Natal Range Research Articles

Occurrences and activities of New Zealand sea lions Phocarctos hookeri at non-natal Macquarie Island (1965–1980)

ABSTRACT The distribution of New Zealand sea lions is typically localised to New Zealand and its remote subantarctic islands. However, non-resident male sea lions were seen on Macquarie Island, 650 km from their nearest natal islands, in all months of all years from 1965 to 1980. The majority of the apparently opportunistic sightings were at the northern end of the island. Sightings increased from May to a September-October peak that was coincident with the cessation of breeding activities in the sea lions’ natal range and the period when resident gentoo and royal penguins, and fur and elephant seals aggregated for breeding, all of which are now confirmed prey for New Zealand sea lions on Macquarie Island. The long-term effect of predation pressure from New Zealand sea lions on resident species remains unmeasured. After sleeping, interacting with southern elephant seals was a core sea lion activity. Predation on seabirds and interactions with elephant seals increase the risk of cross-species disease transmission.

Using Stable Isotopes to Determine Natal Origin and Feeding Habits of the Army Cutworm Moth, Euxoa auxiliaris (Lepidoptera: Noctuidae).

The army cutworm, Euxoa auxiliaris (Grote), is a migratory noctuid that is both an agricultural pest and an important late-season food source for grizzly bears, Ursus arctos horribilis (Linnaeus, Carnivora: Ursidae), within the Greater Yellowstone Ecosystem. Beyond the confirmation of the moths' seasonal, elevational migration in the mid-1900s, little else has been documented about their migratory patterns. To address this missing ecological component, we examined (1) migratory routes during their spring and fall migratory periods throughout their natal range, the Great Plains, and (2) natal origin at two of their summering ranges using stable hydrogen (δ2H) analyses of wings from samples collected within the areas of interest. Stable carbon (δ13C) and stable nitrogen (δ15N) analyses of wings were used to evaluate larval feeding habits of the migrants and agricultural intensity of natal origin sites, respectively. Results suggest that, rather than migrating exclusively east to west, army cutworm moths are also migrating north to south during their spring migration. Moths did not exhibit natal origin site fidelity when returning to the Great Plains. Migrants collected from the Absaroka Range had the highest probability of natal origin in Alberta, British Columbia, Saskatchewan, the most southern region of the Northwest Territories, and second highest probability of origin in Montana, Wyoming, and Idaho. Migrants collected in the Lewis Range had the highest probability of origin in the same provinces of Canada. Results suggest that migrants of the Absaroka Range fed exclusively on C3 plants as larvae and rarely fed in heavily fertilized agroecosystems.

Spatial ecology of translocated American Eel (Anguilla rostrata) in a large freshwater lake

American Eel (Anguilla rostrata) undertake extensive migrations from their rearing grounds to spawn in the Sargasso Sea, and historically the upper St. Lawrence River and Lake Ontario provided an important source for large, fecund female eel. Following declines in the Lake Ontario population, glass eel were translocated from eastern Canada from 2006 to 2010. From 2016 to 2018, large, presumably translocated yellow eel (N = 230) with the potential to begin maturing and out-migrating within their year of capture were collected in spring and fall and tagged with acoustic transmitters. Eel were released into eastern Lake Ontario and tracked to better understand their movement patterns prior to and during migration, and the timing of migration. Most eels successfully migrated out of Lake Ontario (64%). Timing of migration was consistent regardless of year or tagging season and primarily occurred in late summer or fall, with cooling water temperatures and decreasing sky illumination associated with initiation for fall tagged eel. Eels were mostly detected in eastern Lake Ontario and those in western Lake Ontario were mostly detected in shallow waters (< 20 m) close to shore. Eels were detected on fewer receivers in the winter, suggesting reduced movements during this season. Finally, larger individuals spent less time in the system, particularly when tagged in the fall. These findings confirm that translocated eels can migrate out of Lake Ontario; however, the weeks when migration occurred were more aligned with timing in their natal range (i.e., eastern Canada) than with naturally recruited eels from Lake Ontario. This temporal mismatch requires further consideration, since it may influence arrival times of translocated eel to the spawning grounds and their recruitment potential. These results can be used to inform future assessments of eel translocation efficacy and can also aid in the design of future tracking studies to more completely explore the downstream migration success of eel translocated into the highly productive waters of Lake Ontario.

