna in the Gulf Country of the Northern Territory." Wildlife Research 26, no. 2 (1999): 161. http://dx.doi.org/10.1071/wr98025.
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The range of the cane toad has expanded rapidly in the Northern Territory, and there is growing concern that the species may have a detrimental effect on the native fauna. The aim of this study, therefore, was to determine the short-term effects of cane toads on populations of native fauna and, specifically, to compare the species diversity and relative abundance of native fauna before, during and after the invasion of an area by cane toads. Five major groups of fauna (wingless invertebrates, amphibians, reptiles, birds and mammals) were sampled over two years. The study has provided little evidence that cane toads have a significant adverse effect in the short-term on the diversity and abundance of the native fauna examined. However, there was an indication that there may be a long-term indirect effect on some fauna. In the short-term the dingo (Canis lupus dingo) and one Order of insect (Coleoptera) were affected negatively. The possible long-term negative effect was on the small reptile fauna and particularly the small skinks. This may be an indirect effect on their food supply, because the groups affected were those that were considered neither to ingest cane toads nor to be eaten by cane toads.
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Freeland, WJ. "Populations of Cane Toad, Bufo-Marinus, in Relation to Time Since Colonization." Wildlife Research 13, no. 2 (1986): 321. http://dx.doi.org/10.1071/wr9860321.
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A repeatable index of population density for cane toads active around permanent water in the dry season showed that, in the lowlands of the Gulf of Carpentaria, local populations rapidly increased in size following colonization, and remained high (up to 2138 ha-1 on a single night) for at least 19 years. Long-established populations ( ~ 47 years) around Townsville have declined to an average density of 82 ha-1 on a single night. In this area toads are in poor body condition, are smaller, and have a lower proportion of reproductive males than do younger populations. The sizes of fat bodies, and the numbers of ova carried by females, do not appear to have declined in the Townsville populations. The index of population density was found to represent approximately 20% of a Jolly-Seber, capture-recapture estimate of population density for a 2.5-year-old cane toad population. The Jolly-Seber estimate for this young population is up to 45 times the densities of native cane toads in Panama. The numbers of toads captured, toad body sizes and proportions of sexually mature toads in the Townsville populations are very similar to those in Panama.
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Griffiths, Anthony D., and J. Lindley McKay. "Cane toads reduce the abundance and site occupancy of Merten's water monitor (Varanus mertensi)." Wildlife Research 34, no. 8 (2007): 609. http://dx.doi.org/10.1071/wr07024.
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Introduced into Australia in 1935, the cane toad (Chaunus [Bufo] marinus) threatens native vertebrate predators. However, there have been few rigorous quantitative studies on species threatened by this toxic invasive species. This study examines the changes in abundance and proportion of sites occupied by Merten’s water monitor (Varanus mertensi) at a site in the Northern Territory following invasion by cane toads. The study was located at Manton Dam Recreation Area, 70 km south of Darwin, and ran for 18 months. Cane toads were first detected at the study site in February 2005, three months after the first survey, and their abundance remained low until February 2006, when an increase was observed. The abundance of V. mertensi declined substantially 8 months after the arrival of cane toads and remained low. The probability of detection of V. mertensi varied considerably within and among surveys, and was higher in the wet season surveys. The proportion of sites occupied by V. mertensi at the start of the study was 0.95 ± 0.03. Site occupancy remained high for 6 months after the arrival of cane toads, but declined gradually to a low of 0.15 ± 0.16 within 12 months. There has been demonstrable change in the abundance and proportion of sites occupied by V. mertensi following the colonisation of cane toads, but the population has been able to persist. Monitoring of populations impacted by cane toads may provide unique opportunities to understand processes underlying local extinction and colonisation of native predators following the impact of invasive species.
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KELEHEAR, CRYSTAL, KRISTIN SALTONSTALL, and MARK E. TORCHIN. "An introduced pentastomid parasite (Raillietiella frenata) infects native cane toads (Rhinella marina) in Panama." Parasitology 142, no. 5 (November 14, 2014): 675–79. http://dx.doi.org/10.1017/s0031182014001759.
