Dean E. Beyer

Wolf Population Changes in Michigan

This chapter chronicles changes in wolf abundance and identifies the significant events in gray wolf ( Canis lupus ) management in Michigan from the early 1800s to present (Table 5.1 ). We recognize three important time periods. Initially, populations declined (1817–1959) due to public policy that sought to eliminate wolves. During the second period (1960–1988), wolves struggled to maintain their existence in the state. Public policy changed and wolves were granted legal protection. Despite this protection and an increasing shift in public attitudes that favored wolves (and the environment in general), a minority of Michigan residents evidently prevented wolves from reestablishing a population. During the third period (1989–present), wolves staged a remarkable comeback. The speed of their recovery surprised even those charged with aiding it. Although many credit a shift in public attitudes as the primary reason for this recovery, perhaps not enough credit has been given to the resiliency of wolves. This chapter focuses on wolf population changes on the mainland of Michigan. Information on the wolves occupying Isle Royale can be found in Vucetich and Peterson (this volume). Also, information on trends in wolf depredation of livestock during the period of population recovery may be found in Ruid et al. (this volume).

Identifying bobcat Lynx rufus kill sites using a global positioning system

The role of predation in ecological systems has received considerable attention in scientific literature and is one of the most important, yet least understood aspects of carnivore ecology. Knowledge of factors that improve our ability to detect predation events using animal telemetry data could be used to develop strategies to reduce time and resources required to obtain reliable kill estimates. Using Global Positioning System telemetry-collars, we investigated 246 bobcat Lynx rufus location clusters to identify white-tailed deer Odocoileus virginianus kill sites in the Upper Peninsula of Michigan, USA, during May-August, 2009-2011. We documented kills of white-tailed deer at 42 location clusters. We used logistic regression and Akaike Information Criterion for small samples to identify factors (i.e. number of locations in cluster, time from cluster formation to investigation, time of day and land cover) that may influence bobcat behaviour and our ability to detect white-tailed deer kill sites. Clusters with more locations and the search of clusters within 14 days after cluster formation increased odds of detecting bobcat kill sites. The best-performing model was 67% accurate overall and identified 34% of kill sites and 75% of non-kill sites. Applying our best-performing model with the optimal cut-off value would result in a twofold increase in the identification of white-tailed deer kill sites reducing time and effort to find a similar number of kill sites without models by half. Identifying factors that improve our ability to identify bobcat kill sites can reduce field effort and search time.

Effects of maternal nutrition, resource use and multi-predator risk on neonatal white-tailed deer survival.

Growth of ungulate populations is typically most sensitive to survival of neonates, which in turn is influenced by maternal nutritional condition and trade-offs in resource selection and avoidance of predators. We assessed whether resource use, multi-predator risk, maternal nutritional effects, hiding cover, or interactions among these variables best explained variation in daily survival of free-ranging neonatal white-tailed deer (Odocoileus virginianus) during their post-partum period (14 May–31 Aug) in Michigan, USA. We used Cox proportional hazards mixed-effects models to assess survival related to covariates of resource use, composite predation risk of 4 mammalian predators, fawn body mass at birth, winter weather, and vegetation growth phenology. Predation, particularly from coyotes (Canis latrans), was the leading cause of mortality; however, an additive model of non-ideal resource use and maternal nutritional effects explained 71% of the variation in survival. This relationship suggested that dams selected areas where fawns had poor resources, while greater predation in these areas led to additive mortalities beyond those related to resource use alone. Also, maternal nutritional effects suggested that severe winters resulted in dams producing smaller fawns, which decreased their likelihood of survival. Fawn resource use appeared to reflect dam avoidance of lowland forests with poor forage and greater use by wolves (C. lupus), their primary predator. While this strategy led to greater fawn mortality, particularly by coyotes, it likely promoted the life-long reproductive success of dams because many reached late-age (>10 years old) and could have produced multiple generations of fawns. Studies often link resource selection and survival of ungulates, but our results suggested that multiple factors can mediate that relationship, including multi-predator risk. We emphasize the importance of identifying interactions among biological and environmental factors when assessing survival of ungulates.

