Tuesday 17 February 2015

Purple Sandpipers.... Can we age them?!

Not that I have much experience with it, but it seems to me that aging many species of small shorebird as adult (AHY/ASY) or 1st winter/basic (HY/SY) in the winter months is relatively straightforward. The trick more or less relies on focusing in on the wing coverts - do they have crisp white fringing or not?

But it doesn't seem so easy when looking at Purple Sandpipers (PUSA).

There are a few things to focus on when attempting to age a bird - but they don't seem to be very reliable or easy to apply. I've reviewed my album of PUSAs over and over again in an attempt to sort out how to age them - and come to slightly different conclusions every time. This post will share what I think are examples of 1st winters and adults - correct me if you think I got something wrong!

Here's what to focus on when attempting to age a wintering PUSA as a 1st winter:

- 1st winters (immatures) retain their juvenile pale-fringed wing coverts, this creates a contrast between the dull scapulars and 'crisp' coverts
- 1st winters have tertials that are more strongly fringed in white
- 1st winters have neatly arranged wing coverts (this can be a somewhat subjective remark to make)
- I've also heard that there is more extensive orange on the base of the bill of juveniles, but my books don't mention this

To demonstrate, check out this obvious 1st winter PUSA:
There is an obvious contrast between the wing coverts and scapulars, lots of orange at the base of the bill, the tertials have a broad outer border of white, and the coverts seem neatly arranged.

With these tips as a basis, lets try to put them to practice - starting with the easy ones ;)

Don't miss the quiz photo at the bottom of this post!


The following 12 photos are all 1st winters (immatures). 

Note the relatively dark bill here compared to the other immatures in this set:

Note the limited white border to the visible tertial here:


Now onto the suspected adults. Of all the PUSAs I have photographed only these 4-5 met my criteria. Why is there such a low proportion of adults over-wintering in Newfoundland? Where do the adults go?

Note that although there is a contrast between the covert and scapular feathers, it isn't as pronounced as on the immatures above. And, the pale fringe around the coverts is much more diffuse - in other words, it isn't very "crisp".
Compared to all the immatures above, this one has a darker bill than all but one.
The most prominent tertial has a surprisingly thick white border.
The coverts are disorganized.

Similar findings here. The scapulars seem unusually pale, but the paleness is quite diffuse (not very well defined).
Note: very limited orange to bill, diffuse pale edges to the coverts, and the two inner most tertials have dull outer edges.

Hard to get much detail on this distant bird - but it seems to be the most obvious adult of the lot: 


I'm going to leave this last one as a QUIZ!
Tell me what you think, from top to bottom: are these first non-breeding, or adult non-breeding birds?
Comment below or email me with your thoughts.

Photo taken Jan 2