The Canadian Field-Naturalist (E-Journal)
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Displacement of migratory Bull Trout (Salvelinus confluentus) spawning by a newly constructed beaver (Castor canadensis) dam in a west-central Alberta stream
Full text linkDespite broad overlap of the ranges of Bull Trout (Salvelinus confluentus) and North American Beaver (Castor canadensis),relatively little is published in the peer-reviewed literature on their interaction. Beavers are ecosystem engineers with the potential to transform lotic environments, while Bull Trout are of conservation concern and subject to various protective measures throughout their range. The impact of beaver activity on trout populations is context dependent, and our appreciation of the scope of this impact depends on documentation. We report on the disruption of Bull Trout spawning migration by a newly constructed beaver dam in Fall Creek, a west-central Alberta stream in the North Saskatchewan River drainage system. Large Bull Trout have been documented travelling up to 74 km to spawn in Fall Creek. Since 2007, we have used autumn redd counts to monitor the abundance of spawning Bull Trout in the stream. In 2022, we documented displacement of Bull Trout spawning in Fall Creek by a newly constructed beaver dam. Over 60% of Bull Trout redds were observed in a reach downstream of the dam rarely used by spawning fish. We also observed seven post-spawn Bull Trout, representing over 10% of the spawning run, apparently stranded in a shallow impoundment upstream of the dam. It is unclear whether this displacement will have a long-term impact on the Fall Creek Bull Trout population. However, the seasonal impact on spawning adults is unprecedented in the 15 years we have monitored the population
Little evidence that Beach Pea (Lathyrus japonicus) toxins cause gait abnormalities in Sable Island Feral Horse (Equus ferus caballus)
No full textLathyrus is a leguminous plant genus notable for its synthesis of lathyrogens, a group of nonprotein amino acids. Lathyrogens can have a range of toxic effects on mammals when consumed in large quantities, but research on lathyrogens has occurred primarily in an agricultural context and on the syndromes (osteo-, angio-, and neuro-lathyrism) that Lathyrus consumption causes in humans and livestock. We know relatively little about whether the lathyrogens in uncultivated Lathyrus species are more broadly consequential to the ecology of natural ecosystems. For example, the unmanaged Feral Horse (Equus ferus caballus) population inhabiting Sable Island, Nova Scotia, Canada relies on forage from coastal maritime plant communities, including Beach Pea (Lathyrus japonicus). Horses have a strong sensitivity to lathyrogens compared with many other mammals, and symptoms of lathyrism (gait abnormalities, hernias, hoof malformation) are sometimes observed in Sable Island horses. However, it is unclear whether Beach Pea on Sable Island produces lathyrogens at sufficient concentrations to cause disease. Using liquid chromatography–mass spectrometry (LC-MS), we tested immature, mature, and senescent Sable Island Beach Pea samples for two of the most common lathyrogens: L-β-N-oxalyl-α,β-diaminopropionic acid (β-L-ODAP) and β-aminopropionitrile (BAPN). We detected only trace amounts of β-L-ODAP and no BAPN, causing us to conclude that lathyrogens are unlikely to be the cause of the physical abnormalities observed in Sable Island horses. These results from an iconic Canadian ecosystem provide useful toxicological data for a common coastal maritime plant
"Birds of the Mesozoic: an Illustrated Field Guide" by Juan Benito, illustrations by Roc Olivé, 2022 [book review]
No full textApparent predation of a bison (Bison bison) calf by a Grizzly Bear (Ursus arctos) in southwestern Yukon
No full textGrizzly Bear (Ursus arctos) predation on American Bison (Bison bison)—particularly calves—was likely once common.However, with the range-wide collapse of bison near the close of the 19th century, the two species no longer co-occur across much of their current distributions. Over the past 60 years, efforts to reintroduce bison to their native range have resulted in a few small areas where the two species once again co-occur. Yet, predation of bison by bears is apparently rare and has not been observed outside Yellowstone National Park, where both species have existed for millennia. On 28 June 2023, we observed an adult male Grizzly Bear protecting a buried bison calf that it had apparently killed in Yukon, Canada. This is the first observation of apparent predation of a bison by a Grizzly Bear outside Yellowstone National Park. Our observation further highlights how reintroduced bison are becoming integrated into local food webs, which is a key indicator of ecological restoration
Reaching new heights: novel use of alpine talus by a Red Squirrel (Tamiasciurus hudsonicus)
No full textRed Squirrel (Tamiasciurus hudsonicus) is common in the boreal forest, where it is chiefly arboreal and intricately tied to conifer trees for food and shelter. As such, these squirrels are found in close association with contiguous conifer forest.However, we observed a Red Squirrel in a talus patch in an alpine valley in southwestern Yukon, Canada. The valley wasdevoid of trees, with the nearest conifer ~3.6 km away and contiguous conifer forest ~4.8 km from our observation. Howor why the Red Squirrel came to be in the alpine talus is unknown; however, it likely represented an unusual natal dispersalevent. Our observation provides a novel record of this arboreal species in a talus patch located in an alpine valley thatlacked trees
"COPOUT: How Governments Have Failed the People on Climate—an Insider’s View of Climate Change Conferences, from Paris to Dubai" by Nick Breeze, 2024 [book review]
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A substantial eastern disjunction of Douglas’ Knotweed (Polygonum douglasii Greene, Polygonaceae) in New Brunswick, Canada
Full text linkWe report an isolated population of the native annual Douglas’ Knotweed (Polygonum douglasii Greene) from a dry, south-facing outcrop of conglomerate and sandstone at Big Bluff, near Sussex Corner, New Brunswick, Canada, consisting of about 2500 plants in 2018 and 2022. This occurrence is disjunct by ~450 km from the eastern limit of the known range of Douglas’ Knotweed in southwestern Maine, USA. The nearest known occurrence in Canada is in southern Quebec, ~660 km from Big Bluff. Several lines of evidence indicate that the population in New Brunswick is native. New state records for Wisconsin and Alaska found in online data sources are also verified