Agricultural land use shapes dispersal in white-tailed deer (Odocoileus virginianus)

BackgroundDispersal is a fundamental process to animal population dynamics and gene flow. In white-tailed deer (WTD; Odocoileus virginianus), dispersal also presents an increasingly relevant risk for the spread of infectious diseases. Across their wide range, WTD dispersal is believed to be driven by a suite of landscape and host behavioral factors, but these can vary by region, season, and sex. Our objectives were to (1) identify dispersal events in Wisconsin WTD and determine drivers of dispersal rates and distances, and (2) determine how landscape features (e.g., rivers, roads) structure deer dispersal paths.MethodsWe developed an algorithmic approach to detect dispersal events from GPS collar data for 590 juvenile, yearling, and adult WTD. We used statistical models to identify host and landscape drivers of dispersal rates and distances, including the role of agricultural land use, the traversability of the landscape, and potential interactions between deer. We then performed a step selection analysis to determine how landscape features such as agricultural land use, elevation, rivers, and roads affected deer dispersal paths.ResultsDispersal predominantly occurred in juvenile males, of which 64.2% dispersed, with dispersal events uncommon in other sex and age classes. Juvenile male dispersal probability was positively associated with the proportion of the natal range that was classified as agricultural land use, but only during the spring. Dispersal distances were typically short (median 5.77 km, range: 1.3–68.3 km), especially in the fall. Further, dispersal distances were positively associated with agricultural land use in potential dispersal paths but negatively associated with the number of proximate deer in the natal range. Lastly, we found that, during dispersal, juvenile males typically avoided agricultural land use but selected for areas near rivers and streams.ConclusionLand use—particularly agricultural—was a key driver of dispersal rates, distances, and paths in Wisconsin WTD. In addition, our results support the importance of deer social environments in shaping dispersal behavior. Our findings reinforce knowledge of dispersal ecology in WTD and how landscape factors—including major rivers, roads, and land-use patterns—structure host gene flow and potential pathogen transmission.

Recruiting a long way from home: Domino damselfish Dascyllus trimaculatus can detect new temperate coral habitat and conspecifics

Climate change is driving tropicalisation of temperate reefs, yet it is unclear how range‐shifting tropical fishes locate suitable habitat. The authors tested whether juvenile tropical damsels Dascyllus trimaculatus could detect rare coral habitat (Pocillopora aliciae) and conspecifics on temperate rocky reefs using olfactory and visual preference experiments. For all cues, individuals selected and spent more time than expected in aquarium areas with the cue present, which included coral odour and conspecific odour and visual cues. This indicates that vagrant coral‐reef fish can detect rare suitable habitat outside of their natal range.

Postfledging survival and movements of juvenile Gray-backed Thrushes (Turdus hortulorum)

The postfledging period is a critical phase of avian life history. In the initial few weeks after fledging, juveniles face various hazards and develop necessary life skills. Knowledge of the postfledging period is important for understanding the fate of juvenile birds. From May to July of 2015, we tracked 22 Gray-backed Thrush (Turdus hortulorum) juveniles from 20 nests in a population in northeastern China using radiotelemetry. Juveniles dispersed from their natal sites for a mean (± SE) of 21.0 ± 2.4 d after fledging. The initial dispersal distance was 560.9 ± 109.4 m (the distance between the natal area and the first postdispersal area). The natal range size of the juveniles had a mean of 1.7 ± 0.5 ha (95% minimum convex polygons). Ten of 22 (45.5%) of the monitored fledglings died within the first 4 weeks after fledging, and predation was the primary cause of mortality. The Cox proportional-hazards regression model showed that there was a positive correlation between tarsus length and the survival rate of fledglings, while the influences of fledgling weight, date of fledging, and brood size on survival were not significant. Our results indicate that mammalian predators were the main threat to juveniles in the first few days after fledging when the juveniles had limited mobility. After the first week postfledging, raptors became the most important source of juvenile mortality.

