Conservation and Ecology of Mammals – Cervids II

Contributed Paper
ROOM: Room 235 – Mesilla
SESSION NUMBER: 58
 

10:30AM Reproductive Effort and Success of Male White-tailed Deer: Trade-Offs in Time Spent Foraging Vs Mate-Search
Aaron M. Foley; Randy DeYoung; David Hewitt; Matthew Schnupp
Quantifying male reproductive effort and success provides insight into life-history characteristics. Knowledge is scant regarding age-specific reproductive effort, the role of endogenous reserves on reproductive effort, and age-specific temporal reproductive success of male white-tailed deer (Odocoileus virginianus). We used a combination of harvest records, GPS radio-collar data, and molecular genetics from a study site in South Texas to quantify empirical body mass loss, modeled costs of locomotion, and dates of reproductive success. Body mass loss due to locomotion alone (8%) in prime-age males (≥3.5 years old) was lower than empirical body mass loss (18%). Prime-aged males clearly reduced foraging during rut which likely facilitated siring of ~70% offspring across the rut. In 2.5 year old males, body mass loss due to locomotion alone (12%) approximated empirical body mass loss (14%) which suggest a negligible change in foraging behavior during rut. However, number of days 2.5 year old males lost body mass (49 days) was shorter than range of conception days (67 days) and most of successful conceptions were limited to peak rut when most females were available. The relatively brief period of reproductive success suggest that intraspecific competition or inexperience was a factor for 2.5 year old males. Yearling (1.5 year old) males lost ~14% body mass due to locomotion alone but empirical body mass loss was 0%. The differential suggests that yearlings must have spent significant time foraging and the ~10% of offspring sired was likely a function of alternative mating strategies that enabled concurrent foraging. Cumulatively, our analyses reveal male white-tailed deer face trade-offs in terms of allocating time to foraging vs mate-search; the trade-offs change as males become physically mature and capable of accumulating endogenous reserves.
10:50AM Genetic Contribution of Northern Stock Sources to Free-Range Populations of White-tailed Deer in Southcentral United States
Jordan L. Youngmann; Steve Demarais; Randy W. DeYoung; Bronson Strickland; Johnathan Bordelon; Chris Cook; William McKinley
Current populations of white-tailed deer (Odocoileus virginianus) in the southeastern United States are genetically admixed as a result of historic translocations during the mid-1900s. Translocated individuals came from remnant, native stock as well as across the country including northern deer from Michigan, Wisconsin, and New York. The adaptive ability of these individuals to withstand drastically different climates and novel diseases is questionable and little is known about their long term contribution to the current genetic structure of southeastern deer. We sampled free-range populations across Louisiana, Mississippi, and Alabama at sites with known historic translocations of northern deer as well as stock source populations from Iron Mountain, MI; Sandhill Wildlife Area, WI; and the Adirondacks in NY. Genetic relationships were tested through the use of 15 microsatellite DNA markers. Southeastern populations were admixed and divided east to west along the Mississippi River with further substructure apparent in populations that received deer from North Carolina as well as native Alabama populations that received no stocking. Analysis of genetic distance revealed a relationship between Black Warrior WMA in Alabama, and Iron Mountain, MI which provided 105 (74%) translocated deer to that area. This was the only evidence of a northern genetic signature still present in these southeastern populations. It is clear that careful consideration must be taken in choosing stock sources for restoration efforts. This research brings to light the potential inefficacy of using sources from vastly different climates and evolutionary histories.
11:10AM While Males Fight, Females Choose: Male Phenotypic Quality Informs Female Mate Choice in Mammals
Daniel L. Morina; Steve Demarais; Bronson K. Strickland; Jamie E. Larson
