The Canadian Field-Naturalist

Cover

2024-05-31T22:44:49-07:00

Diet of cisco (Coregonus spp.) in Algonquin Park region lakes: variation among forms

2021-08-20T12:54:25-07:00

Efforts to conserve cisco (Coregonus spp.) diversity in Canadian lakes have been impeded by the unresolved taxonomy of North American ciscoes. When a strictly taxonomic-based approach is not possible, conservation units of infraspecific diversity can be identified using biological, morphological, ecological, and genetic evidence. Distinct cisco forms have been reported from deep oligotrophic lakes within boundaries of the historical outflow of glacial Lake Algonquin. In this study, we described the diet of three cisco forms netted from eight lakes located in or adjacent to Algonquin Provincial Park, Ontario. Opossum Shrimp (Mysis diluviana) was the dominant prey of benthic, low gill raker count forms in Trout and White Partridge Lakes, and of a large-bodied, high gill raker count form in Hogan Lake. Zooplankton was the most important prey item of small-bodied, pelagic forms in White Partridge Lake, and Cisco (Coregonus artedi) collected from five other Algonquin Park lakes. The diet of Trout Lake Cisco was a broader mix of prey items, including chironomid pupae, Opossum Shrimp, phantom midges (Chaboridae spp.), and zooplankton. Our study provides strong dietary evidence of the special ecological context occupied by cisco forms in White Partridge Lake, and moderate evidence for Trout Lake. Past reports of Shortjaw Cisco (Coregonus zenithicus) in six of the study lakes were not supported by our sampling, because low gill raker count forms were not captured.

A review of beaked whale (Ziphiidae) stranding incidents from the inshore waters of eastern Canada

2022-06-28T09:56:47-07:00

Cetaceans of the family Ziphiidae (beaked whales) include some of the least known whale species. We review 78 ziphiid stranding incidents from the inshore waters of eastern Canada (defined as the Atlantic provinces north to central Labrador, including the Gulf coast of Quebec, from ~latitude 43.5°N to 55.0°W), with outcomes that involve 84 individual whales. This includes all eastern Canadian ziphiid stranding incidents known to us from the first report of 24 February 1934 to 31 December 2021 for the five species documented from eastern Canada: Northern Bottlenose Whale (Hyperoodon ampullatus), Sowerby’s Beaked Whale (Mesoplodon bidens), Blainville’s Beaked Whale (Mesoplodon densirostris), True’s Beaked Whale (Mesoplodon mirus), and Cuvier’s Beaked Whale (Ziphius cavirostris). Northern Bottlenose Whale (41.0% of incidents, 40.4% of individuals) and Sowerby’s Beaked Whale (46.1% of incidents, 46.4% of individuals) have stranded most frequently, with the remaining three species stranding very rarely in the region. An average of 0.55 individual ziphiids/year were reported stranded from 1934 to 1999 in eastern Canada, but since 2000 this has increased to an average of 2.2 stranded individuals/year. Much of this increase is undoubtedly due to improved reporting, but other factors may also be involved. We emphasize the importance of the ongoing documentation of cetacean stranding incidents, but especially the need to better understand causes of ziphiid mortality, particularly for those species that reach the edge of their range in the western North Atlantic or are of conservation concern.

Assessing terrestrial movements of Eastern Musk Turtle (Sternotherus odoratus) using iNaturalist Canada

2023-01-29T20:41:22-08:00

Eastern Musk Turtle (Sternotherus odoratus) is known to be a highly aquatic species, yet it is occasionally found away from waterbodies. If such movements are common, then road mortality may pose a substantial risk to the species. We examined iNaturalist Canada observations of Eastern Musk Turtle on roads and found 15 in which individuals were >25 m from water. The median distance to the nearest permanent waterbody was 100 m (range 30–330 m). All observations that were ≥100 m from the nearest waterbody occurred from mid-July onward, suggesting that the movements were not related to nesting activity. At least under some circumstances, Eastern Musk Turtle can move >100 m away from waterbodies increasing the risk of road mortality.

