Thomas D. Drummer

WINTER PREY SELECTION AND ESTIMATION OF WOLF KILL RATES IN YELLOWSTONE NATIONAL PARK, 1995–2000

Abstract Wolf (Canis lupus) impacts on prey are a central post-wolf-reintroduction issue in the greater Yellowstone ecosystem (GYE) of the western United States. Further, estimates of wolf kill rates, used to understand these impacts, can be biased due to unrecovered kills. In Yellowstone National Park (YNP), visibility of wolves allowed us to combine independent aerial and ground observations and use a double-count method to estimate the probability of recovering kills. We consequently used these data to adjust estimates of wolf kill rates. We conducted monitoring annually from 1995 to 2000 during 2 30-day periods in early (15 Nov–14 Dec) and late winter (Mar). Estimated recovery rates of wolf kills for ground and aerial crews were 50% and 45%, respectively, although we determined that this varied by location (distance from road) and possibly age (calf or adult) of the kill. The estimated combined recovery rate was 73%. Estimated wolf kill rates were higher in late winter (2.2 kills/wolf/month) compared to early winter (1.6 kills/wolf/month), with an overall estimated rate of 1.9 kills/wolf/month. The primary prey of wolves in winter was elk (Cervus elaphus; 90%). During our study, 43% of the elk killed were calves, 28% were adult females (cows), 21% were adult males (bulls), and 9% were of unknown age/sex. Comparing prey selection to prey availability, wolf packs residing on the northern range (NR) of the GYE selected for calves, against cows, and approximately proportional to availability for bulls. Prey use was different for wolf packs occupying the NR compared to packs residing in other areas (non-northern range [NNR]) and varied seasonally for NR packs. Variation in wolf kill rates by season, and the relative stability of the northern Yellowstone elk herd during a series of mild winters despite increases in wolf density, suggest that kill rates and ultimately elk population size are influenced by winter weather. Management of ungulates should reflect the addition of wolves combined with the unpredictability of winter weather in the mountainous terrain of the western United States.

Modeling temperature gradients across edges over time in a managed landscape

Landscape management requires an understanding of the distribution of habitat patches in space and time. Regions of edge influence can form dominant components of both managed and naturally patchy ecosystems. However, the boundaries of these regions are spatially and temporally dynamic. Further, areas of edge influence can be defined by either biotic (e.g. overstory cover) vs. abiotic (e.g. microclimate) characteristics, or structural (e.g. vegetation height) vs. functional (e.g. decomposition rates) features. Edges defined by different characteristics are not always concordant; the degree of spatial concurrence varies with time. Thus, edge effects are difficult to generalize or quantify across a landscape. We examined temperature at eight times of the day across the edge between a clearing and a 50-year-old pine stand. We used simple, nonlinear equations to model and predict temperature gradients across this edge over time. The depth of edge influence (DEI) on temperature varied from 0 to 40 m, depending on the patch type and time of day. Two equations were required to model adequately (r 2 >0.50) patterns of temperature at all eight times of the day. Model fit was best at night (r 2 a0.97) and lowest in the afternoon (r 2 a0.50). Parameters for the models could be predicted from local, reference weather conditions. However, these linear relationships varied among parameters and with time of day (0.29r 2 0.99). Model validation was weak, with mean absolute percent error >10% for all day-time combinations. The models tended to underestimate DEI for both patch types, though edge depth was more accurately predicted in the closed-canopy stand than in the clearing. The difference between observed and predicted edge effects was highest at midday in the clearing and during the morning under closed canopy. The models predicted the location of peak temperature and the slope of temperature change (i.e. pattern of temperature variation) across the edge and the range of temperature better than actual values. We suggest that this approach may, therefore, be useful for characterizing edge dynamics if a wider range of local weather conditions could be monitored during initial data collection. The empirical evidence for temporal changes in position and intensity of abiotic edge effects emphasized the need to quantify these dynamics across time and space for sound planning at the landscape scale. # 1999 Elsevier Science B.V. All rights reserved.

