Mean Home Range Size Research Articles

Environmental drivers of global variation in home range size of terrestrial and marine mammals.

As animal home range size (HRS) provides valuable information for species conservation, it is important to understand the driving factors of HRS variation. It is widely known that differences in species traits (e.g. body mass) are major contributors to variation in mammal HRS. However, most studies examining how environmental variation explains mammal HRS variation have been limited to a few species, or only included a single (mean) HRS estimate for the majority of species, neglecting intraspecific HRS variation. Additionally, most studies examining environmental drivers of HRS variation included only terrestrial species, neglecting marine species. Using a novel dataset of 2800 HRS estimates from 586 terrestrial and 27 marine mammal species, we quantified the relationships between HRS and environmental variables, accounting for species traits. Our results indicate that terrestrial mammal HRS was on average 5.3 times larger in areas with low human disturbance (human footprint index [HFI] = 0), compared to areas with maximum human disturbance (HFI = 50). Similarly, HRS was on average 5.4 times larger in areas with low annual mean productivity (NDVI = 0), compared to areas with high productivity (NDVI = 1). In addition, HRS increased by a factor of 1.9 on average from low to high seasonality in productivity (standard deviation (SD) of monthly NDVI from 0 to 0.36). Of these environmental variables, human disturbance and annual mean productivity explained a larger proportion of HRS variance than seasonality in productivity. Marine mammal HRS decreased, on average, by a factor of 3.7 per 10°C decline in annual mean sea surface temperature (SST), and increased by a factor of 1.5 per 1°C increase in SST seasonality (SD of monthly values). Annual mean SST explained more variance in HRS than SST seasonality. Due to the small sample size, caution should be taken when interpreting the marine mammal results. Our results indicate that environmental variation is relevant for HRS and that future environmental changes might alter the HRS of individuals, with potential consequences for ecosystem functioning and the effectiveness of conservation actions.

Satellite telemetry reveals space use of diamondback terrapins

Movement and space use information of exploited and imperiled coastal species is critical to management and conservation actions. While satellite telemetry has been successfully used to document movements of marine turtles, the large tag sizes available have limited use on smaller turtle species. We used small Argos-based satellite tags to document movement patterns of diamondback terrapins (Malaclemys terrapin), the only estuarine turtle species in North America. Movement data from ten terrapins in St. Joseph Bay, Florida were gathered between July 13, 2018 and July 22, 2021. We estimated seasonal space use using the daily locations generated from a Bayesian hierarchical state-space model to calculate minimum convex polygons (95% MCP) and kernel density estimates (50% and 95% KDE). Mean tracking duration was 125 days and mean home range size was 9.4 km2 (95% MCP) and 8.1 km2 (95% KDE). Seagrass habitat comprised 55.8% of all home ranges on average, whereas salt marsh comprised a mean of 3.0%. Mean elevation used by terrapins was − 0.13 m (95% MCP) and -0.35 m (95% KDE). Satellite telemetry provided broad-scale spatiotemporal movement and space use data; however, Argos error produced considerable noise relative to true terrapin movements given their size, speed, and behavior. Terrapin home ranges were greater than previously reported and three of the ten terrapins exhibited repeated long-distance, directed movements within the bay. Small patches of salt marsh habitat were centralized within home ranges, despite comprising only a small percentage for each terrapin. Moreover, the percentage of salt marsh present in each core use area was positively correlated with terrapin mass. Although considered an estuarine species, seagrass habitat comprised a large portion of terrapin home ranges; however, our data did not provide the detail necessary to understand how terrapins were using this habitat. As northward-expanding mangroves continue to infringe upon salt marsh habitat, there is potential for negative impacts to terrapin populations across the northern Gulf of Mexico. As salt marsh habitat continues to be infringed upon by northward-expanding mangroves impacts to terrapins across the northern Gulf of Mexico.

POTENTIAL SHARED DISEASE RISK AMONG DOGS AND COYOTES (CANIS LATRANS) EXEMPLIFIED BY THE ECOLOGY OF RICKETTSIOSIS IN A ROCKY MOUNTAIN SPOTTED FEVER-EPIDEMIC REGION IN NORTHERN MEXICO.

