Female White-tailed Deer Research Articles

PREGNANCY RATE AND NUMBER OF FETUSES OF WHITE-TAILED DEER RELATED TO BODY MEASUREMENTS AND SERUM METABOLITES

This study aimed to assess the association between fertility and the number of fetuses of free-ranging concentrate-supplemented white-tailed deer (Odocoileus virginianus, texanus, Mearns 1898) from northern Mexico (27 °N) with body measurements and serum metabolites indicative of nutritional status. We studied 119 female deer (31 yearlings and 88 adults) captured in January 2021 using a net gun fired from a helicopter. Ultrasound scanning showed 100 and 97.8 % pregnancy rate and 1.52 ± 0.51 and 1.50 ± 0.59 fetuses/pregnant doe for yearlings and adult does, respectively, with no difference (p > 0.05) between age classes Thoracic circumference (cm) was higher (85.9 ± 4.9 vs. 84.1 ± 4.2; p = 0.039) for does carrying twins vs. singles. None of the serum metabolites indicative of nutritional status affected the fetal number of pregnant does. It was concluded that free-ranging white-tailed deer receiving concentrate supplementation in winter on a semi-arid rangeland has a high reproductive potential. Also, these results indicate that variation in maternal age within this population was not a significant driver of reproductive metrics of white-tailed deer. The plane of nutrition used in the present study was reflected in adequate serum metabolites indicative of nutritional status. Also, thoracic circumference may have prognostic value as a physical marker of multiple fetuses in female white-tailed deer.

Physiological carry-over effects of variable precipitation are mediated by reproductive status in a long-lived ungulate.

In the age of global climate change, extreme climatic events are expected to increase in frequency and severity. Animals will be forced to cope with these novel stressors in their environment. Glucocorticoids (i.e. 'stress' hormones) facilitate an animal's ability to cope with their environment. To date, most studies involving glucocorticoids focus on the immediate physiological effects of an environmental stressor on an individual, few studies have investigated the long-term physiological impacts of such stressors. Here, we tested the hypothesis that previous exposure to an environmental stressor will impart lasting consequences to an individual's glucocorticoid levels. In semi-arid environments, variable rainfall drives forage availability for herbivores. Reduced seasonal precipitation can present an extreme environmental stressor potentially imparting long-term impacts on an individual's glucocorticoid levels. We examined the effects of rainfall and environmental characteristics (i.e. soil and vegetation attributes) during fawn-rearing (i.e. summer) on subsequent glucocorticoid levels of female white-tailed deer (Odocoileus virginianus) in autumn. We captured 124 adult (≥2.5-year-old) female deer via aerial net-gunning during autumn of 2015, 2016 and 2021 across four populations spanning a gradient of environmental characteristics and rainfall in the semi-arid environment of South Texas, USA. We found for every 1cm decrease in summer rainfall, faecal glucocorticoid levels in autumn increased 6.9%, but only in lactating females. Glucocorticoid levels in non-lactating, female deer were relatively insensitive to environmental conditions. Our study demonstrates the long-lasting effects of environmental stressors on an individual's glucocorticoid levels. A better understanding of the long-term effects stressors impart on an individual's glucocorticoid levels will help to evaluate the totality of the cost of a stressor to an individual's welfare and predict the consequences of future climate scenarios.

Population Dynamics of a Declining White-Tailed Deer Population in the Southern Appalachian Region of the United States

Although generally abundant, white-tailed deer (Odocoileus virginianus) populations in the southeastern United States have recently experienced several localized declines attributed to reduced fawn recruitment following the establishment of coyotes (Canis latrans). The Southern Appalachians is a mountainous region suggested to be experiencing white-tailed deer declines, as harvest numbers and hunter success rates have substantially decreased in northern Georgia since 1979. Low fawn survival (16%) was also recently documented in the Chattahoochee National Forest (CNF) in northern Georgia, necessitating further examination. We radio-collared 14 yearling and 45 adult female white-tailed deer along with 71 fawns during 2018–2020 in the CNF to estimate field-based vital rates (i.e., survival and fecundity) and parameterize stage-structured population models. We projected population growth rates (λ) over 10 years to evaluate the current rate of decline and various other management scenarios. Our results indicated that the observed population would decline by an average of 4.0% annually (λ = 0.960) under current conditions. Only scenarios including antlerless harvest restrictions in addition to improved fawn survival resulted in positive growth (λ = 1.019, 1.085), suggesting these measures are likely necessary for population recovery in the region. This approach can be applied by wildlife managers to inform site-specific management strategies.

