On August 19, 2012 I was at Lake Balmorhea
in Reeves county, west Texas. There was a loose flock of 8 - 10 Black Terns feeding over the lake, and I had already scanned them for anything more interesting - albeit from quite a distance away (some of the terns were occasionally loafing on a distant shoreline with some Forster's Terns). The terns moved closer to part of the shoreline so I drove over to that area and started to photograph the terns, hoping to get a half-decent image to use for Region 4 on the Texas Bird Images website. While looking at the birds only through my camera viewfinder I thought I saw a bird with some black on the underwing coverts; knowing the implication of this I tried to relocate it in my binoculars but everything I looked at seemed normal for Black Tern, so I presumed I'd been mistaken and continued to photograph the Black Terns. After a short while all the terns moved higher and seemed to fly away to the east, so I also left to the east, for the long drive home to San Antonio.
Today (August 22)
I started to go through the many photos I took of birds, butterflies and dragonflies (over 4 days) to weed out the rejects. As I worked my way through the tern pics from Balmorhea, I found the image below. I checked those ahead and behind it and I am sure that I have no other images of this bird; NOTE the images have been cropped but no other modification has been done to them - this is exactly how they were recorded by the camera:
The uncropped image:
The image cropped down, but at 100% (i.e. its actual size):
An enlargement of the cropped image:
A BLACK TERN from the same event, for comparison:
Back to the subject bird - enlarged much more:
The same image as above but annotated with arrows pointing to:
the apparent extent of white in the upper lesser secondary coverts.
B: the apparent extent of dark on the distal underwing coverts.
C: the apparent length of the bill.
D: the apparent isolated dark eye in the pale head.
- I am not sure what we are seeing in the rump/tail area - a lateral view?
The features A-D above are each suggestive of White-winged Tern. Below are some images of White-winged Tern found on the Internet, to provide some comparisons - if one of your images appears below and you prefer that I not use it this way, please contact me directly - thank you:
Three images that demonstrate how the upper wings of WWTE can look like the subject bird:
A series of images that show black on the underwing coverts from angles varyingly close to the angle visible in the subject image:
Leaving aside the impossible-to-resolve issue of hybrids (which may well be occurring in North America), this bird is either:
- A White-winged Tern (are there any anti-WWTE features visible in the photo? - perhaps the mantle/back is too pale for the amount of blackish still on the nape and underparts - ?? should the tail/rump area be whiter at this time of year/stage of molt - ??)
- A Black Tern that in this one image seems to show blackish on the underwing coverts, extensive white in lesser uppering coverts, and a short bill - i.e. the discernable detail in this image is unreliable.
I believe that latter option is the correct one, and that this experience provides a Cautionary Tale when dealing with poor images!