*Changes to Health Parameters of White-Tailed Deer during a Drought in the US Virgin Islands DOI: http://dx.doi.org/10.5772/intechopen.108270*

each field season were trained to determine body condition, musculature, coat condition and tick levels by completing both pre-visit trainings and in-field calibration sessions to reduce the amount of inter-observer variability and to retain a high fidelity of rating. A body scoring system that uses anatomical landmarks provided an immediate evaluation that is non-invasive [25]. Data were collected in real time using binoculars, iPads, and a custom app for data storage that was specifically designed for this project. For examples of the different parameters measured, see **Figure 3** and **Table 1**. Pregnant deer and fawns were purposefully excluded.

The second method of data collection was conducted via direct assessment when deer were tranquilized. This method was only used during the recovery phase of the drought [22]. Deer data were collected throughout St. John [21] and were geographically representative of the deer population in all areas of the island. Pregnant or nursing does and deer that were one year old were not tranquilized. In total, twenty-three adult deer were tranquilized using butorphanol, azaperone, and medetomidine (BAM, Wildlife Pharmaceuticals, Windsor, Colorado, USA). Relative body size was used to determine the administered dose according to the manufacturer's guidelines. Most deer

#### **Figure 3.**

*(A) A white-tailed deer (Odocoileus virginianus) showing excellent coat condition, musculature, and body condition, and an absence of ticks (B) showing good coat condition, musculature, and body condition, and no ticks (C) showing fair coat condition, musculature, and body condition, with some ticks and (D) showing a poor body condition, with a high degree of tick infestation in the ears. These conditions were observed in a study of deer health indicators during the onset, peak, and recovery phases of a 2015–2016 drought on St. John Island.*


#### **Table 1.**

*White-tailed deer (Odocoileus virginianus) were scored as excellent, good, fair, and poor for body condition, coat condition, and musculature on St. John Island during the onset, peak, and recovery phases of a 2015–2016 regional drought. Ratings loosely follow [26].*

were small to medium in size (41.1 ± 13.2 kg), receiving 1.0–1.5 mL intra-muscularly in the hind quarter by pneumatic dart gun (Pneu-Dart, Williamsport, Pennsylvania, USA). Vitals monitored included heart rate, respiratory rate, mucous membrane color, body temperature, time to recumbency, and recovery. Body temperatures were stabilized with a wet cooling blanket (Equi Cool-Down, Jacksonville, Florida, USA). After examination, the anesthesia was reversed with 2–3 mL of atipamezole (25 mg/ mL) and 0.5 mL of naltrexone (50 mg/mL, Wildlife Pharmaceuticals). This work was conducted under Scientific Research and Collection Permit VIIS-2016-SCI-0026 for the Virgin Islands National Park to S. Nelson and IACUC (1602.01-15Mar2016) from the University of Colorado at Boulder and the National Park Service to S. Nelson.

Stress hormones were analyzed from fresh deer fecal material. Feces were collected opportunistically throughout St. John when we could directly attribute the fecal deposit to an individual deer, which allowed us to describe the age, sex, and health condition of the deer [27, 28]. Fecal samples were collected using sterile gloves and placed into labeled plastic bags, stored with ice packs, and given a unique identifying number [29]. The samples were frozen and sent to the Wasser lab at the University of Washington for stress hormone analysis. Samples were analyzed for both cortisol (ng/g) and T3 levels (ng/g). All samples were freeze-dried and homogenized, and then 0.1 g was extracted using 15 ml of 70% ethanol [30].

#### **2.2 Statistical analysis**

Deer musculature, coat condition, body condition, and tick levels were determined to be excellent, good, fair, or poor (**Figure 3** and **Table 1**). The initial four categories of excellent, good, fair, and poor were collapsed into binary outcomes: *Good/Excellent* vs. *Fair/Poor* to simplify interpretation and bolster sample sizes. Borderline cases were

#### *Changes to Health Parameters of White-Tailed Deer during a Drought in the US Virgin Islands DOI: http://dx.doi.org/10.5772/intechopen.108270*

omitted (e.g., deer rated as "Good/Fair"). After collapsing, all four variables satisfied conventional conditions for sample size for Chi-Square tests of independence to assess the relationship between deer health and time point (onset, peak, and recovery phase, respectively). In post-hoc analyses, for each of these measures three pairwise two-proportion two-tailed z-tests were conducted to discern differences between time points: drought onset vs. recovery, peak vs. recovery, and onset vs. peak. No corrections for multiple testing were used so as to flag potential effects for future study.

To evaluate relationships between the four health indicators collected via visual assessment (musculature, body condition, coat condition, and ticks; both remote and direct), the phi coefficient was calculated for each of the pairwise relationships. Marginal distributions indicate that it is impossible for phi to reach a magnitude of 1; to avoid inflating the perceived relationships, no adjustment was made. The resultant correlations are conservative.

Two deer that had been tranquilized were also observed remotely in July 2016 following the drought. The remote observations were removed from the primary analyses, but used to check consistency between data collected remotely and data collected by tranquilizing. Observations of body condition and musculature were rated the same, however, ticks were observed more readily within the tranquilized deer when compared when they were viewed remotely. Thus, to promote consistency when comparing across time periods, observations of tranquilized deer were not included in the analysis for ticks. Data from tranquilized deer were included for the other variables because inconsistencies were not meaningful after the collapse into binary groups.

To quantify the stress from drought using fecal cortisol levels, two F-tests were conducted (one for average cortisol and one for average T3 levels). There were no extreme outliers and conditions for the test were otherwise adequately met. In post-hoc analyses three pairwise two-sample t-tests were conducted to discern differences between time points. All analyses were conducted using R statistical software (version 3.6.0).
