Christopher S. DePerno

MOVEMENT OF FEMALE WHITE-TAILED DEER: EFFECTS OF CLIMATE AND INTENSIVE ROW-CROP AGRICULTURE

Abstract Movements (e.g., migration, dispersal) of white-tailed deer (Odocoileus virginianus) vary greatly over the geographic range of the species. Therefore, region-specific, empirical information is needed to effectively manage deer populations. Movements of white-tailed deer have been well documented in forest dominated habitats; however, little information related to white-tailed deer movements exists in intensively (>80%) cultivated areas. From January 2001 to August 2002, we monitored movements of 77 (61 adult, 16 young) female white-tailed deer in southwest Minnesota. We collected 6,867 locations, calculated 130 home ranges, and documented 149 seasonal movements. Fifteen percent of deer were nonmigratory, whereas 35% were facultative migrators, and 42.5% were obligate migrators. Mean distance between summer and winter home range was 10.1 km. Temperature and snow depth had the greatest influence on initiation of seasonal migration, whereas crop emergence and harvest had minimal effects. Four deer (8%) dispersed a mean distance of 71.3 km with 1 adult female moving a straight-line distance of 205 km. All dispersing deer occupied a temporary staging area for approximately 1 month between previous winter and new summer ranges. Mean home range (95% use area) in winter (5.2 km2) was over twice as large as home range in summer (2.3 km2). Movements exhibited by white-tailed deer in southwest Minnesota were influenced by large annual fluctuations in climate and a highly fragmented landscape dominated by row-crop agriculture. We provide data beneficial to biologists managing northern populations of white-tailed deer in fragmented environments by detailing the relationship between climate, intensive agriculture, and deer movements.

Survival of white-tailed deer in an intensively farmed region of Minnesota

Abstract Survival and cause-specific mortality of white-tailed deer (Odocoileus virginianus) have been well documented in forested habitat, but limited information has been collected in intensively farmed regions. The objectives of this study were to determine survival and cause-specific mortality of neonate, fawn female, and adult female white-tailed deer in an intensively farmed (>80% land cover) region of Minnesota. We captured and radiocollared 77 female deer >8 months old (61 adults, 16 fawns) and 39 neonates (17 male, 22 female). Hunting was the greatest cause of mortality among adult deer, with 43% of mortalities attributed to firearms hunters. Annual survival rate of all adult and fawn (≥8 months) radiocollared deer was 0.77 (n = 58, SE = 0.06). Overall (Jan. 2001-Aug. 2002) adult survival was 0.75 (n = 77, SE = 0.05) and was similar to survival rates reported elsewhere for female white-tailed deer. Natural causes (e.g., disease, predation) of mortality were minor compared to human-related causes (e.g., hunting, vehicle collision). In total, 67% of neonate mortalities were due to predators. Neonate summer survival rate pooled over years was 0.84 (n = 39, SE = 0.06) and was high compared to other studies. High neonate survival was likely associated with a low predator density, quality vegetation structure at neonate bed sites, and high nutritional condition of dams. Deer management in the highly fragmented and intensively farmed regions of Minnesota relies on hunter harvest to maintain deer populations at levels tolerable to landowners.

Evaluating Ungulate Mortality Associated With Helicopter Net‐Gun Captures in the Northern Great Plains

Abstract Ungulate mortality from capture-related injuries is a recurring concern for researchers and game managers throughout North America and elsewhere. We evaluated effects of 7 variables to determine whether ungulate mortality could be reduced by modifying capture and handling procedures during helicopter net-gunning. During winter 2001–2006, we captured 208 white-tailed deer (Odocoileus virginianus) and 281 pronghorn (Antilocapra americana) by helicopter net-gunning throughout the Northern Great Plains. Of 281 pronghorn, 25 (8.9%) died from capture-related injuries; 12 were from direct injuries during capture, and 13 occurred postrelease. Of 208 deer, 3 (1.4%) died from injuries sustained during helicopter captures, with no mortalities documented postrelease. We used logistic regression to evaluate the probability that ungulates would die of injuries associated with helicopter net-gun captures by analyzing effects of snow depth, transport distance, ambient and rectal temperatures, pursuit and handling times, and whether individuals were transported to processing sites. The probability of capture-related mortality postrelease decreased 58% when transport distance was reduced from 14.5 km to 0 km and by 69% when pursuit time decreased from 9 minutes to <1 minute. Wildlife managers and researchers using helicopter capture services in landscapes of the Midwest should limit pursuit time and eliminate animal transport during pronghorn and white-tailed deer capture operations to minimize mortality rates postrelease.