MONITORING AND HABITAT ANALYSIS FOR WOLVES IN UPPER MICHIGAN

Abstract Gray wolves (Canis lupus) in upper Michigan, USA, have been monitored since 1991 when breeding activity in mainland Michigan was documented for the first time since 1954. Based on winter track counts, the mean annual rate of increase in abundance was 19% from 1995 to 2002, with the population reaching an estimated 278 animals in 2002. Our objectives were to (1) increase the efficiency of wolf management in Michigan by evaluating alternative and less extensive sampling approaches for population estimation, and (2) evaluate habitat for wolves based on occupancy after a decade of recovery. For the first analysis, we created 22 discrete sampling units that cover upper Michigan, and we evaluated abundance estimates based on various sampling plans using known distribution and populations from the 2000–2002 winter track surveys. We evaluated each plan based on the precision, bias, and confidence interval coverage. A random sampling plan with regression estimator returned the most precise estimates, but a stratified sampling plan, using low, medium, and high wolf density strata had the greatest precision at lowest effort. For the habitat evaluation, we compared white-tailed (Odocoileus virginianus) deer density and road density between wolf pack locations from 1995 to 2001 to random locations outside of the current wolf range. We estimated white-tailed deer density by a spatial interpolation of pellet group counts. Our resource selection function indicated that probability of wolf occupation of an area was positively correlated with deer density, and it was relatively constant for road densities <0.4 km/km2 but declined sharply at higher road densities. For areas habitable by wolves in upper Michigan, we predict a road density threshold of 0.7 km/km2 and a deer density threshold of approximately 2.3–5.8 deer/km2. We believe that these results will aid managers who need to estimate wolf abundance and predict wolf distribution.

Grizzly bears (Ursus arctos horribilis) and black bears (Ursus americanus) prevent trabecular bone loss during disuse (hibernation)

Disuse typically causes an imbalance in bone formation and bone resorption, leading to losses of cortical and trabecular bone. In contrast, bears maintain balanced intracortical remodeling and prevent cortical bone loss during disuse (hibernation). Trabecular bone, however, is more detrimentally affected than cortical bone in other animal models of disuse. Here we investigated the effects of hibernation on bone remodeling, architectural properties, and mineral density of grizzly bear (Ursus arctos horribilis) and black bear (Ursus americanus) trabecular bone in several skeletal locations. There were no differences in bone volume fraction or tissue mineral density between hibernating and active bears or between pre- and post-hibernation bears in the ilium, distal femur, or calcaneus. Though indices of cellular activity level (mineral apposition rate, osteoid thickness) decreased, trabecular bone resorption and formation indices remained balanced in hibernating grizzly bears. These data suggest that bears prevent bone loss during disuse by maintaining a balance between bone formation and bone resorption, which consequently preserves bone structure and strength. Further investigation of bone metabolism in hibernating bears may lead to the translation of mechanisms preventing disuse-induced bone loss in bears into novel treatments for osteoporosis.

Six months of disuse during hibernation does not increase intracortical porosity or decrease cortical bone geometry, strength, or mineralization in black bear (Ursus americanus) femurs.

Disuse typically uncouples bone formation from resorption, leading to bone loss which compromises bone mechanical properties and increases the risk of bone fracture. Previous studies suggest that bears can prevent bone loss during long periods of disuse (hibernation), but small sample sizes have limited the conclusions that can be drawn regarding the effects of hibernation on bone structure and strength in bears. Here we quantified the effects of hibernation on structural, mineral, and mechanical properties of black bear (Ursus americanus) cortical bone by studying femurs from large groups of male and female bears (with wide age ranges) killed during pre-hibernation (fall) and post-hibernation (spring) periods. Bone properties that are affected by body mass (e.g. bone geometrical properties) tended to be larger in male compared to female bears. There were no differences (p>0.226) in bone structure, mineral content, or mechanical properties between fall and spring bears. Bone geometrical properties differed by less than 5% and bone mechanical properties differed by less than 10% between fall and spring bears. Porosity (fall: 5.5+/-2.2%; spring: 4.8+/-1.6%) and ash fraction (fall: 0.694+/-0.011; spring: 0.696+/-0.010) also showed no change (p>0.304) between seasons. Statistical power was high (>72%) for these analyses. Furthermore, bone geometrical properties and ash fraction (a measure of mineral content) increased with age and porosity decreased with age. These results support the idea that bears possess a biological mechanism to prevent disuse and age-related osteoporoses.

