Yukon

Interior Alaska–Yukon lowland taiga, Northern Cordillera forests, Northwest Territories taiga,Yukon Interior dry forests, Alaska-St. Elias Range tundra, Arctic coastal tundra, Brooks-British Range tundra, Interior Yukon-Alaska alpine tundra, Ogilvie-MacKenzie alpine tundra, Pacific Coastal Mountain icefields and tundra

Vertebrate scavenging can impact food web dynamics, but our understanding of this process stems predominantly from monitoring herbivore carrion and extrapolating results across carcass types. Recent evidence suggests carnivores may avoid intraguild scavenging to reduce parasite transmission. If this behavior is widespread across diverse ecosystems, estimation of nutrient cycling and community scavenging rates are likely biased to a currently unknown degree. We examined whether the time to initiate scavenging, carcass persistence, or the richness of species scavenging in the boreal forest of Yukon, Canada, differed between carnivore and herbivore carcasses. Vertebrates took longer to initiate scavenging on carnivore carcasses (3.2 d) relative to herbivore carcasses (1.1 d), and carnivore carcasses persisted on the landscape for over a month longer (48.4 d and 5.5 d, respectively). The longer persistence times were due to the reduction in scavenging by carnivores such as Canada lynx (Lynx canadensis). Decreased scavenging was caused by changes in the propensity to consume carnivore carrion, as the number of species detecting a carcass within the first week did not differ between carnivore and herbivore carcasses. These results have ramifications for our understanding of nutrient cycling and food web dynamics in the boreal forest and provide further support that carcass type should be included in future studies.

We investigate if and how diets of gray wolves from the Yukon Territory, Canada, have changed from the Pleistocene (>52.8 ka BP to 26.5 ka BP [±170 y BP]) to the recent Holocene (1960s) using dental microwear analysis of carnassial teeth and stable isotope analyses of carbonates (δ13CCO3 and δ18OCO3) and collagen (δ13Ccol and δ15Ncol) from bone. We find that dental microwear patterns are similar between the Pleistocene and Holocene specimens, indicating that there has been no change in carcass utilization behaviours, where flesh, not bone, is primarily consumed. Based on minimal changes in δ13CCO3 and δ13Ccol values, we find that, over thousands of years, Yukon gray wolves have remained generalist predators feeding upon several large ungulate species. Interestingly, δ15Ncol values suggest that the extinction of megafaunal species at ~11.7 Ka induced a shift from a diet comprised primarily of horse (Equus sp.) to one based on cervids (i.e. moose and caribou). Survival of large-bodied cervids, such as caribou (Rangifer tarandus), was likely key to wolf survival. Although gray wolves survived the end Pleistocene megafauna extinction and demonstrate a degree of ecological flexibility, we suggest that failure to preserve major elements of their current niche (e.G. caribou) may result in continued population declines, especially in the face of increasing anthropogenic influences.