The Canadian Field-Naturalist (E-Journal)
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"The Silken Thread: Five Insects and their Impacts on Human History" by Robert N. Wiedenmann and J. Ray Fisher, 2021. [book review]
No full textSerum biochemistry suggests a physiological response to environmental stress in a native urban Eastern Gray Squirrel (Sciurus carolinensis) population
Get PDFUrban wildlife populations experience human-driven environmental changes that can be both beneficial and detrimental to individual health. We measured body condition and serum chemistry (electrolyte levels, markers of kidney and liver function, protein, glucose, and cholesterol) in a native urban and rural population of Eastern Gray Squirrel (Sciurus carolinensis) to assess whether we could detect physiological responses to environmental stressors or dietary differences. We found no differences in body condition between habitats and no evidence of malnutrition at either site. However, urban squirrels had higher blood glucose, lower potassium, phosphorus, chloride, and albumin:globulin ratios. These results align with previous findings of increased dietary sugar in cities and suggest that urban populations of gray squirrels are under greater environmental stress than rural populations, providing future directions for studying physiological responses to urbanization
Continuing expansion of Narrow-leaved Cattail (Typha angustifolia) and decline of a provincially rare fen in the Holland Marsh, Ontario
Get PDFAt the time of European settlement, an extensive graminoid wetland existed at the confluence of the East and West Holland Rivers at the southern end of Lake Simcoe, Ontario. However, by 1925, clearing and draining of the marsh for specialty agriculture (i.e., market gardens) had begun and, by the 1940s, ~46% of the wetland had been cleared and another 13% was lost before 2016. Concurrent with marsh conversion has been an increase in Narrow-leaved Cattail (Typha angustifolia) in the remnant wetland. This study documents the change in the Holland Marsh wetland by delineating boundaries between marsh, fen, and shrub communities on aerial photographs taken at ~10-year intervals between 1946 and 2015 and documenting vegetation change along transects running perpendicular to tributaries bisecting the wetland. The extent of fen habitat within the Holland Marsh has been decreasing since 1946 at an average rate of 0.24 ha/year because of increases in both shrub and marsh (i.e., T. angustifolia) communities. Typha angustifolia expansion has been predominantly from along the margins of the Holland River where soil phosphorus concentration is significantly higher than in the core of the fen. Beyond 30 m from the river, vegetation dominance shifts from T. angustifolia to sedges (Cyperaceae). Managing phosphorus loading from upstream land uses will be of critical importance in protecting this habitat, which is rare in southern Ontario
First record of Azalea Sawfly (Euura lipovskyi, Hymenoptera: Tenthredinidae) in Canada
Get PDFAzalea Sawfly (Euura lipovskyi) larvae found feeding on foliage and flowers of cultivated Flame Azalea (Rhododendron calendulaceum) in Ottawa, Ontario, in late May 2021 are the first records of this sawfly in Canada. The native range of Azalea Sawfly includes the eastern United States, but the species has extended its distribution recently to the Pacific northwest of North America and Europe. Recorded foodplants include Rhododendron calendulaceum, Rhododendron luteum, Rhododendron obtrusum, Rhododendron occidentale, Rhododendron molle, Rhododendron viscosum, and possibly Early Azalea (Rhododendron prinophyllum), all in Rhododendron section Pentanthera. The new combinations Euura lipovskyi and Euura azaleae are proposed
Evidence of successful hatching by introduced Red-eared Slider (Trachemys scripta elegans) in British Columbia, Canada
Get PDFGlobally, competition and disease from introduced Red-eared Slider (Trachemys scripta elegans) is a threat to co-existing native turtles. Red-eared Slider has been introduced throughout south coastal British Columbia (BC), mainly as pet turtle releases. Urban centres receive the most individuals, particularly in the Lower Mainland area outlying Vancouver, on southern Vancouver Island, and on the Sunshine Coast. The range of Red-eared Sliders in BC overlaps that of the Threatened Pacific Coast population of Western Painted Turtle (Chrysemys picta bellii). Herein we report on a survey for both species, noting presence, assessed population sizes, and nesting activity. Across 19 sites in the south coast occupied by both turtle species, we found the median abundance of Red-eared Sliders to be 2.5 times larger than that of Western Painted Turtles (Mann–Whitney U = 104, n1 = n2 = 19, Z-Score = −2.2188, P = 0.02642, two-tailed). There had been no evidence of Red-eared Sliders successfully hatching in the wild in BC until our study. We observed complete development, with 19 neonates from three different nesting sites between 2015 and 2017. Thus, Red-eared Slider is indeed established and able to breed in BC and thus competition and disease introduction from the species likely contributes to the decline of the Pacific Coast population of Western Painted Turtle, particularly at sites with low painted turtle numbers. The scale and mechanisms of impact requires further investigation