Sex differences in sympathetic neural and limb vascular reactivity to mental stress in humans.

Mental stress elicits a robust and consistent forearm vasodilation, but vascular reactivity in the calf remains inconsistent. It has been reported that calf vascular responses to MS may be sex dependent. Muscle sympathetic nerve activity (MSNA) is an important contributor to calf blood flow (CBF), yet the relations between sex, limb blood flow, and MSNA reactivity to mental stress have not been explored. We hypothesized that mental stress would elicit more dramatic vasodilation of the limbs in women and that this might be explained by reduced MSNA reactivity and/or blunted sympathetic vascular transduction. We measured heart rate (HR), mean arterial pressure (MAP), CBF, calf vascular conductance (CVC), forearm blood flow (FBF), forearm vascular conductance (FVC), and MSNA concurrently in 18 men (age: 23 ± 2 yr) and 16 women (age: 24 ± 2 yr) during 5 min of supine baseline and 5 min of mental stress. Mental stress elicited similar increases in MAP (Δ10 ± 1 vs. Δ11 ± 1 mmHg), HR (Δ16 ± 2 vs. Δ17 ± 2 beats/min), FBF (Δ81 ± 16% vs. Δ83 ± 15%), and FVC (Δ62 ± 13% vs. Δ65 ± 13%) in men and women, respectively. In contrast, CBF (Δ16 ± 8% vs. Δ37 ± 9%, P = 0.036) and CVC (Δ4 ± 7% vs. Δ24 ± 8%, P = 0.036) responses were exaggerated in women compared with men. Changes in FVC were significantly correlated with changes in CVC in women (r = 0.681, P = 0.004) but not in men. MSNA reactivity to mental stress was not different between men and women; however, changes in CVC were negatively correlated with increases of MSNA in men (r = -0.411, P = 0.045) but not in women. In conclusion, our data suggest different patterns of calf vascular reactivity to mental stress in men and women that might relate, in part, to altered vascular transduction of MSNA.

Sharp-Tailed Grouse Lek Attendance and Fidelity in Upper Michigan

ABSTRACT To assess and improve existing monitoring protocols for sharp-tailed grouse (Tympanuchus phasianellus) in the eastern Upper Peninsula of Michigan, we used data from 58 radio-collared grouse (46 M, 12 F) monitored within 3 openland landscape types: a xeric, conifer-dominated site, a wetland-dominated site, and a site dominated by low-intensity agriculture. We used lek counts and radio telemetry to determine lek attendance rates, factors affecting lek attendance rates, lek fidelity, and inter-sexual variation in these parameters. Our analysis indicated lek attendance varied with respect to sex of bird, day of year, time after sunrise, and wind speed. Peak male lek attendance rates exceeded those of females by up to 40%, and peak lekking activity for both males and females occurred during the second and third weeks of April. Male lekking activity occurred earlier and was sustained longer than that of females. Lekking activity was negatively related to time of day and wind speed. We observed strong lek fidelity as radio-collared birds attended a primary lek 94% of the time, indicating a low probability of multiple counting of individual birds. We also proposed a method to adjust lek count data for the probability that birds are on a lek during lek counts. Our proposed method can be used by researchers and managers to improve estimates of the number of birds attending a lek by reducing the negative bias associated with observed counts.

