Wednesday, June 8, 2016

THE ANGELIC AND DEVILISH PIED-BILLED GREBE

Pied-billed Grebes, Podilymbus podiceps, breed at several lakes within the city of Seattle and doubtless within many other cities in the Pacific Northwest. One of our breeding sites is Magnuson Park, where one or two pairs of grebes began to breed just last year at the Shore Lagoon, the pond closest to Lake Washington. The male started calling early this spring.



And in mid May I saw the adults taking care of 5 downy young. They are very striking, with their striped heads and reddish markings. The young grebes have a strong predilection for riding on the back of the female, and I saw this numerous times. Four young at once would try to crowd onto her back, a logistical impossibility, but I saw her holding three on a few occasions. As they got larger, of course, this behavior became less likely. But it was very cute to see, a picture of parental care in a bird that can't be beat.



For several years this pond, the result of a wetland mitigation, had no fish in it. Last year the grebes fed their young primarily large dragonfly larvae, and these common insects were apparently sufficient food for the family. By this summer, Oriental weatherfish, Misgurnus anguillicaudatus, an introduced member of the loach family, had found their way into the pond somehow, perhaps through a drain into Lake Washington. So they have been the hot items on the diet this summer.


The young laze around until an adult comes up with a fish, then immediately crowd in. At first the loaches were too large, and I saw the female attempt to offer them to one young after another with no success. They swallow their food whole, so this wasn't doing it, and I assume there must have been smaller food items fed to the young when I wasn't watching. There were originally five young, but two weeks later I could see only four, so a predator may have taken one. A young bird that fledges may have moved from one narrow escape to another.


However, these grebes, especially the male, dominated the pond. He would call often and loud, sounding like a challenge to me. One day I saw something I wish I had been able to photograph. Two Mallard ducklings were following their mother across the pond, when one of them disappeared. I wondered if someone had introduced a large bass or snapping turtle into the pond, when a few seconds later the male grebe surfaced right at that spot. I didn't see the duckling again, and 10 minutes later I found it floating dead on the surface, with wounds on its head.

In additional visits, I saw the grebe chase both ducklings and adults ducks numerous times, and one of my friends saw the grebe kill two ducklings in a row. The literature about Pied-billed Grebes makes it clear that they are fiercely territorial against each other and other water birds, and a case of a Pied-billed killing the chicks of a Least Grebe was reported. The male that I watched regularly was astonishingly aggressive, chasing every bird that it came near, and I started calling it the Devil Grebe. Of course it was just exercising normal behavior for the species, and it's not the only water bird that has been reported to kill the chicks of other species. Nature is something else.



Dennis Paulson

3 comments:

Unknown said...

Great capture and blog! I initially noticed that huge fish (the mother?) has caught for the family. So since none of the chicks could manage what became of the fish? Was it spared becoming a family meal?!


-Kyle

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