Dan L. Baker

Comparative Nutritional Ecology of Montane Ungulates during Winter

Comparisons of botanical and nutritional characteristics of winter diets of elk (Cervus elaphus nelsoni), mule deer (Odocoileus hemionus hemionus), and mountain sheep (Ovis canadensis canadensis) revealed sharp divergence in food niches. Deer diets contained the most browse and lignin, were intermediate in crude protein, and contained the least in vitro digestible dry matter (IVDDM). Mountain sheep diets were dominated by forbs and were consistently highest in protein and IVDDM. Cell solubles were higher and nonlignified cell wall lower in mule deer and mountain sheep diets compared with elk diets. Elk diets contained the most grass, were intermediate in IVDDM, and were lowest in crude protein. Protein and cell soluble content of diets were correlated with diet selectivity. These species ate less grass and more dicots when the crude protein and cell soluble content of grasses declined. Our findings are discussed in context of current theory on trophic ecology of wild ungulates. We propose that mule deer fit some aspects of this theory poorly and suggest that recent findings on their digestive physiology may explain this inconsistency. J. WILDL. MANAGE. 47(1):1-16 The process of diet selection is fundamental to understanding many aspects of ungulate ecology. An animals body size and morphology limit the range of foods it can efficiently eat and assimilate (Hoffman 1973, Janis 1976, Kay et al. 1980). Food selection and assimilation ability are important determinants of the relative suitability of habitats for ungulates and are closely related to their social structures, patterns of dispersal, and tactics of predator avoidance (Bell 1970, Jarman 1974, Maddock 1979). Food choices affect community organization (Vesey-FitzGerald 1960, McNaughton 1978, Jarman and Sinclair 1979) and ecosystem function (Ellis et al. 1976; McNaughton 1976, 1979). Previous studies of trophic relations of wild ungulates have been largely observational, focusing on taxonomic and morphological differences in animal diets. Here we report experimental comparisons of nutritional attributes of winter diets of 3 montane ungulates: mule deer, elk, and mountain sheep. We test predictions of theory on physical, chemical, and botanical composition of ungulate diets relative to body size, social organization, digestive morphology, and changes in food

Ungulate Grazing in Sagebrush Grassland: Mechanisms of Resource Competition

In many areas of western North America, populations of Rocky Mountain elk (Cervus elaphus canadensis) avoid snow at high elevations during winter by migrating to sagebrush grassland communities in mountain valleys, communities that are used by cattle in the spring and early summer. As a result of these patterns of habitat use, the impact of elk on forage supplies for cattle has emerged as an important issue in range and wildlife management throughout the West. We examined effects of variation in population density of elk on the availability and use of forage resources by cattle in a randomized complete block experiment conducted in sagebrush grassland during four years. We manipulated elk numbers to achieve four levels of population density (0, 9, 15, and 31 elk/kM2), replicated each level three times, and observed responses of vegetation and cattle to these manipulations. At high densities (31 animals/kM2), elk annually removed 57% of the standing crop of dead perennial grass and 12% of the total annual production of live perennial grass. Standing crops of dead perennial grass in early spring declined in direct proportion to increasing elk density (linear effect F,,6 = 10.0, P = 0.02) from a mean of 8.7 g/m2 in the controls (O elk/kM2) to 3.3 g/m2 in the high density (31 elk/kM2) treatment. Early spring standing crops of live perennial grass also declined as elk population density increased, but these trends only approached significance (linear effect F16 = 3.4, P = 0.12). Effects of elk grazing on herbaceous aboveground net primary production were not significant (minimum P > 0.38), but the total supply of herbaceous dry matter available to cattle (standing dead + primary production) declined in linear relation to elk density (linear effect F1,6 = 7.7, P = 0.03). Canopy cover of shrubs was least and canopy cover of grass was greatest at intermediate levels of elk density (quadratic effect F1,6 = 9.4, P = 0.03).