Survival of White-Tailed Deer Neonates in Minnesota and South Dakota

ABSTRACT Understanding the influence of intrinsic (e.g., age, birth mass, and sex) and habitat factors on survival of neonate white-tailed deer improves understanding of population ecology. During 2002–2004, we captured and radiocollared 78 neonates in eastern South Dakota and southwestern Minnesota, of which 16 died before 1 September. Predation accounted for 80% of mortality; the remaining 20% was attributed to starvation. Canids (coyotes [Canis latrans], domestic dogs) accounted for 100% of predation on neonates. We used known fate analysis in Program MARK to estimate survival rates and investigate the influence of intrinsic and habitat variables on survival. We developed 2 a priori model sets, including intrinsic variables (model set 1) and habitat variables (model set 2; forested cover, wetlands, grasslands, and croplands). For model set 1, model {Sage-interval} the lowest AICc (Akaikes information criterion for small sample size) value, indicating that age at mortality (3-stage age-interval: 0–2 weeks, 2–8 weeks, and >8 weeks) best explained survival. Model set 2 indicated that habitat variables did not further influence survival in the study area; &bgr;-estimates and 95% confidence intervals for habitat variables in competing models encompassed zero; thus, we excluded these models from consideration. Overall survival rate using model {Sage-interval} was 0.87 (95% CI = 0.83–0.91); 61% of mortalities occurred at 0–2 weeks of age, 26% at 2–8 weeks of age, and 13% at >8 weeks of age. Our results indicate that variables influencing survival may be area specific. Region-specific data are needed to determine influences of intrinsic and habitat variables on neonate survival before wildlife managers can determine which habitat management activities influence neonate populations.

Do biological and bedsite characteristics influence survival of neonatal white-tailed deer?

Coyotes recently expanded into the eastern U.S. and potentially have caused localized white-tailed deer population declines. Research has focused on quantifying coyote predation on neonates, but little research has addressed the potential influence of bedsite characteristics on survival. In 2011 and 2012, we radiocollared 65 neonates, monitored them intensively for 16 weeks, and assigned mortality causes. We used Program MARK to estimate survival to 16 weeks and included biological covariates (i.e., sex, sibling status [whether or not it had a sibling], birth weight, and Julian date of birth). Survival to 16 weeks was 0.141 (95% CI = 0.075-0.249) and the top model included only sibling status, which indicated survival was lower for neonates that had a sibling. Predation was the leading cause of mortality (35 of 55; 64%) and coyotes were responsible for the majority of depredations (30 of 35; 86%). Additionally, we relocated neonates for the first 10 days of life and measured distance to firebreak, visual obstruction, and plant diversity at bedsites. Survival of predation to 10 days (0.726; 95% CI = 0.586-0.833) was weakly associated with plant diversity at bedsites but not related to visual obstruction. Our results indicate that neonate survival was low and coyote predation was an important source of mortality, which corroborates several recent studies from the region. Additionally, we detected only weak support for bedsite cover as a covariate to neonate survival, which indicates that mitigating effects of coyote predation on neonates may be more complicated than simply managing for increased hiding cover.

Maximum sustained yield harvest versus trophy management

We examined hypotheses regarding compatibility of managing white-tailed deer (Odocoileus virginianus) populations for trophy males (i.e., ≥8 points) and maximum sustained yield (MSY) harvests. Harvest of white-tailed deer on Oak Ridge Reservation, Tennessee, USA, began in 1985 following 45 years of protection. We examined several harvest characteristics (e.g., age and sex composition, antler and body size of males) under the assumption that the population had attained an equilibrium during this period and hunter bias toward males was constant across years. During 1985, 273 deer were killed by vehicles on the reservation; by 1994, mortality from vehicles declined to 143 deer. During the study period, annual harvest declined from 923 to 470 deer. We suspect that although the population had attained an equilibrium, it was likely below ecological carrying capacity (K) because of substantial vehicle mortality. Because of the absence of predators and other sources of natural mortality, we assumed that deer-vehicle collisions prior to hunting was the primary factor maintaining the population below K. After the initiation of hunting in 1985, several demographic parameters indicated the population was intensively harvested: 98% of the harvest was composed of males <4 years of age, deer-vehicle mortality was reduced by 50%, and modeling indicated that the population had stabilized at 61% of the prehunt population. Average age of trophy males declined following harvest. Body size of 1.5-year-old males increased following the initial hunt but became variable over the remaining period. Proportion of trophy males harvested declined from 36% to 15% throughout the study period. Following the initial harvest, the high proportion of yearling males harvested suggests that the age distribution of males became truncated. Results from our empirical example support the hypothesis that sustained production of trophy males is a consequence of MSY of either-sex harvests when males are considered trophy with ≥8 points, when annual recruitment at MSY consistently approaches unity, and when hunters show no selectivity bias. These constraints are unlikely under current management prescriptions.

