[Tweeters] Fwd: Heron Colony Abandonment Dynamics (fwd)

Christine Southwick clsouth at u.washington.edu
Wed Mar 14 15:50:35 PDT 2007


Posting for Don Norman, who is not currently a member

Christine Southwick
N Seattle/ Shoreline

clsouthwick at comcast.net
From: "Puget Sound Birds" <pugetsoundbird at gmail.com>
To: szkrom at drizzle.com, tweeters at u.washington.edu, science at seattleaudubon.org
Date: Wed, 14 Mar 2007 16:36:08 -0500
Subject: Heron Colony Abandonment Dynamics
Suzanne-
It is great that you have continued to monitor the Black River colony
to note the change in its numbers. Data from annual monitoring by the
Province and Canadian Wildlife Service in BC has shown that heron
colonies do change over time, likely due to changes in food supply in
an area, as well as possibly some age dynamics in colonies. We know
that Black River has even been abandoned and re-occupied over the past
20 years. We still do not have repository for observations to be
sent. Perhaps we can see if ebird has the capacity to receive such
data. Obviously, the details of number of nests etc.. is more detail
than is currently collected by ebird. Check out the Avian Knowledge
Network, also part of Cornell. Getting an online dataentry system for
such observations beyone ebird is a major objective of the newly
formed Puget Sound Bird Observatory.

It is important to note that this year we had three MAJOR storm events
that could have also drastically increased the mortality of herons
across the NW over the winter. The two worst freezes in well over a
decade and the worst wind storm in 40 years are both heron killers.
Can other folks looking at colonies send Russell Link and myself info?
It is likely that specific disturbances coupled with such stressors
may be responsible for fewer birds being at the colony. The colony at
Maury Island, which had 120 nests suddenly abandoned in the middle of
the nesting season in 1994, with the possibility that there was a
shooting of a heron (never confirmed). Those birds have never
returned. We have no idea where they went. Bainbridge?

Having monitored the Kenmore colony closely when the Park and Ride was
being constructed, and also having Adolphson biologists onsite, we
never even noticed at least 13 visits in March and April into the
colonty by GeoCachers, obviously not right when we were doing the
monitoring, that went UNDER the colony to put their name in the can
left there. We have no idea whether that caused the failure of nests,
but it is certainly a possibility. With so much access at Black
River, it is certainly possible some is causing disturbance.

Finally, I have been interested in whether the adult female herons
were using the mouth of the Cedar River as a location to store up
calories for their eggs by feeding on spawning smelt. I have observed
birds feeding at night there in the past and changes in that area
could be responsible for disrupting the females. This has always been
a theory of why this colony starts earlier than the saltwater
colonies, which Rob Butler showed were related to daytime spring
tides.

Changes continue to occur in the area where most of the herons appear
to be foraging to the south of the colony in the Kent valley, so we
must also remember that there needs to be foraging areas, as well as
alternative nesting sites protected for the herons.

I wonder if there are volunteers who wish to brave the cold evenings
at Lake Sammamish State Park, the mouth of the Sammamish Slough at
Kenmore to look for the smelt spawning. I have heard reports from
Issaquah Creek of herons foraging at night, but never confirmed them,
and looked for birds at Kenmore but never saw any the one FREEZING
night I went out in a canoe... perhaps on clear nights the smelt can
see the herons???

I have excellent protocols as well as datasheets to record arrivals
and departures, and would be glad to email them to anyone
interested...

don
Please note that I have a new email on gmail and do not check my AOL
account daily.

Donald Norman
Norman Wildlife Consulting
and Go Natives Nursery (Email: gonatives at gmail.com)
www.gonatives.com





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