An overview of known species killed during Alberta’s Gray Wolf (Canis lupus) strychnine program, 2005–2020

2023-07-20T14:05:40-07:00

To determine the minimum effect of strychnine baits placed for wolves in winter during a program targetting Gray Wolf
(Canis lupus) in west-central Alberta from 2005 to 2020, I present a summary of all recorded species killed (n = 522). Fewer
wolves (n = 245) were killed compared with non-target animals (n = 277), which included 10 mammal and four bird species.
These data provide context on the environmental and ethical impacts of using poison as a component of wildlife management.

A tribute to Laurie D. Murison, 1959–2021

2024-03-09T09:40:00-08:00

Full Issue PDF

2024-05-31T22:47:18-07:00

An observation of incest avoidance in Gray Wolf (Canis lupus)

2022-12-23T07:23:01-08:00

Free-ranging Gray Wolf (Canis lupus) tends to avoid inbreeding, but there is no information about how they manage this avoidance. Our observation of a female wolf in Yellowstone National Park actively rebuffing her father’s sexual advances but then copulating with a distantly related male is the first and only report of one means by which wolf pack members avoid inbreeding.

Himalayan Blackberry (Rubus bifrons) in eastern Canada: a timely discovery

2022-08-18T11:22:23-07:00

Currently, the invasive Himalayan Blackberry (Rubus bifrons Vest) is sparsely distributed in eastern Canada and the northeastern United States, documented in Ontario, Quebec, and New England. In summer 2022, patches of this plant were found in Yarmouth, Nova Scotia, at the shrubby edges of gravel parking lots and in the town maintenance area. Of most concern is its occurrence along a former railway line that is now a trail system connecting many communities. In the fall and winter of 2022 established populations were noticed at three locations in Digby County, Nova Scotia, between 80 km and 100 km northeast of Yarmouth, where the evergreen thickets were noticeable from a distance. Climate warming and a variety of dispersal agents have likely contributed to the recent spread. Control is recommended to protect native biodiversity from this highly competitive invasive shrub.

Red Squirrel (Tamiasciurus hudsonicus) feeding on Balsam Poplar (Populus balsamifera) galls induced by aphids

2022-12-06T16:07:40-08:00

Red Squirrel (Tamiasciurus hudsonicus) specializes in feeding on conifer cone seeds but will feed opportunistically on a wide variety of other food items, including fungi, eggs, small vertebrates, and invertebrates. In much of their range, Red Squirrels experience fluctuations in the availability of their primary diet (conifer seeds) seasonally and annually because of variation in seed production. We document a seemingly uncommon or unreported feeding behaviour by a Red Squirrel in a year of an exceedingly low conifer cone production in Yukon, Canada: a squirrel foraging for and feeding on aphids hidden within galls formed on Balsam Poplar (Populus balsamifera). We searched for community-reported observations of Red Squirrels through iNaturalist and found additional evidence of apparently similar gall feeding behaviour elsewhere in Canada. We estimate that aphids can be a substantial source of caloric energy for Red Squirrels. Our observation represents another example of the diet breadth of Red Squirrels during periods of low conifer seed availability.

Canada Jay (Perisoreus canadensis) harvesting and caching fruits of Thin-leaved Snowberry (Symphoricarpos albus)

