Good tips (pun intended) on assessing age of gray jays in the field. -----Original Message----- From: NBHC ID-FRONTIERS Frontiers of Field Identification [mailto:[email protected]] On Behalf Of Jean Iron Sent: Monday, October 30, 2006 8:44 PM To: [email protected] 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 [email protected] 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 >[email protected] Join or Leave BIRDWG01: http://listserv.arizona.edu/cgi-bin/wa?SUBED1=3Dbirdwg01 Archives: http://listserv.arizona.edu/archives/birdwg01.html
