Tesi sul tema "Wildlife and habitat management"

Rails (Family: Rallidae) are among the least studied birds in North America, in large part due to their elusive nature. As a wetland-dependent species, understanding the timing of their migration and their habitat needs during migration is especially important since management needs to be timed to balance the needs of many species. I developed and verified a new distance sampling based nocturnal ATV spotlight survey because traditional call-broadcast surveys are not effective during autumn migration because of the drop off in call rate after the breeding season. These surveys allow us to ask point-level questions about what habitats rails select during migration and how it changes over time. Through these standardized surveys from 2012-2016 across 11 public properties in Missouri, USA, I documented the migratory timing and habitat use of migratory rails. Sora (Porzana carolina) have a wide migratory window, beginning in early August and continuing through the end of October with a peak in late September. Virginia Rail (Rallus limicola) and Yellow Rails (Coturnicops noveboracensis) have shorter migratory periods, from late September through the end of October. Rails, especially Sora, migrate earlier than waterfowl, which can create a mismatch of habitat needs. We performed a 3 year experiment to examine the response of Sora and waterfowl to early autumn wetland flooding. Sora responded positively without a negative impact on waterfowl. I used monitoring data to create species distribution models to inform estimates of migratory connectivity for all three species using stable hydrogen isotopes. Sora and Yellow Rails were estimated to migrate generally north-south, with Virginia Rails coming from a wider east-west range. Through better understanding the migratory connectivity, timing and habitat use of rails in the autumn I provide a foundation to inform conservation and management of these fascinating and elusive birds. We provide a description of all variables used (Appendix II), GPS data of survey tracks and detection points (Appendix III), data sets of bird observation points, survey data, and vegetation information (Appendix IV), data sets of stable hydrogen isotope data (Appendix V), data sets of species distribution models (Appendix VI).

For mule deer (Odocoileus hemionus) in the Intermountain West, alterations to habitat are outpacing strategies to mitigate human disturbance on critical seasonal ranges and migration routes.

Conserving mule deer habitat requires cooperation between a diverse group of stakeholders, state wildlife agencies, and federal land management agencies. The first chapter of this thesis explores the current and historical relationship between state wildlife agencies, citizen stakeholders, and federal agencies in order to highlight opportunities to improve cooperative habitat conservation in the United States. Conservation is a result of social, political, and economic action, but relies upon science to inform policy. The second chapter explores the seasonal habitat use of mule deer in southwestern Wyoming. In response to low fawn recruitment, the Wyoming Game and Fish Department deployed 15 GPS collars on adult female mule deer in an effort to enhance knowledge of mule deer population dynamics, migrations, and habitat use. The study captured two winter climate regimes, with greater winter severity during the 2010-11 winter compared to the winter of 2011-12. Deer migrated an average of 23.9 km (SE = 2.2) between seasonal ranges, and completed spring migrations nearly one month earlier following the milder winter of 2011-12 (t19 = 5.53, df = 19, P ≤ 0.001). Pooled, the average area of winter ranges (1057 ha, SE = 103, n = 26) was larger than summer ranges (423 ha, SE = 51 ha, n = 25) (t = −5.44, df = 49, P ≤ 0.001), with no increase or decrease in size of seasonal ranges detected between years (P = 0.243) according to a post-hoc Tukey HSD test. Between years, deer were observed to shift the geographic center of winter ranges (2.9 km, SE = 1.1, n = 12) to a larger degree than summer ranges (0.4 km, SE = 0.1, n = 12) (t = −2.20, df = 22, P = 0.040). Survival and pregnancy rates (86% and 96%, respectively) correlated closely with other mule deer studies, and neither factor appears to negatively impact population growth.