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SUMMARYThe pentastomid parasite, Raillietiella frenata, is native to Asia where it infects the Asian House gecko, Hemidactylus frenatus. This gecko has been widely introduced and recently R. frenata was found in introduced populations of cane toads (Rhinella marina) in Australia, indicating a host-switch from introduced geckos to toads. Here we report non-native adult R. frenata infecting the lungs of native cane toads in Panama. Eight of 64 toads were infected (median = 2·5, range = 1–80 pentastomids/toad) and pentastomid prevalence was positively associated with the number of buildings at a site, though further sampling is needed to confirm this pattern. We postulate that this pattern is likely due to a host shift of this parasite from an urban-associated introduced gecko. This is the first record of this parasite infecting cane toads in their native range, and the first instance of this parasite occurring in Central America.
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Pikacha, Patrick, Tyrone Lavery, and Luke K. P. Leung. "What factors affect the density of cane toads (Rhinella marina) in the Solomon Islands?" Pacific Conservation Biology 21, no. 3 (2015): 200. http://dx.doi.org/10.1071/pc14918.
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Cane toads (Rhinella marina) were introduced to the Solomon Islands in the 1940s, and quickly spread across the archipelago. Between May 2009 and August 2012, cane toads were recorded on 11 of 13 islands surveyed, and the densities of toads were estimated by distance sampling on seven of these islands. Modified Akaike’s Information Criterion (AICc) tests were used to find the most parsimonious model for cane toad density in the Solomon Islands. The results showed that mean toad density was higher on Gatokae and Guadalcanal than on Bougainville, Choiseul, Kolombangara and Rendova. A plausible explanation for this is that Guadalcanal had an abundance of breeding sites, and that Gatokae may have been recently colonised with a typical sharp rise in toad densities. The model also showed that mean toad density was higher in coastal forests than in other forest types (e.g lowland, hill and montane forests). Coastal forests have higher disturbance levels as a result of villages and towns. Disturbance was associated with increased toad densities in the model. These findings suggest that cane toad management efforts should target coastal forests and disturbed areas along roads and tracks leading to important biodiversity reserves.
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Doody, J. Sean, Colin McHenry, Mike Letnic, Corinne Everitt, Graeme Sawyer, and Simon Clulow. "Forecasting the spatiotemporal pattern of the cane toad invasion into north-western Australia." Wildlife Research 45, no. 8 (2018): 718. http://dx.doi.org/10.1071/wr18091.
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Context The toxic cane toad (Rhinella marina) has invaded over 50 countries and is a serious conservation issue in Australia. Because the cane toad has taken several decades to colonise northern Australia, due to the large size of the continent and the east–west invasion axis, there is scope for making testable predictions about how toads will invade new areas. The western toad invasion front is far from linear, providing clear evidence for heterogeneity in invasion speed. Aims Several ad hoc hypotheses have been offered to explain this heterogeneity, including the evolution of traits that could facilitate dispersal, and spatial heterogeneity in climate patterns. Here an alternative hypothesis is offered, and a prediction generated for the spatiotemporal pattern of invasion into the Kimberley Region – the next frontier for the invading toads in Australia. Methods Using observations of spatiotemporal patterns of cane toad colonisation in northern Australia over the last 15 years, a conceptual model is offered, based on the orientation of wet season river flows relative to the invasion axis, as well as toad rafting and floating behaviour during the wet season. Key results Our model predicts that toads will invade southern areas before northern areas; an alternative model based on rainfall amounts makes the opposite prediction. The models can now be tested by monitoring the spread of invasion front over the next 5–10 years. Conclusions Our conceptual models present a pleuralistic approach to understanding the spatiotemporal invasion dynamics of toads; such an approach and evaluation of the models could prove useful for managing other invasive species. Implications Although control of cane toads has largely proved ineffective, knowledge of the spatiotemporal pattern of the toad invasion in the Kimberley could: (1) facilitate potential management tools for slowing the spread of toads; (2) inform stakeholders in the local planning for the invasion; (3) provide researchers with a temporal context for quantifying toad impacts on animal communities; and (4) reveal the mechanism(s) causing the heterogeneity in invasion speed.