A PRELIMINARY INVESTIGATION OF PATHOGEN EXPOSURE OF ADULT FEMALE WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS) AND SURVIVAL OF ASSOCIATED FAWNS IN THE WESTERN DAKOTAS, USA.

Exposure of a dam to pathogens may potentially affect her fawns positively or negatively. Mammalian females transfer immunologic protection to their offspring via colostrum obtained while nursing. Conversely, chronic diseases in dams may potentially result in small and weak neonates, reduced milk production or quality, or infection. Little is known about how pathogen exposure in adult female white-tailed deer (Odocoileus virginianus) affects offspring survival. Our objective was to assess pathogen exposure for female white-tailed deer and subsequent survival rates of fawns in Dunn and Grant counties, North Dakota, and Perkins County, South Dakota, USA. We collected blood serum from 150 adult female deer during 2014. We compared survival of 49 fawns to maternal exposure to 10 pathogens from 37 of 150 adult females. There was no difference in fawn mass between dams based on antibody status and no difference in fawn survival for nine pathogens. The 12-wk survival for fawns born to mothers with antibodies against bovine herpesvirus 1 (BoHV-1, causing infectious bovine rhinotracheitis) was lower than for fawns born from mothers without antibodies against BoHV-1; however, the indirect or direct impacts of BoHV-1 exposure in mothers on fawn survival are unclear. Although our findings suggest that the cost of exposure to previous diseases may have minimal impact on short-term fawn survival for most pathogens, additional research with increased sample sizes is needed to confirm our findings.

Contemporary hybridization between female mule deer and male white-tailed deer in west Texas differs from the hypothesized sex mating patterns recovered from ancient hybridization events

Introgressive hybridization between members of Odocoileus was examined using the mitochondrial cytochrome-b (maternal marker) and paternal sex-determining region Y ( Sry) genes. Eight out of 130 free-ranging individuals from the Panhandle and Trans-Pecos regions of Texas were determined to possess the mitochondrial haplotype of mule deer ( Odocoileus hemionus (Rafinesque, 1817)) and the paternal haplotype of white-tailed deer ( Odocoileus virginianus Rafinesque, 1832). Results indicated that hybridization between deer species in Texas (6.15%) was more broadly distributed than previously reported. Previous studies demonstrated that ancient hybridization events (1.32 mya) involved the capture of the white-tailed deer mitochondrial genome by mule deer, indicating a male mule deer × a female white-tailed deer directionality relevant to hybridization. Alternatively, contemporary hybridization events indicated a reversal in directionality and suggested a cross between a female mule deer × a male white-tailed deer. The Sry gene and species assignment based on morphological characters consistently were in agreement. Further, phylogenetic relationships between Odocoileus virginianus couesi and Odocoileus hemionus eremicus warrant additional investigation as recent hybridization (>200 years) may be a mechanism that allowed these two subspecies to evolve a unique evolutionary trajectory.

Spatiotemporal patterns of male and female white-tailed deer on a hunted landscape.

