Rich, I have been spending a fair amount of time on the western part of the West Unit of the Pawnee Grasslands this summer tracking the activities of loggerhead shrikes. I have seen virtually no Swainson's Hawks. I recorded a whopping 1 on each of two 150-mile loops in the last month. Grasshopper expert Tim McNary, formerly of USDA-APHIS and now an affiliate of the Gillette Museum at Colorado State recently went out to Crow Valley and came home with only a dozen or so specimens of hoppers of, I think, four species! Tim can usually find that many before he gets out of the car! Normally the most commonly impaled object of shrikes are grasshoppers (particularly two species, Xanthippus corallipes and Arphia conspersa). This summer, I've maybe seen a total of 10 grasshoppers impaled. I've seen 5X that many hoppers impaled in one shrike territory in years past. Very few big hoppers this year on the northern prairie. The shrikes have compensated by terrorizing herps and various crickets.
I have heard the hopper population in southeastern CO is just the opposite, at least at present in terms of nymphs. Clouds of them when you walk thru a pasture. Maybe there are also good hopper populations in the meadows of the Wet Mountains. All the moisture is growing green hopper food, i.e. plants. Maybe what you saw is a regional relocation of hawks in response to food abundance, sort of like what we're seeing with dickcissels. Maybe many of the hawks that normally populate the northern plains never made it up here, or maybe had second thoughts once they got here and drifted back south, who knows? I do know I had that big number of 160+ Swainson's hawks on my Lamar BBS route which was bizarre in my experience. I received comments that these were probably mostly young, non-breeding birds that just come north to loaf and feed for their first independent summer before returning south. Maybe the majority of what you saw was this age group. My bet would be the majority of buteos were Swainson's, and that they were also somewhat staging for their later departure south. Interesting, whatever it was. Thanks for your post. Dave Leatherman Fort Collins ________________________________ From: millerrichj via Colorado Birds <[email protected]> Sent: Sunday, July 30, 2017 12:00 AM To: [email protected] Subject: [cobirds] Hawks Galore in Wetmore (Custer) This morning in the fields north of Wetmore I counted over 100 buteos in an area of maybe 50 acres. Most were perched on fence posts, a few were on the ground. None were flying. They were mixed buteo species. I identified Red-tailed, Swainson's and a Harrier. It was private property and most were too far away to identify as species, however, they appeared to be mostly buteos. I don't remember ever seeing anything like this before It was almost surreal. Why would so many hawks converge on one area in late July? Rich Miller Canon City -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. To post to this group, send email to [email protected]<mailto:[email protected]>. To view this discussion on the web visit https://groups.google.com/d/msgid/cobirds/154697.77ba384a.46aecff5%40aol.com<https://groups.google.com/d/msgid/cobirds/154697.77ba384a.46aecff5%40aol.com?utm_medium=email&utm_source=footer>. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/cobirds/SN1PR0601MB16158700AF58DA591CFDD00CC1BD0%40SN1PR0601MB1615.namprd06.prod.outlook.com. For more options, visit https://groups.google.com/d/optout.
