The Canadian Field-Naturalist

Large winter falcons and their Rock Pigeon (Columba livia) prey at an urban grain terminal in Edmonton, Alberta: an update

2020-12-21T15:56:42-08:00

In winter, Gyrfalcon (Falco rusticolus) and Prairie Falcon (Falco mexicanus) frequent a 96-year-old grain terminal, in Edmonton, Alberta, hunting Rock Pigeon (Columba livia). This phenomenon was reviewed shortly after it was first noticed by others in 1998 and, since then, we have observed hunting success and methods of Gyrfalcons and Prairie Falcons that were similar but not identical to earlier observations, with success rates of 21.0% and 10.6%, respectively, compared with 10.6% and 26.0% earlier. The most frequently observed hunting strategy for both species was a repeated upward attack on swirling Rock Pigeon flocks, resulting in success rates of 10.7% and 11.4%, respectively. Notably, 50% of downward dive hunts made by Gyrfalcon were successful, although only eight hunts using this method were recorded. The falcons were mildly selective with respect to pigeon colour morphs, with an apparent preference for pied colouration. Contrary to previous interpretations, Rock Pigeon do not appear to eat spilled grain on the building to any great extent; instead, the terminal may simply provide abundant roosting sites, which attain surface temperatures roughly 10°C warmer than ambient on sunny days and at temperatures below −20°C when the building is warmed internally.

Freshwater turtle by-catch from angling in New Brunswick, Canada

2020-12-21T15:56:43-08:00

Turtles are among the most threatened vertebrate taxa, with populations especially vulnerable to any increase in adult mortality. By-catch from freshwater angling, as a potential cause of turtle mortality is poorly documented and little understood. Here we document cases of turtle by-catch by recreational anglers in an urban park in New Brunswick and among the wider angling communities in the province. We also consider factors that may influence rates of hooking. Although we are unable to estimate turtle hooking frequency for the provincial recreational angling community as a whole, five of 75 (~7%) anglers interviewed in the urban park reported interactions with a turtle, with most reported incidents (75%) involving hooking. Snapping Turtles (Chelydra serpentina) seem to be more prone to hooking than Eastern Painted Turtles (Chrysemys picta picta). Although we conclude that turtle hooking by recreational anglers appears to be generally uncommon in New Brunswick, even apparently low by-catch rates may be sufficient to lead to population declines at heavily fished sites. The collection of additional data on turtle by-catch in the recreational fishery in Canada is warranted.

Disjunctions of Needle-leaved Sedge (Carex duriuscula) and Thread-leaved Sedge (Carex filifolia) in the Husky Lakes area of Northwest Territories—first records for the Canadian true Arctic and possible Pleistocene relicts

2020-12-21T15:56:43-08:00

Disjunctions are reported for Needle-leaved Sedge (Carex duriuscula) and Thread-leaved Sedge (Carex filifolia) into the Arctic region of Northwest Territories at the Husky Lakes south of Tuktoyaktuk. These are significant additions to the Canadian Arctic flora and may be part of a group of relicts of the Arctic vegetation of the Pleistocene, specifically the Tundra-steppe. The occurrence of relict vegetation east of the Mackenzie Delta is east of its frequently cited eastern limit in North America.

Distribution and status of Howell’s Quillwort (Isoetes howellii, Isoetaceae) in Canada and its relation to Bolander’s Quillwort (Isoetes bolanderi)

2020-12-21T15:56:43-08:00

The sparsely documented lycophyte, Howell’s Quillwort (Isoetes howellii), occurs in Canada in four distinct areas of British Columbia in a variety of microhabitats. Before 2010, two areas of occurrence were known in Canada. Two additional clusters of occurrences have been discovered in the last decade. In Canada, I. howellii is found in open, ephemeral wet swales, shallow ponds, and periodically flooded shorelines, channels, and back beach meadows. Habitat rarity may be the primary reason for the large gaps between areas of occurrence. The current viability of the Canadian population is dependent on maintaining the recently discovered large number of individuals in the North Thompson River Region. Isoetes howellii shares many similarities with fellow diploid, Bolander’s Quillwort (Isoetes bolanderi). The possibility that it represents a low-elevation subspecies of I. bolanderi requires further investigation. Isoetes howellii is rare in British Columbia and warrants consideration as a species at risk in Canada.