Identifying seasonal ranges and migration routes, and quantifying seasonal habitat use, will assist Wyoming Game and Fish Department efforts to protect mule deer seasonal habitats and migration routes, and direct vegetation manipulations intended to improve the nutritional quality of habitats. On average, winter ranges included a later percentage of shrub-dominated habitat (83.8%, SE = 0.3, n = 26) than summer ranges (57.5%, SE = 2.0, n = 25) (t = −4.42, df = 49, P ≤ 0.001). Summer ranges averaged a greater proportion of agricultural lands (2.8%, SE = 1.1, n = 25) and aspen (Populus tremuloides ) habitats (9.0%, SE = 2.2, n = 25) than winter ranges (0.1%, SE = 0.1, n = 26 and 0.2%, SE = 0.0, n = 26, respectively) (t = 3.03, df = 49, P = 0.004 and t= 3.86, df = 49, P ≤ 0.001, respectively). Mule deer ranges are primarily located on Bureau of Land Management (73%, SE = 2.8, n = 51) and privately owned (17.3%, SE = 2.9, n = 51) lands, highlighting opportunities for cooperative partnerships for mule deer habitat conservation.

Non-habituated coyotes (Canis latrans) avoid direct interactions with humans. Reliance on human food sources has been linked to gradual habituation, a precursor to conflict and attacks on domestic pets and humans. Diet and activity patterns of urban coyotes inhabiting natural fragments in Long Beach, CA were monitored through scat collection and camera trapping over a year (Aug 2016 – Aug 2017). Local urban coyotes are relying predominately on natural foods, with an increase in mammalian prey in the wet season and an increase in vegetation and insect consumption in the dry season. Anthropogenic items, food and food related inedible items, appeared in 14% of scats overall, with no significant seasonal change. Cat remains were found in 14% of scat samples, but only triggered cameras once throughout the 2,857 camera nights of the study. Coyote activity was centered on nights in both seasons, with greater dawn activity in the dry season, indicating an avoidance of peak human activity. This reliance on natural foods and avoidance of human activity reduces the opportunities for human-wildlife conflicts in our local area.

Unregulated hunting and habitat loss led to a near extirpation of moose (Alces alces) in New Hampshire in the 1800s. After state protection in 1901, the estimated population increased slowly to ∼500 moose in 1977, then increased rapidly in the next 2 decades to ∼7500 following an increase in browse habitat created by spruce budworm (Choristoneura fumiferana ) and related timber salvage operations, and then halved from 1998-2016 despite highly available optimal habitat. The declining population was partially related to the specific management objective to reduce moose-vehicle collisions, and a possible change in deer hunter and moose behavior that influence population estimates. But given the substantial decline in productivity and condition of cows, and frequent episodes of high calf mortality in April, the primary cause of decline was presumed to be is an increase in winter tick abundance.

This study examined the relationships among moose density, optimal habitat, weather/ground conditions, winter tick abundance, and natal dispersal in northern New England. Comparing movement data from the previous (2002-2006) and current (2014-2016) productivity studies in New Hampshire and Maine, the distance of natal dispersal, home and core range size, and home and core range overlap did not significantly (P > 0.05) change despite an increase in optimal habitat and a decrease in moose density.

Geographic changes in tick abundance were related to an interaction between moose density, and the onset and length of winter. Annual changes in tick abundance in northern New Hampshire are driven by desiccating late summer conditions, as well as the length of the fall questing season. Lower precipitation (6.4 cm) and higher minimum temperatures (9.8 °C) specifically concentrated during larval quiescence from mid-August through mid-September reduces winter tick abundance and the likelihood of an epizootic event. The onset of winter, defined by the first snowfall event (> 2.54 cm), influenced the length of the questing season relative to the date of long-term first snowfall event (14 November). In the epizootic region, average winter tick abundance on moose harvested in mid-October indicated a threshold of 36.9 ticks, above which an epizootic is like to occur unless an early snowfall event shortened the fall questing season. Optimal habitat created by forest harvesting was produced at an annual rate of 1.3% (1999-2011) and is not considered limiting in northern New Hampshire, but likely concentrates moose density locally (∼4 moose/km²) facilitating the exchange of winter ticks. In northern New Hampshire, snow cover late into April did not reduce tick abundance in the following year and cold temperatures (< 17 °C) that induced replete adult female mortality are extremely rare in April.

