The Canadian Field-Naturalist

"Symbiosis: a Very Short Introduction" by Nancy A. Moran, 2025 [book review]

2026-06-14T16:34:51+00:00

"Victorian Nightshades: How the Solanaceae Shaped the Modern World" by Elizabeth A. Campbell, 2025 [book review]

2026-06-14T16:37:38+00:00

"Beyond Equilibria: Historical Approaches to Ecology and Evolution. Oxford Series in Ecology and Evolution" by Hamish G. Spencer, 2025 [book review]

2026-06-14T16:40:41+00:00

"Raising Hare: the Heart-Warming True Story of an Unlikely Friendship" by Chloe Dalton, illustrations by Denise Nestor, 2025 [book review]

2026-06-14T16:43:15+00:00

New Titles

2026-06-14T16:45:51+00:00

Minutes of the 147th Annual Business Meeting (ABM) of the Ottawa Field Naturalists’ Club, 14 January 2026, 7:30 p.m. (draft)

2026-06-16T17:19:47+00:00

Annual Ottawa Field Naturalists’ Club Committee Reports for 2025

2026-06-16T17:31:20+00:00

The Ottawa Field Naturalists’ Club Awards for 2025, presented April 2026

2026-06-16T17:38:08+00:00

News and Comment

2026-06-18T03:24:17+00:00

The freshwater mussel (Bivalvia: Unionidae) assemblage of the Mississagi River, Ontario: a stronghold for the federally Endangered Hickorynut (Obovaria olivaria)

2025-01-15T07:50:01+00:00

Federally Endangered Hickorynut (Obovaria olivaria) was historically known to occupy a short section of the Mississagi River. Whether this distribution represented the true range of the species or simply reflected a paucity of directed mussel sampling was unclear. The Mississagi River was systematically surveyed in 2023 to evaluate the freshwater mussel assemblage in the watershed, focussing on Hickorynut. The river was divided into 21 contiguous reaches, the first of which was 1 km long, followed by 20, 2 km reaches from the Red Rock Falls Generating Station downstream to the mouth at Lake Huron. Each reach was surveyed at least once using SCUBA; additional surveys were conducted in some reaches if warranted (e.g., historical presence of Hickorynut). In total, 35 sites were surveyed (26 SCUBA, nine snorkel) and 7590 mussels of seven species, including 141 Hickorynut were found. A single Lake Floater (Pyganodon lacustris) was found and genetically verified, representing the third confirmed detection of the species in Canada. Eastern Elliptio (Elliptio complanata) was the most common species found, occurring at all sites. Our results clarify the distribution of mussels throughout this stretch of the Mississagi River and extend the known distribution of Hickorynut ~22 km upstream of its previously known range. These findings will aid in the conservation and management of freshwater mussels in Canada and inform future assessments of atrisk mussel species.

Pilfering of North American Red Squirrel (Tamiasciurus hudsonicus) middens by Northern Flying Squirrel (Glaucomys sabrinus) during spring and summer is unlikely

2025-08-20T15:49:57+00:00

The overlapping ranges of North American Red Squirrel (Tamiasciurus hudsonicus) and Northern Flying Squirrel (Glaucomys sabrinus) and the observation of the latter pilfering fungi from the former’s middens throughout the year in interior Alaska
suggest that kleptoparasitism (resource stealing) could be occurring. Between May and August 2022, we deployed 15 camera traps focussed on active red squirrel middens and nearby reference sites in the central interior of British Columbia, Canada, to document possible nocturnal food pilfering by flying squirrels. Flying squirrels were not detected at red squirrel middens at higher rates than at reference sites. Further, the single observation of foraging-like behaviour in the 12 flying squirrel detections at red squirrel middens suggests that pilfering is unlikely. Epigeal fungi were in apparent abundance during the study period, but not conspicuously stored at middens. The opposing diurnal activity patterns of the squirrels also reduced the likelihood of aggressive territorial behaviour or vigilant midden guarding by red squirrels. Future investigations should focus on the potential for food-pilfering events in relation to local food abundance and on habitat features more likely to contain fungal caches.