Identifying nesting grounds for juvenile migratory birds with dual isotope: an initial test using North American raptors

AbstractUnderstanding seasonal mobility, population connectivity, and site fidelity is critical for managing and preserving migratory species. We investigated the potential of coupling strontium (87Sr/86Sr) and hydrogen (δ2H) isotopes in feathers for quantitatively constraining natal origin for juvenile migratory predatory birds (raptors) using a probabilistic framework. We first calibrated single‐isotope models that predict spatial isotope variability in raptor feathers (called isoscapes) by analyzing and compiling isotope data for juvenile birds with known origins in North America and comparing their values to existing isotopic baselines in precipitation (for δ2H) and bioavailable strontium (for 87Sr/86Sr). We then compared the potential of hydrogen and strontium isotopes for refining geographic assignments either independently or combined. While yielding very different probability maps, hydrogen and strontium isotopes performed equally well at constraining regions of natal origin. However, thanks to the complementarity of these isotopes, dual δ2H and 87Sr/86Sr assignments increased predictive precision by an order of magnitude compared to either isotope alone. Lastly, we used the models to predict natal origin for juveniles with unknown origins that were sampled in southwestern Idaho, USA, during their autumn migration. The precision of geographic assignments for birds with unknown origins varied. Nevertheless, dual‐isotope assignments clearly distinguished individuals born outside of southwestern Idaho, and overall, predicted geographic assignments matched breeding ranges for the study species. Quantitative dual‐isotope geographic assignments enhance our ability to predict natal range of migratory raptors and complement other methods for monitoring movement and population connectivity. Combining isotopic data from feathers with other intrinsic geochemical and genetic data, as well as extrinsic markers, such as transmitters or bands, and niche‐modeling approaches will further refine key nesting areas for migratory birds.

Sex differences in condition dependence of natal dispersal in a large herbivore: dispersal propensity and distance are decoupled.

Evolution should favour plasticity in dispersal decisions in response to spatial heterogeneity in social and environmental contexts. Sex differences in individual optimization of dispersal decisions are poorly documented in mammals, because species where both sexes commonly disperse are rare. To elucidate the sex-specific drivers governing dispersal, we investigated sex differences in condition dependence in the propensity and distance of natal dispersal in one such species, the roe deer, using fine-scale monitoring of 146 GPS-collared juveniles in an intensively monitored population in southwest France. Dispersal propensity increased with body mass in males such that 36% of light individuals dispersed, whereas 62% of heavy individuals did so, but there was no evidence for condition dependence in dispersal propensity among females. By contrast, dispersal distance increased with body mass at a similar rate in both sexes such that heavy dispersers travelled around twice as far as light dispersers. Sex differences in the strength of condition-dependent dispersal may result from different selection pressures acting on the behaviour of males and females. We suggest that females disperse prior to habitat saturation being reached, likely in relation to the risk of inbreeding. By contrast, natal dispersal in males is likely governed by competitive exclusion through male-male competition for breeding opportunities in this strongly territorial mammal. Our study is, to our knowledge, a first demonstration that condition dependence in dispersal propensity and dispersal distance may be decoupled, indicating contrasting selection pressures drive the behavioural decisions of whether or not to leave the natal range, and where to settle.

In situ feeding as a new management tool to conserve orphaned Eurasian lynx (lynx lynx).

High human‐caused mortality due to wildlife‐vehicle‐collisions and illegal killing leads to frequent cases of orphaned Eurasian lynx juveniles. Under natural conditions, this would result in starvation of the young. To avoid this, wildlife managers conventionally rear animals in captivity and release them later. However, this measure is an undesirable outcome for species conservation, managers, and animals alike. Increased awareness of Eurasian lynx orphaned by human‐caused mortality means managers must often intervene in endangered populations. In this study, we report for the first time a successful case of in situ feeding designed to avoid captivity of two orphaned Eurasian lynx. We exposed 13 roe deer and 7 red deer carcasses in the field to successfully support two orphans to the age of independence and confirm dispersal from the natal range. We present this management approach as a feasible and complimentary tool that can be considered in small or isolated large carnivore populations where every individual counts toward population viability.

