Bruce L. Smith

Winter feeding of elk in Western North America

Winter feeding of elk (Cervus elaphus) is a topic that has engendered a great deal of debate among wildlife biologists, policy makers, and the general public. The first institutional feeding of elk in North America occurred in Jackson Hole, Wyoming, where several thousand elk are still fed during most winters at the National Elk Refuge. Winter feeding of elk is employed on an annual basis by state agencies in Idaho, Oregon, Utah, Washington, and Wyoming. During 1995-99, an average 31,000 elk were fed in those 5 states at a cost of

Neonatal mortality of elk driven by climate, predator phenology and predator community composition

1.6 million. Most feeding programs originated due to conflicts between elk and agricultural uses of historic elk winter range. Wildlife managers generally resorted to feeding to reduce damage by elk to crops, and to provide economic benefits of maintaining more elk than diminished winter habitat could sustain. Several negative consequences result from feeding elk. These include (1) the monetary costs of feeding, which divert dollars from other resource programs; (2) excessive herbivory that alters plant community structure and consequently affects the value of habitats near elk feedgrounds to other wildlife species; (3) changes in elk behavior that are of both spatial and philosophical siguificance; (4) diseases, which are more readily transmitted among densely concentrated animals, threaten the welfare of elk and other species, and shape resource management; and (5) public perceptions that may lead to the devaluing of habitat. These consequences argue for a shift from a production-consumption model of elk management toward management that embraces conservation of all species, maintenance of ecosystem functions, and sustainability of resources. 1 suggest proactive alternatives to winter feeding, which may avert conflict situations that precipitate public and political pressures to feed elk.

Juvenile survival and population regulation of the Jackson elk herd

1. Understanding the interaction among predators and between predation and climate is critical to understanding the mechanisms for compensatory mortality. We used data from 1999 radio-marked neonatal elk (Cervus elaphus) calves from 12 populations in the north-western United States to test for effects of predation on neonatal survival, and whether predation interacted with climate to render mortality compensatory. 2. Weibull survival models with a random effect for each population were fit as a function of the number of predator species in a community (3-5), seven indices of climatic variability, sex, birth date, birth weight, and all interactions between climate and predators. Cumulative incidence functions (CIF) were used to test whether the effects of individual species of predators were additive or compensatory. 3. Neonatal elk survival to 3 months declined following hotter previous summers and increased with higher May precipitation, especially in areas with wolves and/or grizzly bears. Mortality hazards were significantly lower in systems with only coyotes (Canis latrans), cougars (Puma concolor) and black bears (Ursus americanus) compared to higher mortality hazards experienced with gray wolves (Canis lupus) and grizzly bears (Ursus horribilis). 4. In systems with wolves and grizzly bears, mortality by cougars decreased, and predation by bears was the dominant cause of neonatal mortality. Only bear predation appeared additive and occurred earlier than other predators, which may render later mortality by other predators compensatory as calves age. Wolf predation was low and most likely a compensatory source of mortality for neonatal elk calves. 5. Functional redundancy and interspecific competition among predators may combine with the effects of climate on vulnerability to predation to drive compensatory mortality of neonatal elk calves. The exception was the evidence for additive bear predation. These results suggest that effects of predation by recovering wolves on neonatal elk survival, a contentious issue for management of elk populations, may be less important than the composition of the predator community. Future studies would benefit by synthesizing overwinter calf and adult-survival data sets, ideally from experimental studies, to test the roles of predation in annual compensatory and additive mortality of elk.