White-Tailed Deer Vigilance: The Influence of Social and Environmental Factors

Vigilance behavior may directly affect fitness of prey animals, and understanding factors influencing vigilance may provide important insight into predator-prey interactions. We used 40,540 pictures taken withcamera traps in August 2011 and 2012to evaluate factors influencing individual vigilance behavior of white-tailed deer (Odocoileus virginianus) while foraging at baited sites. We used binary logistic regression to determine if individual vigilance was affected by age, sex, and group size. Additionally, we evaluated whether the time of the day,moon phase,and presence of other non-predatorwildlife species impacted individual vigilance. Juveniles were 11% less vigilant at baited sites than adults. Females were 46% more vigilant when fawns were present. Males and females spent more time feeding as group size increased, but with each addition of 1 individual to a group, males increased feeding time by nearly double that of females. Individual vigilance fluctuated with time of day andwith moon phase but generally was least during diurnal and moonlit nocturnal hours, indicating deer have the ability to adjust vigilance behavior to changing predation risk associated with varyinglight intensity.White-tailed deer increased individual vigilance when other non-predator wildlife were present. Our data indicate that differential effects of environmental and social constraints on vigilance behavior between sexes may encourage sexual segregation in white-tailed deer.

Detection of Clostridium difficile and Salmonella in Feral Swine Population in North Carolina

We sampled 161 feral pigs in eastern North Carolina, USA, to determine the prevalence and antimicrobial resistance profile of Clostridium difficile and Salmonella. Seven (4.4%) and eight (5.0%) pigs tested positive for C. difficile and Salmonella, respectively, highlighting the importance of determining the epidemiology of these pathogens in feral pigs.

CHARACTERIZATION OF CAMPYLOBACTER FROM RESIDENT CANADA GEESE IN AN URBAN ENVIRONMENT

Waterfowl are natural reservoirs for zoonotic pathogens, and abundant resident (nonmigratory) Canada Geese (Branta canadensis) in urban and suburban environments pose the potential for transmission of Campylobacter through human contact with fecal deposits and contaminated water. In June 2008 and July 2009, we collected 318 fecal samples from resident Canada Geese at 21 locations in and around Greensboro, North Carolina, to test for Campylobacter. All campylobacter species detected were C. jejuni isolates, and prevalences in 2008 and 2009 were 5.0% and 16.0%, respectively. Prevalence of C. jejuni–positive sampling sites was 21% (3/14) and 40% (6/15) in 2008 and 2009, respectively. All C. jejuni isolates were susceptible to a panel of six antimicrobial agents (tetracycline, streptomycin, erythromycin, kanamycin, nalidixic acid, and ciprofloxacin). We used pulsed-field gel electrophoresis and fla-typing to identify several strain types among these isolates. Multilocus sequence typing of representative isolates revealed six sequence types, of which two (ST-3708 and ST-4368) were new, two (ST-702 and ST-4080) had been detected previously among C. jejuni from geese, and two (ST-991 and ST-4071) were first reported in C. jejuni from an environmental water source and a human illness, respectively. These results indicate a diverse population of antibiotic-susceptible C. jejuni in resident Canada Geese in and around Greensboro, North Carolina, and suggest a need for additional assessment of the public health risk associated with resident Canada Geese in urban and suburban areas.

Confirmation of Coyote Predation on Adult Female White-tailed Deer in the Southeastern United States

Abstract The recent expansion of Canis latrans (Coyote) into the eastern United States has generated interest among wildlife managers because of the potential impacts on Odocoileus virginianus (White-tailed Deer) populations. Coyotes have been reported as predators of adult and neonate White-tailed Deer in some parts of their range, but recent studies in the Southeast have documented only Coyote predation on neonates. We report 4 confirmed Coyote predation events on adult female White-tailed Deer that were radiocollared, implanted with vaginal implant transmitters, monitored every 4–8 hours, and apparently healthy. Field necropsies confirmed killing-bite wounds to the upper throat and base of the mandible, and feeding behavior on the carcasses was consistent with what has been observed for Coyotes. Further, we used swabs from bite wounds to confirm the presence of predator DNA, and the 3 carcasses that were swabbed tested positive for the presence of Coyote DNA. To our knowledge, our results represent the first scientifically documented Coyote predations on adult female White-tailed Deer in the Southeast.