24 September 2019 – Ruby-throated Hummingbird and Nashville Warbler; plus bonus birds

Birds on the move captured on Nexrad radar tell an important story on the evening of Sep. 23 to the morning of Sep. 24. First, watch migration blow up after local sunrise in the eastern US, and progress to the west.

As the night wore on, storms began to flare up in Oklahoma. Here in Stillwater those storms hit between 1:30 and 2:00 am on Sep. 24. As the storms expand, migration stalls: Birds put down to avoid the storms and for people on the ground, that’s a fallout.

Was there evidence of this fallout on the ground?

Well, there was a bonus Canada Warbler in that troublesome northeastern alcove of the Food and Agricultural Products Center. (This was in addition to a Mourning Warbler and a Wilson’s Warbler I found there on Sep. 21.)

There was a big flight of Nashville Warbler in Stillwater, too. Twelve were reported from Couch Park. I found one in the southwestern alcove and a Ruby-throated Hummingbird in the northeastern alcove.

 

18 October 2018 – Lincoln’s Sparrow, Hermit Thrush, and Nashville Warbler

Tough week here on campus as the casualties pile up.

Today, the northeast alcove had a Lincoln’s Sparrow and the project’s first Hermit Thrush. This now make casualties confirmed for 65 species at the Noble Research Center. The main north entrance claimed a Nashville Warbler, too.

 

Sex was undetermined for all three, but the Nashville Warbler was probably a female. The thrush and warbler looked to be after hatch year, while the sparrow was a hatch year bird. Thrush and sparrow had some fat lain down (I marked each a “one”), but I couldn’t find any fat on the warbler.

Nashville Warbler: 8.0 g

Lincoln’s Sparrow: 15.5 g

Hermit Thrush: 27.0 g

 

 

 

5 October 2018 – Two Nashville Warblers and a Clay-colored Sparrow

It was a bit foggy overnight so perhaps that contributed to the casualties I found today: An AHY male Nashville Warbler in the southwestern alcove (fat = 3) and a Clay-colored Sparrow in the south portico (fat = 2).

The one bright spot was the second Nashville Warbler. It was stunned but alive. On my approach it perked up and flew off strongly.

Screen Shot 2018-10-06 at 2.58.13 PM

 

31 July 2018: end of season wrap-up

Well, here we go. Today marks the end of my 9th year conducting spring/summer monitoring for window-killed birds at the Noble Research Center. Tomorrow I begin year 10. Ten years of near daily monitoring of window-killed birds. Here’s a quick 9-year wrap-up:

  • 40: average minimum casualties annually
  • 360: total casualties (minimum)
  • 64: species confirmed as fatalities
  • 10: average number of days for birds to be removed/scavenged

 

Top ten (eleven) species most commonly encountered as casualties at this site:

  • Lincoln’s Sparrow (45)
  • Ruby-throated Hummingbird (29)
  • Painted Bunting (24)
  • Indigo Bunting (20)    *tie*    Grasshopper Sparrow (20)
  • Mourning Dove (17)
  • Clay-colored Sparrow (16)
  • Nashville Warbler (14)
  • Common Yellowthroat (11)    *tie*   Mourning Warbler (11)  *tie*  Song Sparrow (11)

 

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7–18 October 2017 – all kinds of stuff

I’ve been behind with stacks of papers to grade, and they’ve kept me from keeping up as often as I’d prefer. During the period from October 7–18, I conducted 8 surveys, skipping Oct. 8, 14, and 15. The data from these last 11 days look a bit like this:

  • Oct. 7: HOWR
  • Oct. 9: no casualties
  • Oct. 10: no casualties
  • Oct. 11: LISP
  • Oct. 12: TUTI
  • Oct. 13: no casualties
  • Oct. 16: OCWA, SOSP, LISP, and NAWA
  • Oct. 17: no casualties
  • Oct. 18: no casualties

Just past mid-October, and we are crushing the annual mortality count right now with 55 dead birds.

Oct. 7 – I found just the third House Wren on the project.  This one ended up on a warm air outflow grate from the air conditioning unit and was quickly desiccated.

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Oct. 11 – I collected this Lincoln’s Sparrow from the south portico.

Oct. 12 – This Tufted Titmouse was a surprise in the southwestern alcove.

Oct. 16 – This was not a good day for migrants. I found an Orange-crowned Warbler at the northeast alcove, a Song Sparrow at the south portico, and a Lincoln’s Sparrow at the southwestern alcove. Shortly after completing my survey, a Nashville Warbler was turned in from a collision in the southwestern alcove.

 

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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

 

 

10 May 2017 – Painted Bunting and Nashville Warbler

Today I found a SY Painted Bunting at the main north entrance and a Nashville Warbler at the northwestern alcove.

