The Canadian Field-Naturalist

Cover

2024-10-17T21:45:15-07:00

Limited evidence for the influence of the physical structure and floristics of habitat on a boreal forest bird community

2023-11-15T08:49:39-08:00

Studies conducted at regional and continental scales show that avian richness, community composition, and abundance are associated with variation in the vegetation physical structure and community composition (floristics) within broad habitat types. The relative contributions of physical structure and floristics are contested, and relationships are often taxon-specific. We used 110 microphone arrays deployed across 90 sampling locations and two breeding seasons to survey an avian community in the boreal forest in Labrador, Canada. Our objectives were (1) to describe the avian community of an underrepresented portion of the boreal forest, (2) to estimate the relationships between avian species richness and habitat characteristics, (3) to estimate if species detection at a given location was related to local habitat characteristics, and (4) to investigate the spatial and temporal patterns of the avian community composition. We detected 32 species at our sampling locations; physical structure and floristics were not related to avian species richness, although estimates of richness were higher on warmer days and lower on windier days. Habitat characteristics were associated with the detection of Boreal Chickadee (Poecile hudsonicus), Yellow-rumped Warbler (Setophaga coronata), American Robin (Turdus migratorius), and Black-throated Green Warbler (Setophaga virens). Finally, avian community composition was only moderately consistent among three categorical forest types and between audio sampling periods in two consecutive breeding seasons. Overall, we show that the structural and floristic traits measured at our study site are not related to the detection of most avian species or to species richness.

Description of a relict aspen parkland-associated grassland in the Peace River region of British Columbia, Canada

2022-11-01T06:53:51-07:00

The aspen parkland-associated grasslands of the Peace River region, British Columbia (BC), have been severely reduced in area, primarily because of agricultural and urban development. In this region, the species composition of plant communities is similar to that of prairie grasslands and is topographically influenced, occurring primarily on warm-aspect slopes along the Peace River and some of its tributaries. Historical records show that non-forested grass- and sedge-dominated plant communities occurred on flat and gently rolling terrain in a parkland ecosystem near what are now the communities of Dawson Creek and Fort St. John. The Peace grasslands are not represented in BC’s biogeoclimatic ecosystem classification, perhaps leading to their neglect in regional natural resource management and conservation planning. Here, I describe the vascular plant community of a level-terrain relict aspen parkland-associated grassland in the Peace River region. Its species composition differs from nearby warm-aspect grasslands and includes provincially listed plant species. Increased awareness of grassland communities may support conservation, ecosystem restoration, and climate change adaptation in the southern boreal region of BC.

Frullania stylifera (Frullaniaceae), a new addition to the liverwort flora of Canada

2023-07-09T07:30:51-07:00

Frullania stylifera (R.M. Schust.) R.M. Schust. (Frullaniaceae) is newly reported for Canada. The species grows closely
appressed to the bark of trees and shrubs and was recently documented from two areas of mature forest at Buffalo Point First Nation in extreme southeastern Manitoba, Canada. These localities represent a northern range extension for the species on the continent and include two new phorophyte hosts for North America. Features used to distinguish F. stylifera from other known species of Frullania in Manitoba are provided.

Retrospective comparison of the distribution and abundance of breeding Prairie Warbler (Setophaga discolor) along eastern Georgian Bay, Ontario, Canada

2022-11-11T12:14:32-08:00

Species inhabiting rare habitats or unique geographic regions may be underrepresented in standard surveys. More intensive, periodic surveys may be required to improve data quality, especially for species of conservation concern. Prairie Warbler (Setophaga discolor) has experienced range-wide declines of >50% in recent decades and is a species of conservation concern in Canada. The largest continually occupied breeding population of this species in Canada occurs along the shoreline of eastern Georgian Bay, Ontario, where annual Breeding Bird Survey and eBird coverage is generally poor. In 2015, we replicated a spatially intensive 1997 survey of this species along the eastern shore of Georgian Bay, visiting the same sites and using comparable methods. We detected more male birds at the survey sites in 2015 (estimated >350 breeding pairs) than in 1997 (estimated 265 breeding pairs). We also surveyed sites farther north than those covered in 1997, but the breeding range appears not to have moved substantially northward. We also conducted additional surveys and canoe transects in the core range in southern Georgian Bay to ensure that breeding birds were not being missed. Combining data from all our surveys in 2015, we estimated a total of 427 singing males in eastern Georgian Bay. Although overall numbers here appear to have increased in recent decades, localized declines in some areas warrant further investigation. The population appears to be stable or increasing in this region, but we recommend intensively re-surveying this population on at least a 20-year basis.