Demographic responses of forest-utilizing bats to past climate change in South Africa

AbstractHistorical forest contractions may have restricted the distributions of forest-utilizing fauna while providing opportunities for range expansions for open-habitat species. We aimed to test if habitat associations have played an important role in determining population genetic structure and demographic responses of six bats to oscillations in forest extent since the Last Glacial Maximum (LGM). We hypothesized that forest-associated species would display high levels of population structure and past population contractions as their distribution is dependent on fragmented forests. By contrast, habitat generalists would demonstrate low geographical structuring and historical population stability as suitable habitats are widely available. We used mitochondrial DNA to generate genetic diversity and population structure metrics of three forest-associated species and three habitat generalists in South Africa. Neutrality tests and Bayesian skyline plots were used to investigate demographic histories. A forest habitat association did not inform the population genetics of the study species. Rather, species-specific traits of roosting requirements, philopatry to the natal range and dispersal ability informed the observed structure. All species demonstrated population expansions during the Pleistocene, with no apparent decline during the LGM. It appears that the lower climate change footprint and refuge-status of eastern South Africa prevented population declines of insectivorous bats during the LGM.

Home range establishment and the mechanisms of philopatry among female Bornean orangutans (Pongo pygmaeus wurmbii) at Tuanan

Female orangutans exhibit natal philopatry, living in stable home ranges that overlap with those of their maternal relatives. Using data collected from 2003 to 2017 at Tuanan in Central Kalimantan, Indonesia, we take a longitudinal approach to better understand the mechanisms of female philopatry and the factors that influence the home range establishment process of young female orangutans (Pongo pygmaeus wurmbii). Data on movement and sociality were collected during nest-to-nest focal follows of individual orangutans; four young nulli/primiparous females, their three multiparous mothers, and seven other unrelated adult females living in the same area. Our results show that a young female goes through an ‘exploration phase’, beginning when she is an independent immature and lasting through her adolescence, characterized by an increase in home range size and distance travelled each day. This exploration is facilitated by high resource availability and association with adult males. A young female maintains a high degree of overlap with her natal range but gradually decrease the degree of overlap with her mother’s concurrent range. By the time she is a sexually active adolescent, a young female and her mother share as much overlap as a young female does with other related adult females, although she continues to associate more with her mother than with them, even after the birth of her first offspring. Our findings indicate that the high habitat productivity and high orangutan population density of Tuanan lead to a high degree of life-time site fidelity and overlap among maternal kin. The mechanisms of philopatry and the process of home range establishment among solitary animals with slow life histories are difficult to study and poorly understood for most species. We investigated this process among female Bornean orangutans, using a unique long-term data set comprising 15 years of social and spatial data. We analysed changes in the ranging and association patterns of young female orangutans as they developed, matured and became mothers. We found that females went through a post-dependence phase of exploration characterized by an increase in range size and day journey length, and then settled into home ranges that overlapped highly with their mothers and other female kin, though they associated preferentially with their mothers. Our results illuminate the extreme long-term site fidelity of these female orangutans and emphasize the ecological and social importance of female philopatry among orangutans.