Resource selection in sexually dimorphic ungulates is at least partially explained by sex‐specific resource requirements and risk aversion strategies. Females generally spend more time in areas with less risk and abundant, high‐quality forage due to their smaller body size. However, demographically variable responses to risk are context dependent, and few have concurrently quantified male and female behavior within areas with the same resource base. We captured 111 (54 males, 57 females) adult white‐tailed deer (Odocoileus virginianus) from 2009 to 2018 on a site in South Carolina, USA, where hunters were the primary source of adult mortality. We fit each deer with a GPS collar programmed to collect locations at 30‐min intervals. Upon collar recovery, we analyzed the data to estimate sex‐ and time‐specific selection for, and distance to, various cover types. While both sexes generally avoided risky areas (i.e., sites hunted more frequently) during the day, females (p = .41) were more likely than males (p = .16) to use risky areas containing abundant food resources during the day, where p = probability of selection. Our findings indicate that female white‐tailed deer may be forced to utilize high risk areas during high risk periods due to their smaller body size and increased nutritional demands, whereas larger males are better able to forgo foraging opportunities during risky periods to mitigate risk; however, our study design left room for the possibility that our observations were driven by innate sex‐specific patterns in white‐tailed deer. Nonetheless, our study contributes information to the literature by describing sex‐specific resource selection by diel period on a site where sexes shared the same resources and were presented with the same landscape of risk.

Assessing migration strategies and cause specific mortality of adult female White-tailed Deer (<i>Odocoileus virginianus</i>) in North Dakota, USA

Life-history characteristics of White-tailed Deer (Odocoileus virginianus) have been documented in areas of the Northern Great Plains, but limited information is available in grassland dominated regions. We documented migration strategy, home range use, and survival of adult female White-tailed Deer in central North Dakota. We monitored 62 radio-collared adult (>1.5 year-old) female White-tailed Deer from February 2010 to December 2012. We documented 86 summer home ranges and classified deer as resident, migratory, or exhibiting a late season movement. Mean migration distance between non-overlapping summer and winter home ranges was 11.76 km (SE 0.86, n = 21). Mean late season movements were 20.69 km (SE 2.94, n = 7) and were likely the result of deer exhausting food resources throughout winter. We also developed five competing models that represented variation in survival among time periods (e.g., pre-hunt, hunt, and post-hunt in 2010 and 2011). Our top model indicated that survival (S) was similar between hunt 2010 and post-hunt 2011 periods but was lower (S = 0.82; SE 0.04, 95% CI 0.73–0.89) than the remaining time periods (S = 0.97; SE 0.01, 95% CI 0.93–0.99). Our results suggest that deer migration strategies and survival are likely influenced by a combination of winter severity and food availability. Mortalities attributed to hunter harvest were low during our study, which may indicate that increased recreational opportunities could be made available, even after severe winters.

Translocating captive female white-tailed deer

Context Thousands of captive white-tailed deer (Odocoileus virginianus) breeding facilities exist across North America for the purpose of producing trophy-class deer (i.e. exceptionally large-antlered). Many of these deer get marketed to private landowners, with the expectation that introduced deer will enhance genetics in the population, resulting in larger-antlered male deer. Previous research suggests that survival and reproductive success of translocated wild white-tailed deer are highly variable; however, little is known about the fate of white-tailed deer translocated from captive-breeding operations. Aims To assess the efficacy of translocating captive female white-tailed deer for the purpose of increasing average antler size within a high-fence property. Methods We translocated 24 adult female deer into a private, 300-ha high-fence shooting preserve in east-central Alabama over a 3-year period. We monitored survival, reproductive success, and fawn recruitment for the translocated deer by using VHF radio collars and vaginal-implant transmitters (VITs). Key results We found a 12-month survival rate of 0.54 for translocated deer. We captured nine fawns throughout our study, leading to a rate of 0.9 fawns per VIT, after accounting for doe mortality and premature VIT expulsion. We found 60-day and 6-month fawn survival rates of 0.33 and 0.22 respectively. Conclusions Survival of translocated captive deer was comparable to rates reported in previous studies that translocated wild deer, although lower than what is found in wild populations that undergo no translocation. Translocated does produced a low number of fawns relative to the national average, although fawn recruitment was within the range of survival rates reported in studies of wild deer. Implications We believe our findings provide a baseline of expectations for captive-deer translocations. Given our results, we believe it is infeasible to expect increased average antler size within this study site by translocating adult female white-tailed deer.