The patch mosaic and ecological decomposition across spatial scales in a managed landscape of northern Wisconsin, USA

Summary Understanding landscape organization across scales is vital for determining the impacts of management and retaining structurally and functionally diverse ecosystems. We studied the relationships of a functional variable, decomposition, to microclimatic, vegetative and structural features at multiple scales in two distinct landscapes of northern Wisconsin, USA. We hoped to elucidate any characteristic resolutions of structure-process relationships on these landscapes, and to determine the validity of extrapolation of structure-process associations across scales and management regimes. We used a combination of ANOVA, wavelet, canonical discriminant, and correlation analyses and asked specifically whether: 1) specific combinations of microclimatic, structural, and vegetative features were consistently associated with differences in decomposition among management zones along transects (i.e., within landscapes); and 2) factors influencing decomposition were consistent among resolutions of analysis and depths within and between landscapes. Decomposition was greater on the pine barrens than the small block transect and greater at 4 cm depth than at the surface for both landscapes. Significant differences in decomposition occurred among management patches for both transects and depths, except 4 cm along the pine barrens. In general decomposition was faster for patch types with greater overstory cover at 1 cm (both transects) and lower at 4 cm (small block). Canonical discriminant analysis also separated management patches by overstory cover for both transects. Secondary vectors also separated patches along both transects by microclimate, independent from overstory effects on those variables. Dominant resolutions in the patterns of decomposition differed between transects and depths: 80 m (pine barrens, 1 cm); 500 m (pine barrens 4 cm); 160 m (small block, 1 cm); and 750 m (small block, 4 cm). At the 1 cm depth, the strongest correlations of wavelet transforms of decomposition with structural, microclimatic, and vegetation variables often differed in resolution from those dominant in the decomposition patterns. At the 4 cm depths, many of the strongest correlations occurred at the maximum resolutions examined. Although many important correlates differed between transects and depths within a transect, there were some consistencies. On both transects, surface and soil temperatures were strongly correlated (|r| > 0.40) with decomposition; soil temperatures were stronger correlates along the small block. The direction of association between decomposition and temperatures changed with depth, being negative at 1 cm and positive at 4 cm for both transects. Overstory was an important correlate (|r| > 0.50) for 3 of 4 transect-depth combinations. On both transects, correlations between decomposition and overstory peaked at different resolutions and were different signs (positive at 1 cm and negative at 4 cm) for the two decomposition depths. Along the pine barrens but not the small block, there were two peaks of resolutions of correlation that appeared consistently across variables. Thus, correlates of decomposition changed with scale as well as depth and management regime. This suggests that factors other than management may still be maintaining decomposition patterns on the landscapes. Further, patterns in and relationships to process variables should be examined at multiple scales to develop a comprehensive understanding of the mechanisms driving functional heterogeneity. Das Verstandnis der Landschaftsorganisation ist entscheidend fur die Bestimmung der Auswirkungen von Management und fur den Erhalt von strukturell und funktionell diversen Okosystemen. Wir untersuchten die Beziehungen zwischen einer funktionellen Variablen, der Zersetzung, und mikroklimatischen, Vegetations- und Struktureigenschaften auf multiplen Skalen in zwei unterschiedlichen Landschaften im nordlichen Wisconsin, USA. Wir hofften, charakteristische Losungen fur Struktur-Prozes-Beziehungen in den Landschaften aufzuklaren, sowie die Gultigkeit von Extrapolationen von Struktur-Prozess-Beziehungen uber Skalen und Management-Regimes zu bestimmen. Wir nutzten eine Kombination von ANOVA, “wavelet”-, kanonischer Diskriminanz- und Korrelationsanalysen und fragten uns insbesondere: (1) ob spezielle Kombinationen von mikroklimatischen, strukturellen und Vegetationseigenschaften durchweg mit Unterschieden in der Zersetzung zwischen den Managementzonen entlang der Transekte (d.h. innerhalb der Landschaften) verbunden waren; und (2) ob es bei verschiedenen Auflosungen der Analysen und Tiefen innerhalb und zwischen den Landschaften durchgangige Faktoren waren, die die Zersetzung beeinflusten. Die Zersetzung war in den beiden Landschaften in den Kieferodlandern groser als in den “small block”-Transekten; und in 4 cm Tiefe groser als an der Oberflache. Signifikante Unterschiede in der Zersetzung traten zwischen “Management-patches” sowohl fur die Transekte als auch die Tiefen auf; mit Ausnahme der 4 cm Tiefe in den Kieferodlandern. Im Allgemeinen war die Zersetzung in den “patch”-Typen mit groserer Oberholz-Deckung (overstorey) bei 1 cm schneller (beide Transekte), und bei 4 cm geringer (“small block”-Transekt). Die Kanonische Diskriminanzanalyse trennte ebenfalls gemanagte “patches” nach der Oberholz-Deckung bei beiden Transekten. Sekundare Vektoren) trennten ebenfalls “patches” nach dem Mikroklima, unabhangig vom Oberholz-Einfluss auf diese Variablen. Die dominanten Auflosungen in den Mustern der Zersetzung unterschieden sich zwischen den Transekten und Tiefen: 80 m (Kieferodlander, 1cm), 500 m (Kieferodlander, 4 cm), 160 m (“small block”-Transekt, 1 cm) und 750 m (“small block”-Transekt, 4 cm). Bei 1 cm Tiefe unterschieden sich die starksten Korrelationen der “wavelet”-Transformation der Zersetzung mit strukturellen, mikroklimatischen und Vegetationsvariablen haufig in der Auflosung von denen, die dominant in den Zersetzungsmustern waren. Bei 4 cm Tiefe fanden sich viele der starksten Korrelationen bei der maximalen betrachteten Auflosung. Obwohl sich viele, wichtige korrelierende Variablen (correlates) zwischen den Transekten und den Tiefen innerhalb eines Transektes unterschieden, gab es einige Gemeinsamkeiten. Auf beiden Transekten waren Oberflachen- und Bodentemperatur stark mit der Zersetzung korreliert (|r| > 0.40); die Bodentemperaturen waren die starker korrelierenden Variablen entlang des “small block”-Transekts. Die Richtung der Beziehung zwischen der Zersetzung und der Temperatur anderte sich mit der Tiefe und war negativ in 1 cm und positiv in 4 cm Tiefe bei beiden Transekten. Oberholz war eine wichtige korrelierende Variable (|r| > 0.50) bei 3 von 4 Transekt-Tiefen-Kombinationen. Bei beiden Transekten erreichten die Korrelationen zwischen Zersetzung und Oberholz ihren Hohepunkt bei verschiedenen Auflosungen und zeigten unterschiedliche Vorzeichen fur die beiden Zersetzungstiefen (positiv bei 1 cm, negativ bei 4 cm Tiefe). Entlang der Kieferodlander, jedoch nicht entlang des “small block”-Transekts, gab es zwei Hohepunkte der Auflosung der Korrelation, die bei den Variablen durchweg auftraten. Somit anderten sich die korrelierenden Variablen sowohl mit der Skala als auch mit der Tiefe und dem Management-Regime. Das legt nahe, dass andere Faktoren als das Management die Zersetzungs-Muster in den Landschaften aufrechterhalten. Weiterhin sollten Muster in und Beziehungen zwischen den Prozes-Variablen auf multiplen Skalen untersucht werden, um ein umfassendes Verstandnis der Mechanismen zu entwickeln, die die funktionelle Heterogenitat vorantreiben.

