Tuesday, August 18, 2015 More Avian Predators on Blow Flies

Seward, Alaska

The forecast missed again; instead of “partly cloudy” it was a blue sky, summery day with temps in the mid 70s eased by a delightful south breeze.

I checked on those fascinating salmon carcasses again today at the Lagoon and was not disappointed. The Spotted Sandpipers were away, but young BLACK-BILLED MAGPIES were busy at work on a King salmon carcass, expertly picking off the juicy blow fly larvae. The iridescent blues and greens of their tail feathers and wings exploded in the sunshine; they looked like tropical birds of paradise!

At one point a few Maggies gathered on the quiet road and hunted flies. One juvie crept up to a sunning Flower Fly just a few feet away from me and managed to grab it; a pretty decent job, I thought, for a youngster. Its eyes were still a baby blue, and the feathers around the head were still emerging. Looks like they know where to find food but I hope they understand cars.

Over in the Lagoon, a GLAUCOUS-WINGED GULL ripped into the belly of another salmon carcass. At first, I thought it was just tearing off bits of salmon to eat. Then I looked closer and saw it was excavating into a blow fly larvae hideout. Once the cavity was opened, it gobbled up several at a time, gull style.

Several young NORTHWESTERN CROWS had also figured out the bonanza lurking inside the salmon carcasses.  Standing on or beside the carcasses, they plucked off and ate adult blow flies and larvae with ease.

Author and naturalist Bob Armstrong, who alerted me to blow fly predation by birds, noted that my observations of the Black-billed Magpies and Glaucous-winged Gull bring the documented total of predatory bird species to around 14. There may even be a book forthcoming about salmon and blow flies in Alaska by blow fly experts. Who knew there was such a thing?

The more you look, the more you see!

Happy Birding!
Carol Griswold
Seward Sporadic Bird Report Reporter

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