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Populations of the Water Vole (Microtus richardsoni) occur along headwater streamlets at timberline in the Rocky Mountain front ranges of Alberta. At the 2000-m contour riparian distances between potential habitat patches ranged from 749 to 24,651 m, whereas overland distances ranged from 157 to 5104 m. Reproduction is restricted to a snow-free (May–August) period of 60 to 112 d in which females typically produce 1 to 2 litters of 2 to 10 young. Based on home range overlaps, the mating system appears to be polygynous. Over 4 habitat patches and 9 patch-seasons, reproduction was dominated by overwintered adults and began with effective populations (Ne) of 9.2 (4.1 males and 6.8 females) occupying 3- to 4-ha patches of mesic vegetation. Territorial behavior opposes recruitment into these breeding populations. Few males have an opportunity to breed in their natal colony in their 1st summer, but 5% of 1st-litter female young (50% known to be philopatric) may do so. Young of subsequent litters, including any born to 1st-litter females, are unlikely to breed in the season of their birth. Episodes of predation may facilitate settlement and breeding of philopatric young of the year, or “floaters” of unknown origin. In a typical colony, breeding generated a mean surplus above replacement (potential emigrants) of 8 males and 6 females. Disappearance rates of overwintered adults (the number of voles present in 1 trapping session and not in the next divided by the number of intervening days) remained low until August. Disappearance of the 1st cohort of young averaged 1.8%/d for females and 3.7 %/d for males. Young persisting into September in their natal colonies were the most likely to be present in the following spring. The socially determined window for recruitment appears limited to late summer and early fall. Winter trapping indicated that low temperatures and heavy snow cover inhibit movement between habitat patches during the winter months. The limited genetic analysis available indicates that variation is maintained in local gene pools despite restriction to small isolated habitat patches, small effective population sizes, and territorial behavior. Conservation concerns may arise due to the habitat specificity of M. richardsoni and the constraints on population dynamics and gene flow imposed by the small size and isolation of habitat patches and the harshness of the subalpine environment.
Temperate eelgrass beds are temporally and spatially complex habitats that often provide a transition habitat for many species of juvenile fishes. The feeding habits of young-of-the-year Black Rockfish (Sebastes melanops) and Copper Rockfish (S. caurinus) inhabiting eelgrass (Zostera marina) beds in Humboldt Bay, California, were assessed in 2003 and 2004. A total of 16 prey types were noted for both species. Gammarid amphipods and copepods were the dominant prey types. Shifts in prey type were observed for Copper Rockfish as prey preference shifted from smaller planktonic prey to larger epiphytic prey types over time. No shifts in prey type were noted for Black Rockfish. Prey types for both species were consistent with previous studies conducted in temperate eelgrass habitats, which noted the importance of small crustaceans as prey.
Two brief midwater trawl surveys were conducted at depths of 250–1000 m in the Gulf of Alaska in April 2007 and March 2008, during which several species were recorded for the 1st time from this region. In this report we note the 1st records of Maulisia argipalla, Pachystomias microdon, Lestidiops ringens, and Scopelengys tristis from the Gulf of Alaska, the 1st records of Argyropelecus lychnus and Aristostomias scintillans from the subarctic North Pacific, and the 1st record of the rare alepocephalid Asquamiceps caeruleus from the Pacific Ocean. Meristics, morphometrics, and morphological details are provided in the context of previously reported data for each species. In addition, we provide data for 2 specimens of Caristius macropus encountered for the 1st time in the open waters of the Gulf of Alaska.
The Western Toad (Anaxyrus boreas) is an IUCN red-listed species affected by habitat destruction and emerging infectious diseases. We tested for the chytrid fungus Batrachochytrium dendrobatidis (Bd) in a breeding population of toads in southwestern British Columbia. Although the toads showed no physical signs of infection, 28% of 32 toads tested positive for Bd. To our knowledge, this study provides the first evidence of the chytrid fungus in a population of Western Toads in British Columbia. We also compared body condition to infection prevalence and found no significant relationship. Monitoring population trends and further testing for Bd prevalence are required throughout the province.
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