Effects of fertility control on populations of ungulates : General, stage-structured models

Regulating the abundance of ungulate populations using hunting can prevent populations from reaching levels that cause harm to natural and human dominated systems. However, there are an increasing number of cases where hunting is infeasible, and in such cases, fertility control has been widely advocated as an alternative means for controlling populations. Here, we develop simple analytical models offering general insight into the feasibility of using fertility control to regulate the abundance of ungulates. The models are structured in stages to represent variation in the duration of effect of fertility control agents. Analysis of these models offers several predictions, amenable to testing in field studies. (1) More than 50% of fertile females will need to be maintained infertile to achieve meaningful reductions in ungulate numbers even when fertility rates are low. (2) The relationship between the proportion of females maintained infertile and the steady state density is highly nonlinear. This means that small errors in estimating levels of infertility can lead to large errors in achieved density. It also means that managers should expect to see little change in steady-state density across a broad range of delivery rates. (3) The efficacy of fertility control as a management technique depends strongly on the persistence of the effect of the fertility control agent and the ability of managers to recognize previously treated animals. (4) Fertility control using long-lived agents can be more efficient than culling in regulating ungulate numbers. (5) Treating small populations with irreversible agents magnifies the likelihood of population extinction relative to treatment by culling. As with all techniques, managing population fertility must extend from a sound understanding of the influence of management actions on the state and dynamics of the population.

Effectiveness of capsaicin and bitrex repellents for deterring browsing by captive mule deer

Because mule deer (Odocoileus hemionus) and white-tailed deer (O. virginianus) cause extensive and costly damage to orchards, nurseries, shelterbelts, and ornamental plantings in Colorado, we evaluated 3 concentrations (0.062, 0.62, and 6.2 %) of Hot Sauce Animal Repellent® (Hot Sauce), habanero peppers, Tabasco® sauce, Ani-spray®, and liquid MGK® Big Game Repellent (BGR) as browsing deterrents on tame mule deer from 31 December 1991 to 25 January 1992. While consumption of apple twigs treated with Anispray and the 0.062 % concentration of Hot Sauce did not differ (P > 0.05) from the control (tap water), a 6.2 % concentration of Hot Sauce (100 times the concentration labeled for deer) and BGR reduced (P < 0.05) consumption relative to the control and other repellents

RELATIVE PREFERENCE OF CAPTIVE COW ELK FOR REPELLENT-TREATED DIETS

Because of the extent and cost of elk (Cervus elaphus nelsoni) damage in Colorado, we tested the repellency of MGK? Big Game Repellent (BGR), chicken eggs, coyote (Canis latrans) urine, Hinder?, Hot Sauce Animal Repellent? (Hot Sauce), Ro -pel?, and thiram on tame cow elk there from December 1990 to February 1991. At the concentrations used, coyote urine and BGR performed better than the other repellents for deterring elk from feeding on cubed alfalfa hay. Consumption of rations treated with odor repellents (BGR, chicken eggs, coyote urine, and Hinder) increased from day 1 through day 5 of the trial, but consumption of rations treated with thiram (a taste repellent) decreased. In a second trial, hungry elk consumed significantly more repellent-treated apple twigs (Malus domestica) than did elk that were maintained on an ad libitum diet. Hot Sauce, applied at 100 times (6.2%) the labeled concentration for deer (Odocoileus spp.), deterred all 9 satiated elk and 7 of 9 hungry elk from browsing on apple twigs, but the labeled concentration (0.06%) failed to deter most elk fed ad libitum and all elk when hungry. Coyote urine, at 10% and 100% concentrations, failed to deter hungry elk, but the 100% solution moderately deterred elk fed ad libitum from browsing on apple twigs. Thiram applied at the labeled concentration and at 10% of the labeled concentration for deer failed to deter any elk when hungry and most elk when fed ad libitum. In a third trial, Hot Sauce at concentrations of 0.06%, 0.20%, and 0.62% did not deter any of 9 elk fed 50% of their average daily intake, but the 2.0% and 6.2% concentrations deterred 2 and 6 elk, respectively. Hot Sauce, at concentrations of 6.2% and 12.4%, and 100% coyote urine were not phytotoxic to apple trees. Abstract: Because of the extent and cost of elk (Cervus elaphus nelsoni) damage in Colorado, we tested the repellency of MGK? Big Game Repellent (BGR), chicken eggs, coyote (Canis latrans) urine, Hinder?, Hot Sauce Animal Repellent? (Hot Sauce), Ro -pel?, and thiram on tame cow elk there from December 1990 to February 1991. At the concentrations used, coyote urine and BGR performed better than the other repellents for deterring elk from feeding on cubed alfalfa hay. Consumption of rations treated with odor repellents (BGR, chicken eggs, coyote urine, and Hinder) increased from day 1 through day 5 of the trial, but consumption of rations treated with thiram (a taste repellent) decreased. In a second trial, hungry elk consumed significantly more repellent-treated apple twigs (Malus domestica) than did elk that were maintained on an ad libitum diet. Hot Sauce, applied at 100 times (6.2%) the labeled concentration for deer (Odocoileus spp.), deterred all 9 satiated elk and 7 of 9 hungry elk from browsing on apple twigs, but the labeled concentration (0.06%) failed to deter most elk fed ad libitum and all elk when hungry. Coyote urine, at 10% and 100% concentrations, failed to deter hungry elk, but the 100% solution moderately deterred elk fed ad libitum from browsing on apple twigs. Thiram applied at the labeled concentration and at 10% of the labeled concentration for deer failed to deter any elk when hungry and most elk when fed ad libitum. In a third trial, Hot Sauce at concentrations of 0.06%, 0.20%, and 0.62% did not deter any of 9 elk fed 50% of their average daily intake, but the 2.0% and 6.2% concentrations deterred 2 and 6 elk, respectively. Hot Sauce, at concentrations of 6.2% and 12.4%, and 100% coyote urine were not phytotoxic to apple trees.

