The Canadian Field-Naturalist

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2023-06-22T08:30:45-07:00

Malocclusion in an Arctic Wolf (Canis lupus arctos) from northeast Greenland

2022-09-07T13:47:44-07:00

I document the first case of malocclusion in an Arctic Wolf (Canis lupus arctos) from Greenland. All canine teeth of a wolf found dead on the tundra of northeast Greenland showed evidence of heavy anterior wear resulting from occlusion with the opposite teeth. Additional heavy wear on the incisors indicated a level bite. No cases of malocclusion were found in the largest museum collection of Arctic Wolf skulls (n = 11) from Greenland. However, the collection consisted exclusively of specimens from a northeast Greenland wolf population extirpated ca. 1939; thus, it provided no information on the incidence of malocclusion in more contemporary wolves. A finding of malocclusion in the more recent wolf population could be important because the condition is genetically based and the trait is expressed more frequently with increased inbreeding. The small, geographically isolated wolf population that this wolf was a part of disappeared for reasons unknown after 2002 and genetic conditions cannot be excluded as a contributing factor. Future study of the prevalence and severity of this abnormality in Arctic Wolves from Greenland will be problematic because of the difficulty of acquiring comparative material, but could be conducted on other populations of Arctic Wolves.

American Marten (Martes americana) and Northern Goshawk (Accipiter gentilis) simultaneously attack Gray Squirrel (Sciurus carolinensis)

2022-09-22T10:27:38-07:00

A 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.

Cases of freeze-dried freshwater turtles at the northern limit of their ranges in southern Ontario

2022-04-22T19:41:26-07:00

Turtles in northern latitudes are at the limit of their ranges and display various strategies for surviving the winter, including moving under the ice and out of water. Anthropogenic disturbances are often at the root of local habitat changes that can cause turtles to move from underwater refugia onto land, sometimes resulting in freezing and death. Turtles may also leave the water under natural freeze–thaw cycles, with early exits potentially maladaptive and lethal. We document cases of freshwater turtles freezing out of water at all life stages. We give a brief description of the circumstances surrounding the discovery of freeze-dried carcasses and highlight some of the climatic challenges facing overwintering turtles in southern Ontario.

Estimated effects of clear-cuts and burns associated with habitat use by female Newfoundland Caribou (Rangifer tarandus)

2021-12-07T16:50:49-08:00

The decline of Caribou (Rangifer tarandus) is mainly attributed to anthropogenic disturbance from resource development (i.e., logging, oil and gas extraction), which causes habitat loss and increased predation risk. Natural landscape disturbance, particularly from fire, can have similar effects, and cumulative effects from disturbance have been associated with lower neonate recruitment. Our objective was to evaluate the potential effects of land cover types on resource selection by females, with an emphasis on clear-cuts and fire, during the calving season (May–June) in three neighbouring herds (Middle Ridge, Gaff Topsails, and Pot Hill) on insular Newfoundland, Canada, and compare results with pre-existing information on calf recruitment. We applied a resource selection framework to analyze location data collected from global positioning system collars between 2007–2010 and estimate relative probability of use for different cover types. Recruitment was lowest in Pot Hill, where ≤10-year old clear-cuts were favoured, whereas recruitment was highest in Middle Ridge and Gaff Topsails, where females favoured burns, suggesting that burns could be more beneficial to Caribou fitness. Further investigation will be needed to more closely examine how anthropogenic versus natural disturbance affects Caribou fitness in Newfoundland and improve our understanding of important habitat for calving females.

Observations of Grizzly Bear (Ursus arctos) associated with abundance of spawning Kokanee (Oncorhynchus nerka) at an inland river, British Columbia, Canada

2020-09-29T16:36:00-07:00

Salmon (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.

