The Canadian Field-Naturalist

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2023-02-20T20:21:19-08:00

Tabusintac Bay (New Brunswick, Canada): an important spring migratory stopover for Atlantic Brant (Branta bernicla hrota)

2022-03-12T04:21:40-08:00

Atlantic 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.

Impact of grazing and conservation opportunities for nesting grassland birds in a community pasture

2021-11-04T09:27:22-07:00

Multiple bird species-at-risk nest on the ground in hayfields and pastures, making nests susceptible to inadvertent destruction from agricultural activity (e.g., trampling by livestock). To better understand the impact of Domestic Cattle (Bos taurus) grazing, we assessed the distribution and breeding status of nesting grassland birds in 2019 and 2020 at the Grey Dufferin Community Pasture, a ~234 ha pasture in southern Ontario, Canada. We estimated there were 86 male Bobolink (Dolichonyx oryzivorus) in the community pasture in 2019 and 100 in 2020 before grazing began; observed abundance decreased by 73% in fields after grazing in 2020. Eastern Meadowlark (Sturnella magna) maintained territories after grazing and fledged young in 67% (n = 21) of territories. Savannah Sparrow (Passerculus sandwichensis) was common across the community pasture before and after grazing occurred. We detected evidence of nesting more frequently in Bobolink and Savannah Sparrow territories in ungrazed than in grazed fields. Our results support previous research indicating nesting Bobolink often disperse from moderately to heavily grazed fields, whereas Eastern Meadowlark and Savannah Sparrow largely remain and renest. Despite the inadvertent negative impacts of cattle stepping or laying on nests and consuming vegetative cover, the community pasture provides areas for successful nesting, with Eastern Meadowlark faring better than Bobolink. Flexibility in the timing and duration of grazing in rotational grazing systems may enable strategic management in target fields (e.g., maintaining enough vegetation for nesting Bobolink). Information about the distribution and abundance of birds can be used to target particular fields for conservation.

Natural and human-made nesting habitat use by Bank Swallow (Riparia riparia) in Canada

2021-07-16T04:05:49-07:00

Bank Swallow (Riparia riparia) is a Threatened migratory bird in Canada that nests colonially in burrows excavated in both human-made and natural banks. Until the mid-20th century, nest record cards reported 60% of Bank Swallows in Canada nested in human-made habitats. Here we provide an update on the proportion of Bank Swallow nesting colonies in natural and human-made habitats in Canada’s provinces and territories based on data from a variety of sources including breeding bird atlases and eBird. Bank Swallow nesting colonies reported from 2001 to 2017 throughout Canada indicate a reversal in the dominant type of habitat used for nesting, with a 56% probability that nesting occurrences are now found in natural habitats. We discuss possible mechanisms responsible for the apparent reversal and recommend that natural nesting habitat be formally protected and restored where it has been altered, especially where co-benefits include climate change resiliency. With the support of landowners and industry, active colonies in human-made habitats will likely make an important contribution to a resilient Bank Swallow population, the majority of which presently appears to nest in natural habitats across the country.

Gray Wolves (Canis lupus) consume free-ranging horses (Equus ferus caballus) on the Chilcotin plateau, British Columbia

2021-01-07T10:38:55-08:00

We analyzed 122 Gray Wolf (Canis lupus) scats, collected at all seasons during 2013–2017, to determine what wolves were eating in two adjacent study areas of the Chilcotin region, British Columbia: Brittany Triangle and Nemiah Valley. Free-ranging horses (Equus ferus caballus), Mule Deer (Odocoileus hemionus), Moose (Alces americanus), and small mammals contributed to wolf diet throughout the year. In both study areas, horse appeared more frequently than other species in occurrence-per-faeces (OF) and occurrence-per-item (OI) analyses. Horse occurred in 58 of 97 wolf scats from Brittany (OF 59.8%, OI 52.7%), deer in 26 (OF 26.8%, OI 23.6%), small mammals in 17 (OF 17.5%, OI 17.3%), Moose in four (OF 4.1%, OI 3.6%), and bird and fish minimally (both OF <2.5%, OI <2.5%). The sample size in the more human-developed Nemiah Valley was too small to estimate reliable patterns, but results suggest a similar ranking of dietary items. Domestic Cattle (Bos taurus), available in both study areas, appeared infrequently (combined area OF <3.5%, OI <3.0%). Based on our scat findings, free-ranging horses were a regular dietary item for wolves in the area. Studies elsewhere have found that, where wolves and free-ranging horses are sympatric, a predator–prey relationship exists.