Rocky Mountain spotted fever (RMSF), caused by the bacterium Rickettsia rickettsii, is a re-emerging tick-borne zoonosis in North America, with hundreds of human fatalities in multiple outbreaks in northern Mexico and the southwestern US in the past few decades. Free-roaming dogs are key because they are reservoirs for the pathogen and the main hosts of the brown dog tick (Rhipicephalus sanguineus), which vectors RMSF in this region. Because coyotes (Canis latrans) can be infected with R. rickettsii and infested with Rh. sanguineus, we hypothesized that space sharing among dogs and coyotes could enhance disease risks. In summer 2021, we captured and sampled 11 coyotes at two sites in Baja California, Mexico, near population centers with human cases of RMSF, and fitted seven individuals with GPS logging collars. We also tested tissue samples, sera, and ectoparasites for DNA of R. rickettsii with PCR and used serology to detect antibodies to R. rickettsii. Finally, we deployed an array of cameras to document dog-coyote interactions. Mean home range size was 40.37 km2. Both GPS and camera data showed considerable home range overlap both between individual coyotes and between coyotes and dogs. Coyotes were active in areas where dogs occur including the domestic interface surrounding human settlements. Although none of our samples were positive for R. rickettsii on PCR, 72.7% (8/11) of the samples were seropositive with titers ≥64. Our data confirm shared space use and risk of shared parasites and disease between coyotes and dogs.

Post-release ecology of rehabilitated Hoffmann’s two-toed sloths in Panamá

The field of wildlife rescue and rehabilitation continues to grow as human expansion increases the rate of deforestation in Latin America. Sloths (Bradypus spp. and Choloepus spp.) are often admitted to rescue centers throughout Latin America due to their poor dispersal abilities and vulnerability to anthropogenic impacts. Although post-release monitoring is fundamental to measuring the success of wildlife rescue programs, few studies have assessed the outcomes of releasing hand-reared sloths back into the wild. We studied the ecology of rehabilitated and relocated Hoffmann’s two-toed sloths (Choloepus hoffmanni) in central Panamá during 2019- 2020. Eleven two-toed sloths rescued from the wild were hand-reared in captivity for 727±193 days and then radiomarked, placed in an outdoor 500 m2 soft-release enclosure for 3 months, and released in a nearby national park. While in the softrelease enclosure, two-toed sloths spent 80.0% of their time resting and became active and more alert in the evening (p=0.01). Upon release into the wild, two-toed sloths traveled a mean linear distance of 82.3±21.6 m and a mean distance of 25.6±9.5 m between successive radiolocations. The mean home range size was 2.92±1.19 ha, with females occupying larger areas than males. Two-toed sloths used trees with a smaller dbh than available (p≤0.001; p≤0.015) and selected trees with dense crowns and ≥50% lianas. Eight mortalities were recorded, with predation and natural causes being the main causes of mortality. Monthly survival was 0.72±0.14 and did not differ (p≤0.30) between males (1.00±0.00) and females (0.44±0.22). Rehabilitated two-toed sloths exhibited behavioral and space use patterns similar to wild two-toed sloths, with the exception of having lower survival rates following release in the wild. Our study provides information that can be useful in evaluating the efficacy of sloth rescue and rehabilitation programs throughout Latin America.

Effects of habitat loss on Brazilian primates: assessing extinction thresholds in the Amazon and Atlantic Forest

Habitat loss has major impacts on biodiversity. Yet, such impacts are not always linear, as there can be threshold values of habitat amount below which species become extirpated from human-modified landscapes (extinction thresholds). This may be particularly the case for species with high habitat spatial requirements, especially in regions with a long land-use history, which have a lower extinction debt. To address these issues, we evaluated the linear and non-linear effects of landscape-scale forest (habitat) loss on primate species richness in regions with relatively new (Amazon) and old (Atlantic Forest) histories of land-use change. We also evaluated the role of mean home range size in regulating species responses to forest loss. Extinction thresholds were higher in the Atlantic Forest (78% remaining forest cover) than in the Amazon (45%), but primate-landscape associations were stronger in the Amazon. Thus, despite its recent land-use history, Amazon primates are more sensitive to habitat loss. As predicted, mean home range size decreased with forest loss in both biomes. Our findings highlight the importance of stopping deforestation in both biomes to maintain habitat amount above these thresholds. Yet, as <30% of the Atlantic Forest cover remains today, promoting restoration initiatives across this biome is paramount.

