Monday 31 July 2017

Re: [cobirds] Hawks Galore in Wetmore (Custer)

Rich (and Dave),

I too have witnessed what would seem to be the same phenomenon maybe 3-4 years ago. I was driving in the same general area near Wetmore (possibly Waterbarrel Road, possibly Siloam Road, I just don't remember) when I noticed (audibly at first) that the road was literally covered in large green insects. There were so many it was impossible to dodge them. I found a place to pull off and inspect what I was unintentionally slaughtering. They looked much like this (though this is a picture from a different time and place):

IMG_8418.jpeg

I then noticed that there were Swainson's Hawks perched everywhere around me, in trees, on fence posts, utility poles, ground, etc. I'd been so focus and repulsed at all the bugs I was crushing that I hadn't noticed the birds before. And as I drove further, I noticed more hawks lining the road; I probably saw more than 200 total. Eventually I passed out of this slaughterhouse, and as the insects dried up (pun intended), so did the hawks. There may have been some Red-tails in the mix, but at least 90% were Swainson's. I'm certain they were feasting on these insects, and I would guess they were in just this area specifically for the purpose of feasting on these insects. My entomology skills are zilch, but perhaps Dave can identify this guy. 

Cool phenomenon, though the crunchy drive was actually quite disturbing.

-- 
Cheers,
Dan Maynard
Denver, CO

On Sun, Jul 30, 2017 at 8:32 AM, DAVID A LEATHERMAN <daleatherman@msn.com> wrote:

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 <cobirds@googlegroups.com>
Sent: Sunday, July 30, 2017 12:00 AM
To: cobirds@googlegroups.com
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

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