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Thursday, October 3, 2013

Jaeger confirmed as Parasitic by measurements

Forwarded from Rick Brigham and Janet Hinshaw, via Mich-chat:


Some of you may already be aware of this, but the ill jaeger that was
initially found frequenting the beaches in Holland MI on 20 Sept, expired
on 22 Sept. It was picked up on the south side of the channel and
transferred to Janet Hinshaw at the University of Michigan Museum of
Zoology for analysis and has been added to their collection. Janet's study
of the bird confirmed it to be a Parasitic Jaeger, as most observers had
already surmised. She also concluded it to be an immature female. Janet has
forwarded the physical measurements of the bird. They are listed below for
those interested.

exposed culmen 30.0mm
nostril-tip 13.6mm
depth 10.5mm
base of bill to nail 15.6, nail 14.7mm
tarsus 45.0mm
chord 316.5mm
tail 134mm
weight 303.0g (very thin)
forearm 115mm

The last dimension is the clincher in this ID. Long-tailed Jaeger does not
achieve a greater forearm length than 102mm (Pyle 2008). Another supporting
characteristic for for Parasitic is based on the location of the gonys,
anterior to the nostril.

Hope this brings closure to this story for some folks.

Rick Brigham
Douglas MI