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Richard Rowlett writes

>... I fear there might be some speculation and mis-information
>circulating around here when some of the answers are probably plainly to be
>found in literature which I don't have easily at hand. I would imagine that
>the Marbled Murrelet biologists who are intimately involved and have conducted
>extensive coastal at sea surveys targeting this species probably have a pretty
>good fix on this matter of 'abandonment' and could clear it up in very short
>order.

Unfortunately, it's not that easy to clear up this question. To begin with,
I should remind people that the sample size of *active* nests at which
Marbled Murrelet behavior has been observed is very small. (First of all,
it's pretty difficult even to find one!). Of those that have been watched,
most have failed, largely due to predation. Only a few are known for
certain to have successfully fledged a chick, and to my knowledge the
number of people who have actually witnessed a chick leaving (in low light
conditions, no less) can be counted on one hand. When people give evidence
of abandonment, it is often inferred by the behavior of the adults, whether
they decrease or stop making feeding visits before the chick is seen to be
gone from the nest. Unfortunately, once the fledglings are on the water
it's too late to be able to tell if they were abandoned before they got
there. True, you can get some idea of production and recruitment by
counting the number of birds in black-and-white fledgling plumage -- at
least until the adults start molting in late summer/early fall -- but I
don't see how that could reveal anything about what happened at the nest.

>If it is generally true, and Marbled Murrelet chicks are abandoned by their
>parents, then this is quite the contrast from some of those flightless "tiny
>little ping-pong balls of downy fluff" (Ancient Murrelet chicks) that I have
>seen 'with their parents' (I presume parents) 150 to 200 nmiles off (south of)
>Attu, Agattu, and Buldir in mid-late June to mid-July. Most such encounters
>consist of one or two chicks with two adult birds, so it would seem that
>Ancient Murrelet chicks are not abandoned by their parents as has been
>suggested for Marbled.

You're quite right. (It's also in contrast with the strategy of murres,
where the father alone accompanies the jumpling chick and feeds it at sea.)
Ancient Murrelets nest in burrows, and within a couple days of hatching the
adults go down to the water and start calling. The fluffy chicks respond by
tumbling out of the burrows and scrambling down to the water to rejoin
their parents. They head out to sea and apparently are soon well offshore
as a happy family.

For those interested in details of the biology of this interesting species,
there is a lengthy monograph/book written by Anthony Gaston and Ian Jones,
called simply (I think) _The Ancient Murrelet_. I've seen it for sale in
several places, including Flora & Fauna in Seattle. One of these days I'll
add it to my own library.

-- Janet Hardin
Port Townsend, WA
wings at olympus.net