>Minks are in rivers throughout Washington at low to mid elevations. They
>also swim in the Sound and live on the San Juans. On the San Juans, they
>branch out from their more traditional fare of anything alive in and near
>the water they can overpower and hunt the abundant European Rabbits in the
>uplands.

I might as well chime in on this mink thing...in reference to the Malheur
NWR.

One of the nice thing about having the Frenchglen Mercantile change
hands a couple of springs ago is that the new owners are not only nice
people, a pleasant contrast from the past, but they opened the "Buckaroo
Room". This features long-necked Bud for the cowboys and micro-brews
for the rest of us, which allows for easy and safe identification of the
two types of customers at a distance.

Refuge types often drop in for a brew or two after work, in particular
those who live at the P Ranch, especially a couple living there the
past two seasons, both biologists. The boy half of this couple chose
to take a seasonal job with the water crew (opening/closing drainage
ditches) rather than as a seasonal refuge biologist because the pay's
something like a third more, which should be a comfort to all the
wildlife biology students on tweeters :) The girl half was working
with the crane monitoring (the bird kind, that is) crew.

Bear with me...I'm getting to the point.

A few years ago (over ten, I think), it was determined that raven
predation on eggs and coyote predation on colts were the major source
of very low crane production on the refuge.

So raven and coyote control operations were introduced, with the
reluctant support of Portland Audubon (reluctance in part because
the coyote portion of the problem is to some degree an artifact of
the grazing program on the refuge, which I'll skip over for the
moment).

What's interesting is that in the past few years the mink population
on the refuge has boomed, due to the removal of coyotes which apparently
helped keep them in check. I don't know if predation on young mink or
simple competition for food was the cause of this - there used to be
hundreds of coyotes on the refuge. It took a few years to knock them
down in numbers, and a few more for mink numbers to take off. Ten
years ago you'd see coyotes by the dozen in a days drive around the
refuge, but almost never mink (at least wouldn't!). Now, it is very
common to see mink. Damned cute, I'll admit.

So, crane production is down again and guess why?

Yep. Mink get into the eggs and young. And they can get to floating
nests much earlier in the year than coyotes could, 'cause they swim
better (the crane often nest in four-five feet of water). She (the
underpaid young biologist) told me the percentage lost to mink predation
but I forget the number. It's been the major identifiable cause, though,
I remember that.

This sequence of events was not predicted when coyote controls were
introduced, another example of how little we understand system dynamics
at times, even managed systems like the refuge.

- Don Baccus, Portland OR <donb at rational.com>
Nature photos, on-line guides, at (NEW) http://donb.photo.net