Tim L. Hiller

Evaluating the efficacy of adaptive management approaches: Is there a formula for success?

Within the field of natural-resources management, the application of adaptive management is appropriate for complex problems high in uncertainty. Adaptive management is becoming an increasingly popular management-decision tool within the scientific community and has developed into two primary schools of thought: the Resilience-Experimentalist School (with high emphasis on stakeholder involvement, resilience, and highly complex models) and the Decision-Theoretic School (which results in relatively simple models through emphasizing stakeholder involvement for identifying management objectives). Because of these differences, adaptive management plans implemented under each of these schools may yield varying levels of success. We evaluated peer-reviewed literature focused on incorporation of adaptive management to identify components of successful adaptive management plans. Our evaluation included adaptive management elements such as stakeholder involvement, definitions of management objectives and actions, use and complexity of predictive models, and the sequence in which these elements were applied. We also defined a scale of degrees of success to make comparisons between the two adaptive management schools of thought. Our results include the relationship between the adaptive management process documented in the reviewed literature and our defined continuum of successful outcomes. Our data suggest an increase in the number of published articles with substantive discussion of adaptive management from 2000 to 2009 at a mean rate of annual change of 0.92 (r² = 0.56). Additionally, our examination of data for temporal patterns related to each school resulted in an increase in acknowledgement of the Decision-Theoretic School of thought at a mean annual rate of change of 0.02 (r² = 0.6679) and a stable acknowledgement for the Resilience-Experimentalist School of thought (r² = 0.0042; slope = 0.0013). Identifying the elements of successful adaptive management will be advantageous to natural-resources managers considering adaptive management as a decision tool.

Survival and Space Use of Fawn White-Tailed Deer in Southern Michigan

ABSTRACT Many cervids exhibit similar behavior near and following parturition. For example, during their first 2 mo of life, fawn white-tailed deer (Odocoileus virginianus) are relatively sedentary, may be at their highest risk for mortality and are not yet functional ruminants. Relatively few studies describe demographics or space use of fawn white-tailed deer ≤2 mo old despite the potential for mortality through this time period having a relatively large influence on deer population dynamics. Our objectives were to estimate survival, assess cause-specific mortality and describe space use (i.e., cover) of fawn white-tailed deer in an agro-forest ecosystem in south central Michigan. We captured (mid-May to mid-Jun.), radiomarked and monitored 34 fawns during 2004–2006 and pooled data for analyses. Two- and 6-mo survival estimates (Mayfield method) were 81% and 67%, respectively, and canids caused most mortalities during both time periods. Kernel home ranges (95%) during the first 2 mo averaged 40.9 ha (range  =  2.7–166.8), with conifers and lowland deciduous forests selected in proportions higher than available on the study area.

Factors affecting harvests of fishers and American martens in northern michigan

ABSTRACT Harvest data (e.g., number of animals harvested, trapper effort) are an important source of information for state wildlife agencies to manage harvested furbearers. These data provide evidence to support adapting harvest regulations when necessary. Setting appropriate harvest regulations for fishers (Martes pennanti) and American martens (Martes americana) is critical, as these species often exist at low densities, are sensitive to timber-management practices and trapper-harvest, and experience some level of interspecific predation and competition in sympatric populations. We estimated effects of management (e.g., number of fishers or martens harvested per trapper per season [harvest limit], season length) and extrinsic (e.g., weather, pelt prices) factors on regulated harvests of fishers and martens in the Upper Peninsula of Michigan during 1996–2007. We used generalized linear mixed models in an information-theoretic approach (quasi-likelihood adjusted Akaike Information Criterion [QAIC]) to discern which factors most strongly influenced fisher and marten harvests. For harvest of fishers, the 3 QAIC-best models included harvest limit, season length, and number of trappers, suggesting that regulatory changes within the ranges tested may be implemented to influence harvest. The QAIC-best model (harvest limit) contained 26% of the weight of evidence, and using an independent subset of data, showed no difference between model predictions and harvest data. In contrast, harvest of martens was not strongly influenced by any factors we tested. Possible reasons for a lack of measurable effects while modeling harvest of martens include a low harvest limit (i.e., 1 marten) or incidental harvest of martens by fisher or bobcat (Lynx rufus) trappers. Knowledge of influences on harvest will lead to informed decision-making when managers are setting harvest regulations, particularly for low-density furbearers.