Given a continuation of warming climate and conservative moose harvest weather conditions and high local moose densities will continue to favor the life cycle of winter ticks, increasing the frequency of winter tick epizootics and shift the epizootic region slowly northward. Conversely, temporary reduction of moose density may substantially reduce parasite abundance and support a healthier and more productive moose population.

The Mississippi Alluvial Valley (MAV) is an important region for wintering mallards (Anas platyrhynchos) in North America, yet little is known about their spatiotemporal habitat use and related survival in Mississippi. I tracked 126 radio-marked female mallards to quantify survival, habitat use, and use of wildlife management areas (WMAs) with experimental hunt regimes in the south MAV of Mississippi during winters 2010-2012. Daily survival was greatest in agricultural (0.997) and moist-soil (0.999) habitats in winters 2010-2011 and 2011-2012, respectively. Overall interval survival across both winters was 0.60 (SE = 0.02). Forested (40-54%) and moist-soil wetlands (41-59%) received greatest use diurnally and nocturnally, respectively. Mallards used WMAs similarly (P > 0.22) whether they were hunted 2- or 4-days/week. My data suggest that complexes of flooded cropland, forest, and moist-soil habitats are suitable habitats for mallards in the MAV, WMAs can be hunted 4-days/week, and sanctuaries should be revised at two WMAs.

This study investigates the population dynamics, movements, and habitat use of a population of western pond turtles in Orange County, California from 2008-2012 using radio telemetry and mark-recapture data. Western pond turtles have been thought to be declining throughout their range. However, few studies have documented their status in southern California, where urbanization has changed the landscape drastically in recent decades. I individually marked 236 pond turtles using hoop-net funnel traps and estimated the population size at 308 individuals, which is the largest estimate reported in southern California. Mean capture per unit effort was 5.03±0.87. Mean female carapace length (CL) (142±14mm) was not significantly larger than males (139±14 mm). I also documented 20 nest and 9 estivation locations. Mean distances included 176 ±130.80 meters (m) and 91±58.6 m. These data identify the population demography, which can be a metric of population stability. Other known populations need to be estimated to determine their regional status.

The Golden-winged Warbler (Vermivora chrysoptera) is an imperiled migratory songbird that nests in young forest habitats of eastern North America. As such, this species has recently been the focus of an intensive multi-year, range-wide, breeding ecology study. A major focus of this research involved spot-mapping color banded males to examine relationships between nesting success and territory-scale habitat variables. I compared differences in space and habitat use of individual male Golden-winged Warblers that were monitored using both spot mapping and radio telemetry. An individual's telemetry delineated use area was on average 3.6 times larger than its spot-mapped territory. Almost half (46%) of all telemetry locations were located outside their respective male's spot-mapped territory. Number of saplings was higher in telemetry use areas (22.49 ± 2.14) than spot-mapped territories (11.80 ± 1.86). Although the exact motive for extra-territorial movements is unknown, foraging and/or suggestive observations of extra-pair copulation are likely motivating factors. The results of my study suggest Golden-winged Warblers are seeking resources outside their spot-mapped delineated territories. Furthermore, Golden-winged Warblers were found to have more telemetry locations in mature forest than found through spot-mapping. Ultimately, spot mapping alone does not accurately reflect Golden-winged Warbler space use and habitat needs.

The management and research of mule deer (Odocoileus hemionus ) in Colorado and throughout the Rocky Mountain West is an exciting arena for wildlife professionals as the prevailing view among biologists, managers, researchers, hunters, wildlife viewers and general wildlife enthusiasts is that they would like to see more deer on the landscape.