Caution is warranted when using animal space-use and movement to infer behavioral states

BackgroundIdentifying the behavioral state for wild animals that can’t be directly observed is of growing interest to the ecological community. Advances in telemetry technology and statistical methodologies allow researchers to use space-use and movement metrics to infer the underlying, latent, behavioral state of an animal without direct observations. For example, researchers studying ungulate ecology have started using these methods to quantify behaviors related to mating strategies. However, little work has been done to determine if assumed behaviors inferred from movement and space-use patterns correspond to actual behaviors of individuals.MethodsUsing a dataset with male and female white-tailed deer location data, we evaluated the ability of these two methods to correctly identify male-female interaction events (MFIEs). We identified MFIEs using the proximity of their locations in space as indicators of when mating could have occurred. We then tested the ability of utilization distributions (UDs) and hidden Markov models (HMMs) rendered with single sex location data to identify these events.ResultsFor white-tailed deer, male and female space-use and movement behavior did not vary consistently when with a potential mate. There was no evidence that a probability contour threshold based on UD volume applied to an individual’s UD could be used to identify MFIEs. Additionally, HMMs were unable to identify MFIEs, as single MFIEs were often split across multiple states and the primary state of each MFIE was not consistent across events.ConclusionsCaution is warranted when interpreting behavioral insights rendered from statistical models applied to location data, particularly when there is no form of validation data. For these models to detect latent behaviors, the individual needs to exhibit a consistently different type of space-use and movement when engaged in the behavior. Unvalidated assumptions about that relationship may lead to incorrect inference about mating strategies or other behaviors.

Presumptive Primary Cerebral T-Cell Lymphoma in a White-Tailed Deer (Odocoileus virginianus)

Primary central nervous system (CNS) lymphomas are rare in humans and even more uncommon in animals. We report the clinical, pathological and immunohistochemical features of a presumptive primary cerebral T-cell lymphoma (PCTCL) in an aged female white-tailed deer (Odocoileus virginianus) that had chronic progressive neurological disease characterized by ataxia, claudication and eventual circling. The animal was euthanized due to poor prognosis. Grossly, a 2.5cm dark red, friable nodule effaced the cortical neuroparenchyma of the left anterior cingulate cortex (LACC). Microscopically, the meningeal vasculature and adjacent grey and white matter cortical neuroparenchyma of the LACC were infiltrated by a poorly demarcated, unencapsulated and densely cellular round cell neoplasm with a consistent angiocentric pattern. The neoplasm was associated with extensive regions of haemorrhage and liquefactive necrosis. Neoplastic cells immunolabelled for CD3 antigen and had high proliferative activity, as indicated by Ki-67 labelling. Based on the cytohistomorphological and immunohistochemical features and absence of metastasis, a diagnosis of PCTCL was determined. This case indicates that PCTCL should be considered in the differential diagnosis of neurological disease and intracranial, intra-axial CNS masses in deer.

Risky movements? Natal dispersal does not decrease survival of a large herbivore.

Natal dispersal is assumed to be a particularly risky movement behavior as individuals transfer, often long distances, from birth site to site of potential first reproduction. Though, because this behavior persists in populations, it is assumed that dispersal increases the fitness of individuals despite the potential for increased risk of mortality. The extent of dispersal risk, however, has rarely been tested, especially for large mammals. Therefore, we aimed to test the relationship between dispersal and survival for both males and females in a large herbivore. Using a radio‐transmittered sample of 398 juvenile male and 276 juvenile female white‐tailed deer (Odocoileus virginianus), we compared survival rates of dispersers and nondispersers. We predicted that dispersing deer would experience greater overall mortality than philopatric deer due to direct transfer‐related risks (e.g., vehicular collision), indirect immigration‐related mortality attributable to colonization of unfamiliar habitat, and increased overwinter mortality associated with energetic costs of movement and unfamiliarity with recently colonized habitat. For both male and female yearlings, survival rates of dispersers (male = 49.9%, female = 64.0%) did not differ from nondispersers (male = 51.6%, female = 70.7%). Only two individuals (both female) were killed by vehicular collision during transfer, and overwinter survival patterns were similar between the two groups. Although dispersal movement likely incurs energetic costs on dispersers, these costs do not necessarily translate to decreased survival. In many species, including white‐tailed deer, dispersal is likely condition‐dependent, such that larger and healthier individuals are more likely to disperse; therefore, costs associated with dispersal are more likely to be borne successfully by those individuals that do disperse. Whether low‐risk dispersal of large mammals is the rule or the exception will require additional research. Further, future research is needed to evaluate nonsurvival fitness‐related costs and benefits of dispersal (e.g., increased reproductive opportunities for dispersers).

