Mature Male White-tailed Deer Research Articles

Nutrition and ontogeny influence weapon development in a long-lived mammal

Selection in male cervids should optimize allocation of nutritional resources to the competing demands of body growth versus weapon development. We investigated allocation decisions of growing and mature male white-tailed deer (Odocoileus virginianus (Zimmerman, 1780)) from three regions of low, moderate, and high diet quality. We tested (i) if deer under greater nutritional limitations would allocate proportionally less to antler growth, (ii) if antler and body mass became less variable with age, and (iii) if antler size consistently exhibited positive allometry with body mass across age classes and nutritional planes. Greater nutrition increased antler allocation in 2.5 to 4.5 year olds but not in yearlings or prime-aged males. Variability of antler mass decreased with age and was generally less in more fertile regions, but body mass was equally variable across all ages and regions. Antler mass was positively allometric with body mass for all combinations of age class and region but exhibited age- and region-related differences. Our results suggest that accruing body mass is more important to lifetime reproductive success than increasing weapon size. Reduced allometric coefficients in older males likely stem from increasing use of skeletal mineral reserves, selective pressures favoring greater body mass, and possible selection for optimal weapon strength and structure.

Spring Excursions of Mature Male White-tailed Deer (Odocoileus virginianus) in North Central Pennsylvania

Abstract During the breeding season, male white-tailed deer (Odocoileus virginianus)have been reported to take excursions outside of their normal home ranges, likely in search of receptive females. However, we documented additional excursive movements by males during spring in north central Pennsylvania. From December 2011 – April 2012, we equipped 13 mature (≥2.5 y old) male white-tailed deer with global positioning system (GPS) collars programmed to record locations hourly. We defined an excursion as any occasion where a male traveled ≥1.6 km outside of its 95% home range boundaries for ≥12 h. Between 6 April and 6 June 2012, nine males (69.2%) made excursions with six making ≥2 excursions. Mean total path distance and duration of excursions was 4.0 km (range = 1.7-8.0 km) and 22 h (range = 12–40 h), respectively. Although the reason for spring excursions is obscure, hypotheses such as increased doe aggression before parturition, males returning to natal home ranges, or visitation to mineral sites d...

EPIZOOTIOLOGY OF CRANIAL ABSCESS DISEASE IN WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS) OF GEORGIA, USA.

Intracranial abscess disease is a cause of natural mortality for mature male white-tailed deer (Odocoileus virginianus). Most cases of abscesses are associated with bacterial infection by Trueperella (Arcanobacterium) pyogenes, but a complete understanding of the epidemiology of this disease is lacking. We quantified the effects of individual characteristics, site-specific herd demographics, land cover, and soil variables in estimating the probability of this disease. We examined 7,545 white-tailed deer from 60 sites throughout Georgia US for signs of cranial abscesses, the predecessor of intracranial abscesses, and recorded the presence or absence of cranial abscesses for each individual examined. We detected no cranial abscesses in 2,562 female deer but 91 abscesses in 4,983 male deer examined (1.8%). A generalized linear mixed model, treating site as a random effect, was used to examine several potential explanatory risk factors including site-level landscape and soil characteristics (soil and forest type), demographic factors (deer density and male to female ratio), and individual host factors (deer sex and age). Model results indicated that the probability of a male having a cranial abscess increased with age and that adult sex ratio (male:female) was positively associated with this disease. Site-specific variables for land cover and soil types were not strongly associated with observations of the disease at the scale measured and a large amount of among-site variability remained. Given the demonstrated effect of age, gender, and local sex ratios but the remaining unexplained spatial variability, additional investigation into spatiotemporal variation of the presumed bacterial causative agent of cranial abscesses appears warranted.

Survival and Cause‐Specific Mortality of Mature Male White‐Tailed Deer

ABSTRACT Understanding sources of male deer mortality is a prerequisite to a successful management program, especially in Texas, USA, where white‐tailed deer (Odocoileus virginianus) are the most economically important game species. South Texas, USA, is one of the few areas where males reach older age classes (> 4.5 yr), in part because of intense population management. Therefore, we obtained survival rates and causes of mortality of 48 mature male deer in south Texas, USA, over 2 years. We calculated Kaplan—Meier survival estimates during 2 study years modified for a staggered‐entry design and annual survival rates for one cohort of deer from 1998 to 2004 using recapture and radiotelemetry data. We documented 21 mortalities (16 harvest and 5 nonhunting mortalities). Average annual survival of the known‐aged 1998 cohort was 82% with 52% of surviving to 6.5 years of age. Survival in study year 2 (0.497 ± 0.069) was less than in study year 1 (0.781 ± 0.073; P = 0.0047), largely because males had finally reached harvestable age (> 6.5 yr old). All but one non‐harvest mortality occurred during the rut or postrut periods. It appears that a large percentage of males can reach mature age classes under intense population management, making them available for harvest when at peak antler size. This allows for increased economic returns on intensively managed white‐tailed deer populations.

Putative Chemical Signals from White-Tailed Deer (Odocoileus virginianus): Social and Seasonal Effects on Urinary Volatile Excretion in Males

Urine samples collected from dominant and subordinate male white-tailed deer during the breeding and nonbreeding season were analyzed by combined gas chromatography–mass spectrometry (GC-MS). Fifty-five volatiles were found in measurable quantities. Ketones were most numerous, followed by alcohols and alkanes. Nine compounds were common to both dominants and subordinates during the breeding season. Of these nine, three were present in higher concentrations in dominants, and six were higher in subordinates. During the breeding season, nine compounds were found exclusively in the urine of dominants, whereas 19 compounds were found exclusively in the urine of subordinates. Concentrations of several compounds were dependent on the time of year (breeding vs. nonbreeding season). Differences in compound presence and concentration may produce a rank-specific odor, although we suggest that differing concentrations of these suites of compounds may be more important for the identification of social status than the presence of individual compounds. Since mature male white-tailed deer urinate on their tarsal glands frequently during the breeding season, this behavior may allow a deer to simultaneously scent-mark its environment and carry intraspecific cues indicative of social status.