In Chapter 1, I used 4 years of data and 8 study units to evaluate the effect of habitat management on the overwinter survival of mule deer fawns. Habitat management consisted of different levels of habitat management efforts: reference study units received no habitat management, traditional habitat treatment units received mechanical disturbance and advanced habitat treatment units were comprised of both mechanical disturbances as well as follow-up chemical control of weeds and reseeding with desirable browse species. Mule deer fawns that overwintered on areas that received both a traditional treatment as well as follow-up treatments experienced an improvement in survival ( Ŝ = 0.768, SE = 0.085) over deer on winter range without habitat treatments (Ŝ = 0.675, SE = 0.112). When partitioned into different levels of treatment intensity, mule deer inhabiting winter range that advanced treatments (i.e., both traditional treatments and follow-up treatments) experienced higher survival (Ŝ = 0.768, SE = 0.0849) than deer on areas that experienced only traditional treatments (Ŝ = 0.687, SE = 0.108), which in turn experienced higher survival than in areas that had received no treatments (Ŝ = 0.669, SE = 0.113).

In my second chapter, I relied on recent advancements in abundance estimation methodologies to determine if habitat management strategies increased mule deer density. In order to estimate mule deer density, I conducted annual helicopter mark-resight surveys across the 8 study units that were utilized in chapter 1. Resighting probabilities (range 0.070–0.567) were best modeled as an interactive function of study unit and year, although sampling method was also important. A consistent pattern of higher deer density on advanced treatment study units was not observed despite its being the primary hypothesis of the study. Total deer densities did vary by latitude with 20–84 deer/km² in southern study units and 4–12 deer/km² in northern study units. I conclude that if population density is to be used as a population response variable, it only be used in tandem with other, possibly more sensitive parameters, such as overwinter survival of mule deer fawns.

In my third chapter, I investigate the relationships between habitat, body condition, and life history characteristics. With the increased availability of portable ultrasound machines and the refinement of hormonal assays, assessment of ungulate body condition has become a more accessible monitoring strategy. I employed body condition scoring, estimation of % ingesta-free body fat (%IFBF) and assessment of thyroid hormones (FT4 and FT3) as metrics to determine if landscape-level habitat manipulation affected body condition of adult (≥1.5 years old) female mule deer.

For my final chapter, I assimilate the knowledge and information gained from my first 3 chapters with the existing knowledge base surrounding mule deer population dynamics and population limitation within Colorado. Such reviews have been conducted periodically (e.g., 1960s and late 1990s) and have been precipitated by mule deer population declines. A dramatic decline in mule deer populations was detected during the final years of my field research but the underlying cause of this decline is yet to be determined. (Abstract shortened by UMI.)

The Rusty Blackbird (Euphagus carolinus) is a migratory songbird that breeds in and near the boreal wetlands of northern New England and Canada. Although the Rusty Blackbird was once common, the species has declined by an estimated 90% since the 1960’s (Greenberg et al. 2010). I used single-season occupancy analysis to model breeding Rusty Blackbirds’ use of 60 beaver (Castor canadensis) influenced wetlands in Coos County, New Hampshire and Oxford County, Maine. I conducted three 30 minute detected/ not detected surveys, surveyed food availability and foraging habitat, and digitized each survey wetland. Rusty Blackbirds’ use of wetlands was best predicted by the site covariates mud and invertebrate abundance and detectability was best predicted by survey period. Probability of wetland use decreased with increasing mud cover and increased with increasing aquatic invertebrate abundance. I recommend that future researchers survey for Rusty Blackbirds for 30 minute periods to maximize survey coverage.