King rail (Rallus elegans) home range and microhabitat characteristics in western Lake Erie coastal marshes.

The king rail (Rallus elegans) is a secretive marsh bird that is threatened or endangered in eight of nine states and provinces in the Laurentian Great Lakes (Great Lakes) region. Available survey data suggests that this species has undergone population declines across this region and these are believed to have been driven by habitat loss and degradation. An improved understanding of the amount and type of habitat king rails require during the breeding season at sites within the Great Lakes region would inform and improve progress toward conservation goals. During 2019-2021, we caught and radio-tagged 14 king rails in northwestern Ohio and southeastern Michigan within impounded coastal wetlands of western Lake Erie. We used radio telemetry to identify breeding season (May-August) home-range characteristics and third order habitat selection within home ranges (hereafter microhabitat). For the birds whose home range stabilized (N = 10), we found a mean home-range size of 8.8 ha (±1.63 [SE]; range = 1.9 to 15.8). We generated a classification tree to determine which habitat characteristics were associated with king rail presence within home ranges in our study. We found that vegetative density within home ranges was particularly associated with king rail presence. Phragmites australis was also associated with king rail presence, despite its invasiveness and negative ecological impacts in the region, and could be selectively maintained to benefit king rails. Our results suggest that managers may be able to provide microhabitat for king rails by maintaining water depths of 6 to 17 cm and by promoting native, robust vegetation in the genera Carex and Juncus. Our findings could help inform wetland managers and conservation planners in the Great Lakes region, particularly in western Lake Erie coastal marshes, of patch sizes, water depths, plant communities, and vegetative structure preferred by king rails.

Activity and nocturnal home range size of male common hippopotamus in Kruger National Park, South Africa

AbstractThe common hippopotamus (Hippopotamus amphibius) is a driver of ecological processes in African savannah aquatic and terrestrial ecosystems. Recent studies have highlighted the ecological impacts of hippos in these systems; however, these lack behavioural data to contextualise their ecological inputs. We fitted global positioning system (GPS) transmitter bracelets on male hippos (n = 3) in Kruger National Park, South Africa. The mean home range size for hippos using Adaptive Local Convex Hull (a‐LoCoH) home range (~6 km2) was smaller than previously documented. This study contributes baseline behavioural data for managing hippos in Kruger National Park and southern Africa.

Movement and ranging behaviour of long-nosed potoroos (Potorous tridactylus) in south-west Victoria, Australia

Context A comprehensive understanding of movements and space use can underpin the effective management of threatened species. GPS dataloggers can collect large amounts of high-quality movement data, and recent advances in statistical approaches allow for robust estimates of home range size to be generated. Until recently, technological and practical constraints have generally restricted the collection of movement data via GPS dataloggers to larger species. However, reductions in the size and weight of GPS dataloggers now allow for this technology to be applied to smaller species. Aims The aim of this study was to describe the home range and movement patterns of a nationally vulnerable, native Australian ground-dwelling mammal, the long-nosed potoroo (Potorous tridactylus), in south-west Victoria, mainland Australia. Methods We attached GPS dataloggers to 40 long-nosed potoroos between 2020 and 2022 and estimated home range size using dynamic Brownian Bridge movement models. We evaluated the influence of physiological factors such as body mass and sex on home range size and described patterns of home range overlap between and within sexes. Key results Mean home range sizes were estimated to be 13.73 ha (95% CI: 10.9–16.6) and 6.67 ha (95% CI: 5.49–7.85) for males and females respectively. Home range size scaled with body mass in males but not females, and ranges were largely overlapping – although there was some evidence of intrasexual spatial partitioning of core range areas in females. Conclusions Ours is the first application of GPS dataloggers to this species, and our home range estimates are over twice as large as other reported estimates for mainland Australia. Long-nosed potoroos may range across larger areas than previously predicted on mainland Australia. Implications This knowledge may be used to optimise the management of long-nosed potoroo populations before and after fire – a key threatening process for this species. Our study highlights the value of integrating GPS dataloggers and robust home range estimators when describing the movement ecology of a population.

