Re: Points of discussion

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: To answer your questions: : 1) Within species, home range size tends to be : correlated with individual size, food : availability, sex, and in some species, the : availability of specific refugia. Males often : have larger home ranges than females per unit : body mass. There are significant differences : between species, which in some cases are : attributable to differences in foraging : behavior. Active cruisers tend to have larger : home ranges than sit-and-wait predators, : presumably because they consume more energy per : unit body mass. Population biologists often use : the concept of the "core area," in which the : individual spends most of its time, as a more : realistic measure of home range size than the : total range. However, based on telemetry : studies this concept seems to apply poorly to : snakes. : : 2) Telemetry studies and other observations : indicate that adamanteus does not den communally : as horridus does, even in the northern part of : its range. It is not uncommon to find 2 or 3 : individuals sharing an overwintering site, but : I am unaware of large numbers being found at a : single site. Overwintering sites are generally : imbedded within the animal's warm season range, : no significant migration is needed to bring the : snakes to them. : 3) It seems reasonable that average home range : size in adamanteus has increased, but there are : no hard data that I know of. If we presume that : the density of prey animals has generally : declined, which as an average is probably : correct, we should expect that home ranges have : increased. However, we may also presume that : adamanteus density has declined, which tends to : bring the per capita food availability up. My : guess is that this has not fully compensated for : the former, and that home range size has : increased modestly. : I think your point about the diminishing effects : of roads as you move away from them is perfectly : valid, although I believe the population many : miles from the road can be significantly : affected. Edge effects can propagate inward to : a much greater extent than one might think. : Many tend to assume that any population declines : will be compensated for by the influx of : individuals from nearby populations. But if : dispersal cannot keep up with edge mortality, : this is exactly what can reduce population : densities miles away from the edge. A ripple : effect can propagate far to the interior as : individuals disperse toward the periphery. To : my knowledge this has never been studied in : rattlesnakes.

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