11-29-2011, 08:45 AM
The Yellowstone wolves are just a case study. Here's a passage from the same source cited above. Note this book is about wolves in general, not just Yellowstone wolves. Some parts bolded by me for emphasis.
The point is that it's relatively harder on the prey than the wolves, so they have a comparatively easy time catching them. In fact, the worse the winter is, the better off the wolves are! It doesn't look like it has to do with geography so much as the kinds of prey available. Maybe the prey in Norway are better adapted to snow and can outpace the wolves? Is there any scientific literature you can cite that explains how the wolves have a hard time in Norway's winter?
Either way, I'm not thinking our wolves would have an issue since heavy prey like deer, elk, moose, etc. are what's on the menu and they'd succumb to the issues cited in the article. Perhaps a secui would have a rougher time because it's heavier, and definitely an optime, but they usually hunt with advanced weaponry anyway (bow & arrow, spear, etc).
e Side note -- This book is totally awesome o__o I'm thinking of picking up a copy for reference~
Quote:Because wolves tend to kill prey that are vulnerable, and because prey vulnerability is greatly affected by weather conditions, weather is important to wolf-prey relations. The most significant weather factor is snow conditions, including snow depth, density, duration, and hardness.
Snow affects prey animals primarily by hindering their movements, including foraging and escape from wolves. The effect of snow on prey escape is mechanical: the deeper and denser the snow, the harder it is for prey to run through it. Most prey probably have a heavier foot loading than do wolves, so they would sink deeper and be hindered more than wolves. Estimates for foot loading in deer, for example, range from 211 g/cm² (Mech et al. 1971) to 431-1,124 g/cm² (Kelsall 1969), whereas for wolves, the estimate is about 103 g/cm² (Foromozov 1946). Ungulates are usually much heavier than wolves and possess hard hooves that puncture snow much more easily than the spreading, webbed toes of a wolf foot. This difference can tilt the balance toward wolves during predation attempts on animals from the size of deer (Mech et al. 1971) to bison (D. R. MacNulty, personal communication).
The condition of snow changes daily, even hourly, and wolves and their prey are very sensitive to subtle changes that might work to their advantage or disadvantage. R. Peterson (personal observation) has seen packs of wolves sleep through late afternoon and early evening during midwinter thaws, apparently waiting of the crusted snow that will follow when the temperature drops at night. During daily tracking of a pack of five wolves in upper Michigan during a 3-month period, B. Huntzinger (personal communication) documented three cases of the pack killing five to ten deer overnight; during two of these instances the kills were made during heavy blizzards, and in the third case wolves took advantage of a strong snow crust that supported them, but not the deer.
In addition to the acute effect of hindering prey escape, deep snow has a longer, more pervasive effect on prey nutrition. Snow resistance reduces foraging profitability for ungulates and causes them to lose weight over the winter, the amount depending on snow depth and density and duration of cover. During severe winters, prey often starve. The combination of reduced nutrition and poor escape conditions for prey can result in a bonanza for wolves (Pimlott et al. 1969; Mech et al. 1971, 1998, 2001; Peterson and Allen 1974; Mech and Karns 1977; Peterson 1977; Nelson and Mech 1986c).
... [some interesting stuff about how winters can actually affect prey reproduction and bias in the wolves' favour, but since this article won't copy and paste and I'm typing it manually, y'all can reference the link if you really care XD]
The effects of weather, especially snow, so pervade wolf-prey relations that some workers believe that they actually drive wolf-prey systems (Mech and Karns 1977; Mech 1990a; Mech et al. 1998; Poste et al. 1999). When snow conditions are severe over a period of years, they reduce prey survival and productivity, and wolves increase for a few years, whereas during periods of mild winters, the opposite happens. This bottom-up interpretation of driving factors may seem to conflict with a top-down interpretation (McLaren and Peterson 1994). However, ecosystems are complex and dynamic, with multiple food chains, so they can include both bottom-up and top-down influences.
The point is that it's relatively harder on the prey than the wolves, so they have a comparatively easy time catching them. In fact, the worse the winter is, the better off the wolves are! It doesn't look like it has to do with geography so much as the kinds of prey available. Maybe the prey in Norway are better adapted to snow and can outpace the wolves? Is there any scientific literature you can cite that explains how the wolves have a hard time in Norway's winter?
Either way, I'm not thinking our wolves would have an issue since heavy prey like deer, elk, moose, etc. are what's on the menu and they'd succumb to the issues cited in the article. Perhaps a secui would have a rougher time because it's heavier, and definitely an optime, but they usually hunt with advanced weaponry anyway (bow & arrow, spear, etc).
e Side note -- This book is totally awesome o__o I'm thinking of picking up a copy for reference~