Adult Home Range Size and Juvenile Movements of Gray Hawks in the Lower Rio Grande Valley, Texas, USA

ABSTRACT We studied the natural history of Gray Hawks (Buteo plagiatus) in the Lower Rio Grande Valley of Texas. We used GPS-GSM telemetry to quantify dispersal time and distance, winter home range size of juveniles, and home range size of adults. Home ranges were calculated using the kernel Brownian bridge home range estimator. The median dispersal date for 14 juvenile Gray Hawks was 11 August and they traveled a median straight-line distance of 453 km. Mean winter home range sizes for 11 juveniles was 707 ha. For juveniles, female winter home ranges were larger than those of males, and juvenile winter home ranges were larger in natural than in urban areas. Mean 95% home range sizes for 20 adult Gray Hawks was 530 ha. Mean adult male home range size was larger in natural than in urban areas. Adult Gray Hawks remained in their home ranges year-round.

Drivers of habitat quality for a reintroduced elk herd

Understanding spatiotemporal variation in habitat quality is essential for guiding wildlife reintroduction and restoration programs. The habitat productivity hypothesis posits that home range size is inversely related to habitat quality. Thus, home range size may be used as a proxy for habitat quality and can identify important land cover features for a recovering species. We sought to quantify variation in home range size across the biological cycle (seasons) for a reintroduced elk (Cervus canadensis) population in southwestern Virginia, USA and quantify habitat quality by linking home range sizes to the land cover types they contain using linear mixed-effects models. We found mean home range size was largest during late gestation for female elk. Additionally, throughout the year, smaller home ranges were associated with larger proportions of non-forested habitats whereas forested habitats were generally the opposite. However, both presumed poor- and high-quality habitats influenced female elk space use. Our approach revealed spatial variation in habitat quality for a recovering elk herd, demonstrated the importance of non-forested habitats to elk, can guide decisions regarding the location of future elk reintroduction programs, and serve as a model for evaluating habitat quality associated with wildlife reintroductions.

Ocelot, Leopardus pardalis (Mammalia, Carnivora, Felidae), home range in the Lowland Atlantic Forest of Southeastern Brazil

The ocelot is an important Neotropical mesopredator and information on its spatial ecology remains scarce. Here we estimated the ocelot home range in a remnant of Lowland Atlantic Forest in Southeastern Brazil. The data were collected by camera traps installed at eight known ocelot latrines. We estimated the home range both based on the Minimum Convex Polygon (MCP) and the 95% adaptive Kernel density estimator (95%K) to compare with other published studies. We identified 22 ocelots (adult males = 8; adult females = 12; cubs = 2). Six males were recorded at more than one latrine, while all females were recorded at only one sampling point. In addition to male ocelots being recorded at a large number of points, they showed greater intrasexual spatial overlap as they used the same latrines, suggesting larger home ranges than females. The mean home range size for males was 12.1 ± SE 4.4 km2(range = 6.2 to 20.8 km2) using MCP, and 19.9 ± SE 9.5 km2(range = 10.1 to 38.9 km2) applying 95%K. Despite our estimates representing an approximation of the total area used by males, both values are consistent with those reported from other locations. Our data complemented the gradient of vegetation type sampled for ocelots in Atlantic Forest and support the suggestion that this environmental variable and, consequently, its effect on prey availability, influence the home range size of ocelot. Information on population ecology and other spatial ecology data are also presented.

Home range of pampas deer in a human–dominated agro–ecosystem

The subspecies of pampas deer Ozotocerus bezoarticus uruguayensis is an endemic and endangered cervid from southeast Uruguay. However, knowledge regarding its home range requirements in agroecosystems is scarce. Our aim was to survey ten radio–collared pampas deer for two years to monitor their movements. The mean home–range size was 5.54 ± 3.18 km2. The core area size for all individuals monitored was 0.87 km2, which concurs with grazing crops for beef cattle. The population showed philopatric behavior and no significant differences were detected in the total area of occupation in respect to sex and season.