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Peacock, David, Gresley A. Wakelin-King, and Ben Shepherd. "Cane toads (Rhinella marina) in south-western Queensland: invasion front, spread and how Cooper Creek geomorphology could enable invasion into north-eastern South Australia." Australian Journal of Zoology 62, no. 5 (2014): 366. http://dx.doi.org/10.1071/zo14025.
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The invasion of northern Australia by the poisonous cane toad is well recognised, as is its devastating impacts on numerous local native species. However, there is little recognition that the toads are spreading into south-western Queensland. Utilising local knowledge, a limited survey was undertaken within the Cooper Creek catchment to locate the invasion front. Dispersal during 2010–11 floods has established cane toads as far south as Jundah. Integrating this information with landform mapping indicates that cane toad invasion can continue south-west down the Cooper Creek. Though arid, Cooper Creek’s geomorphology renders it partially independent of local climate, and permanent and semipermanent waterholes (including RAMSAR-listed wetlands) are found downstream from Windorah and into the Strzelecki Desert. Natural landforms provide potential daytime shelter and breeding sites, and additional suitable habitat created by human activity is also widespread. Even unsuccessful attempts at breeding may be detrimental to regional ecology, especially fish populations, at critical stages of their boom/bust cycle. We conclude that there is no reason why cane toads cannot penetrate further down the Cooper Creek, threatening wetlands in north-eastern South Australia. Published models of cane toad expansion, which conclude that north-eastern South Australia is too dry for cane toad populations to establish, are based on climatic parameters that significantly under-represent true habitat availability.
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Hagman, Mattias, and Richard Shine. "Australian tadpoles do not avoid chemical cues from invasive cane toads (Bufo marinus)." Wildlife Research 35, no. 1 (2008): 59. http://dx.doi.org/10.1071/wr07113.
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If invasive species are phylogenetically distinct from native taxa, divergence in intraspecific communication systems may allow control via methods that invoke behavioural responses by the invasives but not by local species. Previous work has exploited sexual signals in this respect (e.g. species-specific mate-attraction pheromones) but there is equal potential to exploit non-sexual signals, such as chemically mediated behavioural responses of anuran larvae. Cane toads (Bufo marinus), originally from Central and South America, are creating major ecological problems during their invasion through Australia. In an earlier study, we showed that cane toad tadpoles are strongly repulsed by chemical cues from crushed conspecifics, suggesting that these animals possess significant chemical communication systems. To be useful in control of toads, such a response would need to be restricted to cane toads rather than all anurans. In laboratory trials, we detected only minor behavioural responses of six native Australian anuran species to chemical cues from cane toads. Native tadpoles (both hylids and myobatrachids) either ignored the stimulus, or tended to approach it rather than to avoid it. These results are encouraging for the potential use of toad-specific chemicals to manipulate the behaviour of tadpoles in the field, with few collateral effects on native Australian anurans.
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Smart, Adam S., Reid Tingley, and Ben L. Phillips. "Estimating the benefit of quarantine: eradicating invasive cane toads from islands." NeoBiota 60 (October 1, 2020): 117–36. http://dx.doi.org/10.3897/neobiota.60.34941.
