Date of Award
12-1-2010
Degree Name
Doctor of Philosophy
Department
Zoology
First Advisor
Nielsen, Clayton
Abstract
Current research is necessary to focus management of white-tailed deer (Odocoileus virginianus) in the agricultural Midwest, especially given the novel presence of chronic wasting disease in the region. My objectives were to: 1) examine the potential effects of weather and row-crop harvest on daily harvest of white-tailed deer by archery, and individual hunter variables (e.g., age, weapon preference, preference of hunting method) on individual hunter efficiency and success in 2 regions of Illinois (i.e., east-central and southern Illinois); 2) estimate white-tailed deer densities using direct (i.e., spotlighting deer from road transects) and indirect (i.e., counting pellet groups on randomly-placed transects) techniques across 3 study areas in the midwestern U.S.; 3) quantify sex, age, and season-specific survival and dispersal rates of white-tailed deer in east-central Illinois; and 4) assess habitat selection of white-tailed deer during the summer months in east-central Illinois. Knowledge of factors affecting hunter efficiency and success is vital given current trends in hunter attitudes and behaviors that are leading to a reduction in the efficacy of white-tailed deer hunting as a population management tool nationwide. Numerous techniques of density estimation for white-tailed deer have been developed, including aerial surveys, mark-recapture or resight methods, pellet counts, and thermal infrared imaging surveys. Distance sampling has shown great potential for estimating white-tailed deer density at a reduced cost relative to traditional survey techniques and may be useful within the agriculturally-dominated Midwest. Survival and dispersal rates are pertinent model parameters when examining chronic wasting disease (CWD) geographic spread. Structural changes in agricultural landscapes are frequent (i.e., temporally) and ecologically abrupt (i.e., spatially) due to crop harvest and rotation and human development. Providing sex-specific data on site selection would benefit agencies and private land owners by allowing compartmental focus for selective management strategies for either male or female white-tailed deer. Following the 2006 hunting season, I queried white-tailed deer hunters regarding factors potentially affecting hunter efficiency and success in east-central and southern Illinois using a mail-in survey (n = 2,000). I also examined the influence of weather and row-crop harvest progress on daily harvest of white-tailed deer by archery hunting. Hunter efficiency ( ¡À SE= 0.12 ¡À 0.01 deer/day) and hunter success (range = 1.25-1.39 deer/hunter) were similar between study areas. No relationship (r2 <0.01) was detected between respondent age and hunter efficiency, but had a weak influence (r2 = 0.006) on hunter success. Respondents that preferred shotguns, used 1 weapon, and those that preferred still hunting had 62%, 58%, and 52%, respectively, greater (P ¡Ü 0.001) mean hunter efficiency than those in the lowest group within their particular categories. There was no apparent difference (P ¡Ý 0.087) in hunter efficiency across categories of area familiarity, number of hunting methods used, and scouting hours, or categories related to access and use of reconnaissance tools. Respondents that had ¡Ý11 years of area familiarity, preferred archery hunting, used ¡Ý 3 weapons, used ¡Ý3 hunting methods, scouted ¡Ý30 hours, and preferred tree stands had 51%, 45%, 62%, 35%, 61% and 41%, respectively, greater (P ¡Ü 0.001) mean hunter success than those in the lowest group within their particular categories. Access and use of GIS did not appear to affect (P = 0.376) hunter success. Respondents that had access and used topographic maps, aerial or satellite photographs, or GPS had 35%, 34%, and 29% greater (P ¡Ü 0.049), respectively, hunter success than those in the lowest group within their particular categories. Crop harvest progress did not (P = 0.780) appear to affect daily harvest of white-tailed deer by archery hunting. Three models of weather impacts on daily harvest of white-tailed deer by archery hunting had AICc <2. The most parsimonious models¡¯ covariates were MaxWSP, MSLP, and WDSP1, with MaxWSP (¦Â = -0.005) having a negative influence and MSLP (¦Â = 0.00007) and WDSP1 (¦Â = 0.006) having a positive influence on daily harvest of white-tailed deer by archery. I compared direct- and indirect distance sampling techniques for estimating white-tailed deer densities on study areas in east-central Illinois (ECI), southern Illinois (SI, 2007 only), and northern lower peninsula of Michigan (MI) during winter 2007-08. Density estimates obtained via indirect distance sampling for MI, ECI, and SI were 6.1-12.7, 11.2-15.8, and 15.4 deer/km2, respectively. Density estimates obtained via direct distance sampling for MI, ECI, and SI were 18.3-25.2, 14.4-18.1, and 19.0 deer/km2, respectively. Upon examining confidence interval (CI) overlap between direct- and indirect distance sampling techniques by year and study area, only the MI study had non-overlapping CI values. An examination of sites used by deer in summer and quantification of their survival and dispersal rates were conducted in east-central Illinois. From December 2005 to September 2009, I monitored 105 white-tailed deer for 35,478 radiodays for survival and dispersal analysis. I used Program MARK to estimate rates of annual survival, seasonal survival, and dispersal for fawns, yearlings, and adults. I measured habitat variables at sites used by white-tailed deer in summer and random locations in east-central Illinois, examining potential differences in site selection by sex and at multiple scales. Male and female full-season (winter/spring [16 Dec¨C14 May], summer [15 May-30 Sep], fall/winter [1 Oct¨C15 Dec]) survival rate ranged from 0.56 to 0.95 and 0.84 to 0.95, respectively. Male survival was lower than that of females during the fall/winter season for a model not accounting for overdispersion. Averaging across parsimonious models, the dispersal rate for yearling and fawn males and yearling and fawn females were 0.44 ¡À 0.07 and 0.41 ¡À 0.07, respectively. Adult male dispersal rate was 0.46 ¡À 0.15 and no adult females dispersed. Slight differences were observed in habitat variables at sites used by male and female white-tailed deer, but hypotheses of sexual segregation between the sexes were not supported. Males were never observed in developed landcover. Sex differences in the use of developed landcover approached significance with females using sites with that landcover 131% more than males; they also used sites with 87% higher patch density of wetland landcover than males. Based on the best-fit AIC model, overall (i.e., both males and females) site selection of white-tailed deer was influenced by patch density of agriculture landcover, percentage of fallow field landcover, disjunct core area of the landscape, upper visual obstruction, and percentage of shrubs. Increases in upper visual obstruction and percent of shrub increased the likelihood of a site being selected. Decreases in patch density of agriculture landcover, percentage of fallow field landcover, and disjunct core area of the landscape increased the likelihood of a site being selected. This study provides updated information regarding white-tailed deer demographics, habitat use, survey methods, and hunter behavior to white-tailed deer managers in the Midwest. The data produced from mail-in surveys may provide knowledge of influences on hunter efficiency and success that may be used to manipulate deer harvest under a declining number of hunters in the U.S. Consistent estimates of density between indirect- and direct distance sampling shows utility for use of direct distance sampling within agriculturally-dominated regions of the Midwest. Fine-scale management by private landowners may benefit from my data by demonstrating a preference for a particular landscape signature by deer during the summer.
Access
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