American black bear predation of an adult white-tailed deer

Abstract American black bears (Ursus americanus) are opportunistic omnivores and can be proficient predators of neonate ungulates, but predation of adult ungulates is rare. In November 2009 we investigated a probable black bear predation of a radiocollared, adult (7.5 years old) female white-tailed deer (Odocoileus virginianus) in a densely vegetated, lowland conifer forest in the Upper Peninsula of Michigan, USA. The deer carcass was 80% buried with puncture wounds and lacerations on the back and hindquarters. The hide was everted, the intestines and stomach partially eaten, the mammary glands were punctured, and the skeleton remained articulated. All woody vegetation <5.0 cm diameter within 5 m of the carcass was trampled and contained bear and deer hair. We found no evidence of other carnivores. Based on the condition of the carcass, physical evidence at the site, and the similarity of this predation to reported black bear predations, we suggest this deer was attacked and killed by a black bear.

Intra-seasonal variation in wolf Canis lupus kill rates

Knowing kill rate is essential for knowing the basic nature of predation. We compared estimates of kill rate for previously observed wolf-prey systems with new observations from wolves Canis lupus which preyed on white-tailed deer Odocoileus virginianus in Michigan, USA. For the five packs that we studied during 2001-2004, the mean kill rate was 0.68 kill/pack/day (∼7.7 kg/wolf/day). However, kill rates varied considerably. In particular, the coefficient of variation associated with the means was 0.55 for kills/pack/day and 0.68 for kg/wolf/day. Our analysis of previously observed kill rates also revealed a negative correlation between the duration of observation and the estimated kill rate. This correlation is the basis for showing how most published estimates of kill rate for wolves during winter tend to overestimate, by 50%, the season-long average kill rate during winter. The negative association between duration of observation and estimated kill rate occurs, in part, because wolves are unable to maintain very high kill rates for a long time. We also document how estimates of kill rate based on ground tracking tended to be 3.3 times greater than aerial-based estimates (2.4 vs 7.9 kg/wolf/day). Ground tracking is better able to detect multiple carcasses at one site, and better able to detect carcasses when wolves bed far from their kills. These previously undocumented biases are surprising given that wolves are so extensively studied.

Measurement Error and Survey Design in Sightability Model Development

ABSTRACT Measurement error of explanatory variables used in sightability models can result in biased population estimates and associated measures of precision. We developed a Monte Carlo simulation procedure that can be implemented within the sightability model framework when measurement error is present. Additionally, we developed simulation and sample survey methods, for determining the optimal allocation of survey effort to maximize precision of population estimates for a fixed survey cost, when a complete survey of a study area is not feasible. We used data from aerial surveys of elk during 2004–2006 in Michigan to demonstrate the application of these techniques. By accounting for measurement error and applying appropriate survey design practices, managers employing sightability models may be able to generate more accurate and cost-effective population estimates and accompanying measures of precision than is possible if these techniques are ignored.

Bear-Baiting May Exacerbate Wolf-Hunting Dog Conflict

Background The influence of policy on the incidence of human-wildlife conflict can be complex and not entirely anticipated. Policies for managing bear hunter success and depredation on hunting dogs by wolves represent an important case because with increasing wolves, depredations are expected to increase. This case is challenging because compensation for wolf depredation on hunting dogs as compared to livestock is less common and more likely to be opposed. Therefore, actions that minimize the likelihood of such conflicts are a conservation need. Methodology/Principal Findings We used data from two US states with similar wolf populations but markedly different wolf/hunting dog depredation patterns to examine the influence of bear hunting regulations, bear hunter to wolf ratios, hunter method, and hunter effort on wolf depredation trends. Results indicated that the ratio of bear hunting permits sold per wolf, and hunter method are important factors affecting wolf depredation trends in the Upper Great Lakes region, but strong differences exist between Michigan and Wisconsin related in part to the timing and duration of bear-baiting (i.e., free feeding). The probability that a wolf depredated a bear-hunting dog increases with the duration of bear-baiting, resulting in a relative risk of depredation 2.12–7.22× greater in Wisconsin than Michigan. The net effect of compensation for hunting dog depredation in Wisconsin may also contribute to the difference between states. Conclusions/Significance These results identified a potential tradeoff between bear hunting success and wolf/bear-hunting dog conflict. These results indicate that management options to minimize conflict exist, such as adjusting baiting regulations. If reducing depredations is an important goal, this analysis indicates that actions aside from (or in addition to) reducing wolf abundance might achieve that goal. This study also stresses the need to better understand the relationship among baiting practices, the effect of compensation on hunter behavior, and depredation occurrence.