Territorial scent-marking and proestrus in a recolonizing wild Gray Wolf (Canis lupus) population in central Wisconsin

2022-02-08T09:34:43-08:00

Gray Wolf (Canis lupus) uses scent-marking to communicate breeding status, dominance, and territorial boundaries. Despite its importance for reproduction and pack dynamics, information on scent-marking and proestrus in wild wolf populations is limited to a handful of locations. We estimated the rate of territorial scent-marking and the probability of proestrus in a recolonizing Gray Wolf population near the species southern range extent in eastern North America. An analysis of 221 pack-winters of tracking data show that the incremental addition of one wolf pack increased marking rates by 3.4%, whereas increasing the number of wolves in a pack decreased marking rates by 12.1%. Scent-marking rates subsequently increased from 1.9 times/km during recolonization to 3.0 times/km once the population was saturated. We observed evidence of proestrus from 19 December to 14 March with the highest probability of proestrus occurring around 6 February, after peak marking rates around 26 January. Repeated observations of bloody urinations within individual packs suggest proestrus averages 27.9 days. Our study reveals the role of population growth on territorial behaviours and provides a foundation for studies exploring the role of geographic and temporal variation on territorial and reproductive behaviours in wolves.

Quantifying seeds egested by field-collected earthworms: a dynamic and overlooked pool in forest soil seed banks

2021-08-30T08:33:57-07:00

Although awareness of the influence of earthworms on soil seed banks in Canadian forests is growing, there have been few direct field measurements. We used a novel pairing of field-collected earthworms from a central Great Lakes forest in Ontario with a laboratory seed egestion assay to obtain a snapshot of the number of seeds passing through earthworms compared with seeds found in the surrounding soil. We identified a pool of seeds egested by earthworms that accounted for 2.4% of all seeds found in the earthworms and the top 0–10 cm of soil. Individual earthworms contained 0–5 seeds. The large-bodied adult anecic non-native Dew Worm or Common Nightcrawler (Lumbricus terrestris) egested a disproportionate number of seeds for its abundance (50% of egested seeds from 17% of earthworms), but smaller earthworms were also an important source of egested seeds (the other 50%). This small-scale proof-of-concept study demonstrates a method of directly measuring earthworm–seed interactions in the field. It can also detect seeds egested by earthworms below ground that would otherwise be missed by other seed accounting methods and it highlights the importance of granivory by non-surface casting earthworms.

Range expansion of Fisher (Pekania pennanti) in Nova Scotia

2022-02-28T09:35:48-08:00

Fisher (Pekania pennanti) is a medium-sized mesocarnivore that typically occupies mature hardwood and softwood forest where its preferred prey is abundant. In Nova Scotia, Fisher populations are reported as restricted to the mainland; they have been absent from Cape Breton Island for the past 50–80 years. A record of a Fisher on Cape Breton Island in February 2002 prompted us to collate and analyze other records of Cape Breton Island sightings of the species from that date to May 2021. Based on reported sightings, we conclude that Fisher has extended its range from mainland Nova Scotia, apparently crossing the Strait of Canso, and that a breeding population now exists on Cape Breton Island and is expanding. We also comment on possible negative interactions between this expanding Fisher population and the provincially Endangered American Marten (Martes americana) population on the island.

