Funny that Marc should mention nutria. In my post yesterday about the PBGR that were nesting north of the Montlake Playfield ( the one that disappeared under water) , I neglected to mention an encounter the pair of birds had with a near by beaver. I do not have any proof of what was happening under water, but I observed the beaver swimming directly to the nest and one of the adult grebes diving under water. My first thought was that the grebe was trying to disrupt the beaver from further approach to the nest. The grebe that dove, came up in the same spot around the nest more than once (as compared to diving and swimming a distance away). It sure looked like he was attacking the beaver from below. Again this is just conjecture on my part! I did not have my binoculars to closely observe what the beaver was doing. I wondered if the beaver was interested in pulling apart some of the reeds that the "floating" nest platform was attached (?).

There is an increase in beaver activity along Montlake and the Arboretum.....can this be another effect of the "busy beavers"?

There is another PBGR nest that I have been following. This pair spooks very easily. I don't think they would ever be successful at a place like Green Lake.I am certain if there were kayakers/canoes visiting this particular nest, these birds would abandon the eggs.

Eric Kowalczyk
Seattle


----- Original Message -----
From: Marc Hoffman
To: Gene Bullock;tweeters at u.washington.edu
Sent: 7/1/2008 8:45:06 AM
Subject: Re: [Tweeters] Fate of nesting pied-billed grebes in theArboretum


I've paddled the Arboretum frequently enough the past month to say with confidence that there have been no Pied-Billed Grebe chicks in the areas where I saw four nests. So the failure would be a failure to hatch, not a failure for chicks to thrive. By the way, I still see about the same number of adults PBGR's in the area, and assume they're the same pairs that were nesting earlier.

I don't know if the floating nests have the ability to rise with water levels., nor do I know if the water levels have gone up appreciably. I do know that I've been unable to find the three nests that were there a month ago, so a rising water level might account for that. Anybody know where to research Lake Washington's water levels over the past two months or so? I found data on levels at the locks for June, and variation was about four inches. Couldn't find data for earlier months.

On Sunday, I found a newer PBGR nest with four eggs and will try to monitor it. Unfortunately, it's considerably more exposed to canoe traffic than the nests that are now missing.

One thing I wonder about is predators. Nutria are said to be strict vegetarians (can anyone confirm this?). Muskrats are primarily herbivores but occasionally carnivorous. I imagine Great Blue Herons and crows could be a big problem for the grebes. Predation would not account for the disappearance of existing nests, however.

Marc Hoffman
Kirkland, WA
http://www.dartfrogmedia.com
mailto: tweeters at dartfrogmedia dot com


At 07:21 AM 7/1/2008, you wrote:

I've visited sewage treatment plants in the U.S. and Mexico. The birds are drawn to them! I doubt that human fecal contamination threatens birds as much as accumulated bird droppings on platform feeders, which can incubate Salmonella, etc. However, human sewage is laced with household chemicals and other bad stuff routinely flushed down the drain, and that is bad for all living things. The major sources of harmful pollutants are stormwater runoff from our highways and industrial chemicals that concentrate in food stocks (fish) and make their way up the food chain.
Gene Bullock
Poulsbo
----- Original Message ----- From: <notcalm at comcast.net>
To: "Tina Blade" <tinablade at comcast.net>; "'Tweeters'" <tweeters at u.washington.edu>
Sent: Monday, June 30, 2008 11:23 PM
Subject: Re: [Tweeters] Fate of nesting pied-billed grebes in the Arboretum



Hello,

Was there any study of nesting birds during and following the sewage spill?
Some of the marshes and ponds at Montlake (UBNA) were posted as contaminated for a period of time. Are very young birds vulnerable to this type of pollution?

Dan Reiff
Mercer Island


-------------- Original message ----------------------
From: "Tina Blade" <tinablade at comcast.net>

Hi Tweets,
I'm wondering whether any of you can explain what's happened to the many
Pied-Billed Grebes who were nesting in the Arboretum this spring.

About a month or so ago, I saw many of them nesting there, and eagerly
awaited the arrival of their babies. I've gone back several times since, and
have not seen any Pied-Billed mamas with babies either in tow or on their
backs.

I'm wondering if they couldn't handle the stress of the human traffic in the
area.

Thanks,

Tina Blade
Kirkland, WA
mailto:tinablade at comcast.net