Full Issue PDF

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Cover

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Tribute to R. Yorke Edwards, 1924–2011

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"The Cougar Conundrum: Sharing the World with a Successful Predator" by Mark Elbroch, 2020. [book review]

2020-12-21T15:56:44-08:00

"The Inside Out of Flies" by Erica McAlister, 2020. [book review]

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"The Call of Carnivores: Travels of a Field Biologist" by Hans Kruuk, 2019. [book review]

2020-12-21T15:56:44-08:00

"Chasing Nature: An Ecologist’s Lifetime of Adventures and Observations" by Robert E. Wrigley. Illustrated by Rob Gillespie, 2020. [book review]

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New Titles

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News and Comment

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News and Comment

First verified sighting of a Western Fence Lizard (Sceloporus occidentalis) in British Columbia, Canada

2020-12-21T15:56:43-08:00

Western Fence Lizard (Sceloporus occidentalis) is known from Baja California, Mexico, north to north-central Washington State, including Puget Sound, where scattered populations extend from the Cherry Point area south to Tacoma and along the west side of Puget Sound to Port Townsend. On 6 June 2020, a single juvenile S. occidentalis was photographed in a Cloverdale area garden, Surrey, British Columbia, representing the first verified sighting of this species in Canada. No other S. occidentalis were sighted in the area, and we could not determine how the specimen entered the province.

New records of grasshoppers (Orthoptera) from the Northwest Territories

2020-12-21T15:56:43-08:00

We provide information on two additions to the fauna of Northwest Territories, Canada: Two-striped Grasshopper (Melanoplus bivittatus) and Huron Short-winged Locust (Melanoplus huroni). We suspect that both are long established but were overlooked in the past as a consequence of general rarity.

A case of a Pustulated Carrion Beetle (Nicrophorus pustulatus, Coleoptera: Silphidae) burying live Tree Swallow (Tachycineta bicolor, Passeriformes: Hirundinidae) nestlings under the nest

2020-12-21T15:56:43-08:00

The ecology of Pustulated Burying Beetle (Nicrophorus pustulatus, Coleoptera: Silphidae) appears distinct among Nicrophorus species, with evidence of it parasitizing snake eggs and foraging primarily above the ground and into the forest canopy. Here we document an extension of its aberrant ecology and behaviour: a case of N. pustulatus burying 2-day-old live and dead nestlings of Tree Swallow (Tachycineta bicolor, Passeriformes: Hirundinidae) under the nest, behaviour consistent with the early stages of breeding in N. pustulatus. Based on different levels of decomposition, we suspect that N. pustulatus responded to one dead swallow nestling in the brood of five and went on to bury all of the nestlings at the bottom of the nest box. The observation provides the first evidence, to our knowledge, of Nicrophorus burying live vertebrates.

Potential case of pseudo-hermaphroditism in Elk (Cervus canadensis) in Alberta, Canada

2020-12-21T15:56:43-08:00

Cases of true and pseudo-hermaphroditism, in which animals possess both ovaries and testes or have a single chromosomal and gonadal sex but secondary features of the other sex, have been documented in several cervids, including Odocoileus (deer) and Capreolus (roe deer) species. Another form of intersexuality that has been well documented in Domestic Cattle (Bos taurus) and induced in Red Deer (Cervus elaphus) is freemartinism, where blood is shared between heterosexual twins leading to XX/XY chimeras. We report the first case of pseudo-hermaphroditism in wild Elk (Cervus canadensis), observed in the central east slopes of the Rocky Mountains of Alberta, Canada, from September through December 2019. The Elk had no antlers, exhibited female external genitalia, and displayed male secondary sexual characteristics, including colouring and breeding behaviour. To determine whether this is a case of true hermaphroditism, pseudo-hermaphroditism, or freemartinism would require blood analysis and inspection of internal sex organs by necropsy.

Late-autumn record of Little Brown Myotis (Myotis lucifugus) in north-central British Columbia

2020-12-21T15:56:43-08:00

Little Brown Myotis (Myotis lucifugus) inhabits north-central British Columbia (BC), but its flight activity at the onset of hibernation is not well known. On 31 October 2019, we saw three bats flying in patterns that suggested feeding, near the north shore of the Fraser River near Prince George, BC. Observations of Little Brown Myotis flying this late in the autumn have not previously been documented this far north in interior BC. We photographed the bats, and here we describe the encounter and discuss the scientific value of our observation.

Cougar (Puma concolor) predation on Northern Mountain Caribou (Rangifer tarandus caribou) in central British Columbia

2020-12-21T15:56:44-08:00

Caribou (Rangifer tarandus) populations are sympatric with Cougars (Puma concolor) in only a few areas, primarily in western Canada. Records of Cougar–Caribou interactions are limited and no published accounts describe Cougar predation on the shallow-snow, terrestrial-lichen-eating Northern Mountain Caribou (Rangifer tarandus caribou), referred to as Designatable Unit (DU) 7 by the Committee on the Status of Endangered Wildlife in Canada. In 2018 and 2019, two incidents of confirmed Cougar predation on radio-collared Caribou were documented in the declining Itcha-Ilgachuz subpopulation in west-central British Columbia. To the best of our knowledge, this is the first published record of Cougar predation on DU7 Northern Mountain Caribou. Increased landscape disturbance and climate change may be increasing apparent competition between deer (Odocoileus spp.), feral Horses (Equus ferus caballus), and Caribou, leading to Cougar predation in areas of Caribou range where it previously has not been documented. Cougar predation may become a conservation concern, as declining Caribou herds are susceptible to any increased predation pressure.