Unmonitored releases of small animals? The importance of considering natural dispersal, health, and human habituation when releasing a territorial mammal threatened by wildlife trade

Unmonitored release is a common practice, especially in small animals, that present a series of adverse conditions if not well-planned. Small research centers and non-governmental organizations in developing countries often receive animals that are then subject to unmonitored releases. We explored the patterns of post-release and natal dispersal in the Javan slow loris, a Critically Endangered venomous and territorial mammal that is highly threatened by wildlife trade. We then determined the importance of health status and human habituation for the survival of translocated and natally dispersing animals. We collected data from 2012 to 2018 on pre-release and pre-dispersal health conditions and human habituation, post-release and post-dispersal presence of wounds, behavior, and ranging patterns of 11 translocated and 11 natally dispersing individuals and compared them with 12 stable resident individuals. Translocated animals had a larger home range size (15.9 ± 4.1 ha) and higher wound presence during recaptures (0.47 ± 0.13) than stable resident individuals (3.2 ± 3.0 ha; 0.10 ± 0.06) but they did not differ from natally dispersing individuals (13.8 ± 3.7 ha; 0.28 ± 0.11). Both translocated and natally dispersing individuals can move to a different habitat type compared to their release area or natal range. The fate of both translocated and natally dispersing individuals was influenced by their health state (p < 0.001), and human habituation significantly affected the possibility of being captured for wildlife trade of translocated individuals (p = 0.048). We highlight the importance of considering natal dispersal, health state, and human habituation before the release of small animals to avoid death and capture for wildlife trade.

Beyond dispersal versus philopatry? Alternative behavioural tactics of juvenile roe deer in a heterogeneous landscape

Although inter‐individual heterogeneity in many aspects of dispersal behaviour is widely reported, this key life‐history trait is predominantly modelled as a dichotomous state of philopatry versus dispersal. The increasing body of evidence for dispersal syndromes (i.e. a suite of correlated morphological, behavioural and life‐history traits associated with dispersal) implies substantial but, to date, undocumented individual heterogeneity in behavioural tactics during dispersal. Using a large sample (n = 154) of GPS monitored juvenile roe deer Capreolus capreolus, we evaluated among‐individual behavioural heterogeneity in dispersal tactics, and the individual and environmental drivers of these alternative tactics. We developed a sequential three‐stage decision tree based on space use stability, exploration events and the directionality of movement. We identified six discrete alternative behavioural tactics during the dispersal period which were characterised by different timing, amplitude and duration in movement: slightly less than half of the deer were sedentary, either ‘strictly philopatric’ or ‘explorers’, which subsequently settled on their natal range; around 40% dispersed (‘classic dispersal’), of which, one in six subsequently aborted, moving back to their natal range (‘aborted dispersal’); finally, around 15% expressed either a ‘progressive dispersal’ tactic, gradually moving away from their natal area to settle elsewhere, or a ‘multi‐range’ tactic. The propensity to express an alternative dispersal tactic was strongly influenced by an individual's local environment. In particular, when landscape heterogeneity, resource quality and human‐related disturbance in the natal range were low, individuals were 1) more likely to adopt the alternative tactics of either progressive dispersal or multi‐ranging, but 2) also more likely to abort their dispersal attempt. Our work indicates that natal dispersal is likely not a single uniform behaviour, but that individuals may adopt a variety of alternative movement tactics which are likely governed by different selection pressures, with potentially important impacts for population dynamics and functioning.

An initial record of a long-distance dispersal route of a male sika deer in central Japan

Abstract We conducted a global positioning system (GPS) tracking of a male sika deer (Cervus nippon) and his mother in the eastern foothills of the northern Japanese Alps, central Japan. Sika deer exhibited similar seasonal movement patterns; however, the male deer left his natal group at 11 months of age. At 15 months of age, the male deer settled in the neighboring mountain, which was 74 km away from his natal range. This is the first record of long-distance (&gt;50 km) natal dispersal of the sika deer. Our findings might help to explain the expanding distribution of the sika deer.

Natal habitat preference induction in large mammals-Like mother, like child?