Evaluation of intramuscular sodium nitroprusside injection to improve oxygenation in white-tailed deer (Odocoileus virginianus) anesthetized with medetomidine–alfaxalone–azaperone

ObjectiveIn ungulates, α2-adrenergic agonists can decrease oxygenation possibly through alteration of pulmonary perfusion. Sodium nitroprusside can decrease pulmonary vascular resistance (PVR) and increase cardiac output (Q˙t) through vasodilation. The objective was to determine if sodium nitroprusside would improve pulmonary perfusion and attenuate the increased alveolar–arterial (a–a) gradient resulting from medetomidine–azaperone–alfaxalone (MAA) administration. Study designProspective, randomized, crossover study with a 2 week rest period. AnimalsA group of eight adult female captive white-tailed deer (Odocoileus virginianus). MethodsDeer were administered MAA intramuscularly (IM), and auricular artery and pulmonary artery balloon catheters were placed. Deer spontaneously breathed air. Saline or sodium nitroprusside (0.07 mg kg–1) were administered IM 40 minutes after MAA injection. Heart rate (HR), mean arterial pressure (MAP), mean pulmonary arterial pressure (MPAP), pulmonary artery occlusion pressure (PAOP), right atrial pressure (RAP), Q˙t, arterial pH, PaCO2 and PaO2 were obtained immediately before nitroprusside injection (baseline) and 5, 10 and 15 minutes afterwards. Mixed venous blood samples were obtained at baseline and at 5 minutes. Systemic vascular resistance (SVR), PVR, intrapulmonary shunt fraction (Q˙s/Q˙t), a–a gradient, oxygen delivery (D˙O2) and oxygen extraction ratio (O2ER) were calculated. Statistical analysis was performed with repeated measures analysis of variance with correction factors. A p value < 0.05 was considered significant. ResultsWith nitroprusside, MAP, MPAP, PAOP, RAP, SVR and O2ER significantly decreased and HR, Q˙t and D˙O2 increased compared with baseline and between treatments. There was a significant decrease in PVR and a–a gradient and increase in PaO2 compared with baseline and saline treatment. Changes were not sustained. Conclusions and clinical relevanceNitroprusside temporarily changed hemodynamic variables, increased PaO2 and decreased a–a gradient. Nitroprusside possibly led to better pulmonary perfusion of ventilated alveoli. However, IM nitroprusside at this dose is not recommended because of severe systemic hypotension and short action.

White-tailed deer use of overstory hardwoods in longleaf pine woodlands

Restoration of the longleaf pine ecosystem is a conservation priority throughout the southeastern United States, but the role of hardwoods in providing food and cover for wildlife within this system is poorly understood. We investigated white-tailed deer (Odocoileus virginianus) movement and habitat selection relative to overstory hardwood distribution in a longleaf pine ecosystem at Fort Bragg Military Installation in the Sandhills physiographic region of North Carolina from March 2011–July 2013. We monitored GPS-collared female white-tailed deer and used generalized linear mixed models and step-selection functions to determine the influence of overstory composition and understory cover on seasonal white-tailed deer habitat selection. During fall and winter, deer selection increased with increasing upland hardwood overstory until reaching an upper threshold (12% and 7%; respectively) where increasing cover of upland hardwoods no longer increased selection. Also, in the fall and winter, deer selected areas with greater bottomland hardwood overstory until an upper threshold of 33% bottomland hardwood overstory was reached. In the spring, deer selected areas with <22% upland hardwood overstory. The effect size of understory cover, defined as lidar-classified vegetation with height <2 m, was larger than any other variable, regardless of season, and deer consistently selected areas with 20–75% understory cover. When managing longleaf pine woodlands for white-tailed deer, our results indicate maintaining a well-developed woody understory with 20–50% canopy closure is important, ideally with mature upland hardwood overstory cover between 4 and 12% to ensure mast production in fall and winter.

