Today was my first 2024 survey of the western Pawnee National Grasslands to monitor shrike impaling.
Imagine you are a shrike in the late 1800s having to impale your prey on stiff plant stubs, yucca fronds and in the branch crotches of trees. Suddenly the whole world comes your direction with the invention of barbed wire. You now have options, trillions of them. But everything is subject to change and today was a good example. Apparently, the summer rains of 2023 combined with the ferocious winds of last week packed Russian thistle stems (aka “tumbleweed”) against hundreds of miles of fence such that the wire is mostly unusable for shrike impaling. A manager at the Central Plains Experimental Range told me besides fences being packed to the breaking point, they estimate 9 miles of fenced pasture with at least one of the four strands (usually the top one) pulled from posts and in need of repair.
Most loggerhead shrikes are migratory. When I was in the Lamar area last week they were mostly back on territory. Over the years I have come to recognize the plant and animal phenology of the southeastern plains is about 7-10 days different from the northeastern plains. Spring springs earlier in the southeast. Fall falls earlier in the northeast. Male shrikes usually arrive in habitat suitable for nesting before the females. One of the major reason newly-arrived males impale in to attract mates. What I saw today makes me wonder how the shrikes will cope. Will they move (far away if necessary) to areas without tumbleweed-packed fences? Will they revert to “old school” methodology? Will they wait a while to nest in the hopes wind unpacks the fences the same way it packed them?
I remember the late Dr. Paul Opler discovering during Breeding Bird Atlas 1 that a subset of Red-winged Blackbirds on the Pawnee nest in tumbleweed-packed fence habitat. They should do well this year.
All the above said, I did find about 17 objects on barbed wire today (I would have expected 100 or more given the date). These included usual items like redshank and Arphia grasshoppers, black field crickets (Gryllus sp.) and a couple lesser earless lizards. Notable were an unrecognizable rodent, the back half of a vole (Microtus sp.), and (drumroll) the first bumble bee I’ve ever seen impaled (probably Bombus huntii).
The Pawnee is very dry. While shrikes were the mission, I did find good numbers of both Thick-billed and Chestnut-collared Longspurs, a few Vesper Sparrows, no Grasshopper or Cassin’s Sparrows, no raptors except for two kestrels and one Northern Harrier.
Dave Leatherman
Fort Collins
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