Date: 11/7/17 5:04 am
From: Tim Helentjaris <tnhelentjaris...>
Subject: [AZNMbirds] When did Gray Hawks move into the Sky Islands, RFI?
Got this inquiry from Ariana LaPorte the other day, wondering what we know about when GRAY HAWKS began to move up into the Sky Islands in addition to nesting in lower riparian habitats. She has been studying Gray Hawk nesting success, contrasting between that of lower habitats, especially along the San Pedro, with that up in the foothills. Here is the gist of her inquiry:

"I am trying to pinpoint when gray hawks first settled in the Sky Islands, hopefully to write a paper about the potential environmental changes that facilitated their expansion into higher elevations. I'm looking for someone who has reliable, consistent observations from one (or several) of the canyons that go back to the 80s or 90s. I'm pretty sure they started settling there around 2000, but in order to be sure, I need written records from before they showed up and after, ideally made by the same person in some systematic way."

I think we have good IBA survey documentation from the 2000’s of them nesting higher up, especially in the Patagonia Mts and the eBird records start to improve around then as well. What she really needs are comparative, and negative, observations from earlier periods to document when this change happened. If you can help out, please respond to her at: ariana.laporte AT gmail.com<http://gmail.com>, probably off-line for more extensive comments so as not to clog up this site. I’m sure she’ll appreciate it.

I will just add in one comment from my own perspective. Have been involved in a lot of YELLOW-BILLED CUCKOO surveys the last few years with Jennie MacFarland, IBA and Tucson Audubon, focusing upon higher elevations in Forest Service lands in the Sky Islands. Much like Gray Hawks, cuckoos are now often found nesting higher up in the foothills as well and I don’t believe that was true to the same degree twenty years ago? Seems like our southwestern variety prefers many of the same habitat considerations as Gray hawks, we have often noted them nesting close together, i.e. within earshot of each other. To my mind, Gray Hawks are one of our best “bio-markers” for finding cuckoos, and I wonder if it doesn’t go beyond simple habitat preferences, noting that the presence of Cooper’s Hawks in these same habitats seems as just as powerful an “exclusionary” factor in nature. Wonder if cuckoo’s are preferring to nest around Gray Hawks as they might “exclude” the presence of the more predatory Cooper’s? Any way, just an idea I throw out there for you to think about and look for, the next time you are out in the summer.

Tim Helentjaris
Tucson, AZ

“We have an unknown distance yet to run, an unknown river to explore.”
- John Wesley Powell



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