Efficacy of N-mixture models for surveying and monitoring white-tailed deer populations

Automated cameras have become increasingly common for monitoring wildlife populations and estimating abundance. Most analytical methods, however, fail to account for incomplete and variable detection probabilities, which biases abundance estimates. Methods which do account for detection have not been thoroughly tested, and those that have been tested were compared to other methods of abundance estimation. The goal of this study was to evaluate the accuracy and effectiveness of the N-mixture method, which explicitly incorporates detection probability, to monitor white-tailed deer (Odocoileus virginianus) by using camera surveys and a known, marked population to collect data and estimate abundance. Motion-triggered camera surveys were conducted at Auburn University’s deer research facility in 2010. Abundance estimates were generated using N-mixture models and compared to the known number of marked deer in the population. We compared abundance estimates generated from a decreasing number of survey days used in analysis and by time periods (DAY, NIGHT, SUNRISE, SUNSET, CREPUSCULAR, ALL TIMES). Accurate abundance estimates were generated using 24 h of data and nighttime only data. Accuracy of abundance estimates increased with increasing number of survey days until day 5, and there was no improvement with additional data. This suggests that, for our system, 5-day camera surveys conducted at night were adequate for abundance estimation and population monitoring. Further, our study demonstrates that camera surveys and N-mixture models may be a highly effective method for estimation and monitoring of ungulate populations.     

Identification of assemblage A Giardia in white-tailed deer

Fecal samples were collected from hunter-killed white-tailed deer (Odocoileus virginianus) during a managed hunt in a central Maryland county. Fecal samples were cleaned of debris and concentrated by CsCl density gradient centrifugation and stained with MerIFluor reagents. Stained samples were examined by fluorescent microscopy for the presence of Giardia sp. cysts. One of 26 samples was found to be positive for Giardia sp. Polymerase chain reaction amplification using primers directed to the beta-giardin and TPI genes identified the same sample as the only positive one. Sequencing of the beta-giardin and TPI genes revealed that the Giardia sp. belonged to assemblage A, a genotype infectious for humans and also reported in a small percentage of cattle. This is the first report of assemblage A Giardia sp. in deer and suggests that deer could be a potential source of infectious cysts for humans and cattle.     

Spatial heterogeneity of mitochondrial DNA and allozymes among populations of white-tailed deer and mule deer.

A white-tailed deer (Odocoileus virginianus) population in northeastern Minnesota and a mule deer (O. hemionus) population in the Bridger Mountains Montana, have previously been shown to be spatially subdivided into contiguous subpopulations. We assessed the degree of genetic differentiation among subpopulations and tested the hypothesis that differentiation will be greater for mitochondrial DNA (mtDNA) than for nuclear-encoded allozymes. Differentiation of the white-tailed deer subpopulations was significant for two allozyme loci but not for mtDNA, and the overall degree of differentiation was low. Gene flow, recent founding of the subpopulations, and polygamous breeding structure may all have contributed to this pattern. Greater differentiation was evident among disjunct populations than between the contiguous subpopulations of white-tailed deer. The contiguous mule deer subpopulations were significantly differentiated for mtDNA and one allozyme locus. Differentiation was greater for mtDNA than for allozymes. These results are consistent with demographic data that indicate mule deer males disperse more than do females. Disjunct mule deer populations may be similar or dramatically different in mtDNA haplotype frequencies that do not necessarily vary with geographic distance. Current and historical gene flow and breeding structure will influence population genetic patterns.     

Parasites, diseases and health status of sympatric populations of sambar deer and white-tailed deer in Florida

From December 1983 to December 1984 a study on parasites, diseases and health status was conducted on sympatric populations of sambar deer (Cervus unicolor) and white-tailed deer (Odocoileus virginianus) from St. Vincent Island, Franklin County, Florida. Ten sambar and six white-tailed deer were examined. White-tailed deer had antibodies to epizootic hemorrhagic disease virus and bluetongue virus. Serologic tests for antibodies to the etiologic agents of bovine virus diarrhea, infectious bovine rhinotracheitis, vesicular stomatitis, parainfluenza 3, brucellosis, and leptospirosis were negative in both species of deer. White-tailed deer harbored 19 species of parasites; all were typical of the parasite fauna of this species in coastal regions of the southeastern United States. Sambar deer harbored 13 species of parasites, which apparently were derived largely from white-tailed deer. The only exception was Dermacentor variabilis which occurs frequently on wild swine on the island. The general health status of sambar deer appeared to be better than that of white-tailed deer. This was hypothesized to result from the sambar deer's utilization of food resources unavailable or unacceptable to white-tailed deer and to the absence and/or lower frequency of certain pathogens in sambar deer.     