Combining current and historical biodiversity surveys reveals order of magnitude greater richness in a British Columbia marine protected area

2022-02-10T11:38:39-08:00

The value of biodiversity and of documented biodiversity surveys is well established. Extracting historical biodiversity data and synthesizing them with current data can provide a more comprehensive estimate of total diversity and guide future monitoring. We demonstrate the utility of compiling historical and recent biodiversity data to better characterize taxon richness and composition. Our focus is an otherwise unmonitored habitat in an unmonitored British Columbia provincial park, in a heavily impacted region of the Salish Sea that was designated a United Nation Biosphere Reserve in 2021. We conducted surveys and compiled historical records that together spanned three intertidal habitats and 43 years. From these combined data we report a total of 99 taxa, an order of magnitude increase over the number listed in the park’s Master Plan. These include seven non-native species, of which four are newly reported here. Rarefaction, extrapolation, and multivariate dissimilarity analyses revealed the roles of methods and habitat types in contributing to differences in taxon richness and composition among surveys. This data compilation illustrates many of the challenges and opportunities in aligning and assembling independent space-time snapshots of alpha (i.e., local) diversity to better understand the gamma (i.e., regional) diversity of a marine protected area and provides the foundational data needed to design effective future monitoring at molecular to ecosystem scales.

Impact of anthropogenic disturbance on nesting Chimney Swift (Chaetura pelagica) including best practices for conservation

2022-06-13T04:38:42-07:00

The 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.

Red-eared Slider (Trachemys scripta elegans) nests in the Greater Toronto Area

2022-07-18T20:14:30-07:00

Red-eared Slider (Trachemys scripta elegans) is a non-native turtle found in abundance in Toronto’s wetlands as a result of pet releases. Although this species is known to reproduce successfully in southwestern Ontario, Canada, there is yet no evidence to suggest successful reproduction in the Greater Toronto Area (GTA). As part of a native turtle nest protection program, volunteers inadvertently placed nest protector boxes over four slider nests in 2021 and 10 nests in 2022. This gave us the opportunity to determine whether nests produced viable offspring and whether these hatchlings would emerge in the fall. The exact nesting date for each nest was recorded. In 2021, eight of the 41 eggs from the slider nests showed very late-stage arrested embryonic development. In 2022, one of the nests had four hatchlings out of their eggshells but still inside the nest cavity. It is unclear whether the hatchlings would emerge later in the fall or overwinter in the nest cavity and emerge the following spring. If the small population sampled accurately reflects what occurs in the GTA, complete egg development may be possible for this species in some years, in some locations, with the right local micro-climate and micro-habitat. We discuss implications for turtle nest protection in Toronto.

Cover

2023-06-21T22:49:03-07:00

News and Comment

2023-06-21T22:43:02-07:00

"Flora of North America: Volume 10, Magnoliophyta: Proteaceae to Elaeagnaceae" by Flora of North America Editorial Committee, 2021 [book review]

2023-06-21T22:04:36-07:00

"Swamplands: Tundra Beavers, Quaking Bogs, and the Improbable World of Peat" by Edward Struzik, 2021 [book review]

2023-06-21T22:08:23-07:00

"Empire of Ants: the Hidden Worlds and Extraordinary Lives of Earth’s Tiny Conquerors" by Susanne Foitzik and Olaf Fritsche, translated by Ayça Türkoğlu, 2021 [book review]

2023-06-21T22:11:59-07:00

"The Alpha Female Wolf: the Fierce Legacy of Yellowstone’s 06" by Rick McIntyre, 2022 [book review]

2023-06-21T22:15:09-07:00

"Beavers: Ecology, Behaviour, Conservation, and Management" by Frank Rosell and Róisín Campbell-Palmer, 2022 [book review]

2023-06-21T22:23:30-07:00

"Field Guide to Whales, Dolphins and Porpoises" by Mark Carwardine, illustrations by Martin Camm, 2022 [book review]

2023-06-21T22:26:28-07:00

"Why Sharks Matter: a Deep Dive with the World’s Most Misunderstood Predator" by David Shiffman, 2022 [book review]

2023-06-21T22:30:00-07:00

New Titles

2023-06-21T22:34:08-07:00

Index to Volume 136

2023-06-21T22:45:38-07:00