Using Advancements in Cable-Trapping to Overcome Barriers to Furbearer Management in the United States

Abstract Harvest of furbearers through trapping has been challenged by anti-trapping organizations for centuries, with organizational goals often including prohibition of all forms of trapping. Challenges to trapping may also include dissention among state wildlife agencies, pro-hunting organizations, and pro-trapping organizations. Despite recent efforts by anti-trapping organizations and occasional dissention among consumptive-use groups, national trends in snaring regulations included less restrictive regulations through time. This positive trend may offer opportunities for state wildlife agencies and pro-trapping organizations to enhance the public image of trapping, increase recruitment of trappers, and reverse the increasing trend of wildlife damage and associated costs. We offer support and suggestions to state wildlife agencies and pro-trapping organizations to help achieve these goals, with their partnership likely having a synergistic effect. Although we attempt to illuminate approaches for increasing support for trapping within the constraints of the cultural norms of the United States, we hope our approaches are useful to and promote dialogue in other jurisdictions experiencing similar problems.

Resource selection by recolonizing American black bears in a fragmented forest landscape

Abstract Following functional extirpation in Missouri, American black bear (Ursus americanus) populations in this state have been increasing in recent years through recolonization from re-established populations in northern Arkansas. To increase our understanding of resource selection by recolonizing black bears in the Ozark Highlands of the United States, we attached Global Positioning System (GPS) transmitters to 54 black bears during May–August 2010–2013, and used location data based on biological seasons. We constructed models with anthropogenic (distance to nearest development, distance to nearest road), biological (sex, age class, season), and environmental (distance to nearest water, land cover) categories. We used infinitely weighted logistic regression to approximate the inhomogeneous Poisson point process model for presence-only (i.e., GPS locations) data to fit models. We used Bayesian Information Criterion and found that the best-performing model in the set of 81 models included all independent variables except sex and all combinations of 2-way interactions except those between biological covariates. Forested areas generally were more strongly selected than non-forested areas and bears generally selected areas distant from roads and other human development. However, selection for areas proximate to roads in the composite cover type (e.g., shrub–scrub, woody wetlands) occurred, where roads may have been used as travel corridors in unsuitable cover during the breeding season (ad) or dispersal (subad), or alternatively as a potential barrier, depending on road type and traffic volume. Use of apparent lower quality non-forested areas by bears suggests that the current level of human development in southern Missouri is unlikely to halt their recolonization.

Comparison of Two Age-Estimation Techniques for Cougars

Abstract Age estimation in wildlife is crucial for population assessment and management decision-making. Estimation errors may reduce the efficacy of management programs or potentially result in poor management decisions. Our objective was to compare aging techniques (gum-line measurement and cementum annuli analysis) for Cougars (Puma concolor) using harvest data collected during 2006–2010 in Oregon. Differences in paired age estimates (cementum annuli estimate minus gum-line recession estimate) had 95% confidence limits of −0.28 and −0.06. Linear regression showed a relatively high level of agreement (<1.0-y difference) between the 2 aging techniques considered for individuals ≥1-y and ≤17-y old. The slope suggests that each 1 y increase in estimated age using cementum annuli analysis adds 1.03 y to the predicted estimated age using gum-line measurements. Disparity between estimates increases with age. Individuals estimated to be 1-y old using x (cementum annuli counts) are predicted to be 1.09-y old using y (gum-line measurements), and individuals estimated to be 12-y old using x are predicted to be 12.42-y old using y. The use of >1 age-estimation technique, implementation of standardized protocols (if not currently in place), and additional training to potentially increase consistency and reduce bias among observers will be beneficial for Cougar management.

Estimation and Implications of Space Use for White-Tailed Deer Management in Southern Michigan

Abstract Studies assessing space use are often descriptive but sometimes lack guidance for managers whose objectives include altering wildlife abundance through habitat management programs. The concept of usable space (i.e., species-specific permanent cover situations that maximize fitness) collapses commonly used home-range estimates (e.g., kernel estimators) by excluding cover types contained within individual home ranges that lack direct evidence of use and by reducing cover types containing large areas but small proportions of location estimates. In theory, estimates of usable space provide a potentially more accurate biological representation of space use compared to kernel estimators and provide guidance for managing avoided cover types (i.e., used in a proportion less than available). Our objectives were to compare white-tailed deer (Odocoileus virginianus) space use under the kernel and usable-space methods and to discuss the implications of cover conversions under the usable-space concept. Using radiomarked adult female deer (n = 20) in south central Michigan, USA, during 2004–2006, we found that fixed-kernel home-range estimates (x = 77.5 ha ± 9.6 SE for the agricultural growing season, x = 140.4 ha ± 23.4 SE for the nongrowing season) included cover types with no evidence of use (e.g., no telemetry locations). Usable-space estimates (ha) were approximately 75% that of kernel home ranges and were dominated (approx. 87%) by upland deciduous forest, lowland shrub, agriculture, and coniferous cover types. Under the assumption that deer densities are positively correlated with the amount of usable space, we provided several cover-conversion scenarios (i.e., habitat manipulation) that would theoretically change deer densities on our study area by increasing or decreasing the amount of usable space. Effects of land-use changes (e.g., increasing urbanization, such as on our study area and throughout much of the midwestern United States) on usable space and inferences on deer population responses may also be assessed using our approach. Regardless of the wildlife species being managed, decisions regarding habitat manipulation are often constrained by several factors (e.g., social, edaphic) and managers should consider ecological processes (e.g., vegetation succession) and implications on broader objectives (e.g., biodiversity conservation).

