Thursday 14 August 2014

Greater Yellowlegs & Ring-billed Gulls

Could there be a less enticing blog post title? Two of the most common species that I too am guilty of brushing over 99% of the time.

But today on a drizzly day those were the two species I focused on.

There were 2 Greater Yellowlegs at the West end of Virginia Lake. One was a juvenile, the other an adult - both were actively catching small fish.

First up is the juv:

And the adult:

If you focus on the wing feathers you'll notice that the adult has a lot less white around the edges and at the tip of those wing feathers (i.e. the scapulars and wing coverts) in comparison to the juvenile. This is what gives the juvenile a more crisp and scaly appearance.

The adult also has a more messy breast band:

The juvenile has a more neat breast band - an effect brought about by the fact that the individual dots are more sharply defined:

A closer look at the scapulars and wing coverts of the adult:
Note that there is a mix of fresh gray and old dark feathers. The fresh ones are a light gray, have a dark streak along their centre, and have white around the outer border. Whereas the old scapular feathers are a dark brown almost approaching black, and the old wing covert feathers are brown and look tattered. This mix of worn and fresh feathers is typical of adult Greater Yellowlegs at this time of year.

At the west end of Quidi Vidi there was a handful of Ring-billed Gulls hanging around (as usual).
All the adult Ring-billed Gulls had very limited to no white at the tip of their black primary feathers. Adult Ring-billed Gulls in high-breeding plumage have prominent white tips to these feathers. But by this time of year the white has mostly worn away.

Here's a closer look at the same bird:

This open wing shot of another adult shows that it only has the outer 5 primary feathers remaining. The inner 5 primary feathers of most gulls are usually lost while the adults are incubating the eggs. They then interrupt their molt and wait until after the chicks are independent to resume their pre-basic molt. So it should be shedding these feathers soon.

A closer look. The two outer primaries have what are called white windows. The one on p10 is larger. Some adult Ring-billed Gulls don't have a window on p9.

Here's a juvenile Ring-billed Gull. Very fresh looking!

And the open wing:

There's a lot of secrets hidden within the feathers of birds. Their molt patterns often reflect their behaviour through the seasons.

Male Northern Pintails are now in eclipse plumage: