Bobcats are widely distributed throughout the United States, but are less common in southern Canada and northern Mexico"............ "The northern range margin of bobcats in British Columbia, Canada, occurs at ~53.5–54.5°N (near Highway 16) and this range edge has been stable for the last eight decades"............. "In these northwestern subboreal and boreal forests, few prey species are available in winter compared to the southern part of the range"............"Further, throughout their northern range, bobcats overlap with a (dieatary)specialist, the Canada lynx which relies on boreal forest for habitat and snowshoe hares(primarily)"............."Lynx have morphological adaptations for snowy winters, including large feet that reduce foot‐loading and long hind legs that facilitate travel, hunting, and capture of hares in deep, soft snow".............."In contrast, bobcats do not face severe winters throughout most of their geographic range"............"Deep snow depth negatively influences bobcat movements and habitat use as they have small feet that sink into soft snow causing an energetic disadvantage competing with the sympatric Lynx for snowshoe hare".........."And interesting enought, Bobcats in northwest Montana did not consume many snowshoe hares"................"Instead, bobcats primarily ate red squirrels and small mammals(see graph below)"..............,...."Although we would need prey densities for the entire prey base to definitively address how much of the bobcat diet in northwestern Montana reflects prey abundance versus bobcat prey selection, we do find it striking that so few hares were consumed in the face of comparatively high hare abundance".............."Bobcats clearly used the entire local prey base, but with a focus on small mammals and red squirrels"............."It is not clear whether bobcats found it easier to hunt these species rather than snowshoe hares in deep snow".............."The studies showing bobcats consuming snowshoe hares in higher proportions are from Eastern populations, in regions that are typically flatter and with lower elevations, and thus are without the deep, persistent snows that bobcats in this Montana study area experience"................"Deer would be available to Eastern bobcats throughout the winter, but in Western localities, deer often overwinter in lowland valleys rather than in forested uplands, thus becoming less available for bobcats that overwinter at higher elevations"................"The predator communities also differ, with many Western forests supporting top predators such as gray wolves and mountain lions (Pumas), whereas Eastern forests often lack these species"..............."Although the top predators do not often consume snowshoe hares, their presence could alter the behavior of bobcats in Montana"................"Finally, recent genetic evidence points to deep lineage splits between Western and Eastern bobcats, so there could potentially be subtle behavioral or phenotypic variation between these groups as well that would affect hunting success of prey selection"

https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.4576

Regional differences in winter diets of bobcats in their northern range

Roberta K. Newbury 

Karen E. Hodges

First published: 09 October 2018

https://doi.org/10.1002/ece3.4576

ARE

Abstract

When generalist predators have wide geographic ranges, diets may differ dramatically, largely as a result of differing prey communities. Bobcats (Lynx rufus) are widely distributed across southern North America, with their northern range edge occurring in southern Canada and in the northern US states.

The smaller non-webbed feet of the Bobcat
causes a higher expenditure of energy hunting
prey is deep, powder snow 

The wide-webbed feet of the Canadian Lynx
provides a deep-snow hunting advantage over Bobcats when the two animals share the same range

Within this northern range, bobcats are exposed to cold and snowy winters and a limited number of prey species, conditions that are atypical for most of the range of bobcats. We examined winter diets of bobcats in high elevation and very snowy forests in northwest Montana to determine how these generalist predators managed in these harsh conditions in comparison with elsewhere in the northern range. 

An adult male bobcat (Lynx rufus pallescens), M1, that was captured and radio‐collared as part of this study on the Tally Lake Ranger District, Flathead National Forest, northwest Montana. M1 weighed ~15 kg when collared on 12 December 2009. In this photograph, M1 was recaptured on 25 January 2010 and released without handling

Bobcats consumed five major prey types: Red squirrels (Tamiasciurus hudsonicus) and Cricetid rodents comprised >78% of the dietary biomass, whereas the larger snowshoe hares (Lepus americanus), deer (Odocoileus spp.), and grouse were consumed much less often. The standardized niche breadth of bobcat diets was 0.29; bobcats from across the northern range also routinely ate multiple prey species, although Eastern bobcats appear to consume more lagomorphs than do Western bobcats.

Prey consumed in winter by bobcats in northwest Montana (this study) versus other studies (Table 4). The “Sciuridae” category reflects red squirrel for Montana bobcats, but in other northern latitudes includes Eastern gray squirrel and northern flying squirrel. Error bars are the exact 95% binomial confidence intervals

These results indicate that bobcats remain generalists in difficult winter conditions while preying primarily on small‐bodied prey, although bobcats have highly variable diets across their northern range.

The northern extent of Bobcat range is Highway 16
(redlined on map) in British Columbia, Canada,  north of the Montana, USA state line