Date: 11/20/20 7:35 am
From: Scott Weidensaul <000001343b2dd726-dmarc-request...>
Subject: Lehigh Co.. snowy owl -- postmortem report

As many of you know, a snowy owl that had been reported in Bethlehem earlier this month was picked up Nov. 12 while non-responsive and died before it could reach a rehabber. Thanks to help from Matt Loyko and coordination by Ted Nichols, we were able to quickly get the carcass to Dr. Erica Miller at the University of Pennsylvania’s School of Veterinary Medicine. Erica is also a senior research investigator on the new Wildlife Futures program, a cooperative venture between the PGC and Penn to understand and address wildlife health threats, and is part of the wildlife vet team at Project SNOWstorm to study snowy owl health.

Because there was a lot of discussion in the Lehigh Valley birding community about the owl’s condition and what might have caused its death, I wanted to share the results of the necropsy and initial lab tests that Erica and her colleagues performed.

The owl was a juvenile male, and extremely emaciated. There was some speculation it may have ingested poison, and while toxicology results did find trace amounts of rodenticide (which is the case these days with almost any raptor, I’m afraid), there was no evidence, such as internal bleeding, to suggest that rodenticides killed it. The bird did have a significant lesion on the brain that could have resulted from trauma like a collision, and an enlarged gall bladder. Erica and her team hope to learn more from the histopathology (tissue) and additional toxicology testing still to be done.

While the tracking work that we’ve done since 2013 through Project SNOWstorm has attracted the most attention, the other major aspect of our work has been this kind of investigation into the health of wild snowy owls. Our vet team, which besides Erica includes Dr. Cindy Driscoll of MD DNR, Dr. Sherrill Davison of Penn and Dr. Ellen Bronson of the Maryland Zoo, has necropsied more than 250 snowy owls and run lab work on blood and tissues from many other live birds caught for banding and tagging. It is by far the largest and most ambitious study of the health landscape for snowy owls in the world.

If you’re interested, you can follow our work at

Scott Weidensaul
Milton, NH (formerly Schuylkill Co.)
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