Theoretical support exists for an exaggerated male structure to serve as both a weapon for intrasexual competition and as an ornament to signal quality and promote female choice. However, there is little, if any, evidence to support this theory in male-male competition breeding systems. Using white-tailed deer (Odocoileus virginianus) as a model species, we manipulated antler size on males while controlling for body size and age and allowed 25 estrus females the opportunity to choose between pairs of segregated males with either large or small antlers. By segregating males, we were able to remove any intrasexual male competition and isolate the effects of female choice. Using various behavioral indications of female choice, we demonstrate that females prefer males with large antlers to those with small antlers. Because antler size is heritable in deer, this female preference for larger antlers may be adaptive by increasing the reproductive success of her male offspring. Our unique antler manipulation study supports the armament-ornament model where male weapons can simultaneously serve as ornaments to females and weapons in male-male competition breeding systems.
11:30AM Do Antler Point Restrictions Make a Notable Impact?
Rebecca L. Cain; Brent Rudolph; William F. Porter; David M. Williams
Hunter dissatisfaction with the number of bucks and number of mature bucks is a problem that a majority of Michigan hunters (67% and 72%, respectively) believe warrants attention from their state wildlife management agency. Since hunters are crucial to the success of wildlife management, their frustration with the size and number of bucks in Michigan is a concern for the Department of Natural Resources. Management seeks to increase the number of older male deer on the landscape and one strategy that has been strongly promoted by a minority of Michigan hunters (33%) is to implement statewide minimum antler point restrictions (APRs). A motivator for these regulations has been the perceived success of APRs in Leelanau County, Michigan since 2003, but it is important to note that the situation leading to the enactment of APRs there was unique. In other areas of the state, “hunter’s choice” regulations allow hunters the opportunity to take only a single buck bearing any number of antler points or the chance to take up to 2 bucks with a minimum APR required for each. It is important to understand the impacts of these regulations to inform future buck harvest regulation strategies across Michigan. We used the biological data that was collected by the Michigan Department of Natural Resources, which includes information about age and physical attributes of harvested white-tailed deer, to assess the influence of antler point restrictions and hunter’s choice on the proportion of adult males in the annual white-tailed deer harvest. We then identified when the change in age structure began relative to the enactment of APRs. Our findings suggest that this change in age structure occurred prior to APRs. We discuss the implications of our results for white-tailed deer management in Michigan and make recommendations for communicating these results to hunters.
11:50AM Evaluation of Selective Harvest on Phenotypic, Demographic, and Genotypic Traits in White-tailed Deer
Masahiro Ohnishi; Randy W. DeYoung; Don A. Draeger; Charles A. DeYoung; Bronson Strickland; Steven Lukefahr; David G. Hewitt
Managers of large mammals commonly use harvest as a form of selection to improve antler or horn traits. However, the effects of harvest on the phenotype of wild populations are poorly understood. We established 3 treatments to study the microevolutionary response to selection for antler traits in a wild population of white-tailed deer (Odocoileus virginianus) in Texas, USA: 1) intensive (14 km²), antlered males of all age classes were culled; 2) moderate (72 km²), males ≥3 years old were culled; and 3) control (20 km²), no culling. Each autumn during 2006-2016, we captured male deer, estimated age, and measured antler characteristics. Males that did not meet antler criteria were sacrificed during 2006-2012. We recorded 5,488 captures of 2,937 individual males, and sacrificed 1,333. We used genetic parentage to estimate breeding values and quantified heritability of antler points and Boone and Crockett score (BCS). Heritability of antler points and BCS for 1- and 2-year-old males was low, and not statistically different from 0, whereas heritability estimates for antler points and BCS for males ≥3 years old were low to moderate (25% [SD = 0.09] and 45% [SD = 0.09], respectively). Most offspring were sired by males that exceeded the culling criteria, yet culling intensities remained high in both treatments (25-75% of captured males), and there was no difference in average breeding values of cohorts. Because phenotypes were not indicative of genetic potential until ≥3 years of age, culling removed many young males and lengthened generation times (8-9 years). It appears selective harvest of males is inefficient for changing genetic potential for antler size in wild populations of white-tailed deer. The results of this study have important implications for harvest management, including antler restrictions commonly employed by state wildlife agencies to manage male age structure.

 

Contributed Paper
Location: Albuquerque Convention Center Date: September 26, 2017 Time: 10:30 am - 12:10 pm