 

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19 April 2017 – Nashville Warbler

This one was twofold odd – the bird was found in an odd spot and I’ve clearly overlooked it for a few days given the state of decomposition.  The beetles, slugs, etc. were all over it.

 

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9 October 2016 – Nashville Warbler

The current gap of collisions I’ve enjoyed over the past week or so was interrupted this morning by a beautiful male Nashville Warbler in the northeast alcove.  He was an AHY bird with a fat score = 2 on my 3-point scale. This is the 11th Nashville Warbler I’ve found on the project.

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19 September 2016 – Nashville Warbler

That southwestern alcove continues to get a workout this fall, but again, the unfortunate victim was found in front of untreated glass panes.

Today it was a hatch-year (HY) Nashville Warbler; sex undetermined with fat score = 2.

 

When I found the bird in position on the cement as indicated in the above photo, it had already been heavily scavenged by ants. I moved the carcass to a location on the grass on the north side of this southwestern alcove (see photo, top right) to set up a removal trial.

21 August 2012 – Nashville Warbler and Ruby-throated Hummingbird

I found a very fresh Nashville Warbler (HY female; fat = 2) at the north entrance and a Ruby-throated Hummingbird (HY male) just a few feet from the Painted Bunting carcass.   The ants had gotten to the hummingbird, so I decided to leave it in place to see how long it lasts.  Here is the warbler:


Here’s the spatial distribution of casualties thusfar:

2 October 2011 – Nashville Warbler and Lincoln’s Sparrow

Today I found a Nashville Warbler (AHY-U, fat = 2) and a Lincoln’s Sparrow (AHY-U, fat = 1) in one of the west alcoves.  I left the warbler in situ as its beak had broken off and it wouldn’t be as useful as a specimen.  Interestingly, the bird was molting, with several pinfeathers along the sides of its breast.  I collected three outer rects and left the rest of the bird there to see how long it lasts before being scavenged.  The sparrow was in great shape, for a dead bird.

 

Six-month summary: July–December 2010

Here is just a quick summary of casualties at the Noble Research Center from July through December 2010:


Very fat Mourning Warbler that never made it to the wintering grounds.

I detected 25 individuals of at least 16 species among the casualties. The complete list:

grasshopper sparrow – 4
ruby-throated hummingbird – 2
mourning warbler – 2
song sparrow – 2
Lincoln’s sparrow – 2
unidentified passerine (1 warbler, 1 sparrow) – 2
black-and-white warbler – 1
Carolina wren – 1
mourning dove (juv) – 1
least flycatcher – 1
common yellowthroat – 1
black-throated green warbler – 1
brown thrasher – 1
house wren – 1
red-breasted nuthatch – 1
white-throated sparrow – 1
field sparrow – 1

Because I was able to get to the NRC earlier each day during autumn than practical in 2009, I encountered more individuals that were stunned and “trapped” by the building for some time period without obvious mortal injury. Most of these birds are presumed to have eventually moved on, but it is quite likely that the house wren and one of the Lincoln’s sparrows on the “stunned” list were unsuccessful in their respective bids to escape from the confusion of the NRC, and are listed above. The bat represents the first mammalian “capture” by the NRC:

Lincoln’s sparrow – 5 (4 in one flock)
house wren – 1
common yellowthroat – 1
Nashville warbler – 1
grasshopper sparrow – 1
dark-eyed junco – 1


It’s dark when migrants like this Lincoln’s sparrow drop out of the sky and try to find a good spot in which to rest for the day. I’m beginning to think that most collisions are occurring in that last hour before sunrise.

A Year in the Death – Aug. 2009–Aug. 2010

On August 20th, I completed a full year of regular surveys for window-killed birds at the Noble Research Center. Here are some vital statistics for August 20 2009–August 20 2010:

Effort.
I conducted (occasionally with help from assistants like Danielle Benson) 153 surveys over the full year of monitoring. This equates to an average of 2.39 days between surveys.

Coverage was irregular throughout the year. For example I did no monitoring in January 2010. For this reason, analysis of casualties by season must be viewed through the lens of dissimilarities in sampling effort among the seasons. I defined sampling effort as the number of surveys per days in a given season. I defined seasons as follows: Dec. 1–Mar. 20 (110 days) = “winter,” Mar. 21–May 20 (61 d) = “spring,” May 21–Aug. 19 (91 d) = “summer,” and Aug. 20–Nov. 30 (102 d) = “autumn.” The 11 winter surveys provided an effort of 0.10. This approximates 10 days on average between surveys. Effort indices were 0.87 for spring (53 surveys in 61 days), 0.44 for summer, and 0.48 for autumn. Thus effort was most consistent during spring with near daily surveys.

Data.
I recorded window strike mortality for 38 individuals of 22 different species over the year of monitoring. This rate of collision mortality places the NRC on par with other high-mortality buildings referenced in Klem 1990 and O’Connell 2001.