Movement, Home Range Size, and Habitat Use of Eastern Black-Tailed Rattlesnakes (Crotalus ornatus) in the Northern Chihuahuan Desert

Despite its wide distribution throughout the northern Chihuahuan Desert, extraordinarily little is known about the ecology or behavior of Eastern Black-tailed Rattlesnakes (Crotalus ornatus). The primary literature for Black-tailed Rattlesnakes was largely based on research conducted on the former conspecific (C. molossus); thus, the revalidation of C. ornatus widened the void in our understanding of the species. The aim of this study was to elucidate movement patterns, home range size, and habitat use by C. ornatus in the northern Chihuahuan Desert of far West Texas. Radiotelemetry was used to monitor individual snakes for at least one active season (March–October) from May 2015 through August 2018. Mean (±1 SE) home range size for all individuals was 22.84 ± 4.49 ha and mean daily distance moved was 9.28 ± 0.93 m/d. Male snakes had larger home range sizes, larger core use areas, and greater daily distance moved than did female snakes. On a monthly basis, male movement peaked in August and female movement was statistically similar throughout the active season. Multinomial logit models were used to analyze habitat use patterns of C. ornatus, while controlling for snake, habitat availability, and season. Despite limited availability within snake home ranges, most observations of snakes occurred in arroyos or on rocky slopes. Microhabitat was also used nonrandomly, with snakes seeking cover in rocky refugia or under dense vegetation, rather than in areas containing high proportions of gravel or plant litter. This study presents the first detailed information about habitat and microhabitat use, along with patterns of movement and home range size for the recently revalidated C. ornatus.

Jaguar (Panthera onca) spatial ecology outside protected areas in the Selva Maya

Jaguars (Panthera onca) are endangered in several countries and a priority species for conservation action. Despite extensive research efforts in Mexico most studies have been associated with natural protected areas far from human habitation. Because protected areas are too few to conserve the jaguar population over the long–term, a landscape approach that includes both protected and unprotected lands is needed. This is the case in Quintana Roo State where an ecological corridor linking two protected areas (Yum Balam and Sian Ka'an) is at risk of disappearing due to tourism–driven activities. Between 2013 and 2015, four male jaguars were captured and monitored using satellite telemetry inside the corridor. The mean home range size (± SD) was 101.5 km2 (± 75.9 km2) for the dry season and 172 km2 (± 107.29 km2) for the rainy season. The mean core area size (± SD) was 17.54 km2 (± 16.21 km2) for the dry season and 29.07 km2 (± 16.19 km2) for the rainy season. No significant seasonal differences were found for home ranges or for core areas. As expected, we observed that jaguars preferred forest or young secondary growth over profusely disturbed areas, using whatever vegetation was available in their home ranges. Although it is not protected, a biological corridor linking Yum Balam and Sian Ka'an still holds its own jaguar population, a population that has learned to coexist with human presence. Conservation actions are recommended at landscape level to maintain what remains of tropical mature forest and to promote the development of long–term secondary growth into close tree canopy

Factors affecting spatiotemporal behaviour in the European brown hareLepus europaeus: a meta‐analysis

AbstractThe European brown hareLepus europaeusis the most widely distributed hare species of the world, being naturally present throughout Eurasia and introduced as a game species in most continents. Despite the importance of this lagomorph for both management and conservation, a quantitative summary of its spatiotemporal behaviour is still lacking.Taking advantage of 51 selected studies conducted throughout the native range of the hare and spanning the last 40 years, we used meta‐analytic approaches in order to: 1) investigate home range size in relation to ecological factors; 2) test preference across major habitat types; and 3) provide a quantitative synthesis of hare activity patterns.Temporally adjusted home range size of hare populations decreased with increasing cropland cover (cereal and non‐cereal crops), suggesting that home range size gets smaller with increasing food availability, and predicting that hare populations living in absence of crops would double their mean home range size compared to those inhabiting areas covered entirely by cropland. Hare populations where more males were sampled showed larger home ranges, in line with the polygynous mating system of this species.Hares preferred cropland and grassland over other habitats for foraging, thus selecting the two habitats characterised by the majority of trophic resources for this species. Yet, habitat types were used proportionally to their availability overall, except for the general avoidance of human settlements. Hares were mainly nocturnal, with the lowest activity during daytime, when activity was about one third of that at night, and showed moonlight avoidance, probably to limit encounters with nocturnal predators.Our work emphasises the importance of open habitats and especially cropland for this lagomorph, but also suggests some plasticity in the use of space and time by hares. Such plasticity may help this mammal to cope with future environmental changes, providing that landscape heterogeneity is maintained.

