5 November 2018 – a pile of feathers and fruits

In a corner of the main north entrance to the Noble Research Center, I encountered this mystery today:

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And I’m all like:

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So let’s get to work on this.

First, this wasn’t here on Nov. 3 (Saturday), I did not check yesterday (Sunday), and when I found it today (Monday, the 5th) it had already been scavenged. I count examples like these as scavenging/removal on day 0.

Okay, so there’s a feather pile and a fruit pile. The fruit pile is on top of the feathers. The fruits show no signs of digestion, other than some of them having been opened and the pits are exposed. There is a single large pit inside a small fruit that is round and black with a highly glossy finish.

After much reading, comparing, consulting, etc., I’m pretty well convinced that these are chokecherries, Prunus virginiana.

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Paul Wray photo, Iowa State University

My guess? I think our bird gorged itself on chokecherries before undertaking a migratory flight that, sadly, ended at a stupid window. The scavenger burst the bulging crop of this poor bird but had no interest in the fruits (in turn, feeding my opinion on the scavenger). So the remnants of this event are a pile of feathers and a pile of chokecherries.

Ah yes – the scavenger!

Well, we know that on campus we have skunks, foxes, opossums, raccoons, and feral cats as the most likely scavengers. The most likely of those to turn up its nose at a pile of chokecherries? I’d say cat. A cat scavenger would also be pretty well supported by the clean shearing of the flight feathers from the wings, visible here:

So what’s the bird? Well it’s clearly a meadowlark, but whether Eastern or Western takes some additional work. As with the fruits, I’ve spent a lot of time reading, consulting, and comparing. Perhaps the best resource for this task was a blog post from Kevin McGowan ca. 2000. (I also couldn’t get the USFWS Feather Atlas to load.)

Everyone knows that Western Meadowlark shows a yellow malar and in Eastern Meadowlark this is whitish. Without the bird’s head this character was of no use to me, however. In fact, there were just three feathers in the pile showing any yellow at all. Two other character differences are more relevant. First, both species have white outer tail feathers, but on Eastern the outer two are fully white and the third is mostly white. On Western the white is less extensive and even the outermost feather isn’t always fully white. In addition, Western looks paler overall than does Eastern, with the pattern on its tail and in the folded wings over the back appearing lighter brown/gray with blackish stripes. On Eastern, those same areas are darker brown with thicker blackish stripes often joined at the center of the feather creating a fern-like shape instead of distinct stripes. What do you think of these?

I’m leaning toward Western Meadowlark as the original owner of these feathers.

So I’m reporting today a pile of feathers that I think was Western Meadowlark, scavenged by a mammal I think was a cat, and that the cat showed no interest in what I think was a pile of chokecherries in what I think was the crop of the meadowlark.

Challenges, thoughts, etc? I welcome any and all!

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19 October 2018 – Lincoln’s Sparrow, plus another Lincoln’s Sparrow

I found two Lincoln’s Sparrow victims today, both in somewhat odd places. At the Noble Research Center, one met its end at the door leading out to the eastern courtyard. This might be only the 2nd or 3rd victim in the courtyard since 2009.

I also occasionally check for window collision victims at the Food and Agricultural Products Center just to the west across the parking lot and Monroe St. This morning there was a Lincoln’s Sparrow in a tiny alcove where I’ve found birds in the past. This one I noticed by looking to my right as I drove down the street this morning.

15 October 2018 – Clay-colored Sparrow

I found a Clay-colored Sparrow in the northwestern corner entrance to the NRC this morning, following the first big front of fall with frost near Woodward. I left the bird in place and it was scavenged by the next morning.

 

17 September 2018 – Ruby-throated Hummingbird

There was an immature male Ruby-throated Hummingbird in the southeastern alcove this morning.

30 August 2018 – Mourning Warbler

The wave of Mourning Warbler migration continues and the casualties mount. Here is an adult male from the southwestern alcove cut down in his prime with fat = 3 and trauma evident on the tip of the upper mandible.

30 July 2018 – Ruby-throated Hummingbird

There was a Ruby-throated Hummingbird in the southwest alcove today.

A sad bonus was this Blue Grosbeak at the Food and Agricultural Products Center.

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9 July 2018 – Mourning Dove remains, and another note on scavenging and removal

I found a pre-scavenged Mourning Dove at the main north entrance today. This is another great example of the difference between scavenging and removal.

The carcass was scavenged even before I found it. The whole point of working to determine scavenging rate is a matter of detectability, i.e., that our raw counts will always underestimate mortality because some carcasses are scavenged before they can be found. But scavenging isn’t the issue per se, removal is. If the carcass is scavenged but not completely removed, then it is still detectable. Therefore, the act of scavenging was irrelevant to my ability to detect the carcass, and thus the event.

We can do some field trials with known specimens and determine that our observers detect, for example, 95% of the carcasses in their search area. We can also do removal trials by setting out specimens and determining what proportion of them are removed in a set period of time. For example, let’s say 25%.

If we do some window-collision monitoring and find 10 dead birds at a building, we can modify our estimate according to our imperfect detection rate: 10.00/0.95 = 10.53. That’s the detection-adjusted estimate of mortality. The removal rate of 0.25 suggests that another 2.5 carcasses were removed before they could be detected (or at least before 95% of them could be detected). Removal rate bias then bumps our estimate from the raw count of 10 to an adjusted count of 12.5. Factoring in the detection rate on that estimate increases our adjusted mortality to 13.16 from the raw count of 10 carcasses we actually found.

This matters naught if our objective is to highlight the total number of casualties. It’s is not the case that public outcry to help solve the problem of window collision mortality with be louder for 13.16 casualties than it is for 10. For comparisons among studies, however, it is important to have this information presented and standardized. If, for example, two sites are compared according to their respective landscaping or lighting influence on mortality, that analysis would be corrupted if there was an unaccounted stark difference in removal rate between the two sites. So it is important to quantify rates of detection and removal in monitoring so that our efforts can be of greatest use.

In this long-term monitoring project, I have approached removal rate differently. I leave some carcasses in place to determine for how long they are detectable. Some are removed before I ever find them; some are immediately scavenged but not removed so I can detect them for weeks after the event. Some are never removed and their feathers and bones can still be detected months afterwards. On average, carcasses in my my study last about 10 days on the ground, and I conduct my surveys every 1–2 days. This means that, on average, I have 5–10 opportunities to detect a carcass before it is removed.

That’s pretty good.

 

5 July 2018 – Painted Bunting

The robin from July 3rd has not yet been touched. New today was this AHY-female Painted Bunting in the southwest alcove. She showed 0 fat and a drying brood patch.

3 July 2018 – American Robin

Although American Robin is one of the most commonly reported window strike victims, this is only the second time I’ve had one at the Noble Research Center. I found this fledgling/local bird in the northwest alcove.

20 May 2018 – two little green birds

Though they might have come in yesterday (when I didn’t check), there were two birds in the southwestern alcove today: a Tennessee Warbler (AHY-U, fat = 2) and a Painted Bunting (SY-U <probably female>, fat = 2).

 

There was also a bonus at the Food and Ag Products Center: a window-killed Yellow-billed Cuckoo and a trapped Black-and-white Warbler. The warbler flew off fine as I approached.

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28 September 2017 – Our first Savannah Sparrow, a trapped yellowthroat, and some bonus birds

Since Monday night, we seem to have received at least 5 inches of rain here in Stillwater.  That’s great as I’ve been lamenting the lack of even clouds for a few weeks. The system that brought the rain might have kept birds bottled up to our north because once it cleared last night (Wed.) there was one heck of a flight.

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Of course, attempts to correlate window collision mortality with big radar echoes of migrating birds are fraught with confirmation bias.  There are plenty of big flights that result in no dead birds on my rounds, and I’m a lot more likely to check “last night’s radar” on a morning when I find multiple casualties.  Today was one of those days.

I walked to the Noble Research Center on a route that took me past the long row of windows on the southern side of the Food and Agricultural Products Building, aka, FAPC. This is just across a parking lot from the NRC and I’ve made several incidental finds there.  Today, these “bonus birds” numbered three: an Ovenbird, a Common Yellowthroat (collected) and, around the corner, a female Indigo Bunting that had been there for at least a few days. So before I even made it to the NRC, I encountered 3 window-killed birds.

The yellowthroat was an apparent AHY-male, with fat = 2 and weighing in at 12 g.

 

At the NRC was another surprise.  Surprisingly, after all these years and considering how common these birds are as migrants and wintering residents, I found the project’s first Savannah Sparrow, in the northwest alcove.

 

 

There was also a trapped Common Yellowthroat at the main north entrance and another Savannah sparrow flitting around – through not trapped – just west of the southern portico entrance. The Savannah Sparrow was AHY-U, weighing 18g with a fat score = 2.

19 August 2017 – Painted Bunting

I actually discovered it on my 8/20 survey, but this poor little bird on the 20th was already seething with maggots so I’m comfortable calling it an 8/19 casualty. This was a second year male.  Check out the feather wear on his primaries.  He was headed south to molt and then continue on further south.

7 August 2017 – Ruby-throated Hummingbird

Well that didn’t take long.  Here’s a HY male Ruby-throated Hummingbird I found this morning at the main north entrance.

On an even more sombre note, this was unofficially the 300th casualty on this project.

Spring/Summer 2017 was busy

As I’m about to head out for a conference this week, spring and summer monitoring comes to a close.  I’ll begin August 2017 the 9th consecutive year of (mostly) daily monitoring for window casualties at the Noble Research Center on the campus of Oklahoma State University in Stillwater, Oklahoma, USA.

It’s been a busy spring.

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Beginning Mar 1st, here’s what has turned up at the Noble Research Center.

Dead Birds

  1. Indigo Bunting – 5
  2. Painted Bunting – 5
  3. Ruby-throated Hummingbird – 3
  4. Lincoln’s Sparrow – 2
  5. Mourning Dove – 2
  6. Nashville Warbler – 2
  7. Orange-crowned Warbler – 2
  8. Baltimore Oriole – 1
  9. Chipping Sparrow – 1
  10. Eastern Meadowlark – 1
  11. House Wren – 1
  12. Northern Parula – 1
  13. Tennessee Warbler – 1
  14. Yellow-billed Cuckoo – 1

That’s 28 individuals of 14 species, and damn, that is disheartening.

On the plus side, my commitment to checking almost every day has put me in position to save a few birds by getting them safely away from the building and taking them someplace secure to rest and recuperate for a bit. I can’t guarantee that all 6 of these survived the ordeal, but they seemed to be in good shape when I last saw them:

  1. Northern Cardinal
  2. Common Yellowthroat
  3. Mourning Dove
  4. Song Sparrow
  5. Yellow Warbler
  6. Carolina Wren

 

 

13 June 2017 – Painted Bunting

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.