Coyotes in Wolves' Clothing

Abstract We report on three presumed wolf pups captured in Michigans northern Lower Peninsula, potentially representing the first documented case of wolf reproduction in the Lower Peninsula since wolves were extirpated there a century ago. The pups, two females and one male, were assumed to be wolves based on physical characteristics. Genetic profiles assigned all three pups as coyotes but revealed evidence of maternal introgression from a Great Lakes wolf in their pedigree. These findings suggest that Great Lakes wolves are capable of interbreeding with coyotes when conspecifics are rare.

Bald Eagle Predation of a White-Tailed Deer Fawn

Abstract Haliaeetus leucocephalus (Bald Eagle) is an adaptable predatory bird that commonly captures live prey, but regularly scavenges. Large mammalian prey (e.g., Odocoileus virginianus [White-tailed Deer]) have been observed in Bald Eagle diets, but were considered scavenged. To our knowledge, Bald Eagle predation of a live ungulate has only been reported once, and occurred in Menominee County, MI. In June 2009, we captured and radiocollared a female White-tailed Deer fawn (2.7 kg) in the south-central Upper Peninsula of Michigan. The fawn was last radiolocated alive 8 h after release in a short-height (20–30 cm) grassland field along a river approximately 570 m from an eagle nest. Estimated time of mortality of the fawn was 10 h post release. Approximately 27 h post release, 2 legs, >50% fawn hide, and the radiocollar were present in the nest along with 2 eagle nestlings (estimated age 9–10 wks). We believe this was a possible predation event based on the 8-h period between fawn relocations, fawn movement, foraging behavior of the nesting eagles, and presence of the carcass remains and radiocollar in the nest.

Flawed analysis and unconvincing interpretation: a comment on Chapron and Treves 2016

Chapron & Treves [1] (hereafter C&T) believe that quantifying poaching is ‘one of the most crucial questions for the conservation of large carnivores’ (p. 2). We agree that evaluating poaching is important and merits rigorous attention. Yet, we argue that C&Ts claim, ‘allowing culling increases poaching’, is not supported by their data. We assert that C&T is based on flawed analysis and unconvincing interpretation of scientific literature. C&T claimed to ‘present the first quantitative evaluation of the hypothesis that culling will reduce poaching’. However, Olson et al . [2] used empirical data (fates of wolves) to demonstrate that illegal killing decreases with increasing availability of lethal depredation management (hereafter, LDM). C&T claimed to ‘show that allowing wolf [ Canis lupus ] culling was substantially more likely to increase poaching than to reduce it’. However, C&T produced no empirical evidence of increased poaching, but only showed a marginal association between policy change allowing LDM and reduction in expected wolf population growth in Wisconsin and Michigan (USA). Additionally, C&T later reported a misalignment in their dataset between wolf population size, number of wolves culled and policy change [3]. C&T claim that the conclusion of their ‘paper is still supported by the correct results’ (p. 1) [3]. However, the lack of a significant change in results following the correction of their data suggests either important design flaws or a phenomena largely uncoupled from their putative ‘policy signals’. C&T also claimed ‘replicated quasi-experimental’ (p. 2) design because changes in policy led to variation in LDM authority [1]. C&T compared ‘treatment’ periods (periods with LDM) with ‘control’ periods (when wolves were federally protected). C&Ts replication claim implies independence among treatments with respect to effect of policy signals [1, p. 3], something most-certainly untrue. …