Community composition of Ixodid ticks parasitizing American black bears in Missouri, USA

Abstract Bears (Ursidae) have extensive home ranges and may move long distances, thereby potentially serving as hosts to, and vectors of, large numbers of ticks. We assessed the composition of the parasitizing tick community on American black bears (Ursus americanus) to discern hard tick species capable of successfully feeding, which is a necessary step for tick reproduction. We counted ticks from free-ranging, live-trapped, or road-killed black bears in southern Missouri, USA, during 2015, and collected a subset of engorged ticks (n = 967). All bears (n = 17) were infected with ticks (n = 6,993), with a mean intensity of 411 ticks/bear, of which 14% were engorged females. The infracommunity size of engorged ticks was 57 ticks/bear. From these engorged ticks, we identified 5 species: Amblyomma americanum, A. maculatum, Dermacentor variabilis, D. albipictus, and Ixodes scapularis. Amblyomma americanum was the most common species, collected on all surveyed bears, and represented 58.2% of engorged ticks, whereas D. albipictus and A. maculatum were the least common species, collected from only 3 and 4 bears, respectively, and representing 4.7% and 2.4% of engorged ticks, respectively. Our data suggest that individual black bears have the potential to host large numbers of ticks to engorgement, and may be important vectors for tick dispersal and for the maintenance of tick populations.

Sex-Age Selectivity and Correlates of Capture for Winter-Trapped White-Tailed Deer

Abstract Despite the common use of Clover traps to capture white-tailed deer (Odocoileus virginianus), little published information exists quantifying trap success, trap selectivity (sex-age selection), or weather correlates of trap success. We quantified these relationships using white-tailed deer data from 3 study sites in the Lower Peninsula of Michigan, USA, during winters 2001–2007. We captured 610 deer in 8,569 trap-nights; pooled capture success was 0.07 deer/trap-night, although site-year success varied from 0.021 to 0.086. We compared sex-age classes (fawn [pooled by sex], ad M, ad F) captured with sex-age classes estimated to be available on each study site during each capture season. We used generalized linear mixed modeling to construct 19 a priori models to describe probability of capture success as a function of weather covariates (daily min. temp [° C], daily snowfall [cm], daily snow depth [cm]), Julian day, site, and year. General selection patterns included fawns captured more than expected and adult males captured less than expected; adult females were generally neutrally selected. The quasi-Akaikes Information Criterion best model within our set was described by the global model without Julian day and contained all 3 weather covariates and site-year effects. Our model provided some evidence that as daily snow depth increased, probability of capture increased; the positive effect of daily snowfall on capture probability was dependent on decreasing daily minimum temperature. Our results may be used to increase efficacy of deer capture programs by researchers and managers through informed decision-making about when to allocate effort (e.g., if extreme winter weather conditions are predicted) and when to consider alternative methods (e.g., if capture of ad M is an objective).

Non-Invasive Survey of Forest Carnivores in the Northern Cascades of Oregon, USA

Abstract Several species of forest carnivores are of state or federal concern in Oregon and are or may be sensitive to timber management practices, wildfires, climate change, and other large-scale disturbances. We implemented a non-invasive survey of forest carnivores in the northern Cascades of Oregon during fall–spring, 2012–2014. We collected 111,148 images from 21 elevated and 39 ground-level baited camera stations located from 586 to 2237 m in elevation. We detected (≥1 image) Red Fox (Vulpes vulpes) at 9 ground stations, of which 4 also detected Coyote (Canis latrans). We detected American Marten (Martes americana) at 63% of all stations (elevation range  =  1252–2237 m), including 5 of 7 stations located in areas that experienced wildfires since 1996 that covered >5000 ha. Other forest carnivores detected included Bobcat (Lynx rufus), Black Bear (Ursus americanus), Mountain Lion (Puma concolor), Northern Raccoon (Procyon lotor), American Mink (Neovison vison), weasel (Mustela spp.), and skunk (Mephitis mephitis, Spilogale gracilis); but we did not detect Wolverine (Gulo gulo), Canada Lynx (Lynx canadensis), Fisher (Martes pennanti), or Gray Wolf (Canis lupus). Future periodic non-invasive surveys of forest carnivores may provide information about changing species composition and distribution, especially in relation to climate change, vegetation succession, and potential recolonization by Gray Wolves.