Parasites, diseases, and health status of sympatric populations of fallow deer and white-tailed deer in Kentucky

In August 1983, a study on parasites, diseases, and health status was conducted on sympatric populations of fallow deer (Dama dama) and white-tailed deer (Odocoileus virginianus) from Land Between The Lakes, Lyon and Trigg counties, Kentucky. Five adult deer of each species were studied. White-tailed deer had antibodies to epizootic hemorrhagic disease (EHD) virus and Leptospira interogans serovariety icterohemorrhagiae, and fallow deer had antibodies to bluetongue and EHD viruses. Serologic tests for bovine virus diarrhea virus, infectious bovine rhinotracheitis virus, parainfluenza3 virus, and Brucella spp. were negative. One white-tailed deer had an infectious cutaneous fibroma, and one fallow deer had pulmonary mucormycosis. White-tailed deer harbored 16 species of parasites, all of which are considered typical of the parasite fauna of this host in the southeastern United States. Fallow deer harbored nine species of parasites, including eight species known to occur in white-tailed deer on the area and one species (Spiculopteragia assymmetrica) that is not. All fallow deer had inflammatory lesions in the spinal cord and/or brain that were attributed to prior infection with meningeal worm (Parelaphostrongylus tenuis), indicating that P. tenuis infections are not always fatal for this species. The apparent high rate of exposure of Land Between The Lakes fallow deer to P. tenuis without a resultant high rate of clinical cerebrospinal parelaphostrongylosis is hypothesized to be due to a low prevalence and intensity of P. tenuis, partial innate resistance of fallow deer, and acquired immunity.     

Parelaphostrongyliasis in white-tailed deer in Missouri

The heads of 137 white-tailed deer (Odocoileus virginianus) were collected on the opening day of the 1996 Missouri (USA) fire-arms deer season and surveyed for the presence of meningeal worm (Parelaphostrongylus tenuis). Eighteen percent of the deer examined were infected. Mean intensity of infection was 2.0 (range 1-7). There were no significant differences of infection or mean intensity when deer were classified and compared according to sex or age class.     

Fertility control in female white-tailed deer

Silastic rods containing either melengestrol acetate (MGA) or levonorgestrel (LN) were placed in anestrous white-tailed deer (Odocoileus virginianus borealis) does to evaluate the contraceptive efficacy of the implants over a 2 yr period. Implants of MGA were placed in five does during mid-pregnancy to evaluate the effect of this treatment on pregnancy, parturition and lactation. Pregnancies were not observed in the five animals implanted with MGA during anestrus. Three of five does implanted with LN became pregnant in the first season. Pregnancy was not interrupted in the five pregnant does implanted with MGA and it was necessary to remove the implants and treat the does with an estrogen to achieve parturition. One of five fawns was delivered alive and was raised by the doe. MGA was effective for 2 yr as a contraceptive in white-tailed deer, LN was ineffective as used, and MGA placed in pregnant does delayed or prevented normal parturition and thus should not be used in pregnant deer.     

Parasites and condition of coexisting populations of white-tailed and exotic deer in south-central Texas.

We examined the parasites and physical condition of coexisting white-tailed deer (Odocoileus virginianus), axis deer (Axis axis), fallow deer (Dama dama), and sika deer (Cervus nippon) on the YO Ranch (Kerr County, Texas, USA) during December 1982 to January 1984. White-tailed deer harbored 12 species of parasites. Exotic deer were infected with nine species of parasites. All parasites recovered from exotic deer and white-tailed deer have been reported from white-tailed deer. Exotic deer had higher condition ratings than white-tailed deer.     

Out-of-season breeding of captive white-tailed deer

Although techniques to induce out-of-season breeding in deer with exogenous hormones are documented, a successful technique has not been developed for use with white-tailed deer (Odocoileus virginianus). The efficacy of using a combined treatment of melatonin, progesterone, and pregnant mare serum gonadotropin to advance seasonal estrus in captive white-tailed deer was tested. First estrus of 12 treated does (n = 16) occurred at least 57 days sooner than did those of 4 non-treated controls (mid-November). Previous estrus dates were known for 11 does, suggesting that their estrus was advanced by 37 to 119 days (X = 82 days). At first estrus, 12 does were bred to untreated bucks that had velvet-covered or recently polished antlers, resulting in a conception rate of 75%. Two does conceived when bred at second or third estrus. Two does failed to conceive when bred at first estrus and displayed no estrous cycling that year, but conceived out-of-season in subsequent years. These data document that this technique is useful for inducing successful, out-of-season breeding of captive white-tailed deer. Furthermore, we demonstrate that some bucks at our facility have adequate fertility and libido to impregnate does during midsummer.     

Morphologic variation in the cranium and mandible of the white-tailed deer (Odocoileus virginianus): A comparative study of geographical and four biological distances

Several biological distances based on cranial and mandibular variation among breeding groups of white-tailed deer were calculated and compared with geographic distances among the groups. Distances based on epigenetic variation among ten groups were calculated using 16 non-metric variants of the cranium and mandible. Penrose's size and shape distances and Mahalanobis' D² distance were calculated for 11 groups; the calculations were based on seven skeletal and seven dental metric variables of the mandible. The biological distances were correlated with geographic distance as follows: the epigenetic distance, 0.74; Penrose's shape distance, 0.71; Penrose's size distance, 0.45; and Mahalanobis' distance, 0.37. All correlations were significant at the 0.01 level. The epigenetic and Penrose shape correlations were significantly higher than the Mahalanobis correlation. Because of the conditions under which the breeding groups were selected, it was assumed that genetic affinites among the groups would be a function of geographic distance. The results suggest that the epigenetic distance and Penrose's shape distance reflect genetic affinities among groups better than do the Penrose size and Mahalanobis distances.