Ungulate Grazing in Sagebrush Grassland: Effects of Resource Competition on Secondary Production

In many areas of western North America, populations of elk are believed to harm production of cattle by competing with them for limited supplies of native forage. We examined effects of variation in the population density of elk (Cervus elaphus canadensis) during winter on growth and reproduction of cattle during spring, using a randomized complete block experiment conducted in sagebrush grassland during four years. We manipulated elk numbers to achieve four levels of population density (0, 9, 15, and 31 elk/km2), replicated each level three times, and observed responses of cattle to these manipulations. Mean birth dates of calves born to cows in the intermediate (9, 15 elk/km2) treatment levels were delayed by 5 d relative to birth dates of calves born to cows in controls (0 elk/km2), but these trends were not statistically significant (quadratic effect F1,6 = 3.2, P = 0.13). Calf body mass at birth was not significantly influenced by treatment, but calf body mass at the end of spring declined linearly (...

GONADOTROPIN-RELEASING HORMONE AGONIST: A NEW APPROACH TO REVERSIBLE CONTRACEPTION IN FEMALE DEER

Fertility control offers a potential alternative for controlling an abundance of wild ungulate populations where lethal methods are infeasible or unacceptable. A promising nonsteroidal, nonimmunologic approach to reversible contraception consists of agonist of gonadotropinreleasing hormone (GnRH). We evaluated the effects of the GnRH agonist, leuprolide, on reproduction, the suppression of luteinizing hormone (LH) and progesterone, blood parameters, and reproductive behavior in captive female mule deer (Odocoileus hemionus) during December 1999 through June 2001. Leuprolide, administered as a controlled release formulation (ATRI-GEL®), was 100% effective in preventing pregnancy for one breeding season. Infertility was achieved by suppressing LH levels, which prevented ovulation and the formation of corpus luteum. Treated females regained normal ovarian function and conceived the following breeding season. Leuprolide had no adverse effects on blood chemistry and hematology, body weight dynamics, or the general health of treated females. In contrast to our predictions, leuprolide did not suppress estrous behavior in female deer during the “normal” breeding period, nor did treated females return to normal ovarian function and exhibit reproductive behaviors during the postbreeding period. This prolonged-release leuprolide formulation offers an alternative approach to reversible contraception in female deer that overcomes some of the problems associated with existing technology.

