An isolated white-tailed deer (Odocoileus virginianus) population on St. John, US Virgin Islands shows low inbreeding and comparable heterozygosity to other larger populations.

This is the first study to document the genetic diversity of the white-tailed deer population on St. John, US Virgin Islands. The island population was founded by a small number of animals, has very limited hunting or predation, and recently experienced a reduction in size following an extended drought in 2015. DNA samples were collected from hair from 23 anesthetized adult deer (13 males, 10 females) ranging in age from 1 to 8 years (3.36 ± 1.9 years) and also from fecal DNA samples, for a total of 42 individuals analyzed for genetic diversity. The St. John deer data set averaged 4.19 alleles per marker and demonstrates the second lowest number of alleles (A) when compared to other populations of Odocoileus virginianus (4.19). Heterozygosity was similar to the other studies (0.54) with little evidence of inbreeding. To explain the level of heterozygosity and level of inbreeding within the St. John population, three hypotheses are proposed, including the effect of intrinsic biological traits within the population, a recent infusion of highly heterogeneous loci from North American populations, and a consistent level of immigration from a nearby island. Additional work is needed to further understand the genetic history of the St. John and regional deer populations.

Hematologic Parameters and Viral Status for Zika, Chikungunya, Bluetongue, and Epizootic Hemorrhagic Disease in White-tailed Deer ( Odocoileus virginianus) on St. John, US Virgin Islands.

A population of white-tailed deer ( Odocoileus virginianus) resides throughout the island of St. John, US Virgin Islands, predominately in the Virgin Islands National Park. Adult deer ( n=23), ranging from 1 yr to 8 yr old, were assessed to characterize body condition and health. Serologic samples were screened for important viral pathogens in the area, including Zika, chikungunya, bluetongue, and epizootic hemorrhagic disease viruses. Samples were collected in July 2016; males were in velvet and all females were in diestrus. Deer had recovered from a severe drought the previous year but were generally healthy, with a low-level but high incidence of tick parasitism. Marked statistically significant changes in hematocrit and hemoglobin levels were associated with the effects of the anesthetic mixture used for capture. No other statistically significant differences were observed. Serum from four deer induced reduction in Zika virus plaques, suggesting possible exposure. No serum was reactive for chikungunya virus. Bluetongue and epizootic hemorrhagic disease antibodies were present in 50% of the sampled deer, but no clinical signs associated with disease were observed during the study period. These data will be valuable for future dynamic health assessment and may help assess changes to the population, such as those induced by climate change, infectious disease, or other demographic events.

Rhipicephalus microplus and Dermacentor nitens (Acari: Ixodidae) Coparasitize White-Tailed Deer on St. John, U.S. Virgin Islands.

Ticks parasitizing introduced white-tailed deer, Odocoileus virginianus (Zimmermann), on St. John, U.S. Virgin Islands, were recorded during and after drought conditions. Tick infestation prevalences were 22% at the start of the drought (July 2015), 66% at the height of the drought (March 2016), and 35% after the drought had ended (July 2016; n = 67 deer). Samples of ticks from 22 tranquilized deer in July 2016 revealed the presence of two species, the southern cattle tick, Rhipicephalus (Boophilus) microplus (Canestrini), and the tropical horse tick, Dermacentor (Anocentor) nitens Neumann. Both tick species have considerable veterinary importance, especially for cattle and horses, respectively, as nuisance biters and also as vectors of parasitic piroplasms or of Anaplasma marginale Theiler. All 22 deer examined were infested by R. microplus, whereas 14 (64%) of the samples also included specimens of D. nitens. Because of the large numbers of ticks recorded, wild deer on St. John could develop associated health problems (pruritis, alopecia, anemia, low weight gain, tick-borne pathogens and parasites) and could also serve as a source of these ticks for cattle and horses.