I had 7 Bohemian Waxwings this morning at the UI Arboretum w/ about 70 Cedar Waxwings (total 150 for my morning walk). This is about the earliest I've had them in Moscow although I'm sure it's not unprecedented. I had a flock of ~300 Cedar Waxwings on campus Thursday (10/29) and was looking carefully for them then but no luck. There have been reports of Bohemians in southern British Columbia and w/ the unsettled and at times cold October weather I figured there was a good chance we'd get some early ones here. Also this morning among 26 species were 2 Cooper's Hawks, 1 Sharp-shinned Hawk, Belted Kingfisher and Great Blue Heron (both present Thursday), flock of 5 Townsend's Solitaires (always nice!), ~10 Black-capped Chickadees, a Ruby-crowned Kinglet, and others.
I haven't had much of a chance to put together a report but have covered the UI arboretum complex 6 times now in the past 2 weeks and birding has continued to be quite good (20+ species on all visits and a good diversity overall). Seems like I usually curtail my fall migration birding here after mid October but this is clearly a mistake! I'll try to post a summary in the next few days but here are a few items of interest.
On Tuesday (10/27) I had an immature
Northern Goshawk flying south through/over the arb. (this is a good time for migrating Goshawks). The Goshawk initially gave the impression of a Sharpie until it got closer and I realized it was much too large to be a Sharpie. "Hawks in Flight" (Dunne et al.) notes that Goshawk and Sharp-shinned Hawk have very similar wing and tail proportions and this is useful (among other things) in separating immature Goshawks and Cooper's Hawk in the field. (According to Dunne et al. "If Sharp-shinned Hawks were the size of Cooper's Hawks, distinguishing between them and Goshawks would border on the impossible". It also notes that high flying Goshawks at hawk watches are likely to be initially mis-identified as Sharpies - until they flap that is.)
The past couple of weeks (but not today) I've been observing a flock of ~15 or so
Yellow-rumped Warblers - I presume mostly the same birds - frequenting the same general part of the arb. It turns out there are a couple of "
Myrtle Warblers" in this group but my post a couple weeks ago was wrong (sort of) in pointing to pale throats as a key feature in separating Myrtles from Audubon's. In actuality basic (fall plumage) Audubon's can have fairly pale throats (most probably 1st fall females). However, with basic plumage Myrtle Warblers the white throat extends in thin arcs under the auriculars (cheek area) and this along w/ several other features makes the face pattern fairly distinctive from Audubon's. This is pointed out well in the big Sibley and in more detail in Dunn and Garret's "Peterson Field Guide to Warblers". Fortunately I was able to study the guides at home and then study this flock further on successive visits. It also turns out after some study there were a good number of adult (after hatch year) male Audubon's Warblers in the group as evidence by the gray streaking on their backs. It may well be that there were both male and female 1st year (hatch year in banding lingo) and adult (after hatch year) Audubon's in this group. According to Dunn and Garret the dullest pale throated birds likely are 1st year (hy) females and the brightest, distinctly marked, yellow-throated birds are adult (ahy) males with the others hard to separate (this is typical of many passerines and often only these 2 plumages are depicted in the major field guides). BTW this may be of more than just academic interest as there is recent research on this species complex that may result in Myrtle and Audubon's Warblers being un-lumped (Dunn and Garret seem to be of the opinion that the split was incorrect and indeed if you look at these 2 they are quite different in appearance although their similarities certainly point to a common ancestor species, and yes they do hybridize in a narrow zone in British Columbia.)
It's always nice to go out and learn new things in your own backyard and to have cooperative birds stay around to be studied on successive visits! More later (hopefully) on my recent UI Arboretum birding - time to go do some raking!
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Charles Swift
Moscow, ID
chaetura@gmail.com
