The Canadian Field-Naturalist (E-Journal)
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Impact of anthropogenic disturbance on nesting Chimney Swift (Chaetura pelagica) including best practices for conservation
Full text linkThe effect of anthropogenic disturbance on nesting Chimney Swift (Chaetura pelagica) is poorly described. We review five case studies of anthropogenic disturbance around Chimney Swift nest sites caused by building construction, demolition, and maintenance activities in St. Adolphe, Manitoba. Chimney Swift behaviour and nest site activity did not appear to be overtly influenced by building demolition and construction conducted on adjacent buildings or lots within 13–30 m of nest chimneys. In contrast, Chimney Swift behaviour and breeding success appeared to be negatively affected by loud interior renovations and rooftop work conducted in or on the same building as the nest chimneys. The presence of humans on the roof of the nest building prevented Chimney Swifts from entering the nest site and reduced the overall rate of feeding young. Based on these observations, we provide conservation best practices for building construction and maintenance projects conducted within or on the same building as nest chimneys to help ensure protection of Chimney Swifts and their nesting habitat during the breeding season
Conspecific nest attendance behaviour of Common Eider (Somateria mollissima) in response to Polar Bear (Ursus maritimus) foraging activity: error or intent?
Full text linkCommon Eider (Somateria mollissima) is a colonial nesting sea duck with extremely high nest attendance rates. Although individuals take few recess breaks away from their nest to feed or preen, previous research has shown that some female eiders in dense nesting assemblages engage in conspecific nest attendance, spending short amounts of time incubating nests of other females. However, to the best of our knowledge, most observations of these behaviours occur during regular recess events, as opposed to instances where females flush from their nest in response to a foraging predator. Using drone videography on East Bay Island, northern Hudson Bay, Nunavut, Canada, we observed conspecific nest attendance behaviours in 11 eiders that flushed in response to a foraging Polar Bear (Ursus maritimus). Of the 11 birds attending to other nests, only two predation events were observed at the focal bird’s nest (i.e., two attenders’ own nests were predated). Of the nine nests that were attended to, we also only observed two predation events. Motivations behind these behaviours are unclear, but conspecific nest attendance may serve as a type of distraction display, whereby activity at another female’s nest leads the predator away from the focal bird’s nest. However, given that, on East Bay Island, eiders are known to nest in proximity to kin, distraction displays at nests of related individuals would incur fitness costs. General confusion on nest location or the concealment of closely related eggs are more likely explanations for these behaviours
Observations of Grizzly Bear (Ursus arctos) associated with abundance of spawning Kokanee (Oncorhynchus nerka) at an inland river, British Columbia, Canada
Full text linkSalmon (Oncorhynchus spp.) are an important food source for Grizzly Bear (Ursus arctos), but many salmon populations are declining. While most research on Grizzly Bear–salmon interactions occurs in coastal ecosystems, declining salmon may also affect Grizzly Bears in inland ecosystems where salmon are also an important part of their diet. We document changes in the number and distribution of observations of Grizzly Bears and changing Kokanee (i.e., landlocked Sockeye Salmon, Oncorhynchus nerka) abundance at an inland river. We hypothesized that reduced abundance of Kokanee would limit the number of Grizzly Bear observations at the river. We compared Kokanee abundance and Grizzly Bear observations (n = 535) between 2012 and 2019 at the Lardeau River, British Columbia, Canada. We used a generalized linear mixed model to test if the number of bear observations changed as a function of Kokanee abundance among four river reaches during eight consecutive years of study. Kokanee abundance was a strong statistical predictor of Grizzly Bear observations (β = 0.52, P = 0.001, CI = 0.12–0.87), and Kokanee abundance and reach explained 73% of the variance. Our results suggest that reduced Kokanee abundance also reduces Grizzly Bear presence, likely because bears seek out other, more available food sources, away from Kokanee spawning habitat. This pattern could limit ecosystem services provided by Grizzly Bears adjacent to spawning areas and it could have implications for bear management and conservation
American Marten (Martes americana) and Northern Goshawk (Accipiter gentilis) simultaneously attack Gray Squirrel (Sciurus carolinensis)
Full text linkA Northern Goshawk (Accipiter gentilis) was observed following an American Marten (Martes americana). The marten’s attempts to capture a Gray Squirrel (Sciurus carolinensis) forced the squirrel into the open where the goshawk repeatedly attempted to capture it as the marten chased it through the trees. Attacks on prey flushed by heterospecific predators have been reported for a few other raptors, but this type of interaction has not been reported previously for either goshawks or martens
"Flora of North America: Volume 10, Magnoliophyta: Proteaceae to Elaeagnaceae" by Flora of North America Editorial Committee, 2021 [book review]
Full text link"Beavers: Ecology, Behaviour, Conservation, and Management" by Frank Rosell and Róisín Campbell-Palmer, 2022 [book review]
Full text link"Field Guide to Whales, Dolphins and Porpoises" by Mark Carwardine, illustrations by Martin Camm, 2022 [book review]
No full textTabusintac Bay (New Brunswick, Canada): an important spring migratory stopover for Atlantic Brant (Branta bernicla hrota)
Full text linkAtlantic Brant (Branta bernicla hrota) is an Arctic-breeding migratory waterfowl that relies heavily on Common Eelgrass (Zostera marina) for food during migration and overwintering. Although the abundance of Atlantic Brant along the coasts of the Maritime provinces has declined drastically over the past decades, some flocks continue to migrate through the area in spring. Here, we present field observations of Atlantic Brant spring staging in the Tabusintac Bay, New Brunswick, Canada. We surveyed the Tabusintac Bay seven times between 26 May and 6 June 2018. We observed a maximum daily count of 1259 individuals, which is comparable to high counts from the 1970s. These spring surveys indicate the continuing importance of Tabusintac Bay to Atlantic Brant for spring staging. There is a pressing need to increase monitoring and research in the region and to preserve or enhance the quality of the area for spring staging brant