News and Comment

2023-02-20T17:36:26-08:00

Erratum: A synopsis of lycophytes in Manitoba, Canada: their status, distribution, abundance, and habitats

2023-01-09T07:50:57-08:00

A fossil beech fern (cf. Phegopteris (C. Presl) Fée) from Driftwood Canyon Provincial Park, British Columbia

2022-06-29T10:29:35-07:00

Ferns are important components of the biodiversity of wet forests across Canada, and the fossil record offers insights into the origins of fern diversity and biogeography. In 1967, Driftwood Canyon Provincial Park in north-central British Columbia was declared an Eocene Epoch plant, insect, fish, bird, and mammal fossil site of national scientific significance to preserve the Driftwood Creek fossil beds. The fossil plants from this important fossil site remain largely unknown. Here, a first record of a beech fern from the Eocene of British Columbia—morphologically comparable to the Phegopteris connectilis group—is illustrated, further revealing the past biodiversity of ancient British Columbia. The absence of sori and other key anatomical characters prevents definitive identification. Today, the circumpolar to temperate species Northern Beech Fern (Phegopteris connectilis) is widespread across British Columbia, occurring in wet coniferous forests; other members of the P. connectilis group also occur in temperate climates.

A late Pleistocene Wood Turtle (Glyptemys insculpta) from Iowa, USA: response of the taxon to glaciation and formation of the current range

2021-02-18T09:10:24-08:00

The partial shell of a Wood Turtle (Glyptemys insculpta) was collected from the West Branch of the East Nishnabotna River in southwestern Iowa, near Malvern. By direct accelerator mass spectrometry, it radiocarbon dates to the late Pleistocene (10 220 ± 30 years before present [BP], 11 975–11 813 calibrated years [cal] BP). Other subfossil evidence indicates that Wood Turtles moved far south of their current range, into the southeastern United States, in response to late Pleistocene glaciation. The specimen suggests that the species also moved south and west, into a previously undocumented western range, where favourable habitat and, in particular, somewhat cooler summer temperatures prevailed until ~10 200 cal BP. My assessment of the Holocene subfossil record suggests that establishment of the western portion of the current range may have occurred within the past 1000 years. Phylogenetic analysis and direct radiometric dating of subfossil specimens are needed to determine additional details about the late Pleistocene dispersal of Wood Turtle and the postglacial formation of their current range.

Conspecific nest attendance behaviour of Common Eider (Somateria mollissima) in response to Polar Bear (Ursus maritimus) foraging activity: error or intent?

2021-11-18T10:38:28-08:00

Common 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.

Salmon Shark (Lamna ditropis) scratching behaviour using floating anthropogenic debris

2022-09-06T13:10:49-07:00

Observations of animal behaviour in the open ocean are relatively rare. However, while conducting surveys in the Northeast Pacific in the summers of 2019 and 2021, we encountered two Salmon Shark (Lamna ditropis) using floating anthropogenic debris to scratch their bodies. We captured the activity with aerial (drone) and underwater cameras. We document and describe this novel behaviour as high energy, high impact, repetitive, fast, and long lasting (e.g., every ~15 s for >20 minutes). We explore these observations in light of traditional ecological knowledge and scientific literature.

Cover

2023-02-20T17:27:15-08:00

"Field Study: Meditations on a Year at the Herbarium" by Helen Humphreys, 2021. [book review]

2023-02-20T16:58:40-08:00

"Effective Conservation: Parks, Rewilding, and Local Development" by Ignacio Jiménez, 2022. [book review]

2023-02-20T17:05:32-08:00

"The Greatest Polar Expedition of All Time: the Arctic Mission to the Epicenter of Climate Change" by Markus Rex, translated by Sarah Pybus, 2022. [book review]

2023-02-20T17:08:19-08:00

"Ants: the Ultimate Social Insects. British Wildlife Collection (Book 11)" by Richard Jones, 2022. [book review]

2023-02-20T17:11:22-08:00

"Woman, Watching: Louise de Kiriline Lawrence and the Songbirds of Pimisi Bay" by Merilyn Simonds, 2022. [book review]

2023-02-20T17:14:29-08:00

"Bats of British Columbia. Second Edition" by Cori L. Lausen, David W. Nagorsen, R. Mark Brigham, and Jared Hobbs, 2022. [book review]

2023-02-20T17:17:25-08:00

"Applied Panarchy: Applications and Diffusion across Disciplines" edited by Lance H. Gunderson, Craig R. Allen, and Ahjond Garmestani. 2022. [book review]

2023-02-20T17:20:26-08:00

New Titles

2023-02-20T17:23:28-08:00

A tribute to George William Argus, 1929–2022

2022-12-09T11:05:39-08:00

[Not necessary for a Tribute.]