Search

Natural selection favors individuals with the highest inclusive fitness (i.e., total number of descendants). In cases where one sex is more productive, one or both parents may maximize their inclusive fitness by investing in the offspring of the more prolific sex. Such preferential production can lead to skewed sex ratios at various life history stages, including at birth, resulting in secondary sex ratio bias. Several competing hypotheses have been proposed to explain observed variation in secondary sex ratios including Fisher's frequency dependence and two hypotheses related to maternal condition: Trivers–Willard and the local resource hypotheses. Although it has been shown that maternal condition can influence the number of offspring produced in white‐tailed deer, there is no consensus as to which of the hypotheses drives sex ratio bias in wild populations. Using a spatiotemporally extensive dataset of pregnant white‐tailed deer from Mississippi, USA, we examined fetal sex ratio in relation to the Fisherian frequency‐dependence hypothesis and hypotheses related to maternal condition. While there was a male‐sex ratio bias in pregnant females that reduced in intensity with the number of offspring, there was no support for condition‐related hypotheses. Instead, secondary sex ratios for white‐tailed deer in Mississippi were nearly consistent with Fisherian frequency dependence. Our findings add to the body of literature on secondary sex biases in white‐tailed deer and help inform sex bias ratios for a southern population of a cervid of management importance in the US. [ABSTRACT FROM AUTHOR]

Wildlife disease outbreaks can lead to population declines, which are usually attributed to increased direct or indirect mortality. Alternatively, behavior associated with sickness can lead to social isolation, potentially decreasing fitness of affected individuals. A useful case study to examine this dynamic is chronic wasting disease (CWD), a neurological disease of cervids, known to affect behavior and movement. In this study, we monitored scraping, a White-tailed Deer (Odocoileus virginianus ; WTD) breeding season behavior, in an area of high CWD prevalence to determine if this reproductive behavior is affected by CWD. At 107 scrape sites, we detected 3,063 scrape interactions and 218 unique bucks. Bucks engaged with scrapes most often, performing 73% of interactions—compared to 23% by does, and 4% by fawns. Twenty-one bucks captured on camera traps at scrape sites were harvested through recreational hunting, 13 testing CWD-positive and 8 CWD not-detected. We found no significant effect of CWD status on specific scraping behaviors. There may, however, have been population-level effects, with shifts toward greater proportions of scraping by yearling bucks and during daylight hours compared to findings from past studies. [ABSTRACT FROM AUTHOR]

Untangling the abiotic and biotic feedback mechanisms driving animal movements and ranges is a core question in ecology, yet progress is hampered by inadequate modelling procedures. Here we show how a recently developed process‐based modelling approach, combining step‐selection functions and individual‐based models, enables a flexible method to infer movement drivers and multi‐scale emergent space use patterns. As a case study, we examine the movement behaviours of a highly invasive social generalist (wild pigs, Sus scrofa) in relation to conspecific space use and multiple land cover types in a complex agricultural landscape, showing that social interactions are predominantly more important to this species than selection for land cover. Thus, animal movement studies should not neglect the effects of sociality when inferring resource driven movements and, crucially, use multi‐scale techniques that incorporate movement processes to untangle drivers of animal space use. [ABSTRACT FROM AUTHOR]

Managers use morphometric data collected from harvested animals as indicators of nutritional condition. Antler or horn size often are considered in ungulates, but there are problems associated with biased and limited harvest data available from male animals in many populations. Adult female body mass also may be collected, but little information exists on how male antler size scales with female body mass. We evaluated the relationship between property‐specific mature male white‐tailed deer (Odocoileus virginianus) antler size and adult female body mass from harvest data collected at 2 spatial scales. Regression predicted a 4.4‐cm increase in average mature male antler size for every 1‐kg increase in female body mass from 31 properties across the eastern United States, 2015–2023. Adult female mass explained 64% of the variation in mature antler size, and including latitude as a covariate did not improve model fit. When we considered data from 174 properties in Mississippi, USA, 1991–1994, we predicted a 4.7‐cm increase in average mature male antler size for every 1‐kg increase in adult female body mass. Including soil resource region in the Mississippi model explained 48% of the variation in mature male antler size by accounting for differences in average sizes across regions. Our results indicate average female body mass correlates with mature male antler size at multiple spatial scales. We recommend managers collect body mass and age from harvested female deer, as female mass represents a useful metric to track management progress and predict changes in antler size. [ABSTRACT FROM AUTHOR]

Animals determine their daily movement trajectories in response to a network of ecological processes, including interactions with other organisms, their memories of previous events, and the changing environment. These combine to cause the emergent space use patterns observed over longer periods of time, such as a whole season. Understanding which processes cause these patterns to emerge, and how, requires a process‐based modelling approach. Individual‐based decisions can be described as a system of partial‐differential equations (PDEs) to produce a dynamic description of space use built from the underlying movement process. Here we combine PDE‐based models with step‐selection analysis to investigate the combined effects of three established ecological processes that partially shape movement and space use: 1) a heterogeneous environment; 2) the environmental markings of moving conspecifics; and 3) the memory of direct interactions with conspecifics. We apply this framework to a large GPS‐based dataset of white‐tailed deer Odocoileus virginianus in the southeastern US. We fit models at the population level to provide predictive models, then tailor these to fit individual deer. We specifically incorporate relationships between each possible pair of deer and define each animal's responses to their unique local environments using separate integrated step‐selection analyses. We show how individual movements and decisions yield emergent patterns in animal distributions, and we provide a full generalised description of the framework so that it may be applied to any species simultaneously responding to multiple potentially interacting stimuli (e.g. sociality, morphology, etc.). We found that the population of bucks had highly varied preferences for vegetation, but were shaping their space use in response to conspecific interactions, dependent on the individual relationships between two deer. We advocate for increased consideration of individual‐based movement rules as determinants of realized animal space use, and particularly how these affect emergent distributions of entire species. [ABSTRACT FROM AUTHOR]

Context. Predation risk, whether from large carnivores or humans, is a primary driver of movement and habitat selection for ungulates. Throughout much of the geographical range of white-tailed deer, predation risk during autumn and winter is driven by hunters; however, information about how deer respond to hunting pressure during a long hunting season is lacking. Aims. We aimed to determine how differences in daily temporal exposure to hunting risk affected habitat selection of adult male white-tailed deer. Methods. We deployed GPS collars on 42 adult male white-tailed deer during the 2017–2018 and 2018–2019 firearm hunting seasons in Mississippi, USA. GPS collars provided fine-scale spatial and temporal information regarding habitat use of our study area. Key results. We showed a mismatch between what hunters and deer selected; landscape characteristics selected most by hunters were least selected by deer during the day, which we believe has never been documented. Fine-scale temporal analysis showed that deer selected for some areas (food plots) as much as five times more often during the night, when no hunting risk was present, than during the day, when risk was present. Conclusions. Habitat selection by deer varies depending on the amount of risk that is present. Even in a high-risk heavily hunted area, adult male white-tailed deer can recognise external cues on the landscape, and shift habitat selection both spatially and temporally to favour areas that present less risk. Implications. This study, to our knowledge, provides the first evidence that white-tailed deer actively selected for habitat characteristics that hunters were not utilising. To minimise the effectiveness ofrisk-avoidance behaviours used by deer, we suggest hunters moderate temporal hunting effort across time to decrease the risk to which deer are exposed, thereby minimising the response by deer. [ABSTRACT FROM AUTHOR]