Seasonal movements of White-tailed Deer (&lt;i&gt;Odocoileus virginianus&lt;/i&gt;) in the Rocky Mountains of British Columbia

Nineteen adult female White-tailed Deer (Odocoileus virginianus), fitted with very high frequency or global positioning system collars in the Rocky Mountains of southeast British Columbia, exhibited straight-line seasonal movements ranging from &lt;4 km to 109 km. Movement was almost entirely along the floor of both low- and high-elevation valleys, although there was some use of mid-elevation mountainsides during early winter. Spatial locations of deer spanned 891–2234 m above sea level. Seasonal movements of these deer from a single winter range extended to two provinces, three national parks, one provincial park, non-park provincial Crown land, and private land. Deer populations with similar movement patterns may be most effectively managed by considering their extensive movements and coordinating approaches across jurisdictions.

An initial performance review of vaginal implant transmitters paired with GPS collars

BackgroundThe vaginal implant transmitter is an effective tool in the study of neonatal survival rates for cervid species. The latest iterations of the vaginal implant transmitter use Global Positioning Systems and ultra-high frequency telemetry technology to create a self-monitoring system in which researchers receive near instantaneous notifications of parturition events via remote transmission. We deployed ultra-high-frequency radio-linked vaginal implant transmitters on 44 adult female white-tailed deer (Odocoileus virginianus) and assessed their performance and possible benefits to field research.ResultsIn 2016, 60% of the females expelled transmitters at the birth sites. Failure to locate a birth site was a result of technological failings (20%) and premature expulsions (20%). Following manufacturer updates in 2017, we observed an apparent reduction in technology malfunctions (8%) but similar rates of premature expulsions (33%), which resulted in 58% of radio-linked transmitters expelled at birth sites. We located similar numbers of neonates per device across both years. The likelihood that researchers would locate > 1 neonate at or near the birth site was greater for radio-linked transmitters than has been reported in studies using traditional vaginal implant transmitters.ConclusionsRadio-linked transmitters allow researchers to increase sample size, expand spatial distribution of study animals, and reduce personnel requirements.

Body mass influences maternal allocation more than parity status for a long-lived cervid mother

AbstractMothers should balance the risk and reward of allocating resources to offspring to optimize the reproductive value of both offspring and mother while maximizing lifetime reproductive success by producing high-quality litters. The reproductive restraint hypothesis suggests maternal allocation should peak for prime-aged mothers and be less for younger mothers such that body condition is not diminished to a level that would jeopardize their survival or future reproductive events. We assessed if reproductive tactics varied by maternal body mass and parity status in captive female white-tailed deer (Odocoileus virginianus) to determine if prime-aged mothers allocate relatively more resources to reproduction than primiparous mothers. Maternal body mass, not parity status, positively affected maternal allocation, with heavier mothers producing both heavy litters and heavy individual offspring. Conversely, maternal body mass alone did not affect litter size, rather the interaction between maternal body mass and parity status positively affected litter size such that maternal body mass displayed a greater effect on litter size for primiparous than multiparous mothers. Our results suggest that heavy white-tailed deer mothers allocate additional resources to current year reproduction, which may be an adaptation allowing mothers to produce high-quality litters and increase their annual reproductive success because survival to the next reproductive attempt is not certain.

Effects of Neonicotinoid Insecticides on Physiology and Reproductive Characteristics of Captive Female and Fawn White-tailed Deer

Over the past decade, abnormalities have been documented in white-tailed deer (Odocoileus virginianus) in west-central Montana. Hypotheses proposed to explain these anomalies included contact with endocrine disrupting pesticides, such as imidacloprid. We evaluated the effects of imidacloprid experimentally at the South Dakota State University Wildlife and Fisheries Captive Facility where adult white-tailed deer females and their fawns were administered aqueous imidacloprid (an untreated control, 1,500 ng/L, 3,000 ng/L, and 15,000 ng/L). Water consumption, thyroid hormone function, behavioral responses, and skull and jawbone measurements were compared among treatments. Additionally, liver, spleen, genital, and brain imidacloprid concentrations were determined by an enzyme-linked immunosorbent assay (ELISA). Results indicated that 1) control deer consumed more water than treatment groups, 2) imidacloprid was present in the organs of our control group, indicating environmental contamination, 3) as imidacloprid increased in the spleen, fawn survival, thyroxine levels, jawbone lengths, body weight, and organ weights decreased, 4) adult female imidacloprid levels in the genitals were negatively correlated with genital organ weight and, 5) behavioral observations indicated that imidacloprid levels in spleens were negatively correlated with activity levels in adult females and fawns. Results demonstrate that imidacloprid has direct effects on white-tailed deer when administered at field–relevant doses.