Adjusting for group size influence in line transect sampling

In some line transect surveys, the population of interest consists of groups or clusters of individuals rather than single items. If group size influences the probability of detecting a group, then the observed group size data are size-biased. This can lead to overestimation of the true mean group size and hence could lead to overestimation of the density of individuals. Our method of line transect sampling incorporates group size as a covariate in line transect detection functions. We applied our method to shipboard surveys of sea otter (Enhydra lutris) and to surveys of pellet groups from barren ground caribou (Rangifer tarandus granti). Group size influence varied in the sea otter surveys. Our method of estimation adequately adjusted for size bias when it was present. Estimates of pellet group density were unaffected by significant size bias. J. WILDL. MANAGE. 54(3):511-514 Many factors can influence the detectability of items in line transect and other surveys of biological populations (e.g., Caughley 1974, Bayliss and Giles 1985, Gasaway et al. 1985). A particular problem occurs when the population consists of groups of items, and the size of the group influences its chance of detection (Quinn 1979, Rao et al. 1981, Drummer and McDonald 1987). We illustrate the procedure proposed by Drummer and McDonald (1987) in which group size is used as a covariate in existing line transect detection functions. Note that our method can also be used more generally to adjust estimates of the mean and total of any auxiliary variable that influences detectability in line transect sur-

