SY Wrentit

A second year wrentit (see molt limit in secondaries):

Wing morph

I should have done this earlier, but here is a quick look at the basic terms for the different feathers on a bird wing. All passerines have 9 or 10 primaries and most have 6 secondaries and 3 tertials (which are actually just more secondaries with a special name). In this picture of a spotted towhee wing you can see that there are 9 primaries, 6 secondaries, and two visible tertials. The median coverts, the greater coverts, the tertials, the inner most secondary, and one of the primaries have been replaced, and are much blacker and fresh looking. This pattern is very indicative of a second year bird (one that hatched last summer).

Red-shafted Northern Flicker

Today we caught a red-shafted northern flicker at palo! Very exciting for us considering the size of the bird and the slowness of the day. This bird was also a great example of how one can age woodpeckers. Unlike most of the passerines we catch, woodpeckers can often be micro-aged up to after-third-year. The reason for this is that they follow a more drawn out pattern of feather replacement than most of the birds we catch. So, by looking at different tracts of feather and determining which ones are worn and which ones are fresh, we can age the bird accurately.

This particular female was determined to be a third year bird. It hatched two summers ago and retained all of its primary coverts and secondaries (and replaced many other feathers). About a year after hatching (last summer)it then replaced the outer three primary coverts, as well as all but two of the secondaries. The contrast between the thrashed and faded retained juvenile feathers and the replaced, darker and more fresh adult feathers is very apparent in the pictures below.







Amanda processing

Wrentit molt

So, usually wrentits will replace all of their feathers during their first molt in the late summer of their hatch year, but the one we caught today seemed to have retained a few, something we rarely see.

Right wing, with one retained secondary (light brown compared to gray)


Left wing, with three retained secondaries

BT

Bushtit




Here is a good example of a molt limit in a bewick's wren wing. You can see a slight color difference between the shafts of the outer three large feathers (the primaries) and the inner ones. The outer feathers have a dark brown color to them, whereas the inner ones have a light brown color. The darker brown indicates newer feathers. When you can see two generations of feathers in a wing at this time of year, it generally means that this is a first year bird because as an adult it would have undergone a complete molt, and would not show any remaining older feathers.

Towhees

California towee, with a single white feather on its head, which shouldn't be there.


Spotted towhee


Spotted towhee wing, showing a typical HY/SY molt pattern: fresh greater and lesser coverts, and tertials (black), and retained juvenile primaries, secondaries, and primary coverts.

SY

Here's a great example of what we look for when aging birds. The rufous/brown tips of those two feathers indicate that they are immature feathers that have not yet been molted, telling us it's a second year bird.