Long-tailed? Jaeger

We’ve been scouring the lake lately for jaegers – those wonderful winged pirates – given all the reports coming from the inland southwest.  We were rewarded a few days ago with a flyby Parasitic that hasn’t shown itself since.  What we have seen a few times is a faraway dark jaeger in flight, disappearing into the haze over California waters.  Today, arriving at my favorite lighthouse on Pittsburgh Point, I spotted a jaeger almost immediately – quite possibly that dark-looking bird that has been so distant before.  It stayed on the water a long time and I was able to digiscope some very bad photos of it.

I initially identified the bird as a Long-tailed based on proportions and shape.  This photo shows the shape best.

It looks evenly proportioned – no shrunken head look – and overall slender and delicate.  The apparent size of the bill varies among all the photos.  In the field, it looked very slim.  After noting the shape and making a tentative ID, the bird swiveled in the water and I was able to see the striking black-and-white barred undertail coverts (not shown well in this photo).  Soon after, it dunked its head underwater, slightly spreading its wings and exposing its full spread tail.  The central rects were very conspicuous, much longer than the surrounding feathers.  They looked full and rounded, quite a contrast with the quick view I had of the recent Parasitic Jaeger.  (Juvenile Parasitic Jaegers have central rects slightly longer than the others, and distinctly pointed – a feature that was easy to see even at a distance on the recent Havasu bird.)  The combination of the pattern on the undertail coverts and the shape of the central rects led me to conclude that this bird was a Long-tailed Jaeger.

These photos show how much the apparent bill size changes from photo to photo!  What is more clear is the pattern of the undertail coverts – barred black and white.  The bird faced away from me many times and I was able to note that this pattern passed across the entire undertail, unbroken.

The apparent color of the bird changes dramatically in the photos depending on the settings I was using, as well as the cloud cover, which varied during my stay there.  In flight, the bird looked very much like this – dark overall.  Even in this photo, where the bird looks much darker than it looked in the field, the black-and-white undertail coverts are visible (though it doesn’t show up well on the smaller blog version).

I saw the bird in flight only twice, and never well.  When it finally left the area, it spent most of its flight flying directly away from me.  As I said above, it looked rather dark overall in flight.  One thing I noticed – which had me scratching my head – was the pattern on the upper surface of the primaries.  A Long-tailed Jaeger should show only 2 primaries with white shafts, but this bird seemed to have 5 or 6.  In active flight, I could only see one or two pale primary shafts – it was when it spread its wings completely before landing, or when it lifted its wings as it sat on the water, that it seemed to have so many pale primary shafts.  This isn’t considered a good field mark, as it is subject to a lot of variables in the field that affect the apparent number of pale shafts, but it did make me scratch my head – could it be a Parasitic?

There are a few other features of this bird that don’t sit right for Long-tailed.  It looks a little brown overall (in the photos as well as in the field), and the bill looks a little big in several of the photos.  In the field, I tried to judge the percent of the bill that was black (the size of the nail), and judged it to be a little less than half.  The photos seem consistent with this.  This photo shows it best:

Despite these points, I think that the pattern of the undertail coverts, the shape of the tail, and the overall shape all point to Long-tailed Jaeger.  I would love to hear opinions from others on this confusing bird.  In the mean time, David and I will certainly be out there tomorrow trying to get better looks and better photos!

About Lauren Harter

I live in Lake Havasu City, Arizona, where I work as a field biologist and spend as much of the rest of my time as possible looking at (and listening to!) birds.
This entry was posted in Identification, Lake Havasu, LCRV, Mohave County, Vagrants. Bookmark the permalink.

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