Western Screech-Owls (Megascops kennicottii) are small, nocturnal owls that occur year-round throughout most of the Trans-Pecos region in West Texas, and are associated with deciduous woodlands and riparian habitats. Roadside nocturnal callback surveys, were established along well-defined trails within the Davis Mountains Preserve, and took place from May until August for two years to ascertain the relative abundance of Western Screech-Owls within the property. Abundance indices (birds detected/visit/station) were calculated for both survey seasons. Radiotelemetry was incorporated to determine certain life-history information, while habitat was characterized from both survey and telemetry sites. Occupancy models with detection probabilities were created using Program PRESENCE based on collected presence-absence data. Based on criteria for suitable screech-owl habitat previously defined in the literature, several models were also generated within ArcGIS to compare with the field data and to help predict areas of occupancy within the property. Owl abundance averaged 1.05 owls/point in 2013 and 0.82 owls/point in 2014. Six owls were marked during the study, and 3 of 6 locations were confirmed as daytime roosting sites. Statistically, there were no significant differences between occupied survey sites and telemetry sites, with only the percentage of canopy being significantly different with a mean difference of 9.32, t₄₂ = -2.36, p = 0.023. Both owls and transmitters were discovered in dense juniper-oak mottes on north-facing slopes, indicating a preference for dense, short, closed canopy areas for roosting. Overall vegetative ground cover for the two seasons averaged 54% and 48%, respectively. It was concluded that none of the included covariates in the models influenced either occupancy or detection probabilities, though detectability demonstrated an overall trend based on time of night. GIS models did not reveal any variable that strongly influenced owl occupancy but did correspond with results from previous literature.

Conservation of endangered Indiana bats (Myotis sodalis) requires knowledge of regional habitat use patterns. I radio-tracked Indiana bats to roosts and foraging areas to document summer habitat use. Sexes selected different roost trees: reproductive females selected maples, whereas males selected elms and other species, but did not use maples. Distribution models based on environmental correlates revealed that soil series was the strongest contributor to niche models. Females selected roosts in silt loams; males selected roosts in muck, silt loam and fine sandy loams. All bats foraged in habitats over fine sandy and gravelly loams. Male roosts and female foraging areas were found near local water body elevations, though males foraged at higher elevations. The niche models suggest that sexes roost and forage separately, but that ranges for these activities overlap. My findings identify habitats selected by Indiana bats thereby enabling more effective conservation for this endangered species.

I estimated patterns of shorebird abundance and species diversity in the Colorado River Delta and Upper Gulf of California wetlands in order to determine the relative contribution of intertidal wetlands and non-tidal anthropogenic wetlands to support shorebird habitat use. Species richness varied from 15 to 26 species among sites and 29 species were detected across sites. Density during the peak migration month was higher at the anthropogenic wetland Cienega de Santa Clara (mean = 168 ind/ha, 95% C.I. 29-367), and the intertidal Golfo de Santa Clara (mean = 153 ind/ha, 95% C.I. 17-323). Anthropogenic wetlands (playa and lagoons) supported high abundance of shorebirds along with intertidal wetlands in the Colorado River Delta (mudflats). In contrast, intertidal wetlands farther south on the Sonoran Coast presented lower abundance but higher diversity of shorebird, likely as a result of the higher diversity of habitats (rocky shore, sandy beach, estuary). I modeled water management scenarios for the Cienega in order to determine the response of the dominant vegetation (southern cattail, Typha domingensis Pers.) and the area of the outflow pool below the marsh to different scenarios of water management. The model indicates that if the inflow rate is reduced below the current 4-5 m ³ s^-1 the vegetated area of the Cienega that supports habitat for marsh birds would decrease in proportion, as would the area of the outflow pool in the Santa Clara Slough identified previously as shorebird habitat. Increases in salinity will also reduce the vegetated area due to the low salt tolerance of T. domingensis. In winter about 90% of inflow water exits the Cienega into the Santa Clara Slough due to low evapotranspiration contributing to inundate areas that are used by wintering and migrating shorebirds. Lastly, I explored the feasibility of using Vegetation Indices (NDVI and EVI) to model Yuma Clapper Rail detections in the Cienega de Santa Clara as well as the effects of adding other habitat variables and the presence of fire events in the performance of linear models based on NDVI. Both NDVI and EVI were positively related to the Yuma Clapper Rail detections. The relationship was weak to moderate, but significant (P < 0.001), which suggests other factors besides the vegetation condition play an important role in the bird distribution pattern. A model including all the variability among years was a better predictor of the rails detected per transect, than models for fire and non-fire years. We did not find a significant effect from adding habitat features (water % or vegetation %), and we recommend to include variables at both microhabitat level and landscape level, relevant before and during the breeding season in order to increase the explanatory power of models.