Animal populations at northern range limits may use habitat differently from those at range cores, requiring distinct conservation plans. Snakes are ectotherms that often have very specific requirements, but few studies have focused on the effect of northern latitudes on habitat selection by grassland snakes. We studied movement and habitat selection of 2 sympatric snake species at their northern range limits on the North American Great Plains: the eastern yellow‐bellied racer (Coluber constrictor flaviventris, hereafter racer), a Threatened species in Canada, and the bullsnake (Pituophis catenifer sayi), which is listed as Data Deficient. Both of these species are potentially vulnerable to extinction in Canada because of habitat loss. Snakes from our study populations traveled up to 10‐times farther from winter dens and occupied home ranges 3–104 times larger than populations further south. Both snake species moved from winter dens in the slopes of a major river valley to habitat in adjacent lowlands, including riparian zones (racers) and hilly areas with native grass species (bullsnakes). Multivariate modeling revealed that proximity to retreat sites was a significant predictor of snake site use for both species. Considering the need for winter dens and summering areas, our data suggest that snakes in northern latitudes should ideally have much larger protected areas compared to snakes near the core of their range. An alternative strategy is to conserve corridors linking wintering dens and summer habitats. Retreat sites such as burrows and shrubs are critical components of local habitat and should be included in conservation plans. © 2011 The Wildlife Society.
The grasslands of southwestern Saskatchewan, Canada are home to several snake species of conservation concern at the northern extreme of their geographic range. To aid conservation assessment and management planning for these snakes, we used radio‐telemetry, a geographic information system, and multivariate modeling to identify and compare macrohabitat selection by eastern yellow‐bellied racers (n = 33; Coluber constrictor flaviventris), bullsnakes (n = 16; Pituophis catenifer sayi), and prairie rattlesnakes (n = 23; Crotalus viridis). All 3 species shared communal hibernacula in the inactive winter season, but dispersed into different macrohabitats across the landscape during the spring and summer. Their home ranges varied in size by species and were dumbbell‐shaped with activity centers near hibernacula and in well‐defined summer grounds; activity centers were connected by narrow movement corridors. Racers strongly selected for riparian areas, bullsnakes selected for valley grassland habitats, and rattlesnakes selected for areas associated with prairie dog colonies. Some rattlesnakes traveled great distances (over 11 km) from the dens compared to the other species (bullsnake max. = 4 km; racer max. = 5 km), which may be a result of their selected macrohabitat being more patchily distributed in the landscape. Our results indicate that management plans for these snakes must consider the den area, corridors, and separate summering grounds, as well as differences in home range size and movement patterns for each species. © 2013 The Wildlife Society.
Antimicrobial resistance is a global problem affecting people and animals. Few investigations describing the presence drug-resistant organisms in wildlife in North America have been published. In this study, resistant Escherichia coli, including extended-spectrum β-lactamase-producing strains, were isolated from wild birds in the Saskatoon region of Canada. We found that the recovery rate of E. coli varied significantly by species and was highest among crows. There was also a significant association between drug resistance and urban vs rural birds. Our results suggest that crows may be a good target for future studies investigating antimicrobial resistance in urban wildlife.
The behaviour of snakes makes them vulnerable to road mortality, which may have conservation implications for some species. We examined factors affecting road mortality of snakes around Grasslands National Park of Canada (GNP), Saskatchewan, an area inhabited by a unique snake community within Canada, including the threatened Eastern Yellow-bellied Racer (Coluber constrictor flaviventris). Systematic surveys (n = 45) of roads in the Grasslands National Park area in 2009 yielded 36 dead and 18 live snakes. Multivariate modelling revealed that proximity to hibernacula was positively correlated with presence of snakes on roads. Paved roads had disproportionately higher numbers of snake mortalities, suggesting that traffic patterns are a bigger risk factor than road use per se. Some radio-tracked Eastern Yellow-bellied Racers (2 of 17; 12%) and Bullsnakes (Pituophis catenifer sayi) (4 of 5; 80%) captured at emergence from hibernacula had road areas in their home ranges. These individuals equipped with radio-transmitters used roads and immediately adjacent areas significantly more than expected, based on their availability, suggesting possible selection for roads. Strategies to reduce road mortality of snakes should focus on key stretches of roads, such as those near winter hibernacula or riparian zones. The placement of paved roads in sensitive areas like those in and around Grasslands National Park should be carefully considered to minimize snake mortality.
An approximately six-month-old wild American black bear (Ursus americanus) was found wandering in Saskatchewan and was presented to the Veterinary Medical Centre of the Western College of Veterinary Medicine for apparent blindness. Clinical examination confirmed an inability to navigate a photopic maze, bilateral tapetal hyper-reflectivity, fundi devoid of retinal vessels, and small pale optic nerve papillae. Single-flash electroretinography revealed A and B-wave amplitudes of approximately 40 and 140 microvolts, respectively, in both eyes. Histologic abnormalities included bilateral optic papillary mineralization and bilateral segmental optic nerve degeneration, with occasional intralesional lymphocytes confirmed with immunohistochemistry for CD3+. There was also bilateral multifocal retinal dysplasia, gliosis, lymphocytic retinitis, a complete lack of retinal blood vessels, an intravitreal vascular membrane, and a mild lymphocytic-plasmacytic uveitis with small pre-iridal cellular membranes. The presence of a positive ERG in a blind bear with numerous retinal ganglion cells and degenerative changes in the optic nerve are most consistent with vision loss due to optic nerve injury, which given the young age of the bear likely occurred during ocular development. The presence of ocular inflammation suggests this injury resulted from an inflammatory/infectious process. The etiology could not be determined. Hepatic concentrations of vitamin A were within the normal reference range for domestic species. Pan-herpesvirus PCR and immunohistochemistry for canine distemper virus and Toxoplasma gondii were negative, although this does not rule out these or other infectious etiologies. This represents the first case report of neonatal or congenital ocular abnormalities in an ursid species.
Cystic endometrial hyperplasia has been documented in a variety of animals, but to the authors' knowledge, this was the first reported case in a chinchilla. Cystic endometrial hyperplasia and chronic endometritis should be considered as a differential diagnosis in an adult sexually intact female chinchilla with a history of suspected hemorrhagic vaginal discharge, suspected hematuria, or hemorrhage from an unknown source.
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