Implications of Cutthroat Trout Declines for Breeding Ospreys and Bald Eagles at Yellowstone Lake

Abstract In Yellowstone National Park (YNP), Ospreys (Pandion haliaetus) feed primarily on cutthroat trout (Oncorhynchus clarki bouvieri) and cutthroat trout represent approximately 23% of prey consumed by Bald Eagles (Haliaeetus leucocephalus) during the breeding season (Swenson 1978, Journal of Wildlife Management 42:87–90; Swenson et al. 1986, Wildlife Monographs 95:3–46). The introduction of exotic lake trout (Salvelinus namaycush) to Yellowstone Lake during the late 1980s caused substantial declines in populations of cutthroat trout. Historically, more than half of all breeding pairs of Ospreys and Bald Eagles in YNP have nested near and foraged at Yellowstone Lake and the decline in cutthroat trout numbers may affect rates of reproduction for these two species. We studied the relationship between an index of cutthroat trout abundance and spring weather on Osprey (1987–2009) and Bald Eagle (1987–2007) reproduction. We documented steep declines in an index of cutthroat trout abundance, Osprey productivity and nesting success, and a dramatic decline in the number of Osprey breeding pairs. Bald Eagle productivity and nesting success also declined, but at a slightly slower rate than that of Ospreys, and the number of breeding pairs of Bald Eagles increased over the study period. Osprey reproduction was positively correlated with an index of cutthroat trout abundance and spring temperatures. However, the relationship between Bald Eagle reproduction and the index of cutthroat trout abundance was unclear. Our study suggested that the recovery of cutthroat trout is important to maintaining a breeding population of Ospreys at Yellowstone Lake, but may be less important for the Yellowstone Lake Bald Eagle population. IMPLICANCIAS DE LA DISMINUCIÓN POBLACIONAL DE ONCORHYNCHUS CLARKI BOUVIERI EN INDIVIDUOS REPRODUCTIVOS DE PANDION HALIAETUS Y HALIAEETUS LEUCOCEPHALUS EN EL LAGO YELLOWSTONE En el Parque Nacional Yellowstone, Pandion haliaetus se alimenta principalmente de truchas de la especie Oncorhynchus clarki bouvieri y estas truchas representan aproximadamente el 23% de las presas consumidas por individuos de Haliaeetus leucocephalus durante la época reproductiva (Swenson 1978, Journal of Wildlife Management 42:87–90; Swenson et al. 1986, Wildlife Monographs 95:3–46). La introducción de una especie de trucha exótica (Salvelinus namaycush) en el Lago Yellowstone durante la última parte de la década de 1980 causó disminuciones substanciales en las poblaciones de O. c. bouvieri. Históricamente, más de la mitad de todas las parejas reproductivas de P. haliaetus y H. leucocephalus han anidado y forrajeado en el Lago Yellowstone y la disminución en los números de O. c. bouvieri podría afectar las tasas reproductivas de estas dos especies. Estudiamos la relación entre el índice de abundancia de O. c. bouvieri y el clima de primavera sobre la reproducción de P. haliaetus (1987–2009) y H. leucocephalus (1987–2007). Documentamos marcadas disminuciones en el índice de abundancia de O. c. bouvieri, en la productividad y en el éxito de anidación de P. haliaetus, y una dramática disminución en el número de parejas reproductivas de P. haliaetus. La productividad y el éxito de anidación de H. leucocephalus también disminuyeron, pero a una tasa un poco menor que la de P. haliaetus, y el número de parejas reproductivas de H. leucocephalus aumentó durante el periodo de estudio. La reproducción de P. haliaetus estuvo positivamente correlacionada con el índice de abundancia de O. c. bouvieri y con las temperaturas primaverales. Sin embargo, la relación entre la reproducción de H. leucocephalus y el índice de abundancia de O. c. bouvieri no fue clara. Nuestro estudio sugirió que la recuperación de O. c. bouvieri es importante para mantener una población reproductiva de P. haliaetus en el Lago Yellowstone, pero puede ser menos importante para las poblaciones de H. leucocephalus del Lago Yellowstone.