Habitat selection has received considerable attention from ecologists during the last decades, yet the underlying forces shaping individual differences in habitat selection are poorly documented. Some of these differences could be explained by the early experience of individuals in their natal habitat. By selecting habitat attributes like those encountered early in life, individuals could improve resource acquisition, survival, and ultimately fitness. This behavior, known as natal habitat preference induction (NHPI), could be particularly common in large mammals, because offspring generally stay with their mother for an extended period. We used three complementary approaches to assess NHPI in a marked population of woodland caribou (Rangifer tarandus caribou): (a) population‐based resource selection functions (RSFs), (b) individual‐based RSFs, and (c) behavioral repeatability analyses. All approaches compared the behavior of calves in their natal range to their behavior as independent subadults during the snow‐covered (Dec–Apr) and snow‐free (May–Nov) seasons. Using RSFs, we found that the magnitude of habitat selection between calf and subadult stages differed for most covariates, yet the signs of statistically significant effects (selection vs. avoidance) were generally the same. We also found that some habitat selection tactics were highly repeatable across life stages. Notably, caribou responses to habitat disturbances were highly repeatable year‐round, meaning that different individuals reacted differently, but consistently, to disturbances. This study highlights the potential role of natal habitat preference induction in shaping individual differences in habitat selection in large mammals and provides valuable knowledge for the management and conservation of a threatened species.

The importance of spatial scale in habitat selection by European beaver

We evaluated habitat selection by European beaver Castor fiber L. across a spatial gradient from local (within the family territory) to a broad, ecoregional scale. Based on aerial photography, we assessed the habitat composition of 150 beaver territories along the main water bodies of the Vistula River delta (northern Poland) and compared these data with 183 randomly selected sites not occupied by the species. The beavers preferred habitats with high availability of woody plants, including shrubs, and avoided anthropogenically modified habitats, such as arable lands. Within a single family territory, we observed decreasing woody plant cover with increasing distance from a colony centre, which suggests that beaver habitat preferences depend on the assessment of both the abundance and spatial distribution of preferred habitat elements. We tested the importance of spatial scale in beaver habitat selection with principal coordinates of neighbour matrices analysis, which showed that the geographical scale explained 46.7% of the variation in habitat composition, while the local beaver density explained only 10.3% of this variability. We found two main spatial gradients that were related to the broad spatial scale: first, the most important gradient was related to the largest distances between beaver sites and was independent of woody plant cover and the local beaver site density. The second most important gradient appeared more locally and was associated with these variables. Our results indicate that European beaver habitat selection was affected by different scale‐related phenomena related 1) to central place foraging behaviour, which resulted in the clumped distribution of woody plants within the territory, and 2) local population density and woody plant cover. Finally, 3) habitat selection occurs independently across the largest spatial scale studied (e.g. between watersheds), which was probably due to the limited natal dispersal range of the animals.

Cougar Dispersal and Natal Homing in a Desert Environment

We present a review of cougar dispersal literature and the first evidence of natural (i.e., unmanipulated) homing behavior by a dispersing male cougar (Puma concolor) that sustained severe injuries crossing the northern Mojave Desert. Based on Global Positioning System and ground tracking data, the male traveled a total distance of 981.1 km at 5.03 km/d, including 170.31 km from the Desert National Wildlife Refuge to the northwestern Grand Canyon, where he sustained severe injuries. The interkill interval increased from 7.1 ± 2.7 d while he was in his natal range to 17.5 ± 4.9 d during dispersal. While homing, the male appeared to consume only reptiles until he died, 33.7 km from his capture site. In desert environments where prey availability is low, homing behavior may be an important strategy for dispersing cougars, providing a mechanism for persistence when the best quality habitats they encounter are already occupied by adult residents. Therefore, managing for habitat connectivity can ensure successful homing as well as dispersal on a greater scale than has been previously suggested. Elucidating the mechanisms that trigger homing during dispersal may provide critical insight into animal movements often overlooked as mundane behavior.

