The water continues very high at Harriman Lake and there is no shoreline to speak of.  Apparently, most of the ducks have vamoosed northward, and even though we are in the midst of shorebird migration we didn’t see a single one – not even a Killdeer.  Sticking to other waterbirds, we did manage to find a few geese, two species of grebes, a Virginia Rail, a bevy of coots, a couple of Double-crested Cormorants, and a Great Blue Heron.  

Among the landbirds we encountered it was great to see several Tree Swallows up close, and we had a Red-breasted Nuthatch.  Highlights were supplied by a single male Yellow-headed Blackbird and a nice little flock of Yellow-rumped Warblers, all of which appeared to be of the Audubon subspecies.  There are actually four subspecies of Yellow-rumps.  Two of these are non-migratory, one being resident in the northern Sierra Madre Occidental of western Mexico and the other is resident in Chiapas (Mexico’s southernmost state) and Guatemala.  Our two subspecies here in the US, and more specifically here in Colorado, are the Myrtle and Audubon’s, and both are migratory.  

For most of the last century these subspecies were regarded as being separate species, but in 1973 they were lumped together as the Yellow-rumped Warbler based on evidence of hybridization in a narrow zone in western Canada.  Myrtle Warbler is found primarily in far northern and eastern North America and is most easily distinguished by its white throat, while Audubon’s Warbler, which has a yellow throat, occurs primarily in the West, only going as far north as central British Columbia.  Young of both subspecies can have a fairly pale yellowish-tinged throat making them more difficult to differentiate, so there are a few other features to look for in distinguishing these two groups.  Overall, Audubon’s have a more uniform gray head while the Myrtle has a darker gray (almost black) auricular patch (ear-patch) and a thin white supercilium (eyebrow).  With Audubon’s the yellow (sometimes pale yellow) throat patch ends below the eye; with Myrtle the white (sometimes pale yellow) throat patch extends farther back below the auricular area.  To complicate things further there are frequent intergrades, not to mention that females and first-year birds are less brilliantly colored.

Harriman Lake Park, May 7, 2022
10 participants
33 species

Canada Goose  4
Gadwall  2
Mallard  4
Ruddy Duck  2
Pied-billed Grebe  4
Western Grebe  3
Eurasian Collared-Dove  3
Mourning Dove  2
Broad-tailed Hummingbird  1
Virginia Rail  1
American Coot  14
Double-crested Cormorant  2
Great Blue Heron  1
Turkey Vulture  1
Red-tailed Hawk  2
Northern Flicker  3
Blue Jay  2
American Crow  2
Tree Swallow  10
Red-breasted Nuthatch  2
House Wren  1
European Starling  1
American Robin  4
House Sparrow  1
House Finch  8
Song Sparrow  7
Yellow-headed Blackbird  1
Western Meadowlark  1
Red-winged Blackbird  25
Brewer’s Blackbird  1
Common Grackle  32
Orange-crowned Warbler  1
Yellow-rumped Warbler (Audubon’s)  10