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Allometric analyses of sexually selected structures have revealed many patterns of evolutionary and behavioural significance, for example, in weapons, ornaments, and genitalia. We investigated allometry of the baculum (penis bone) relative to body size in post-growth adults of three large mustelids: wolverine (Gulo gulo (Linnaeus, 1758)), northern river otter (Lontra canadensis (Linnaeus, 1758)), and sea otter (Erihydra lutris (Linnaeus, 1758)). The baculum grew over a longer period than did body size. Correlations among bacular variables were positive in post-growth adults. No regression slopes expressed positive allometry (i.e., slope > 1 for linear variables). These trends point to the possibility that bacular size is adapted to the average size of the reproductive tract of sexually mature female northern river otters and possibly sea otters, and that pre-ejaculatory ('precopulatory') selection is highest in those species. Bacular size varied more than skull or limb-bone size, and bacular shape also varied greatly. Species differed in size and complexity of the urethral groove and bacular apex, suggesting functional differences in intromission. Substantial variation in bacular shape resulted from healed fractures, especially in sea otter. Knowledge of copulatory behaviour, age of breeding, female reproductive anatomy, and genitalic interactions during intromission is needed for comprehensive understanding of bacular anatomy, allometry, and variation for these species. Key words: allometry, baculum, Mustelidae, museum collections, os penis, sexual selection, Introduction Darwin (1871) noted that sexually selected traits of animals often are striking or extreme, and typically vary considerably within, and across, conspecific populations and related species. Innumerable studies have [...]

Globally, ungulate–vehicle collisions (UVCs) are a major human safety concern and may also represent a significant source of mortality for some ungulate populations. However, records of UVC based on counts of roadside carcasses or reports by drivers involved in these incidents are assuredly underestimated because not all ungulates struck die immediately or at the roadside or are reported by drivers or authorities. Here, we provide an observation and analysis of the movements of a GPS‐collared bison (Bison bison) that was involved in a UVC on the Alaska Highway and died in a thick boreal forest 29 days later. During that time, she moved 49.7 km from where she was hit. Her daily movement rate (in kilometers per hour) and daily net displacement (in kilometers per day) were significantly greater in the 29‐day period before she was struck compared with 29 days afterward. This vivid example illustrates that individuals injured in a UVC can die several weeks later and at a considerable distance from where they were initially struck. Moreover, when they eventually die, it may be where their carcass would not be found or associated with a UVC. Bison are the largest land mammal in North America and perhaps more robust to some lower impact UVC than smaller bodied species. Even so, if not for the GPS collar on this bison, we would have never known the fate of this individual, and the carcass likely never found. Taken together, the movements and final resting place of this bison illuminate how estimates of mortality as a result of UVC can be underestimated when the animal does not die immediately and in a location where it can be found. Given our data, we further urge managers to consider roadside counts of animals killed in UVC as a minimum estimate when considering options for mitigation. [ABSTRACT FROM AUTHOR]

Motion‐sensitive cameras are commonly used to monitor wildlife occupancy rates; however, few studies have assessed whether data from cameras are correlated with density estimates obtained from more traditional labor‐intensive methods such as those based on capture‐mark‐recapture. We used data from a boreal forest community to test whether camera data were correlated with densities estimated from independent monitoring methods. We placed 72 covert cameras in the forest around Lhù'ààn Mân' (Kluane Lake), Yukon, Canada, for 7 years and tracked changes in population densities by camera hit rates. We independently estimated population densities of snowshoe hares (Lepus americanus) and red squirrels (Tamiasciurus hudsonicus) using capture‐mark‐recapture via live trapping, and Canada lynx (Lynx canadensis), coyotes (Canis latrans), and moose (Alces americanus) by snow track transects. Density estimates obtained from conventional aerial surveys were also periodically available for moose. Except for red squirrels, camera hit rates were highly correlated with population density estimates obtained by traditional methods, including across a large range of estimated densities corresponding to cyclic population dynamics in several species. Accordingly, we infer that motion‐sensitive cameras could supplement or replace traditional methods for monitoring key species in boreal forest food webs. Using cameras to monitor population change has several advantages; they require less effort in the field, are non‐invasive compared to live‐trapping, include multiple species at the same time, and rely less on weather than either aerial surveys or snow track transects. Tracking changes across the vast boreal forest is becoming increasingly necessary because of climate and landscape change and our data validate the use of motion‐sensitive cameras to provide a useful quantitative method for state‐of‐the‐environment reporting. [ABSTRACT FROM AUTHOR]

