3 November 2018 – Dark-eyed Junco

This particular junco seemed big to me, with fascinating white wingbars and an apparent extra white tail. These characters strongly make me suspect that this is one of the White-winged race of Dark-eyed Junco from the Black Hills of South Dakota.

 

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28 November 2017 – two Dark-eyed Juncos

Both on the west side; one north and one south. Both evidently adult males, too.  I left both in place for a removal trial.

5 November 2016 – Fox Sparrow and Dark-eyed Junco

I did not get a chance to check the Noble Research Center until 4:00 pm today but when I did there was a sad surprise at the northeastern alcove. It looks for all the world like these two were traveling together, although I certainly cannot establish that to be the case:

AHY-F Dark-eyed Junco, fat = 0.

AHY-U Fox Sparrow, fat = 1.

This is just the second Fox Sparrow I’ve found on this project.

2 March 2011 – 1 stunned junco

I found a Dark-eyed Junco near a west alcove entryway this morning.  The bird was sitting tight and fluffed up, but not panting and showed no signs of blood.  It allowed capture by hand, but did squirm a call a few times.   Upon release in the junipers near Cordell Hall, the bird flew straight to a branch and perched steadily.  I think this one might make it, so I will not count it as a casualty.

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.

1 December 2010 – bonus Ag Hall casualty

Found this Dark-eyed Junco outside the northwest corner window of Ag Hall this morning. That window has produced multiple juncos, cedar waxwings, Swainson’s trush, and an orange-crowned warbler. It’s a good example of how a single window on a building without a large amount of plate glass can be problematic. I concentrate my efforts on the big, glassy Noble Research Center, but I doubt if Ag Hall is all that much behind in the “dead bird” race.

Bonus Ag Hall casualty – 8 November 2010

I noticed this poor junco yesterday morning (11/8). It’s just a few feet from this Mourning Warbler that hit the same window on May 17, and this Sharp-shinned Hawk that hit that same window on Oct. 16, 2009. So the same window has now claimed at least three individuals of three different species in a little more than a year. If you look out from the north window on the 2nd floor of Ag Hall, you can see the junco and the mummified remains of the Mourning Warbler.


See the junco? This is the perspective from which I first noticed all three birds.

Bonus casualties this week

North winds brought in lots of migrants this week, and that led to more birds coming to my attention elsewhere on campus. Ag Hall claimed an Orange-crowned Warbler this week, and there was a very fresh Dark-eyed Junco across the street at the Food and Agricultural Products Center.

2 November 2010 – Field and Grasshopper sparrows

NOTE: I did check on Nov. 1, but neglected to make an entry: no casualties.

I heard several flight calls while walking home from a basketball game around 9:45 last night, so I thought there might be a bird or two around the NRC this morning. There was.

First, I flushed a Grasshopper Sparrow from the hedges on the north side. Eventually, I herded this bird away from the building but he bumped into windows several times while trying to get his bearings. There was also a plump male Dark-eyed Junco similarly trapped by the building this morning, and I tried to herd him away as well. Time will tell if I was successful.

Another Grasshopper Sparrow was not so lucky. I found that bird in good condition but for some ant damage on the face, so I imagine that it came in some time yesterday. Either I missed it on yesterday’s search or it came in during the day. I left the sparrow in place to get some more scavenging rate data.

The second victim was this Field Sparrow, the first of this species I’ve found in window collision monitoring:
(AHY, Fat = 1)

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