with regards to the numbers witnessed by Ray, is it because these were "reared" and some of the natural instincts are dulled or given that i think i read otters actually have quite short lives, these are "wild" otters who for whatever reason are behaving what seems to be abnormally. They also seem far less shy than they used to be, until a couple of years ago, it was only ever a glimpses of otters, now they almost pose for pictures. Bit of a vague post but even the "experts" don't seem to have the answers.
Robert,
As Crooky said, wild mink in the natural state have territories that they defend, to the extent that they will kill young offspring or intruding males if they can't frighten them off. However, the otters that were bred and raised in captivity were obviously forced, by space limitations, to live in groups in tiny enclosed areas or pens. It is said this completely unnatural situation forced them to loose their natural instincts, a case of accept a completely alien crowded situations....or die. As a result, the reintroduced otters run in packs, as they did when being raised from pups in pens, and are not the same beasties as their wild brethren. I have no idea whether this is fact or not...but some of the reports coming in would certainly seem to support that claim.
Initially, the importance of this claim was dismissed on the basis that even if true, the numbers of captive raised otters was so small when compared to the numbers of existing wild otters that the effect would be minimal. However, there have been many claims that the ACTUAL number of released captive bred otters (and injured or starving youngsters that had been gathered up and bought in, kept until healthy again, and then re-released) has been deliberately and wildly underestimated, and that the true figures may never be known. Even the authorities now admit that there were probably many more than those admitted to...and in fact in some areas it is still going on to a certain extent to this day.
Whatever, if this claim of unnatural behaviour IS true, we can only hope it doesn't take TOO long for the otters to return to their traditional way of life. I suppose that would depend on whether that type of behaviour is genetically ingrained...or a learned pattern passed on from father to son, as it were.
As for life expectancy, a study done in the late nineties suggested that due to the large number of accidental deaths, four years was a reasonable average age at death for wild otters. However, one member of their sample group was found to be sixteen years old. I assume then captive otters would grow to to a fairly venerable age....but that the wild lot are incredibly accident prone!
Time will tell.
Cheers, Dave.