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Islands are increasingly used to protect endangered populations from the negative impacts of invasive species. Quarantine efforts on islands are likely to be undervalued in circumstances in which a failure incurs non-economic costs. One approach to ascribe monetary value to such efforts is by modeling the expense of restoring a system to its former state. Using field-based removal experiments on two different islands off northern Australia separated by > 400 km, we estimate cane toad densities, detection probabilities, and the resulting effort needed to eradicate toads from an island. We use these estimates to conservatively evaluate the financial benefit of cane toad quarantine across offshore islands prioritized for conservation management by the Australian federal government. We calculate density as animals per km of freshwater shoreline, and find striking concordance of density estimates across our two island study sites: a mean density of 352 [289, 466] adult toads per kilometre on one island, and a density of 341 [298, 390] on the second. Detection probability differed between our two study islands (Horan Island: 0.1 [0.07, 0.13]; Indian Island: 0.27 [0.22, 0.33]). Using a removal model and the financial costs incurred during toad removal, we estimate that eradicating cane toads would, on average, cost between $22 487 [$14 691, $34 480] (based on Horan Island) and $39 724 [$22 069, $64 001] AUD (Indian Island) per km of available freshwater shoreline. We estimate the remaining value of toad quarantine across islands that have been prioritized for conservation benefit within the toads’ predicted range, and find the net value of quarantine efforts to be $43.4 [28.4–66.6] – $76.7 [42.6–123.6] M depending on which island dataset is used to calibrate the model. We conservatively estimate the potential value of a mainland cane toad containment strategy – to prevent the spread of toads into the Pilbara Bioregion – to be $80 [52.6–123.4] – $142 [79.0–229.0] M. We present a modeling framework that can be used to estimate the value of preventative management, via estimating the length and cost of an eradication program. Our analyses suggest that there is substantial economic value in cane toad quarantine efforts across Australian offshore islands and in a proposed mainland containment strategy.
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Taussig, Michael. ": Cane Toads: An Unnatural History . Tristram Miall." American Anthropologist 92, no. 4 (December 1990): 1110–11. http://dx.doi.org/10.1525/aa.1990.92.4.02a01060.
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Clarke, Gregory S., Cameron M. Hudson, and Richard Shine. "Encounters between freshwater crocodiles and invasive cane toads in north-western Australia: does context determine impact?" Australian Zoologist 41, no. 1 (October 1, 2020): 94–101. http://dx.doi.org/10.7882/az.2020.015.
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ABSTRACT The potent defensive chemicals of cane toads (Rhinella marina) protect them against predators that lack coevolved physiological tolerance to those toxins. That relative invulnerability may explain why major injuries (such as limb loss) appear to be rare in cane toads from most of their global range; however, we noted frequent predator-induced injuries (>4% of adults) in samples from within the toad’s native range (in French Guiana) and from a site (Lake Argyle) in north-western Australia. Toads at Lake Argyle enter the edge of the lake at night to rehydrate, exposing them to foraging freshwater crocodiles (Crocodylus johnstoni). Crocodiles rarely consume toads, but the attacks often result in loss of a limb. Because limbs contain relatively little toxin, attacks to the limbs expose a crocodile to nauseating but non-lethal amounts of toxin; and hence, facilitate taste aversion learning by the predator. The context of the encounters, such as differences in geography, may help to explain why the invasion of cane toads has not significantly impacted on crocodile populations at this site, in contrast to heavy impacts reported from nearby riverine systems.
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Hagman, Mattias, and Richard Shine. "Tadpoles of invasive cane toads (Bufo marinus) do not respond behaviourally to chemical cues from tadpoles of four species of Australian frogs." Australian Journal of Zoology 56, no. 4 (2008): 211. http://dx.doi.org/10.1071/zo08005.
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In previous work, we have shown that tadpoles of invasive cane toads (Bufo marinus) strongly avoid scent cues from crushed conspecific tadpoles. Thus, identifying the identity of the chemical involved may provide novel approaches to toad control, by manipulating the behaviour of toad tadpoles. A first step in the search for that chemical is to see whether toad tadpoles are similarly repelled by chemical cues from crushed tadpoles of other species. Our experimental trials with four native Australian frogs (three hylids, one myobatrachid) show that toads do not respond to chemical cues from these taxa. Hence, the specific chemicals that induce avoidance cannot be generic ones (e.g. body fluids, tissue fragments) but instead, must reflect some underlying chemical divergence in body composition between the tadpoles of cane toads versus the other anurans that we have tested.
