Re: Great-tailed Grackles moving around
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Western Great-tailed Grackles usually require marsh, wetland or a pond to nest. I am sure that having put that down in a statement, I will get a ton of comments on this not being the case. So I guess I should mention, that in my experience they are usually close to water. This is different from the more widespread Great-tailed Grackle farther east in Texas etc., they do not require water. Project #12 on my taxonomic projects, ok, maybe not that far down but it is complex and scary so I am delaying, is to work up a paper that proposes to split the Great-tailed Grackle into two species. The western and eastern birds are quite different in many respects. Who knows, if the stay at home order keeps on going I may get more of these projects done! If they are looking to nest nearby, it will likely be a pond or creek. It can be quite urbanized, but usually they need some larger trees adjacent to the water, or thick aquatic vegetation. In some respects the western birds are more like a Boat-tailed Grackle than the “real” Great-tailed Grackle.
Grackles are often accused of being voracious nest predators, but it does not seem to be the case. If it was, there would be no birds in Austin, TX! Birds of the World (ex BNA) states the following “No evidence of eggshells in diet; thus similar to Common Grackle in that its reputation as a nest robber may be exaggerated.” Diet is mainly of arthropods in the breeding season, it switches to more granivorous in non-breeding, and males tend to be more granivorous than females. I don’t think we have to worry too much about grackles ruining the neighborhood. I bet jays are more adept at predating nests than grackles.
The “Western” Great-tailed Grackle’s distribution is quite a bit more restricted than the “Eastern” bird. In Mexico, the “Western” forms are restricted to the NW of the country. The rest of Mexico, and the populations that continue south to South America are more closely allied to the “Eastern” GT Grackle. Really they are not eastern and western from a global perspective, but if you look at the US, that is how it appears.
I need Great-tailed Grackle for my yard list by the way! I have seen one go by at the end of the street, but not over the house. A point of pain for me.
From: SFBirds@groups.io <SFBirds@groups.io> On Behalf Of Aaron Maizlish
Sent: Wednesday, May 13, 2020 11:08 AM
To: SFBirds <firstname.lastname@example.org>
Subject: [SFBirds] Great-tailed Grackles moving around
Twice this morning a pair of Great-tailed Grackles have flown right by my home office window while I was on a conference call. This is near Mission x Cesar Chavez in a part of the city that has little to no suitable habitat for a Grackle colony. I can’t say that I’m particularly excited to see them here. I noted that there have been a few other sightings of Grackles in the city this month, away from their only known breeding colony at Lake Merced.
So my question is what are they doing? Are they just migrating through, like everything else right now? Are they scouting new territories as they continuing their march northward? Or is this an indication of an effort to form a breeding colony effort in some industrial part of the city? Grackles are particularly hard on native songbird nests, so while their expansion in the city may be inevitable, in the short term this might not be good on the few sturdy birds that breed in our city parks and street trees. By the way, though I don’t have any yard I do have a nice view of the neighborhood parklet and the Mission district skyline. The birds that I see nesting here, within 100 yards of my window are Lesser Goldfinch, House Finch, American Robin, Anna’s Hummingbird, House Sparrow, Chestnut-backed Chickadee, Mourning Dove and Hooded Oriole.