[mou] FW: [BIRDWG01] Aging Gray Jays #2 using photos

[Alt, Mark]

Good tips (pun intended) on assessing age of gray jays in the field.

-----Original Message-----
From: NBHC ID-FRONTIERS Frontiers of Field Identification
[mailto:BIRDWG01@LISTSERV.ARIZONA.EDU] On Behalf Of Jean Iron
Sent: Monday, October 30, 2006 8:44 PM
To: BIRDWG01@LISTSERV.ARIZONA.EDU
Subject: [BIRDWG01] Aging Gray Jays #2 using photos

This is more information including 5 photos to the post of 28 October=20
2006 about aging first year (first basic plumage) and adult=20
(definitive basic plumage) Gray Jays. Today, Dan Strickland and his=20
wife Madeleine Pageot live trapped and photographed several=20
known-aged Gray Jays near Lake Opeongo in Algonquin Provincial Park=20
about 175 miles (245 km) north of Toronto, Ontario. These birds are=20
part of Dan's long-term study. They are uniquely color-banded and=20
also banded with standard aluminum bands issued by the Canadian=20
Wildlife Service. Dan reported today: " The 'pointed' rectrices of=20
the first year bird are clearly different from the 'truncated'=20
rectrices of the two adults but I don't see any convincing difference=20
in their wing coverts." Allow a few seconds to download photos. Note=20
detailed information in the photo captions. Thanks to Jean Iron for=20
putting Dan's photos on her website.

See http://www.jeaniron.ca/2006/GrayJays.htm

Ron Pittaway & Jean Iron
Minden & Toronto ON

Copied below is Post #1 on 28 October 2006.

Mark Alt of Minnesota asked about aging Gray Jays so I asked Dan=20
Strickland who has been color banding and studying Grays Jays since=20
the 1960s in Ontario's Algonquin Provincial Park and in Quebec. Dan=20
is the senior author of the Birds of North America account. Dan said:=20
Determining the age (first year versus older) of the Gray Jays=20
involved in the flight would be an excellent thing to do, but it's a=20
little tricky to describe in words and you have to get a good look at=20
the tail from below. Adult (i.e. one and a half years old or older=20
birds seen at this time of year) have rectrices that are broader than=20
those of first year birds and they are "truncated" i.e., sort of=20
"squared off" compared to the "pointier" shape of the usually thinner=20
rectrices of first year birds. Also, because they are older (grown in=20
April-May in first year birds as opposed to July in adults) the=20
rectrices of first year birds seen in fall are usually much rattier=20
and more heavily worn than those of "adults". Trouble is, of course,=20
that one needs a diagram or photos more than a mere verbal=20
description, and even then it's best to have a bit of practice.

I then asked Dan about the pale tips on the wing coverts. Is there a=20
different between first year birds and adults? He said: Good question=20
and something I should look at. Years ago Henri Ouellet told me you=20
could tell first year jays by the shape of the wing coverts. But when=20
I tried to see what he was talking about with specimens at the=20
National Museum (and with Henri right there) I couldn't see anything=20
and he didn't try to defend his earlier statement. I just sort of=20
gave up on the idea at that point and then had no way to tell first=20
year birds from AHY birds because I didn't become aware of the=20
rectrix shape until much later.

Regarding the color inside the bill, Dan said: One of Pyle's books,=20
by the way, says you can tell by looking for white patches inside the=20
bill of first year birds. It is true that some first year birds do=20
have this feature and sometimes on the outside of the bill as well,=20
but it isn't a sure thing. Some HY birds have all black bills inside=20
and out and some AHY birds have light areas. Almost all individuals,=20
whatever their age, have a small, pale (usually "horn-coloured")=20
patch on the inside of the upper bill, just at the tip.

Ron Pittaway
Minden ON
jeaniron@sympatico.ca

At 08:16 AM 10/27/2006, Alt, Mark wrote:
>We are experiencing a significant irruption/migration of Gray Jays,
>Black-backed Woodpeckers, and Three-toed woodpeckers into Northern
>Minnesota this fall. Are there any tips for identifying first year
>plumage in these birds without having bird in hand?
>
>Mark Alt
>Brooklyn Center, MN
>Mark.alt@bestbuy.com


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