Habitat preferences of adult Canada Jays (Perisoreus canadensis) during the post-breeding period in Algonquin Provincial Park, Ontario, Canada

Habitat preferences in animals are often examined during the breeding period when individuals are easier to observe. However, habitat use may change once young become independent and if resource availability shifts with seasonality. While Canada Jays ( Perisoreus canadensis (Linnaeus, 1766)) in Algonquin Provincial Park, Ontario, Canada, have been studied for several decades, there is no information on habitat use outside of the fall and late-winter nesting period, where they primarily used conifer forests. Using radio telemetry and resource selection functions comparing used versus available habitats, we estimated home-range size and habitat preferences of 12 adult Canada Jays ( n = 334 locations) in the spring and summer. Mean (±SD) home-range size from minimum convex polygons was 84 (±48 ha) and ranged from 35 to 201 ha. Canada Jays strongly preferred forest–wetland edges, showed a weak preference for coniferous forests, a corresponding weak avoidance of shade-tolerant hardwood forests, and used mixed forest and wetlands in proportion to their availability. Our results suggest that, while adult Canada Jays use multiple types of habitat during the post-breeding period, they also key into forest–wetland edges, likely to take advantage of emergent prey while remaining near forested areas to maximize protection from predators.

Movement ecology of vulnerable lowland tapirs between areas of varying human disturbance

BackgroundAnimal movement is a key ecological process that is tightly coupled to local environmental conditions. While agriculture, urbanisation, and transportation infrastructure are critical to human socio-economic improvement, these have spurred substantial changes in animal movement across the globe with potential impacts on fitness and survival. Notably, however, human disturbance can have differential effects across species, and responses to human activities are thus largely taxa and context specific. As human disturbance is only expected to worsen over the next decade it is critical to better understand how species respond to human disturbance in order to develop effective, case-specific conservation strategies.MethodsHere, we use an extensive telemetry dataset collected over 22 years to fill a critical knowledge gap in the movement ecology of lowland tapirs (Tapirus terrestris) across areas of varying human disturbance within three biomes in southern Brazil: the Pantanal, Cerrado, and Atlantic Forest.ResultsFrom these data we found that the mean home range size across all monitored tapirs was 8.31 km2 (95% CI 6.53–10.42), with no evidence that home range sizes differed between sexes nor age groups. Interestingly, although the Atlantic Forest, Cerrado, and Pantanal vary substantially in habitat composition, levels of human disturbance, and tapir population densities, we found that lowland tapir movement behaviour and space use were consistent across all three biomes. Human disturbance also had no detectable effect on lowland tapir movement. Lowland tapirs living in the most altered habitats we monitored exhibited movement behaviour that was comparable to that of tapirs living in a near pristine environment.ConclusionsContrary to our expectations, although we observed individual variability in lowland tapir space use and movement, human impacts on the landscape also had no measurable effect on their movement. Lowland tapir movement behaviour thus appears to exhibit very little phenotypic plasticity in response to human disturbance. Crucially, the lack of any detectable response to anthropogenic disturbance suggests that human modified habitats risk being ecological traps for tapirs and this information should be factored into conservation actions and species management aimed towards protecting lowland tapir populations.