Declining population of Harlequin Duck (Histrionicus histrionicus) on the Bow River, Alberta, Canada: 25 years of monitoring

2023-04-30T17:07:21-07:00

Harlequin Duck (Histrionicus histrionicus) is a small sea duck that winters in coastal waters and breeds on fast-moving
mountain streams in western North America. Because of its dependency on streams and coastal near-shore habitat with healthy macroinvertebrate populations, population trends of this species can be used as an indication of healthy freshwater and marine ecosystems. From 1995 to 2020 we conducted roadside surveys for Harlequin Ducks on the Bow River in Banff National Park, Alberta. We calculated the population’s trend by modelling maximum annual count, which showed a population decline over the 25 years of 3.3% per year. The trajectory varied over time: a relatively stable population from 1995 to 2005, a steep decline until 2011, then stabilising at a much lower level with a slight rebound in recent years. The predicted number of ducks from our state-space model closely tracked the maximum number of ducks observed in annual counts. During stable or slightly increasing population estimates the male:female (M:F) ratio fluctuated considerably but stayed high (1.4:1 and 1.3:1, respectively), and during the period of steep population decline the M:F ratio was at its lowest (1.1:1). This declining population trend is concerning because it is occurring in a protected area, but it is similar to data from other studies in the Rocky Mountains and at the coastal wintering area, suggesting that causes may not be solely due to issues on the breeding streams.

Evolutionary isolation of Canadian terrestrial vertebrate species

2021-08-04T06:32:19-07:00

Conservation prioritization has become increasingly important as a practical response to ongoing biodiversity loss and limited resources. One tool, evolutionary distinctiveness (ED) is based on a measure of evolutionary isolation and has merit for identifying taxa with few close relatives. Here we present the first ever national-level ED scores for any jurisdiction, applying the measures to all Canadian tetrapods. We updated and pruned global dated phylogenies of all terrestrial vertebrates (amphibians, squamates, turtles, mammals, and birds) down to native Canadian species and calculated Canadian ED scores and rankings for each and compared them to their global ED ranks. Canada’s terrestrial ectotherm vertebrates (amphibians and reptiles) include most of Canada’s most evolutionarily isolated species and many score and rank higher nationally than globally in their ED scores. These taxa are also the most imperilled in Canada and so species with populations assessed as at-risk by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) represent, on average, more than expected national evolutionary history. Interestingly, several exotic species also have very high national ED scores. To the extent that evolutionary isolation captures aspects of local and national biodiversity worth preserving, our lists may provide useful input to conservation agencies engaging in conservation prioritization exercises.

News and Comment

2024-10-17T22:02:40-07:00

Editors’ Report for Volume 136 (2022)

2024-10-17T21:51:26-07:00

"Understanding Natural Selection" by Michael Ruse, 2023 [book review]

2024-10-17T20:51:32-07:00

"Wasps: a Guide for Eastern North America: their Biology, Diversity, and Role as Beneficial Insects and Pollinators of Native Plants" by Heather Holm. 2022 [book review]

2024-10-17T20:56:27-07:00

"Turtles of North America: an Illustrated Field Guide to the Turtles of the Continental United States and Canada" by Kyle Horner, 2024 [book review]

2024-10-17T21:02:41-07:00

"Field Guide to North American Flycatchers: Empidonax and Pewees" by Cin-Ty Lee, illustrations by Andrew Birch, 2023 [book review]

2024-10-17T21:10:18-07:00

"The Secret Perfume of Birds: Uncovering the Science of Avian Scent" by Danielle J. Whittaker, 2022 [book review]

2024-10-17T21:23:28-07:00

"André Michaux in North America: Journals & Letters, 1785–1797" edited by Charlie Williams, Eliane M. Norman, and Walter Kingsley Taylor, translated by Eliane M. Norman, foreword by James E. McClellan, 2020 [book review]

2024-10-17T21:31:19-07:00

New Titles

2024-10-17T21:37:12-07:00

Branching Burreed (Sparganium androcladum (Engelmann) Morong; Typhaceae) rediscovered in Ontario, but conservation status unclear

2023-02-03T05:58:52-08:00

We report three new records of Branching Burreed (Sparganium androcladum), which has not been seen in Ontario in several decades. This species is understudied and has been confused with other taxa, primarily American Burreed (Sparganium americanum). It is not known when it was last collected in the province, and its conservation status is unclear. Specimens identified as Branching Burreed are few and do not fully clarify the situation; of the 14 putative S. androcladum specimens we examined, five are too immature to verify confidently, and at least seven are misidentified. Previous specimen-based maps are probably not accurate representations of Branching Burreed’s provincial distribution, but it is likely more widespread than records indicate. We provide a description of our new records and notes on identification to provide a basis for additional study of this plant.

Full Issue PDF

2024-10-17T22:05:03-07:00

Index to Volume 137

2024-10-17T21:57:10-07:00