2022-12-12T02:35:15-08:00

On 17 September 2021, we observed three Canada Jay (Perisoreus canadensis) harvesting and caching Thin-leaved
Snowberry (Symphoricarpos albus) fruits in a mixed conifer forest in western Montana, USA. Thin-leaved Snowberry has
not been reported previously in their diet. During 3 min of direct observation, each jay harvested snowberries similarly and cached them on the trunks of nearby pines. In each case (11 caches), the jay flew by the snowberry shrubs twice, plucking a fruit while airborne, landing on the ground between passes, the first fruit carried in the throat, the second in the bill. The jays then landed, most often out of view on tree trunks, but, nevertheless, appeared to cache the fruits each time. One cache observed in the making contained two harvested fruits wedged in a crevice on the trunk and covered with a flake of bark. Thin-leaved Snowberry is considered a low-quality fall-ripening fruit because of the small energy gain for each fruit consumed. Nevertheless, the energy density of snowberries (16.65 kJ/g dry mass) collected at the same location in October exceeded that required by non-migratory Canada Jays for daily maintenance during winter. It is unlikely jays could cache enough fruits each day to sustain them for several winter months. Instead, snowberries could be an important and readily available autumn and winter food for Canada Jays resident in this region when used to supplement other stored foods with greater energy, fat, and protein content.

Torpor may facilitate opportunistic predation of live-trapped small mammals: a cautionary note

2023-03-27T12:34:29-07:00

Small mammals are often key components in ecological monitoring programs, and live trapping is often used to obtain small mammal density estimates or other metrics. However, an aspect of such trapping that has received little attention is opportunistic predation of captured animals. Here, we report a Common Raven (Corvus corax) preying on a deermouse (Peromyscus spp.) after it was released from a live trap. The mouse was torpid when removed from the trap. The raven preyed on the deermouse right after it was released, likely because the mouse had not yet fully aroused from torpor and was not able to find adequate shelter or evade the raven. Best practices to avoid similar occurrences include passively warming the animal before releasing it or returning it to the trap to arouse from torpor in safety. Our observation further highlights the need for researchers to be vigilant about opportunistic predation of small mammals captured and released from live traps and to take actions to mitigate the risk, especially if the mammals are exhibiting signs of torpor.

Chilostigma itascae (Trichoptera: Limnephilidae), a globally rare caddisfly new for Canada

2023-05-25T17:09:42-07:00

Headwater Chilostigman Caddisfly (Chilostigma itascae) is an enigmatic winter-active caddisfly previously reported solely
from Minnesota. This note reports the first Canadian records from southern Manitoba and northwestern Ontario.

First records of the ant genus Dolichoderus (Hymenoptera: Formicidae) from Saskatchewan, Canada

2022-11-21T09:16:58-08:00

We report the first provincial records of the genus Dolichoderus in Saskatchewan, represented by two species: Taschenberg’s Long-necked Ant (Dolichoderus taschenbergi) and Mary’s Long-necked Ant (Dolichoderus mariae). These species are previously known from eastern Canada and the eastern United States. The new discoveries fill in the range for D. taschenbergi, which has previously been found in Alberta and Manitoba, but has not been reported from Saskatchewan, and they represent a significant westerly range expansion of D. mariae, which has previously been reported in southeastern Manitoba and Ontario.

News and Comment

2024-05-31T22:40:30-07:00

"An Immense World: How Animal Senses Reveal the Hidden Realms Around Us" by Ed Yong, 2022 [book review]

2024-05-31T22:24:45-07:00

"Sex in City Plants, Animals, Fungi, and More: a Guide to Reproductive Diversity" by Kenneth D. Frank, foreword by Jonathan Silvertown, 2022 [book review]

2024-05-31T22:27:25-07:00

"Hymenoptera: the Natural History and Diversity of Wasps, Bees & Ants" by Stephen A. Marshall, 2023 [book review]

2024-05-31T22:29:51-07:00

"The Canada Jay: the National Bird of Canada?" by David Bird, Dan Strickland, Ryan Norris, Alain Goulet, Aaron Kylie, Mark Nadjiwan, Michel Gosselin, and Colleen Archer, foreword by Robert Bateman, 2022 [book review]

2024-05-31T22:32:36-07:00

"Annelida" by Greg W. Rouse, Fredrik Pleijel, and Ekin Tilic, 2022 [book review]

2024-05-31T22:35:07-07:00

New Titles

2024-05-31T22:37:58-07:00