Plasticité squelettogénique chez une espèce d'amphibien en milieux anthropisés

Habitat loss and landscape fragmentation are major causes of numerous amphibian population declines. Although logging activities have been related to serious effects on growth rate and size at metamorphosis in several species, less is known about skeletal developmental modifications associated with disturbed habitats. We studied the effects of forest canopy modifications caused by logging activities on the skeletal development of a pond-breeding anuran, Wood Frog (Lithobates sylvaticus). Biotic and abiotic factors were collected for 30 semi-permanent ponds located in three habitat categories (regenerated forest, along skidding trails, and logged areas). A sample of 58 cleared and double-stained tadpoles were analyzed to compare developmental trajectories among habitats. Water temperature and pond morphometric characteristics, which were correlated with logging-related habitat alteration, had a major impact on tadpole developmental differences among pond categories. Developmental plasticity was evident in both absolute and relative timing of chondrification and ossification between regenerated forest ponds and disturbed ponds (i.e., along skidding trails and in logged areas). Ossification and chondrification patterns had a different response to environmental factors. Notably, we observed the early onset of skeletogenesis in the disturbed ponds, which may result in deleterious effects on the fitness of post-metamorphosed juveniles

A new species of testate amoeba, Arcella prismatica sp. nov. (Amoebozoa: Arcellinida), from peatlands in Ontario and Quebec, Canada

Arcella is a genus of testate amoebae with a radially symmetrical shell composed of secreted material arranged in hexagonal units. Within the genus, species are distinguished by the morphology and dimensions of the shell. We describe a new species, Arcella prismatica sp. nov., discovered in a brown-water lake in the Mer Bleue Bog Conservation Area, a protected wetland in the city of Ottawa, Ontario, Canada. Specimens of the same morphotype have also been found in a subarctic peatland on the James Bay coast, near the village of Chisasibi, Quebec, Canada. The species has a polyhedral shell with a relatively flat dorsal surface and an irregularly crenulated aperture, a combination of characters not found in other members of the genus. The discovery of a novel and evidently widely distributed Arcella within the limits of a populous North American city is a reminder that the diversity of microbial eukaryotes is still poorly understood. Further exploration of undersampled peatland habitats can be expected to reveal new organisms and new relationships among known species

Probable predation by an American Black Bear (Ursus americanus) on a Gray Wolf (Canis lupus) pup in northwestern Wisconsin

On 13 June 2023, we noted probable predation by an American Black Bear (Ursus americanus) on a male Gray Wolf (Canislupus) pup in pine barrens of northern Bayfield County, Wisconsin. The wolf pup, which had been captured and radiocollared on 11 May 2023, was detected by mortality signal on 8 June 2023. Predation by black bears has previously been reported on Eastern Wolf (Canis lycaon), but our observation represents the first documentation of probable predation on Gray Wolves of which we are aware

Distribution and breeding potential of the exotic False Map Turtle (Graptemys pseudogeographica) in Canada

False Map Turtle (Graptemys pseudogeographica) is widespread in the central United States, and its native range extends close to the Canadian border. It is common in the pet trade and has been released into the wild outside its native range. We examined observations of False Map Turtle from iNaturalist Canada, an online platform to document native and non-native species, and confirmed 20 observations in Canada from eight cities in three provinces. The earliest observation was in April 2014 from Victoria, British Columbia. Fourteen of the 20 observations (70%) were from 2020 to February 2024. All the turtles were either large juveniles or adults. Climate data from the northern part of the False Map Turtle’s native range and from Canadian cities suggest that individuals could survive the winter in parts of southern Canada and successfully breed in parts of southern Ontario during the warmest years

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Conservation of wildlife populations requires reliable information on population size, trends, and demographic processes.Such information is sparse for Red-necked Grebe (Podiceps grisegena), a species that is vulnerable to changing wetland conditions in the prairie pothole region. During 2008–2019, I collected breeding pair and reproductive estimates of a recentlyexpanded Red-necked Grebe population on 109 semi-permanent and permanent wetlands (mean ± SE: 2.92 ± 0.41 ha, range 0.01–24.2) in agriculturally-dominated habitat in southwestern Manitoba, Canada, to determine population status and reproductive success. I also looked for effects of changing wetland water levels and the presence of conspecifics and/or wetland size on productivity. Red-necked Grebe breeding densities were the highest reported for solitary-nesting pairs in North America and the breeding population currently appears to be stable. I found that chicks/breeding pair are mostly lower but chicks/successful pair are similar or greater than values reported from other studies. Pairs breeding with conspecifics appeared to be as productive as those on single-pair wetlands. Productivity was positively associated with wetland water levels suggesting that prolonged drought or climate change leading to warmer, drier summers on the prairies could reduce Rednecked Grebe breeding populations