Northern Bobwhite Response to Vegetation Management and Recovery in South Texas

The northern bobwhite (Colinus virginianus; hereafter, bobwhite) requires habitat structure and composition with grass cover for nesting, predator avoidance, and thermal refuge and forb cover for feeding on phytophagous arthropods and seeds. During the past 2 decades, many land managers with interest in promoting quail hunting opportunities have reduced or completely eliminated livestock across South Texas, USA, rangelands. Resting the land from grazing allows vegetation—especially grasses and forbs—to recover and thus provide nesting and foraging habitat for bobwhite and other birds. How bobwhite respond to postgrazing vegetation recovery is of keen interest to rangeland quail managers, but this topic is poorly known because case histories with quantitative data are lacking. Our objective was to investigate how bobwhite respond to the vegetation changes following removal of cattle grazing. Our study was conducted on a private ranch in Jim Hogg County, Texas and involved 3 different categories of postgrazing recovery and management: 1 area at 15 years post-cattle grazing where the landscape has been brush-sculpted and is actively managed since removal of cattle, 1 area at 3 years post-grazing with a previous stocking density of 7 ha/animal unit (high stocking density), and 1 area at 3 years post-grazing with a previous stocking density of 14 ha/animal unit (moderate stocking density). We trapped, radio-marked, and located bobwhites from March to September during 2015–2016 on the 3 comparative units. We estimated nest survival, adult breeding-season survival, home range size, and early winter density. We hypothesized that the 15-year postgrazing site would have higher early winter density, higher adult breeding season survival, and higher nest survival along with smaller mean home range size compared to the 2 more recently grazed sites. On average, the probability of a nest surviving the 23-day incubation period was highest on the 15-year postgrazing site at 0.61 ± 0.12 (mean nest survival ± standard error), with estimates of 0.32 ± 0.12 on the 3-year moderate postgrazing site and 0.33 ± 0.12 on the 3-year high postgrazing site. Adult breeding season survival did not differ among the 3 sites, and was instead influenced mostly by month within the season, probably a result of summer heat. An adult bobwhite had a 0.48 ± 0.04 probability of surviving the breeding season. Early winter density, after summer and fall production was complete, increased on all sites from 2015 to 2016 and was consistently highest on the 15-year postgrazing site. Home range sizes on the

Nonbreeding season ecology and behavior of Eastern Towhees (Pipilo erythropthalmus)

Eastern Towhees (Pipilo erythropthalmus) are partial migrants that inhabit dense thickets of shrubs in both breeding and nonbreeding seasons and have declined range-wide by approximately 50% since the mid-1960s. Few studies have addressed the nonbreeding season natural history of Eastern Towhees. The objectives of our study were to (1) describe and quantify nonbreeding habitat use and social interactions, and (2) relate these metrics to winter weather conditions. We captured and radio-tagged 9 Eastern Towhees and tracked them using homing and triangulation for a total of 528 locations from late November 2015 to March 2016, plus 3 Eastern Towhees tracked in 2014–2015. The mean (± SE) home range size (80% kernel isopleth) was 7.31 ± 0.22 ha, and the mean (± SE) core area (30% kernel isopleth) was 1.52 ± 0.94 ha. The mean overlap of home ranges between neighbors was 36%, and 24% between neighboring core areas. The study area was classified into 4 habitats: mowed, blackberry scrub, woody shrub, and wooded. Habitat use did not directly correspond with availability: Eastern Towhees occupied woody shrub habitat most (48% of locations vs. 35% of available habitat), suggesting that of our 4 habitat types, woody shrub was preferred. For weather, wind speed did not significantly affect habitat use, foraging method, vocalizations, or flock size. Although temperature did not significantly affect any of the behaviors, there were trends for less ground foraging and more use of wooded habitat in freezing temperatures. Snow cover influenced habitat use (odds ratio = 0.60), vocalizations (odds ratio = 1.77), and flock size (odds ratio = 1.97), but not foraging. These results contribute to understanding the nonbreeding natural history of Eastern Towhees and demonstrate that inclement weather in the nonbreeding season may influence habitat use and behaviors in ways that could affect nonbreeding season survival.

Migration and Home Range of the Grey Heron (Ardea cinerea) in the Republic of Korea

This study was conducted to determine the size of the breeding season home range and the migration pattern of Grey Heron (Ardea cinerea) using global positioning system telemetry in Daejeon, Republic of Korea. Four Grey Heron were successfully tracked between 15 March and 16 November 2016. The home range size for Grey Herons was estimated by minimum convex polygon (MCP) and kernel density estimation (KDE) of 90%, 70% and 50%. The mean home range size estimated by MCP varied among individuals, ranging from 14.3 to 1,372.1 km2 (mean = 492.3 km2). The mean home range size using the kernel density estimation, which is indicative of the core area of a home range, was 114.2 km2 (range = 1.8-352.2 km2). Of the four successfully tracked herons, two individuals stopped several times during their migration to the southern part of China. Further studies into habitat selection, seasonal patterns, and species-threatening factors would assist in the proper management of this species.