The distribution of small mammals is constrained by extreme environmental demands and variable food supplies that are commonly incurred at northern latitudes. Little brown bats (Myotis lucifugus (Le Conte, 1831)) are at the northwestern limits of their range in Alaska (USA), where environmental demands are higher and prey availability is more seasonal than elsewhere in their range. We hypothesized that the little brown bat in interior Alaska has adjusted to these constraints by broadening its foraging niche, relative to that of southern conspecifics. We analyzed arthropod fragments (microhistology) in guano to describe prey composition to order. We compared the efficacy of evaluating diet by microhistology with DNA analysis and stable isotope analysis on guano and hair. Bats consumed aerial prey such as Lepidoptera (moths) and Diptera (true flies and mosquitoes), as well as terrestrial arthropods including Araneae (spiders). Shifts in the proportion of aerial prey in the diet were closely linked to ordinal day. Values for [delta][.sup.15]N in hair indicated that bats were generalists in interior Alaska, coastal Alaska, and the Yukon (Canada), but significant outliers indicated that some individuals have distinct diets. The little brown bat's flexibility in feeding strategies likely allows this species to sustain populations in arctic and subarctic regions. Key words: Alaska, arthropods, diet analysis, foraging, bat guano, fecal DNA, generalists, little brown bat, microhistology, Myotis lucifugus, niche. La repartition des petits mammiferes est limitee par les demandes environnementales extremes et la disponibilite variable de nourriture qui caracterisent souvent les latitudes septentrionales. Les vespertilions bruns (Myotis lucifugus (Le Conte, 1831)) sont a la limite nord-ouest de leur aire de repartition en Alaska (Etats-Unis), ou les demandes environnementales sont plus fortes et la disponibilite des proies est plus saisonniere qu'ailleurs dans leur aire. Nous avons postule que les vespertilions bruns dans l'interieur de l'Alaska se sont ajustes a ces contraintes en elargissant leur niche d'approvisionnement par rapport a celle de leurs conspecifiques meridionaux. Nous avons analyse les fragments d'arthropodes (microhistologie) dans le guano pour decrire la composition des proies selon leurs ordres. Nous avons compare l'efficacite d'evaluer le regime alimentaire par microhistologie avec analyse d'ADN et analyse d'isotopes stables dans le guano et les poils. Les vespertilions consommaient des proies aeriennes comme des lepidopteres (papillons nocturnes) et des dipteres (mouches et moustiques), ainsi que des arthropodes terrestres comme des aranees (araignees). Les variations de la proportion des proies aeriennes dans le regime alimentaire etaient etroitement reliees a la date julienne. Les valeurs de [delta][.sup.15]N dans les poils indiquent que les vespertilions sont des generalistes dans l'interieur et le long des cotes de l'Alaska et au Yukon (Canada), mais des valeurs aberrantes significatives indiquent que certains individus ont des regimes alimentaires particuliers. La souplesse des strategies d'alimentation des vespertilions bruns permet vraisemblablement a cette espece de maintenir des populations en regions arctiques et subarctiques. [Traduit par la Redaction] Mots-cles: Alaska, arthropodes, analyse du regime alimentaire, approvisionnement, guano de chauve-souris, ADN fecal, generalistes, vespertilion brun, microhistologie, Myotis lucifugus, niche., Introduction Generalist predators present a challenge for dietary analysis because they consume a variety of species that often includes multiple trophic levels. Small predators such as birds and bats may [...]