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Freeland, WJ, BLJ Delvinqueir, and B. Bonnin. "Food and Parasitism of the Cane Toad, Bufo-Marinus, in Relation to Time Since Colonization." Wildlife Research 13, no. 3 (1986): 489. http://dx.doi.org/10.1071/wr9860489.
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Food habits and parasitism of cane toad, Bufo marinus, populations are documented in relation to time since the populations were first established. Toads from populations less than 2 years old consume greater dry weights of animal prey and greater numbers of prey items per unit time than do those from populations 3-47 years old. There are no significant differences among the dry weights of animal food and numbers of prey items consumed by toads from areas colonized 3-47 years before the study. There are significant regional and interpopulation differences in the taxonomic composition of prey consumed; these appear independent of the age of particular cane toad populations. Rates of parasitism by protozoans and helminths are low in a 2-year-old population, higher in populations 4-19 years old and low in a population approximately 47 years old. Parasitism by Saccamoeba and the opalinate Zelleriella appears to promote parasitism by other taxa. The rates of parasitism by particular taxa are independent of the age and size of the cane toad population. Neither food shortage nor parasitism by helminths or protozoans appears a likely cause for the decline in body condition in populations 47 years old. If this is due to the presence of a microbial pathogen, the low rates of helminth and protozoan parasitism may reflect continuing development of an interactive parasitic community in cane toad populations; isolation of the microbe might provide a mechanism for slowing the rate of spread of cane toads, and reducing their impact on the native fauna.
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Freeland, WJ, and KC Martin. "The Rate of RAnge Expansion by Bufo marinus in Northern Australia, 1980-84." Wildlife Research 12, no. 3 (1985): 555. http://dx.doi.org/10.1071/wr9850555.
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Between 1980 and 1984, the cane toad, Bufo marinus, expanded its range westward from a small, isolated and probably man-introduced population north-west of Burketown in Queensland, at an average rate of 27 km per year. The rate of range expansion is not influenced by rainfall (dry or wet season) and appears to occur by continual colonization of new areas by small, sexually immature toads. If current rates of expansion continue, cane toads will have colonized the 'Top End' of the Northern Territory by the year 2027. However, the high frequency of toad dispersal assisted by man suggests that colonization will be more rapid.
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Selechnik, Daniel, Andrea J. West, Gregory P. Brown, Kerry V. Fanson, BriAnne Addison, Lee A. Rollins, and Richard Shine. "Effects of invasion history on physiological responses to immune system activation in invasive Australian cane toads." PeerJ 5 (October 6, 2017): e3856. http://dx.doi.org/10.7717/peerj.3856.
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The cane toad (Rhinella marina) has undergone rapid evolution during its invasion of tropical Australia. Toads from invasion front populations (in Western Australia) have been reported to exhibit a stronger baseline phagocytic immune response than do conspecifics from range core populations (in Queensland). To explore this difference, we injected wild-caught toads from both areas with the experimental antigen lipopolysaccharide (LPS, to mimic bacterial infection) and measured whole-blood phagocytosis. Because the hypothalamic-pituitary-adrenal axis is stimulated by infection (and may influence immune responses), we measured glucocorticoid response through urinary corticosterone levels. Relative to injection of a control (phosphate-buffered saline), LPS injection increased both phagocytosis and the proportion of neutrophils in the blood. However, responses were similar in toads from both populations. This null result may reflect the ubiquity of bacterial risks across the toad’s invaded range; utilization of this immune pathway may not have altered during the process of invasion. LPS injection also induced a reduction in urinary corticosterone levels, perhaps as a result of chronic stress.
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Ward-Fear, G., D. J. Pearson, G. P. Brown, Balanggarra Rangers, and R. Shine. "Ecological immunization: in situ training of free-ranging predatory lizards reduces their vulnerability to invasive toxic prey." Biology Letters 12, no. 1 (January 2016): 20150863. http://dx.doi.org/10.1098/rsbl.2015.0863.
