The “perrrck” vocalization of Ruffed Grouse (Bonasa umbellus)

The vocal repertoire of Ruffed Grouse (Bonasa umbellus) has been known for decades, but because of the rarity of vocal recordings in the field, few data exist on spectral characteristics of their vocalizations. Here, we provide a spectrogram and analysis of a vocalization rarely heard in the field: the “perrrck” call, which is ~0.5 s in duration and has a fundamental frequency of 613 Hz with several harmonics. We compare this call with the more commonly heard “peet” call, which is much shorter and of higher frequency. Although the function of the perrrck call remains unknown, our analyses show that Ruffed Grouse vocalizations vary in frequency, despite their purportedly weak syrinx

Plural breeding in Gray Wolf (Canis lupus) packs: how often?

The occurrence of more than a single female breeder in North American Gray Wolf (Canis lupus) packs, i.e., plural breeding, is well known, but its incidence has not been estimated since 1982. Using winter pack size as an index to plural breeding inwolves, I reviewed the literature from North American populations least exploited by humans to assess the general incidence of plural breeding. Generally winter packs >15 were associated with incidents of plural breeding. Wolf packs preying primarily on White-tailed Deer (Odocoileus virginianus) and in locations south of 52°N latitude seldom exceeded 10–15. Plural breeding occurred in packs preying primarily on larger ungulates in areas mostly above 52°N. The estimated incidence of plural breeding in the overall wolf population was <15% and perhaps <10%, which is lower than a 1982 estimate of at least 20–40%. I discuss reasons why plural breeding is associated with larger prey

Barred Owl (Strix varia) activity and diet recorded with a camera trap at a natural cavity nest in Manitoba, Canada (2016–2017)

Camera trap images (n = 27 092) collected at a natural Barred Owl (Strix varia) nest site in Manitoba, Canada, 2016–2019, were used to quantify nesting behaviour and identify prey delivered to the nest. Adult Barred Owl activity increased prior to egg laying and again after incubation. Adults were mostly active at night, but daytime activity increased during the nestling period in 2016 and more so with a larger brood in 2017. Nestlings were active at the nest entrance both day and night for 8–9 days prior to fledging at ≤27–32 d old. Two of three nestling activity peaks (0400 and 2000 Central Daylight Time [CDT]) corresponded to prey delivery activity peaks whereas a third (1200 CDT) did not. Only 31/65 prey were identified to species, but 12 new prey taxa were documented for Barred Owl in Manitoba. Activity at the cavity during the non-breeding season before and after a nest predation event were documented; the nest site was abandoned after an American Black Bear (Ursus americanus) visited the nest cavity in May 2018. Factors affecting the quality and quantity of images, and hence data obtained from them, included camera position relative to the nest cavity entrance, light levels, camera trigger speed, non-target species, and the configuration and settings of motion detection sensors. Improved camera traps may overcome these limitations. This is the first published study on this owl species using this increasingly popular technology

The carcass zone: salmon contribution to tree rings in old‑growth Sitka Spruce (Picea sitchensis) throughout coastal British Columbia

The contribution of Pacific salmon to riparian forest biodiversity is widely recognized, yet the direct influence on coniferannual growth rings is less well-established. I examined broad spatial and temporal trends (1945–1999) in ring width, basal area increments (BAI), and nitrogen signatures in heartwood rings of 282 old-growth riparian Sitka Spruce (Picea sitchensis;average age ~300 years) from 79 watersheds in three regions of coastal British Columbia. Several large yearly fluctuations in salmon biomass entering streams were positively but weakly correlated with tree growth, lagged one to four years. General linear models indicate that tree age and salmon carcass proximity were the major growth predictors, while tree distance to stream and riparian slope were not significant. Average annual BAI (marginal means) in carcass zones were 80%, 150%, and 55% higher than adjacent control sites on the Mainland, Mid-coast Islands, and Haida Gwaii, respectively. Nitrogen isotope signatures (δ15N) in heartwood rings ranged from –8.6‰ to 8.0‰ and were about 3‰ higher in carcass trees than control trees. Total nitrogen (TN) ranged from 0.03% to 0.15% and was largely independent of salmon carcass occurrence. Bivariate plots (δ15N against TN) indicate a geographical clustering of elevated TN in Haida Gwaii watersheds, lower δ15N and TN in the Mid-coast Islands, and elevated δ15N and TN in watersheds with exceptionally high salmon carcass transfer and bear activity. These cumulative data robustly quantify accentuated conifer growth from salmon-derived nutrients in riparian zones that are largely independent of climatic influences and tree age

Apparent predation of a bison (Bison bison) calf by a Grizzly Bear (Ursus arctos) in southwestern Yukon

Grizzly Bear (Ursus arctos) predation on American Bison (Bison bison)—particularly calves—was likely once common.However, with the range-wide collapse of bison near the close of the 19th century, the two species no longer co-occur across much of their current distributions. Over the past 60 years, efforts to reintroduce bison to their native range have resulted in a few small areas where the two species once again co-occur. Yet, predation of bison by bears is apparently rare and has not been observed outside Yellowstone National Park, where both species have existed for millennia. On 28 June 2023, we observed an adult male Grizzly Bear protecting a buried bison calf that it had apparently killed in Yukon, Canada. This is the first observation of apparent predation of a bison by a Grizzly Bear outside Yellowstone National Park. Our observation further highlights how reintroduced bison are becoming integrated into local food webs, which is a key indicator of ecological restoration