Development and evaluation of sightability models for summer elk surveys

Elk (Cerous elaphus nelsoni) that summer in Grand Teton National Park (GTNP) are part of the migratory Jackson Elk Herd. They are fed in winter on the National Elk Refuge (NER) and have been hunted in portions of GTNP since 1950 to control population size. However, the number of elk in the Jackson Elk Herd has grown from about 8,000 in 1984 to >16,000 in 1997. We captured and radiocollared 164 newborn calves during 1990-92 to quantify juvenile mortality and its role in regulating the Jackson Elk Herd. Elk captured in GTNP (5.9 elk/km 2 ) and on adjacent national forest lands of lower elk densities (2.4 elk/km 2 ) were radiomonitored through May 1994. Mortality of calves was similar during summer (15.2%), fall (15.3%), and winter (16.5%) 1990-92. Most deaths resulted from predation, hunting, and winter mortality associated with increased precipitation, duration of winter, and epizootic disease. Survival of calves supplementally fed in winter exceeded survival of calves not fed (P = 0.039). All but 1 of 16 deaths of elk ≥1 year old (n = 122) resulted from hunting. Early-born calves experienced higher winter survival (P = 0.02) than late-born calves. Annual calf survival (x = 0.579) was inversely related to birth date (P 0.47). Because much of the variation in juvenile survival was density independent, we recommend management that reduces the dependence of elk on supplemental feed and increases harvests of female elk.

Early development of supplementally fed, free-ranging elk

We developed 2 sightability models from summer helicopter surveys of radiocollared elk (Cervus elaphus) in Grand Teton National Park, Wyoming. Significant variables (P 30% vegetation cover), but this overestimation was ac- counted for by Model B. Thus, we recommend application of the Idaho model during summer surveys where elk are less gregarious (<20 elk) and recommend application of summer Model B to high-density elk popu-

Population dynamics of the Jackson elk herd

Early development of cervids has been correlated with juvenile survival and lifetime reproductive success. We investigated the contributions of elk (Cervus elaphus) densities, weather conditions, and supplemental feeding to birth weights, birthdates and weight gains of neonatal elk in northwest Wyoming during 1978-92. Male calves of free-ranging elk were born later (P = 0.01) and weighed more (P <0.03) than females. Annual rates and duration of supplemental feeding had no measurable effect on birth weight of elk calves. Cohort birth weights varied independently of elk densities on winter and summer ranges, but correlated with December and January temperatures (P <0.001) and with the onset of spring greenup (P <0.04). Winter survival and cohort birth weight were correlated for those calves that entered each winter. Nutritional benefits of winter feeding on maternal condition entering late gestation may have improved milk yields of dams thus producing weight gains through the first week of life that exceeded rates of gain previously reported for elk neonates.

Migrations and management of the Jackson elk herd

Abstract We fit data on elk (Cervus elaphus) population size and composition, survival rates measured from their first week of life, reported harvest, and local weather to a series of alternative population models of the elk herd in Jackson, Wyoming, USA, for the period 1980–2002. Data were corrected for biases in aerial survey visibility, misclassification of juveniles in ground surveys, and harvest reporting. The models included explanatory variables for sex, age, population size, weather, and autocorrelation of survival rates in different periods. Using information–theoretic model selection, we identified the most strongly supported models and effects. Model complexity ranged from 12 to 70 fitted parameters, and the best-supported model contained 25 parameters. We estimated annual natural survival (excluding harvest) of mature (≥1 yr) elk of 96.8% (SE = 1.5%) for males and 97.2% (SE = 2.2%) for females. Natality was 60.4 juveniles/100 mature females (SE = 3.9 juveniles/100 mature females). Sex ratio at birth strongly favored females (45.8% males, SE = 1.6%, Akaike weight = 99.9%). The dynamics of this population were well explained by annual variation in survival of neonates (birth to 31 Jul), juvenile survival during late winter (20 Feb–19 May), and harvest. Survival of neonates was correlated with several weather covariates that apparently affected nutritional status of their mothers. Survival of juveniles during late winter was related to weather conditions during the preceding summer and early winter. We found a compensatory effect of juvenile harvest on subsequent juvenile survival in late winter; 89% of increased juvenile harvest was offset by reduced natural mortality. We also found evidence for a decline in survival of neonates with increasing population size (density dependence). However, the density effect was weak at current population size and recent supplemental feeding rates. Thus, only continued or increased female harvest can maintain this population at current or lower levels if current feeding policies are continued—unless disease prevalence, predator impacts, or other factors substantially alter the historical dynamics. Simulations suggested that harvest rates of mature females must be increased to 15.1% from recent levels of 11.9% to reduce the current population of 15,680 elk (SE = 407) to the target population size of 11,029 set by the Wyoming Game and Fish Department (WGFD). Sensitivity of equilibrium population size at the WGFD target level to harvest rate was very high, requiring regular monitoring and adjustment of harvest to maintain a stable population.