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.

1. Small mammal community composition is almost universally estimated from conventional trapping, which is logistically difficult to scale up for landscape-level assessments. Owl pellets may be a more effective alternative for measuring small mammal community composition over large geographic areas due to the relative ease and low cost of field collections. However, owl pellets may introduce sampling biases that differ from those associated with conventional trapping. A thorough comparison to conventional traps is required before owl pellets can be widely adopted as an alternative research tool for small mammal studies. 2. We conducted a literature review of owl diet-prey availability studies to: (i) compare small mammal community composition between owl pellets and trapping when the two methods were used simultaneously and (ii) assess the influence of owl genus and habitat type on community composition estimated by these two methods. We used data from 27 published studies, which allowed for 32 comparisons between owl pellets and trapping conducted simultaneously. These studies included 15 owl species from five common genera from different major habitats. 3. Rarefied estimates showed that owls consistently sampled identical or higher species richness compared to conventional trapping. Richness estimates rarefied to the lowest sample size per study were not statistically identical (l Drichness = 0Á20 AE 0Á09 SE, P = 0Á30); on average, 0Á95 AE 0Á13 SE additional species were identified from pellets compared to trapping. Measures of species dominance and evenness estimated from both methods were statistically identical (l D1-D = 0Á02 AE 0Á03 SE; l DPIE = 0Á004 AE 0Á04 SE). Species lists, relative species composition and species rank-order abundance were in moderate agreement between sampling methods (Jaccard = 0Á62 AE 0Á04 SE; Bray-Curtis = 0Á53 AE 0Á04 SE; Spearman rho = 0Á41 AE 0Á07 SE). Linear regression and AIC model selection showed that the performance of pellets versus traps did not differ based on owl genus or habitat type. 4. Small mammal community composition estimated via pellets was better represented compared to estimates from conventional trapping. Composition metrics from the two methods were consistent and not affected by owl genera or habitat type. Thus, owls are an effective alternative for landscape-level assessments of small mammal communities.

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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.

Summary1. The frequency and intensity of extreme weather has increased in North America against a backdrop of anthropogenic land change. Few studies have examined how wildlife is affected by extreme weather, and none have examined whether any resulting effects are contingent upon the degree of anthropogenic landscape change. 2. Using an 8-year study in Canada (2003Canada ( -2010, we examined how nest survival of burrowing owls Athene cunicularia varied in relation to weather, vegetation and soil type around the nest. Using a 3-year (1992, 1993 and 1996) feeding experiment, we examined whether food limitation also causes owlet mortality during inclement weather. Lastly, we examined how productivity (i.e. annual fledgling output) between 2003 and 2010 varied as a function of breeding season precipitation anomalies. Using this relationship, we estimated how productivity has changed in response to breeding season precipitation anomalies from 1960 to 2012. 3. During extreme precipitation events, nest survival decreased because of flooding. When burrow flooding did not occur, the youngest owlets in broods that were not food-supplemented had the lowest survival rates when there was precipitation, yet almost all food-supplemented owlets survived bouts of inclement weather. Accordingly, annual productivity from 2003 to 2010 varied inversely with breeding season precipitation anomalies, and we estimated that mean annual productivity decreased by 12% from 1960 to 2012. 4. Synthesis and applications. Extreme rainfall during the breeding season reduced reproductive success of burrowing owls. Given that many raptors experience food limitation during extreme rainfall, large-scale habitat management to increase the abundance and availability of prey may allow these species to better withstand acute food shortages. In light of predicted increases in the frequency and intensity of extreme weather, supplemental feeding could be used in triage situations for burrowing owl management and has the potential to be an effective short-term conservation measure for other raptors. Protecting or reclaiming pastures in uplands that are less prone to flooding would further buffer burrowing owls and other ground-nesting species from extreme precipitation. These actions should mitigate the negative effects of extreme rainfall in the short term; however, long-term persistence of many species will become increasingly uncertain, as climate change scenarios predict an increase in the frequency and intensity of extreme weather.

We examined nest- and roost-burrow characteristics from a declining population of burrowing owls (Athene cunicularia (Molina, 1782)) in Saskatchewan. Between 1992 and 2003, 84% of the 584 nests we found were in grassland pastures, even though these pastures constituted only 7% of the potentially available nesting area within our study area. In contrast, less than 3% of nests were in crop fields, despite these fields comprising 90% of the potentially available area. Within grassland pastures, owls selected nest burrows in areas with a higher density of burrows within 75 m (11.1 burrows/ha) compared with non-nest burrows of similar dimensions (5.6 burrows/ha). Richardson's ground squirrels (Spermophilus richardsonii (Sabine, 1822)) and badgers (Taxidea taxus (Schreber, 1777)) are the primary excavators of suitable nesting burrows in prairie Canada. In our study area, burrowing owls chose to nest and roost in badger-sized burrows, selecting those with taller tunnel entrances and soil mounds relative to unused burrows. We suggest that management for burrowing owl nesting habitat in Canada should consider the owls' avoidance of crop fields and their preference for grassland pastures. Managers should also consider the owls' apparent preference for nesting in areas of high burrow densities and their selection of badger-sized burrows for nesting and roosting.

We examined whether or not sizes of eggs and offspring were related to emergence date or maternal size in a semelparous aquatic insect (the burrowing mayfly, Hexagenia) in which parental care is lacking and oviposited eggs are passively dispersed. We quantified the size of males and female imagos over the emergence span at a site on the Detroit River, Canada, and investigated relationships between emergence date and female size and (1) egg size and (2) size of first-instar nymphs. Although size of female imagos (H. limbata and H. rigida combined) declined significantly (P<0.025) over the emergence season, there was no significant relationship between body length and emergence date for males of either species. Males were significantly (P<0.001) smaller than females. H. limbata eggs, subsampled from three individuals from each of three size classes of female imagos collected on seven sampling dates, were measured using video image analysis. Eggs (n=100) oviposited by each of 63 H. limbata imagos were inspected daily for hatching. Newly hatched nymphs were removed, counted and measured. Egg size (P<0.001) and size of first-instar nymphs (P<0.001) varied significantly with emergence date, but not maternal size. The largest eggs and newly hatched nymphs occurred at peak emergence of adults. The synchronous release of larger (faster-sinking) eggs may result in reduced predation. Plasticity in egg development time and egg and nymph size may account for the ability of this taxon to recover from episodes of massive population reduction.