I made a trip from Fort Collins up to Larimer CR5 (just e of the Rawhide Power Plant), then headed east to check my shrike monitoring areas in the western portion of the Pawnee National Grasslands. I stopped at Crom Lake west of Pierce on the way home.
Larimer CR5 from the Buckeye Road (CR82) north to CR92 was decidedly lackluster. No shrikes, no longspurs, very few grasshoppers, one Golden Eagle.
The western Pawnee Grasslands rarely disappoints in terms of shrikes and their interesting habit of impaling prey. On this trip the fence barb display was comprised of:
31 Western Earless Lizards in various conditions from whole and alive to old shriveled pieces
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Prairie earless lizard male in bright breeding coloration, still alive and wondering what the hell just happened, why is King Kong taking my picture.
3 greater shorthorned lizards
1 prairie hognose snake (about 12 inches long, beheaded)
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Prairie (aka “Western”) Hognose Snake showing dorsal pattern at left, distinctive black underside at right. Total length was about 16 inches, indicating a young one. The shrike had a reason for killing it. I wonder how many other animals, including humans, kill them because of their rattlesnake-similar dorsal pattern?
0 many-lined skinks
3 unidentifiable pieces of birds one of which was possibly a Lark Bunting
1 bird gizzard
0 mammals
2 redshank grasshoppers (more about this later)
0 other grasshoppers
0 beetles (although one impaled pellet contained beetle exoskeleton fragments)
5 camel crickets (a few fresh, the rest fragments, the identifiable ones being Great Plains camel crickets (Daihinia brevipes))
1 black field cricket (Gryllus sp.)
1 white-lined sphinx moth caterpillar
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Shrike-impaled white-lined sphinx moth caterpillar at left. Upper red arrow points to spiracle (white oval with black rim). Lower red arrow points to caudal spine which gives most sphinx moth caterpillars their name of “hornworm”. For those who don’t believe the green blob in the left photo is really a white-lined sphinx moth caterpillar, the right photo shows an intact one for comparison. The dual white arrows at left point to spiracles, while the right one indicates the caudal spine.
I shrike nest, that had 6 eggs on 5/26, had at least 5 nestlings on 6/15 (there might be a 6th youngster in there but I didn’t want to take more than 5 seconds to snap a pic) on 6/15. Note the difference in head size between the lower left bird and the upper bird.
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I saw or heard 0 raptors, 0 sage thrashers, 0 longspurs, 0 Common Nighthawks, 1 Burrowing Owl, only 2 Brewer’s Sparrows, 1 Cassin’s Sparrow, goodly number of Lark Buntings, Western Meadowlarks and Horned Larks.
My take is that although the prairie is starting to green up a bit, small mammals are down, grasshoppers are down. Few rodents means few hawks. Few grasshoppers and beetles (especially darkling, scarab and ground) means reptiles are essentially the only prey shrikes out there have this spring-early summer.
I saw this Horned Lark making a run to its nest near the roadside. The two prey items it is beak are a male robber fly and an unidentified larva. Red arrow shows similarity between what the bird has and the abdomen tip of a live robber fly. Thus, one insectivore falls prey to another. As Kurt Vonnegut aptly put it, “And so it goes.”
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Lastly, at Crom Lake west of Piece I was surprised to see a male Hudsonian Godwit in breeding plumage. Too far away for decent photographs but I did put a few identifiable ones on my partial eBird checklist. In reading of their movements, he should have been in Alaska many weeks ago. I would love to know what shorebirds and ibis get out of Crom Lake’s mud and water but suspect the take includes midge larvae and gastropod snails in the genus Physa.
Dave Leatherman
Fort Collins