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In Australia, large native predators are fatally poisoned when they ingest invasive cane toads ( Rhinella marina ). As a result, the spread of cane toads has caused catastrophic population declines in these predators. Immediately prior to the arrival of toads at a floodplain in the Kimberley region, we induced conditioned taste aversion in free-ranging varanid lizards ( Varanus panoptes ), by offering them small cane toads. By the end of the 18-month study, only one of 31 untrained lizards had survived longer than 110 days, compared to more than half (nine of 16) of trained lizards; the maximum known survival of a trained lizard in the presence of toads was 482 days. In situ aversion training (releasing small toads in advance of the main invasion front) offers a logistically simple and feasible way to buffer the impact of invasive toads on apex predators.
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Shilton, Cathy M., Jan Šlapeta, Richard Shine, and Gregory P. Brown. "Invasive Colonic Entamoebiasis in Wild Cane Toads, Australia." Emerging Infectious Diseases 24, no. 8 (August 2018): 1541–43. http://dx.doi.org/10.3201/eid2408.180101.
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Hernández, Sandra E., Conrad Sernia, and Adrian J. Bradley. "Adrenocortical function in cane toads from different environments." Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 195 (May 2016): 65–72. http://dx.doi.org/10.1016/j.cbpa.2016.02.001.
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BECKMANN, CHRISTA, and RICHARD SHINE. "Impact of Invasive Cane Toads on Australian Birds." Conservation Biology 23, no. 6 (December 2009): 1544–49. http://dx.doi.org/10.1111/j.1523-1739.2009.01261.x.
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Liu, Zizhen, and Jason Kim. "The Piezoelectric Behavior of Cane Toads Achilles Tendon." Journal of Biomechanics 40 (January 2007): S118. http://dx.doi.org/10.1016/s0021-9290(07)70115-x.
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Speare, R., L. Berger, P. O'Shea, P. W. Ladds, and A. D. Thomas. "PATHOLOGY OF MUCORMYCOSIS OF CANE TOADS IN AUSTRALIA." Journal of Wildlife Diseases 33, no. 1 (January 1997): 105–11. http://dx.doi.org/10.7589/0090-3558-33.1.105.
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Brown, G. P., C. Shilton, B. L. Phillips, and R. Shine. "Invasion, stress, and spinal arthritis in cane toads." Proceedings of the National Academy of Sciences 104, no. 45 (October 19, 2007): 17698–700. http://dx.doi.org/10.1073/pnas.0705057104.
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González-Bernal, Edna, Matthew Greenlees, Gregory P. Brown, and Richard Shine. "Cane Toads on Cowpats: Commercial Livestock Production Facilitates Toad Invasion in Tropical Australia." PLoS ONE 7, no. 11 (November 7, 2012): e49351. http://dx.doi.org/10.1371/journal.pone.0049351.
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Urban, Mark C., Ben L. Phillips, David K. Skelly, and Richard Shine. "A Toad More Traveled: The Heterogeneous Invasion Dynamics of Cane Toads in Australia." American Naturalist 171, no. 3 (March 2008): E134—E148. http://dx.doi.org/10.1086/527494.
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Burnett, Scott. "Colonizing Cane Toads cause population declines in native predators: reliable anecdotal information and management implications." Pacific Conservation Biology 3, no. 1 (1997): 65. http://dx.doi.org/10.1071/pc970065.
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This paper presents compelling, anecdotal evidence of severe population declines in five predator species, Dasyurus hallucatus, Varanus gouldii, V. mertensi, V. panoptes, and V. timorensis similis, in almost immediate response to Cane Toad colonization of their habitat in three widely distributed areas of northern Queensland. Furthermore, risk assessment of all quoll and monitor taxa whose distributions overlap the potential distribution of the Cane Toad in Australia (Sutherst et al. 1996), indicates that at the continental scale, three of the four quoll taxa and eight of the 20 monitor species examined are at high risk of severe population declines following Cane Toad colonization. One quoll taxon and seven monitor species are at moderate risk and five monitor species are at low risk. The definition of the threat which Cane Toads pose to native predators has received very little research attention, and fundamental questions including; which predator species are most at risk (testing of the risk assessment hypotheses presented here), the extent of these risks (is there a need to manage Cane Toad impacts upon predators?), and the contexts of intraspecific variation in relative extinction risk (for example, interactions of extinction risk with predator and Cane Toad population demography, climate, landscape, and land use), need to be assessed. Assuming that Cane Toads are found to have an impact across a range of taxa and landscapes (which I propose to be likely), management of the impact of this species on predators can be approached from two not necessarily exclusive directions; management of Cane Toad populations and management of predator populations, through both population and habitat management. At this stage, however, management from either viewpoint is constrained by a lack of published information relevant to autecology and fine scale distribution of predators.
