Wednesday, January 4, 2012

Compare-A-Sharpie

In addition to exciting birding, the new year has also ushered in a time for possible confusion. That is because birds are aged on a calendar system, so a hatch year bird on December 31st is now a second year bird on January 1st. We are comparing three different ages of Sharp-shinned Hawks (SSHA) in this post, but all three birds just passed their "birthday" and became a different age along with the new year. To reduce confusion I will try to break down how these birds are aged and how that relates to plumage differences before I get into the rest of the post.

From hatching until December 31st of that calendar year, these SSHA are considered hatch year (HY). The subsequent year they are considered second year (SY), and so on. Simple enough. But, these birds don't molt on December 31st and January 1st, so the different plumage types don't correlate exactly with their calendar age.  These birds generally molt in the fall; therefore, a SY SSHA early in the year (before molt) looks different than a SY SSHA late in the year (after molt). Also, SSHA that are past their 3rd calendar year don't show enough unique characteristics to age any farther than third year (TY) in December or after third year (ATY) in January. So, even if a SSHA is in its 5th calendar year, it would still be called an ATY.

So, to avoid confusion I will call our three Sharp-shinned Hawks juvenile, sub-adult, and adult. The juvenile hatched in 2011 and was a HY in December but a SY now, the sub-adult hatched in 2010 and just became an third year (TY) bird, and the adult hatched in 2009 or earlier and is now considered an after third year (ATY).
 
Now we will compare our two new SSHA to the one from last month in the post Birds in Hand: A Couple of Recent Favorites.
This is how we weigh birds. There is no harm done by putting the bird in a can or cup. [Photo by Luke Musher]
Here is a juvenile male Sharp-shinned Hawk. Note the yellow iris and thick, brown streaking (running the length of
 the body) as these are characteristic of juvenile SSHA. [Photo by Luke Musher]
Another look at the juvenile male Sharp-shinned Hawk. [Photo by Luke Musher]
This is the sub-adult male Sharp-shinned Hawk that we posted about last month. Note the orange iris characteristic of
 sub-adult male SSHA and the rufous barring (running across the body vs. along the length of the body) characteristic 
of older (sub-adult and adult) Sharp-shinned Hawks. [Photo by Cory Ritter]
A closer look at the sub-adult SSHA (SY last week, ASY today). Again, note the orange iris and rufous barring. [Photo
 by Cory Ritter]
This is a third male Sharp-shinned Hawk that was caught last Saturday. This SSHA is an adult based on the deep red 
iris. Therefore, this bird hatched in 2009 or earlier. So, these three Sharpies hatched in three different years. The top 
bird hatched in 2011, the middle in 2010, and this one in 2009 or earlier. Note how the rufous barring is pretty much
 the same as the middle bird, but the iris is a deeper red. [Photo by Cory Ritter]
We have caught some other pretty sweet birds lately. Below are some photos of some recent captures:
AHY Male Anna's Hummingbird. We feed hummingbirds sugar water, the same that goes into hummingbird feeders, to 
ensure they don't run low on energy during processing. This is a photo of Frenchie feeding this Anna's Hummingbird
 some sugar water. [Photo by Dan Lipp]
Here is another look at the AHY male Anna's Hummingbird. [Photo by Dan Lipp]
Cory measuring the wing-chord of a Bewick's Wren. [Photo by Dan Lipp]
Bewick's Wren posing for the camera. [Photo by Dan Lipp]
Posing, once more. [Photo by Dan Lipp]
This is Red-breasted Sapsucker was caught on New Year's Eve, and was a SY bird (now, in 2012, a third year [TY]
 bird). This photo shows the primary coverts that are uniform in wear and abraded--a trait of SY/ASY Red-breasted
 Sapsuckers. [Photo by Cory Ritter]
This photo shows more evidence of this being a SY/TY bird. There is a block of retained feathers, which are duller
 black and more worn, in the secondaries. Secondaries 1-4 are retained and 5-9 are replaced--this was the same on
 both wings.  HY/SY birds will show all secondaries of the same generation (no contrast) and ASY/ATY birds will show
a mixture of retained and replaced feathers that are neither in a block nor symmetrical on both wings. [Photo by Cory
 Ritter]
SY/TY Red-breasted Sapsucker [Photo by Cory Ritter]
So, we hope we haven't confused you by this post. There are lots of ages being thrown around in this post, and if anything doesn't make sense, please ask us and we can explain it further. Thanks!

By Cory Ritter and Luke Musher

No comments:

Post a Comment

Post a Comment