Of the 38 casualties, 5 were “local” (i.e., recently-fledged offspring of local breeders), 5 were “hatch year” birds (i.e., “immature”, or birds < 1 yr. old), and 28 were adults or of undetermined age.

Of the the 38 casualties, 8 were identifiable as male, 5 as female, and 25 were of undetermined sex.

I encountered more casualties during spring and fall migration periods than in winter or summer (though effort may have played a role in this result):

As in O’Connell 2001, Neotropical migrants in passage comprised the greatest percentage of individuals among all casualties. The birds dying at the NRC are not local residents that commonly occur in the OSU campus. These are transient individuals traveling long distances that just happen to meet their end here. (Note that the number of resident individuals among the casualties is inflated by the fact that 5 of the 7 casualties were recently fledged mourning doves and northern cardinals.)

Non-lethal collisions.
On at least four occasions, I encountered live birds that appeared to be trapped near a window but were not injured from a collision. These individuals are not included in the collision data, but they may have been had I not been there to flush them away from the windows and encourage them to move along:
9/22/09: Grasshopper Sparrow and suspected Swainson’s Thrush
10/19/09: Grasshopper Sparrow
11/2/09: Two Dark-eyed Juncos
6/21/10: Carolina Wren

Scavenging rate.
The scavenging rate proved to be unpredictable over the year. For example, some carcasses left in place remained visible for several weeks and were untouched during that time. Others were identifiable only from feathers left behind of a carcass that, based on the timing of my most recent survey, had been scavenged just a few hours after the bird’s unfortunate collision. Further confounding the interpretation of scavenging rates, some carcasses were scavenged but readily identifiable feathers of the carcass were left behind and still in evidence long after scavenging. For example, the Yellow-billed Cuckoo that I found on 6 June 2010 was scavenged on 15 June. As of 3 September 2010, that bird’s primaries are still readily apparent at the location where I first found it on June 10th, approximately 86 days after the bird’s death.


Scavenged Swainson’s Thrush.

I found evidence of 15 scavenged carcasses over the year. Thus, out of 38 total casualties, 39% were ultimately scavenged. (Of course, I collected the majority of the carcasses I found, most of which were fresh and in excellent condition and were photographed for entries in this blog. Presumably, a high percentage of these would ultimately have been scavenged.) Two carcasses were scavenged on day 0 and three were scavenged after just one day in situ. Four were in evidence for at least 30 days; the average number of days a carcass was apparent in place was 18.6 – nearly 8 times the length of time between consecutive surveys. Thus, the regular, frequent surveys provided ample opportunity to discover carcasses before they were removed or no longer visible. In addition, the most frequent condition of freshly scavenged carcasses of warbler-sized birds was a pile of remiges cleanly sheared off near the base of the feathers. Thus, even small birds were usually left in place after scavenging; this increased the probability that I would find the carcass even if it had been scavenged. Nonetheless, it is likely that at least some individuals were scavenged and removed from the site before I could document the casualty, so mortality rates calculated from my surveys must be viewed as underestimates of actual mortality.

Total data.
The following table lists all the species found as window collision casualties at the Noble Research Center, 8/20 2009–8/20 2010:

species number
Common Yellowthroat 5
Mourning Dove 5
Lincoln’s Sparrow 4
Black-and-White Warbler 3
Grasshopper Sparrow 3
Painted Bunting 2
Mourning Warbler 1
Gray Catbird 1
Wilson’s Warbler 1
Canada Warbler 1
Indigo Bunting 1
Orange-crowned Warbler 1
Song Sparrow 1
Nashville Warbler 1
Dark-eyed Junco 1
Sprague’s Pipit 1
Swainson’s Thrush 1
Orchard Oriole 1
Northern Cardinal 1
Yellow-billed Cuckoo 1
Ruby-throated Hummingbird 1
Carolina Wren 1

O’Connell2001

22 November 2009 – 1 Nashville Warbler

Found a late (unfortunately, too late) Nashville Warbler today.

Photo by Bob Mulvihill, Powdermill Nature Reserve

According to the “Date Guide to the Occurrences of Birds in Oklahoma” (5th edition, 2009), we expect that most Nashville Warblers have left the state by 25 October, so this bird is several weeks behind schedule. It’s destination for winter:

This bird was not in fresh condition like so many of the birds I find. It was still feathered, but its eyes had sunken and the flesh had dried out some. Its condition was exacerbated by the fact that its feathers were badly matted from being soaked in a recent rain. It hasn’t rained for at least 24 hours here in Stillwater, so this bird might have come through several days ago. (I found it in a section that is difficult for me to access on a routine survey, so I might have overlooked it earlier this week.) So the “late date” for this bird is very likely not Nov. 22, but it’s probably no earlier than about Nov. 17.