Genetic insights into dispersal distance and disperser fitness of African lions (Panthera leo) from the latitudinal extremes of the Kruger National Park, South Africa

BackgroundFemale lions generally do not disperse far beyond their natal range, while males can disperse distances of over 200 km. However, in bush-like ecosystems dispersal distances less than 25 km are reported. Here, we investigate dispersal in lions sampled from the northern and southern extremes of Kruger National Park, a bush-like ecosystem in South Africa where bovine tuberculosis prevalence ranges from low to high across a north-south gradient.ResultsA total of 109 individuals sampled from 1998 to 2004 were typed using 11 microsatellite markers, and mitochondrial RS-3 gene sequences were generated for 28 of these individuals. Considerable north-south genetic differentiation was observed in both datasets. Dispersal was male-biased and generally further than 25 km, with long-distance male gene flow (75–200 km, detected for two individuals) confirming that male lions can travel large distances, even in bush-like ecosystems. In contrast, females generally did not disperse further than 20 km, with two distinctive RS-3 gene clusters for northern and southern females indicating no or rare long-distance female dispersal. However, dispersal rate for the predominantly non-territorial females from southern Kruger (fraction dispersers ≥0.68) was higher than previously reported. Of relevance was the below-average body condition of dispersers and their low presence in prides, suggesting low fitness.ConclusionsLarge genetic differences between the two sampling localities, and low relatedness among males and high dispersal rates among females in the south, suggestive of unstable territory structure and high pride turnover, have potential implications for spread of diseases and the management of the Kruger lion population.

The floater's dilemma: use of space by wild solitary Azara's owl monkeys, Aotus azarae, in relation to group ranges

The fate and behaviour of animals that leave their natal group (‘floaters’) is usually poorly understood, which can limit the understanding of a species' population dynamics. Attempted immigrations can have serious negative effects on residents who therefore may forcibly reject intruders. Consequently, floaters face a dilemma: they need to leave their natal range to find a breeding territory while trying to avoid potentially lethal rejections from established groups. To examine the hypothesis that floating Azara's owl monkeys avoid established groups temporally, we compared time-matched locations of floaters and groups with randomly selected distances. To examine the hypothesis that floaters avoid established groups spatially, we compared the utilization distribution overlap indices (UDOIs) for core areas of floaters and groups with randomly expected UDOIs. Based on average home range sizes and areas of overlap between floaters, we estimated the floater density in the study area to be 0.2–0.5 per group. The temporal avoidance hypothesis was not supported, since time-matched distances were smaller than distances of random locations, and not larger as predicted under this hypothesis. The spatial avoidance hypothesis, in contrast, was supported, with smaller UDOIs for core ranges than predicted. In conclusion, solitary owl monkeys seem to solve the floater's dilemma by trying to stay in relatively close proximity to groups while still avoiding their core ranges. Floaters thus maximize the number of groups with which they have contact, while being able to leave a group's territory quickly if detected by residents. While no marked sex differences in patterns were detected, there was a strong stochastic element to the number of floaters of a particular sex, thus resulting in a locally uneven operational sex ratio. This, in turn, can have important consequences for various aspects of the population dynamics.

Proximate influences on female dispersal in white‐tailed deer

ABSTRACTUltimate causes of animal dispersal have been hypothesized to benefit the dispersing individual because dispersal reduces competition for local resources, potential for inbreeding, and competition for breeding partners. However, proximate cues influence important features of dispersal behavior, including when dispersal occurs, how long it lasts, and direction, straightness, and distance of the dispersal path. Therefore, proximate cues that affect dispersal influence ecological processes (e.g., population dynamics, disease transmission, gene flow). We captured and radio‐marked 277 juvenile female white‐tailed deer (Odocoileus virginianus), of which 27 dispersed, to evaluate dispersal behavior and to determine proximate cues that may influence dispersal behavior. Female dispersal largely occurred at 1 year of age and coincided with the fawning season. Dispersal paths varied but generally were non‐linear and prolonged. Physical landscape features (i.e., roadways, rivers, residential areas) influenced dispersal path direction and where dispersal terminated. Additionally, forays outside of the natal range that did not result in dispersal occurred among 52% of global positioning system (GPS)‐collared deer (n = 25) during the dispersal period. Our results suggest intra‐specific social interactions and physical landscape features influence dispersal behavior in female deer. Female dispersal behavior, particularly the lack of directionality, the semi‐permeable nature of physical barriers, and the frequency of forays outside of the natal range, should be considered in regard to population management and controlling the spread of disease. © 2016 The Wildlife Society.