[Tweeters] Regarding river otter predation

[Peter Wimberger]

The past several years at Big Twin Lake, Okanogan County (by Winthrop)
there has been a mini-wildlife spectacle where, at dusk, hundreds of ducks
fly into a small patch of open water kept open by a bubbler. Often one
could see (and hear) 8-10 duck species in the aqueous mosh pit (mostly both
species of goldeneyes, but also buffleheads, common and hooded mergansers,
teal, mallards, scaup, wigeon, sometimes swans or geese), some arriving
after dark. The ducks would depart by first light, presumably to avoid the
ever present Bald Eagles. (BTW - the spectacle was discovered during a
CBC). This year the massive numbers of ducks didn't show up. A few ducks
would land at dusk and then quickly take off. Flocks of goldeneyes and
mergansers would circle a few times and then fly elsewhere. We initially
wondered if it was because it has been warmer and there was more open water
around. We also noted at least one river otter regularly cruising around or
lolling on a dock but didn't connect the dots. At the Twisp CBC potluck I
mentioned this year's lack of ducks and also mentioned that the folks who
came to see the ducks, got to see the otter as consolation. One of the many
amazing naturalists who participate in the Twisp CBC mentioned that river
otters can wreak havoc on waterfowl and showed me multiple photos of otters
carrying scoters and other ducks. The next morning they watched a Hooded
Merganser narrowly escape the otter. It's a cool example of the impact one
or two predator individuals can have on the behavior of hundreds of
individuals (likely the majority of the ducks overwintering in the upper
Methow Valley).

I want to add that I appreciated the folks who posted their CBC reports on
Tweeters (another nice use of Tweeters).  I'll post the Twisp CBC report
soon.

Peter Wimberger
Tacoma, WA
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