Heading into June and, as I’ve seen in previous years, there is evidence of resident birds dispersing in late spring. Here is another Carolina Chickadee, and another female with a brood patch, that apparently met her end during a bout of post-breeding dispersal.
Every day there is a casualty discovered is cause for a twinge of sadness. Some are worse than others, however, especially when our personal biases are affected. My internal monologue on noticing any dead bird is a classic Midwestern ope, but today it escalated to motherf****r! as I got close enough to see what it was lying in front of a glass entry on the northwestern corner of the Noble Research Center. Yep, it was the pinnacle of avian evolution, a Louisiana Waterthrush.
I would be remiss not to mention the unusually rainy, cool spring we’ve enjoyed here in the Southern Plains, and this week flooding has turned deadly. Here in Stillwater, we topped 7″ of rain on Tuesday, with roads and schools closed. But our saturated soils didn’t result from one super storm. Check out these 30-days totals:
In fact, we’re a solid 20″ above average for the year:
This is a pattern of rainfall that often washes out waterthrush nests, built along the banks of streams. Having returned at the end of March, it could easily be the case that our local waterthrushes have attempted to nest, and been flooded out, at least three times. Perhaps a scenario like that might explain how a second-year (check out the feather wear) female (she at least attempted nesting – check out the brood patch) Louisiana Waterthrush ends up outside its territory in unfamiliar habitat to die at a window on the 23rd/24th of May? Is this a local movement to find a new territory less prone to flooding and give it another go? Is this a bird that has given up for 2019 and was on her way to molt and prepare for southbound migration while other birds are still streaming north? These intimate details of birds’ lives provide endless fascination for me and, of course, can lead to new and interesting directions for research that can help these birds better survive their forays into human-dominated landscapes.
Besides the feather wear and brood patch, there were a couple of other interesting things about this bird. It had fat in the furcular hollow! Floods don’t keep waterthrushes from foraging well, despite their threat to nests. Still, actually accumulating fat is hormonally influenced, and it strikes me as odd for a bird to accumulate fat outside of migration. This bird also showed obvious trauma to the tip of the bill, indicating a window strike at full speed. I can’t quite tell if the mark on the right pectoralis major is a contusion from collision or the beginning of the progression of brood patch loss. Many questions . . .
It’s mid-June and, like clockwork, I found a lady songbird today who looks to have been involved in some post-breeding dispersal. This one was a Painted Bunting, an ASY-female with a brood patch at the southeastern alcove.
At this weird building that is the Noble Research Center, I don’t find many local birds dead at the glass. There are no feeders, for example. It’s also not a spot that attracts a lot of baby birds. No, here it’s pretty obvious that migrants are the source of the great majority of the 30–40 victims here each year, with big peaks in mortality during October and May. There is another, smaller peak, however.
That third peak is “June”. For some reason, after the collisions of the northbound migrants have died down by the end of May, birds start showing up again in mid-June. These include migrants as well as local breeders like chickadees and titmice. What’s more, it’s common for these individuals to be females that have recently bred, judging from their brood patches.
Apparently, I am capturing at this site evidence of post-breeding dispersal in females. It is not clear if these birds are looking for a new mate and territory or if they are dispersing to some specific place to molt. It is also not clear if this post-breeding dispersal involves successful or unsuccessful breeding attempts. With respect to today’s bird, however, I have to assume the latter.
Painted Buntings do not arrive here until the first week or so of May. With another week or so of finding a partner, territorial jostling, etc., that means they aren’t even beginning to nest until mid-May, i.e., about 4 weeks ago. It’s possible for a pair to have raised a brood in 4 weeks I suppose, but if so it would be odd for a female to skip town with fledglings fresh out of the nest. Thus, it’s more likely that she was dispersing today following a failed breeding attempt.
This morning, a dead Tufted Titmouse achieved some grim and arbitrary notoriety as the 250th window-killed bird I’ve found at the Noble Research Center since monitoring began on 20 August 2009. She’s right near the entrance to the northwest alcove, and I left her in place to see how long it takes for her to be removed.
Like so many birds I find in June, this was a female (AHY) with a brood patch. This one had a faint stripe of mulberry juice down the front of her breast and little on her beak.
Intrigued by the pattern, I queried my database for June casualties, 2009–2016. Out of 22 window-kills, at least 8 have been females with brood patches (and additional 7 might have been but the data weren’t recorded).
Thanks to Corey Riding & Co. for checking the Noble Research Center while I was away on 6/9 and 6/10.
The cuckoo and House Finch carcasses remain.
I learned on 6/15 that Chrissy Barton from Corey Riding’s team actually did find a window-killed Black-and-White Warbler on the evening of 6/11. The bird is a SY female, and I think I see a gap in the breast feathers that would point to a brood patch . . .
Today marked the first casualty of a species that is common and conspicuous on campus – a House Finch at the southwestern alcove. As seems to be the case with resident birds, June is evidently a time for post-breeding dispersal, and this bird was, like many June casualties before her, a female with a brood patch.
I left her in place for a removal trial.
As reported for May 30 2015, I had observed the beginnings of a pattern when I found the very first window-killed Tufted Titmouse on this project. That was the second titmouse I’d found on campus during the last week of May, and both were females with brood patches. In early June of this year, Corey Riding let me know that he had found a Carolina Chickadee dead at Ag Hall – that bird, too, was a female with brood patch.
Today, that emerging pattern got a bit fuzzier when I found just the second dead Tufted Titmouse at the NRC since daily monitoring began in 2009. This one was an ASY male with fat = 0 in the southwest alcove. So much for patterns, at least that one.
I left this bird in place where it lasted until Thursday, June 25.
Okay, now it’s personal.
Here in my 21st year of monitoring buildings for window-killed birds, I have finally come across a Louisiana Waterthrush. Folks who know me well will instantly recognize the special place this species holds in my life as the Pinnacle of Avian Evolution. Here’s a presentation of mine that discusses waterthrushes as the focus of indicators of watershed condition:
Here’s a basic distribution map from the National Audubon Society’s Online Guide to North American Birds:
Among the many cool attributes of these remarkable birds, Louisiana Waterthrush is one of the earliest Nearctic-Neotropical migrants to arrive on the breeding grounds in spring. I have observed these birds on breeding territories during a snow squall in Pennsylvania. They come back early, weeks before the big wave of other migrant warblers, breed early, and by the end of June become quite scarce. Presumably, they seek sheltered locations for their annual molt for several weeks in late June and July, but by mid-July, many are well on their way south for the winter. It is quite rare to see a waterthrush in fall migration, in part because they go so early but also because, unlike their close relative Northern Waterthrush, Louisianas so rarely are found outside a riparian zone. Whereas Northerns will move with other flocks of warblers and can easily be found on migration at upland sites – including your backyard – Louisianas tend to really stick to the waterways, and they go it alone. The fact that this bird ended up at an upland site, in June, is quite unusual.
Here is today’s victim, bedraggled and rain-splattered from a quick cloudburst this morning, and where she met her end:
She was an ASY (after second-year) female with a brood patch. She had no fat laid down. It’s tough to tell if she was literally on her fall migration or just wandering around in a bit of post-breeding dispersal, but there certainly isn’t anything that remotely qualifies as “waterthrush habitat” in the vicinity of the Noble Research Center. She also had not begun a pre-basic molt, which indicates that she’s probably not migrating yet.
This is the second consecutive day in which a new species was added to the study (49 now).