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Lillie, Mette, Sylvain Dubey, Richard Shine, and Katherine Belov. "Variation in Major Histocompatibility Complex diversity in invasive cane toad populations." Wildlife Research 44, no. 7 (2017): 565. http://dx.doi.org/10.1071/wr17055.
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Context The cane toad (Rhinella marina), a native species of central and southern America, was introduced to Australia in 1935 as a biocontrol agent after a complex history of prior introductions. The population rapidly expanded and has since spread through much of the Australian landmass, with severe impacts on the endemic wildlife, primarily via toxicity to predators. The invasion process has taken its toll on the cane toad, with changes in the immunological capacity across the Australian invasive population. Aims To investigate the immunogenetic underpinnings of these changes, we studied the diversity of the Major Histocompatiblity Complex (MHC) genes in introduced cane toad populations. Methods We studied the diversity of two MHC genes (the classical class I UA locus and a class II DAB locus) and compared these with neutral microsatellite markers in toads from the Australian site of introduction and the Australian invasion front. We also included toads from Hawai’i, the original source of the Australian toads, to infer founder effect. Key results Diversity across all markers was low across Australian and Hawai’ian samples, consistent with a reduction in genetic diversity through multiple founder effects during the course of the successive translocations. In Australia, allelic diversity at the microsatellite markers and the UA locus was reduced at the invasion front, whereas all three alleles at the DAB locus were maintained in the invasion-front toads. Conclusions Loss of allelic diversity observed at the microsatellite markers and the UA locus could be the result of drift and bottlenecking along the invasion process, however, the persistence of DAB diversity warrants further investigation to disentangle the evolutionary forces influencing this locus. Implications Through the use of different molecular markers, we provide a preliminary description of the adaptive genetic processes occurring in this invasive population. The extremely limited MHC diversity may represent low immunogenetic competence across the Australian population, which could be exploited for invasive species management.
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Ekstrom, Laura J., Chris Panzini, and Gary B. Gillis. "Vision fine-tunes preparation for landing in the cane toad, Rhinella marina." Biology Letters 14, no. 9 (September 2018): 20180397. http://dx.doi.org/10.1098/rsbl.2018.0397.
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In toad hopping, the hindlimbs generate the propulsive force for take-off while the forelimbs resist the impact forces associated with landing. Preparing to perform a safe landing, in which impact forces are managed appropriately, likely involves the integration of multiple types of sensory feedback. In toads, vestibular and/or proprioceptive feedback is critical for coordinated landing; however, the role of vision remains unclear. To clarify this, we compare pre-landing forelimb muscle activation patterns before and after removing vision. Specifically, we recorded EMG activity from two antagonistic forelimb muscles, the anconeus and coracoradialis, which demonstrate distance-dependent onset timing and recruitment intensity, respectively. Toads were first recorded hopping normally and then again after their optic nerves were severed to remove visual feedback. When blind, toads exhibited hop kinematics and pre-landing muscle activity similar to when sighted. However, distance-dependent relationships for muscle activity patterns were more variable, if present at all. This study demonstrates that blind toads are still able to perform coordinated landings, reinforcing the importance of proprioceptive and/or vestibular feedback during hopping. But the increased variability in distance-dependent activity patterns indicates that vision is more responsible for fine-tuning the motor control strategy for landing.