Arbuscular mycorrhizal fungal establishment in cordgrasses (Sporobolus spp.) at restored and natural Bay of Fundy salt marshes

2026-01-06T07:37:24+00:00

Salt marshes are dynamic ecosystems recognized for their environmental contributions in mitigating climate change. As
known carbon sinks, they are highly productive ecosystems supporting numerous biotic assemblages, including fungal communities. Arbuscular mycorrhizal fungi (AMF) are endomycorrhizal symbionts that form associations with approximately 80% of plant roots, aiding plants in nutrient and water acquisition. Some AMF species can survive halophytic conditions and are known from roots of keystone cordgrass species in the genus Sporobolus (formerly Spartina). We analyzed AMF establishment in three cordgrass species, each species from low, middle, or high marsh elevations, at 10 salt marshes in the upper Bay of Fundy, Nova Scotia. Arbuscular mycorrhizal fungal establishment significantly varied by salt marsh grass species and was highly variable among sites. Sediment phosphorus and sodium had no significant impact on AMF establishment, whereas sediment nitrogen did influence their establishment in addition to other variables (i.e., tidal inundation). The highest % AMF establishment occurred in cordgrasses from middle and high marsh elevations at older restored and reference (natural) sites. We found the highest AMF establishment (94%) at restored salt marshes in Prairie Cordgrass (Sporobolus michauxianus) roots. Given their underappreciated yet potentially critical roles in coastal ecosystems, the contributions of AMF warrant further investigation to understand their ecological significance in supporting coastal salt marsh resilience.

A field survey of anuran species in two boreal lakes at the Experimental Lakes Area, Ontario, Canada

2025-10-19T21:27:23+00:00

With over 60% of Canada’s amphibian species at-risk, field surveys and studies can contribute important knowledge to better inform assessments and conservation efforts. The diversity of amphibians inhabiting lakes, specifically semi-remote boreal lakes, has been relatively understudied compared to wetlands and temporary waterbodies. The goal of our study was to survey the anuran species associated with freshwater boreal lakes in a historically undocumented area in northwestern Ontario, Canada. In May–August 2022, we conducted egg surveys, larval surveys, and automated call recording surveys at two boreal lakes at the International Institute of Sustainable Development-Experimental Lakes Area. We detected seven anurans: American Toad (Anaxyrus americanus), Gray Treefrog (Hyla versicolor), Green Frog (Lithobates clamitans), Mink Frog (Lithobates septentrionalis), Northern Leopard Frog (Lithobates pipiens), Spring Peeper (Pseudacris crucifer), and Wood Frog (Lithobates sylvaticus). We also incidentally detected adult Central Newt (Notophthalmus viridescens louisianensis). American Toad was the most extensively detected species among our survey methods, with all life stages detected. In contrast, Northern Leopard Frog was infrequently detected in calling surveys at one lake. Although anuran populations can vary annually and within relatively small spatial scales, our results suggest that freshwater boreal lakes harbour a diversity of anurans and should not be overlooked as valuable amphibian habitat. As anthropogenic impacts continue to threaten boreal ecosystems, our surveys provide baseline knowledge of anurans in these semi-remote boreal lakes of Canada, critical for further studies and amphibian conservation efforts.

First sighting of Purple-striped Jellyfish (Chrysaora colorata) in Canadian Pacific waters

2025-07-31T12:53:40+00:00

We report the first record of a Purple-striped Jellyfish (Chrysaora colorata) from Canadian waters. A single specimen, ~65 cm in bell diameter, was collected in a trawl catch on 4 October 2024 in near-surface waters, off Clayoquot Sound, British Columbia, about 400 km from the previous most northern, research-grade record in the United States. Identification of our specimen was confirmed based on bell texture and size, colouration, number and shape of lappets, and the presence of a quadralinga. In the future, changing oceanographic conditions associated with climate change may lead to C. colorata becoming more common at more northerly latitudes.

The European terrestrial flatworm Microplana cf. terrestris (O.F. Müller, 1773) (Platyhelminthes: Geoplanidae) in a wilderness area of New Brunswick, Canada, suggests a previously unreported pathway to introduction

2025-12-23T09:38:18+00:00

The terrestrial flatworm Microplana terrestris (O.F. Müller, 1773) (Platyhelminthes: Geoplanidae) is a western European
native that has been introduced to North America and elsewhere. Introduction of terrestrial flatworms outside their native
ranges has been reported to have occurred via the horticultural trade, mainly in contaminated nursery plants and soil. A
second occurrence from Atlantic Canada is documented from a remote wilderness area. Circumstantial evidence suggests
that vermiculture (i.e., the cultivation of earthworms for use as bait in recreational fishing or composting or the use of worm castings as garden fertilizer) may be a previously unrecognized pathway for terrestrial flatworm introduction.