Reproductive plasticity of female white-tailed deer at high density and under harsh climatic conditions.

Life-history strategies of female ungulates usually depend on density-dependent and independent processes affecting body condition. Using a long-term data set on life-history traits of female white-tailed deer (2002-2014), we investigated the influence of population density and environmental factors on the reproductive effort of females. We also evaluated post-reproductive consequences on body condition using body mass, body fat, and body protein contents in the autumn following conception. We found that under high densities, females had a lower reproductive rate, which corresponds to a conservative reproduction strategy. However, females born at high density were more likely to reproduce and conceive larger litter size than females born at low density, a possible consequence of strong selective pressure in early life. Body condition was affected by reproduction; lactation had a large negative impact on body mass and body reserves, and conception, irrespectively of litter size, had a negative impact on body fat. Our long-term study demonstrates that plasticity in life-history strategies is a major determinant of reproductive potential for females living at high density and under harsh climates.

Home Range and Habitat Use of Female White-Tailed Deer (Odocoileus virginianus) in the Northern Lower Peninsula of Michigan

Because knowledge of home range dynamics and habitat selection is lacking for whitetailed deer (Odocoileus virginianus) in the northern lower peninsula of Michigan, we radiomarked 89 female deer and studied these aspects of their biology during 2005–2008. Mean (± SE) size of annual home ranges and core areas (n = 89) were 2.3 ± 0.1 km2 and 0.5 ± 0.2 km2, respectively, and somewhat smaller than in other northern deer populations. Mean home-range and core-area sizes for the springsummer period (n = 87) were 1.9 ± 0.1 km2 and 0.4 ± 0.1 km2, respectively. Mean home-range and core-area sizes for the fall-winter period (n = 29) were 2.1 ± 0.2 km2 and 0.5 ± 0.1 km2, respectively. Neither home-range nor core-area sizes differed seasonally (P > 0.135), and seasonal home ranges were comparable in size to other northern deer populations. Cover-type use did not differ seasonally between home ranges and core areas (P = 0.752). Most deer resided in the same general area year-round and had overlapping seasonal home ranges and core areas. We conclude that stability observed in seasonal home ranges and habitat selection were influenced by relatively warm winter conditions during our study.

Beyond Castration and Culling: Should We Use Non-surgical, Pharmacological Methods to Control the Sexual Behavior and Reproduction of Animals?

This paper explores ethical issues raised by the application of non-surgical, pharmaceutical fertility control to manage reproductive behaviors in domesticated and wild animal species. We focus on methods that interfere with the effects of GnRH, making animals infertile and significantly suppressing sexual behavior in both sexes. The paper is anchored by considering ethical issues raised by four diverse cases: the use of pharmaceutical fertility control in (a) male slaughter pigs, (b) domesticated stallions and mares, (c) male companion dogs and (d) female white-tailed deer. Ethical concerns explored include animals’ welfare, the possible violation of animals’ rights, including rights to life, reproduction and bodily integrity; and potential concerns about loss of wildness. We compare ethical concerns about pharmaceutical fertility control with alternative strategies for managing animals’ reproductive behavior including (where appropriate) spaying and neutering, sex separation, sex sorting, culling, and doing nothing. The paper concludes that there are some cases where pharmaceutical fertility control is the best ethical choice in current circumstances; but that there are other cases where alternative choices, including doing nothing, would be ethically preferable. This suggests that in ethical terms a case-by-case approach should be taken to the use of pharmaceutical fertility control in animals.