Vegetation Characteristics Influencing Site Selection by Male White-Tailed Deer in Texas

We studied the effects of vegetation characteristics in southern Texas on site selection by mature, male white-tailed deer (Odocoileus virginianus Raf.). Thirteen, radio-collared animals were monitored during winter, spring, summer, and fall of 1986-87 and 1987-88 to determine area-usage patterns within each animal's respective seasonal home range. After each season, structural vegetation attributes were measured with transect-oriented data collection techniques inside the most heavily used and unused areas of each animal's home range. Comparisons were made between these areas to determine whether site selection by deer was in response to differing vegetation characteristics. In general, the most heavily used areas possessed a greater amount of woody canopy cover (greater than or equal to 85%), woody species richness (18-20), and horizontal screening cover than areas with no use. In contrast, herbaceous densities did not differ between the most heavily used and unused areas. Consequently, habitat management manipulations conducted specifically for mature male white-tailed deer in southern Texas, should include provisions for creation or maintenance of sites possessing dense woody canopy cover, a high number of woody species and dense horizontal screening cover.

The effect of yohimbine on plasma levels of T3, T4 and cortisol in xylazine-immobilized white-tailed deer

1. The effect of yohimbine (Y) on blood levels of thyroxine (T 4), triiodothyronine (T 3), and Cortisol was investigated in 5 mature male white-tailed deer immobilized with xylazine hydrochloride (X). 2. T 4 levels were erratic in X-treated deer, but stabilized in the X- and Y-treated deer. 3. T 3 remained unchanged in both groups. 4. Cortisol levels have increased in X-treated deer, but declined in X- and Y-treated deer. 5. Yohimbine is a potent and safe antidote of X not affecting T 3 and T 4. Caution should be used in using R or Y in cortisol studies.

The effect of thyroxine (T4) administration on plasma levels of tri-iodothyronine (T3) and T4 in male white-tailed deer

1.1. Plasma concentrations of thyroxine (T4) and tri-iodothyronine (T3) were monitored for 6 hr in mature male white-tailed deer following i.m. administration of synthetic T4.2.2. Oral administration of 600, 800 and 1000 μg of T4 was mostly ineffectual in increasing plasma levels of T3 and T4.3.3. On the other hand i.m. administration of similar doses of T4 was followed by a higher degree of increase in T3 and lesser degree of increase in T4 levels.4.4. It appears that high doses of T4 (e.g. 1000 μg) are less effective in raising plasma values of T3 or T4 than low or intermediate doses.

Seasonal levels of cortisol and thyroid hormones in intact and castrated mature male white-tailed deer

Plasma L-thyroxine (T4), triiodo-L-thyronine (T3), and cortisol concentrations were measured seasonally in castrated and intact mature white-tailed deer. Both intact and castrated bucks exhibited a statistically significant seasonal rhythm in plasma T4 levels. However, the overall values in the castrated bucks were about 15% lower than in intact animals. Seasonal changes in plasma T3 levels were only found in the intact bucks, with highest values in the April – May period. Two peaks (in June and October) of plasma cortisol were detected in castrated bucks, but only one peak (in the September–October period) was found in intact bucks. In a second experiment in which cortisol levels were measured in "excitable" and "calm" intact bucks, there was no noticeable seasonal rhythm of cortisol in the "excitable" group, but a clear seasonal pattern, with a distinct peak in the October–November period, in the "calm" animals.

Circadian and circannual rhythms of LH, FSH, testosterone (T), prolactin, cortisol, T 3 and T 4 in plasma of mature, male white-tailed deer

1. 1. Circadian and circannual rhythm of plasma LH, FSH, testosterone (T), prolactin, cortisol, triiodothyronine (T 3) and thyroxine (T 4) were investigated in two mature male white-tailed deer. 2. 2. No circadian rhythms were detected. 3. 3. Seasonal levels of LH and FSH were reached in September and October; troughs occur in May and June. 4. 4. Maximal T values were detected in November and December (the time of the rut); minimal levels occur between February and July. 5. 5. Prolactin peaked in May and June; minimal levels were detected between October and February. 6. 6. T 3 exhibited two maxima; the first in the May-June period, the second in the September-October period. T 4 showed no recognizable circannual rhythm. 7. 7. Cortisol levels were found to be much higher during cold months (December-April) than during the rest of the year. 8. 8. The least variable circadian levels were that of FSH and prolactin, with LH, T 4, T 3, cortisol and testosterone following in descending order. 9. 9. Cannulation stress might have some effect on the levels of testosterone, LH and cortisol. 10. 10. Correlation between LH and testosterone levels were detected mainly during sexually active periods.

Thyroxine levels in male and female white-tailed deer (Odocoileus virginianus).

Four major findings are described: (1) The episodic secretion of thyroxine in mature male white-tailed deer is most pronounced in the warmer months (June and September) and least demonstrated during the coldest months (November and January); (2) no clear annual rhythm of thyroxine was demonstrated in juvenile or mature male or mature barren female white-tailed deer. The monthly mean levels in mature males and females oscillate between 11 and 14 microgram/100 ml throughout the year; (3) the seasonal levels of thyroxine in mature males are almost identical with the thyroxine levels of adult barren females; (4) the seasonal thyroxine levels of juvenile males are constantly higher than levels found in mature males. However, when these deer reach the age of 3 years, their thyroxine levels decrease to those of the adult. The collected data could serve as a tool of evaluation of population structure for wildlife management purposes.