Fertility Control in Free-Ranging Elk Using Gonadotropin-Releasing Hormone Agonist Leuprolide: Effects on Reproduction, Behavior, and Body Condition

Abstract Overabundant elk (Cervus elaphus) populations have become a significant problem in many areas of North America. This is particularly true for protected areas where high densities of elk can cause long-term ecological degradation. When lethal control is not acceptable in these environments, resource managers must often consider alternative methods for reducing the size of resident elk populations. A potential management alternative is controlling the fertility of female elk. A promising new approach to wildlife contraception involves the use of biodegradable implants containing the gonadotropin-releasing hormone (GnRH) agonist leuprolide. During fall 2002–spring 2004, we compared pregnancy rates, reproductive behavior, daily activity patterns, and body condition of 17 free-ranging female elk treated with a leuprolide formulation with 17 untreated females, in Rocky Mountain National Park, Colorado, USA. After treatment, the pregnancy rate of treated elk was 0%, whereas 79% of control elk became pregnant. The effects of treatment were reversed the subsequent year with the pregnancy rate of treated females 100% compared with 91% for controls. Reproductive behaviors were similar for treated and control elk during the breeding and postbreeding seasons; treated elk did not exhibit postrut reproductive behaviors. Moreover, we found no differences in daily activity patterns of experimental groups during the breeding or postbreeding seasons. Treated elk did not show improved body condition over pregnant females. Instead, treated females catabolized proportionately more body fat during winter after treatment and at a higher rate than pregnant control elk. However, this effect was reversed the next spring with no difference in body fat between treated and control elk. We conclude from this experiment that leuprolide, administered as a controlled release formulation, offers a safe and effective method of controlling fertility in free-ranging female elk. However, practical application is limited by treatment duration and the need to treat females before the breeding season.

Effects of Gonadotropin-Releasing Hormone Immunization on Reproductive Function and Behavior in Captive Female Rocky Mountain Elk (Cervus elaphus nelsoni)

ABSTRACT Fertility control is a potential method for managing overabundant wildlife populations; however, current technology is limited by duration of treatment efficacy and unacceptable side effects. The objective of this study was to determine the efficacy of a single immunization with gonadotropin-releasing hormone (GnRH) vaccine to suppress reproductive function in pregnant female elk and to evaluate potential behavioral and pathological side effects of treatment. Eighteen captive adult female elk were randomly allocated to one of two experimental groups. Ten females were administered a conjugated and adjuvanted GnRH vaccine intramuscularly, and eight elk received an adjuvant sham vaccine without conjugated GnRH. We compared success of existing pregnancy, neonatal survival, subsequent fertility, reproductive behavior rates, and side effects of treatment between January 2006 and January 2010. The GnRH vaccination did not affect existing pregnancy or calf survival during the year that it was applied; however, it reduced the proportion of pregnant females for 3 yr. Male precopulatory behavior rates exhibited toward GnRH-vaccinated females tended to be greater than those directed at sham-vaccinated females during the second half of the breeding season, when GnRH vaccinates continued to be proceptive. Strong immune and inflammatory responses, including robust GnRH antibody concentrations in GnRH vaccinates, and sterile pyogranulomatous injection site abscesses in both groups, were consistent with vaccination. In conclusion, this GnRH vaccine resulted in prolonged, albeit reversible, impairment of fertility, and is associated with extended reproductive behaviors and partial suppression of hypothalamic-pituitary-gonadal axis function in captive female elk.

Effectiveness of hot sauce® and deer away® repellents for deterring elk browsing of aspen sprouts

In western North America, large concentrations of elk (Cervus elaphus) can have detrimental effects on aspen (Populus tremuloides) regeneration and clone survival. In some situations, management intervention to protect aspen sprouts is needed. We conducted an experiment to evaluate the effectiveness of Hot Sauce Animal Repellent (r) (HS) and Deer Away (r) (DA) in deterring elk from browsing aspen sprouts during summer. We examined the responses of elk browsing on aspen sprouts at 3 levels of HS (0.062%, 0.62%, 6.2%) and 1 level of DA at 2 time periods (2 and weeks postapplication). high concentration HS (6.2%) and DA were the most effective repellents; browsing on aspen sprouts was reduced by 45% with HS and 27% with DA compared to controls. Elk browsing on aspen sprouts decreased linearly (P < 0.001) with increased concentration of HS. Levels of elk browsing on aspen sprouts were similar (P = 0.249) for repellent treatments applied 2 and 5 weeks prior to exposure to elk. We conclude that HS (6.2%) and DA will provide protection of aspen sprouts from browsing by elk for at least 5 weeks during the growing season, but current economic costs limit the practicality of large-scale use of these repellents.