I went to Welchester Park yesterday to try and figure out the "stick-and-stay" of the Blue-winged Warbler found and kindly reported weeks ago by Stephanie Jones. In short, other than the area at the east end of the park and nearby private land to the east appearing to fit their habitat requirements, I can only guess what that bird is eating. As Steve and others have mentioned, despite its persistent singing, the bird is very difficult to find visually and then observe. I did not do any playing of tapes, which probably would have been good for better seeing/photographing a hormone-filled male like that, but not for observing natural behavior.
I did see it foraging more than once, presumably for lepidopteran caterpillars, in peachleaf willows. The small thicket of green ash saplings just east of the easternmost park fenceline seemed to be a favorite haunt, at least for singing. Ash could have green fruitworms, tiger swallowtail butterfly caterpillars, plant bugs, and many other insects. The Russian-olives, which are generally insect-poor except for aphids, did still have a few flowers. Steve mentioned the bird being in R-o a lot and insects attracted to the flowers may explain part of that. The chokecherries in the thick woods in the western part of its apparent territory (i.e. just west of the main area it frequents) have lots of lace bugs on the undersides of their leaves and would seem to be a good prey item. Of course, cottonwoods have lots of caterpillars and other insects, and the bird spent a fair amount of time in them.
I was particularly intrigued by a statement in the Blue-winged Warbler BNA account that mentioned "water hemlock" as being a part of at least one habitat/food habit study. There is a big patch of that, or a related Umbellaceae plant, along the sunny, open fenceline just north of the ash and Russian-olive areas it seems to really like. Lots of insects come to its flowering heads.
In short, the area has big open areas surrounded by diverse shrubs and rich forest edges. Perfect choice for a Blue-winged Warbler. Now if it could just find a mate! I guess we don't know for sure it doesn't, but the way it seems to be singing so much and moving around indicates a lack of fulfillment. I hope its fans can document the extent of its stay.
If anyone has photos showing a prey item, I'd love to see them.
And I hope this habitat continues to be monitored, even without reports of a rarity. How many such gems go virtually unsurveyed?
Dave Leatherman
Fort Collins
I did see it foraging more than once, presumably for lepidopteran caterpillars, in peachleaf willows. The small thicket of green ash saplings just east of the easternmost park fenceline seemed to be a favorite haunt, at least for singing. Ash could have green fruitworms, tiger swallowtail butterfly caterpillars, plant bugs, and many other insects. The Russian-olives, which are generally insect-poor except for aphids, did still have a few flowers. Steve mentioned the bird being in R-o a lot and insects attracted to the flowers may explain part of that. The chokecherries in the thick woods in the western part of its apparent territory (i.e. just west of the main area it frequents) have lots of lace bugs on the undersides of their leaves and would seem to be a good prey item. Of course, cottonwoods have lots of caterpillars and other insects, and the bird spent a fair amount of time in them.
I was particularly intrigued by a statement in the Blue-winged Warbler BNA account that mentioned "water hemlock" as being a part of at least one habitat/food habit study. There is a big patch of that, or a related Umbellaceae plant, along the sunny, open fenceline just north of the ash and Russian-olive areas it seems to really like. Lots of insects come to its flowering heads.
In short, the area has big open areas surrounded by diverse shrubs and rich forest edges. Perfect choice for a Blue-winged Warbler. Now if it could just find a mate! I guess we don't know for sure it doesn't, but the way it seems to be singing so much and moving around indicates a lack of fulfillment. I hope its fans can document the extent of its stay.
If anyone has photos showing a prey item, I'd love to see them.
And I hope this habitat continues to be monitored, even without reports of a rarity. How many such gems go virtually unsurveyed?
Dave Leatherman
Fort Collins
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