[IBLE] rarity, behavior and hopefully assistance

I spent the morning near the west end of American Falls Reservoir hoping
for the wide array of shorebirds, gulls, terns and waterfowl that many
birders have been enjoying recently. Unfortunately, I struck out on birds
like semipalmated plover and sandpiper, western sandpiper and black tern.
But that was more then made up for by sightings of 2 jaegers!

The first bird was seen while I was in the silo area, but it was further
east. I am hoping others get to see the bird, because I believe it was a
Pomarine. I have never had a good look at a pom before but I have been
able to get studying looks at parasitics. From the bat, this bird appeared
bigger and bulkier than a parasitic jaeger and the ring-billed gulls it was
chasing. I was surprised because it seemed to effortlessly close the gap
in the distance between it and the birds it was chasing, and each time the
gull would “put on the brakes” and swoop upward, but the jaeger was not
fooled and stayed w/ the bird. But, it would soon thereafter give up and
move on to other gulls to chase. It was a light phase adult.
Unfortunately, I could not see it well enough to confirm the twisted
central tail feathers, or other more fine-tuned field marks. I also see
that there are only 3 records in eBird for pomarine jaeger. Unless,
someone gets a better shot at it, it will remain in the category of “I bet
that was a pomarine.”

The second bird was a definite dark parasitic and I found it from the
Willow Bay pier. The differences in flight style and shape were immediately
noticeable. Also in contrast, it engaged gulls in long, twisting, turning,
tail chases. There may actually have been 2 dark parasitics because I
found birds in different telescope scans in far different locations, but I
know these birds can cover a lot of ground fast.

I hope the birds stay around long enough so others can see them.

Steven F. Kahl
Deputy Project Leader
Southeast Idaho National Wildlife Refuge Complex
4425 Burley Dr., Ste. A
Chubbuck, ID 83202
C (208) 252-0805
P (208) 237-6615 ext 112
F (208) 237-8213

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