Wednesday, April 25, 2012

Aging and sexing Piping Plovers

Below is an entry from AAfCW technician Sean Graesser, an expert on molt and appearance:

This Piping Plover female, that we built an exclosure for already, has managed to lay four eggs.  The four eggs were actually already a hint that she was on the younger side. Typically, younger birds lay four eggs in their first or second attempt at breeding.  As the birds get older, they usually lay fewer eggs. This is most likely due to the fact that through experience they have learned that it is difficult to look after that many chicks. The amount of energy expended vs. resulting fledging success does not equal out, so they adjust as they get older and wiser.

Piping Plover have a Northern Hemisphere molting strategy that I will go into more detail in future postings, but we can look at the different feathers and know what type of generations the bird is currently sporting.  When the birds arrive here, they have most recently gone through an alternate plumage molt on their wintering grounds. An alternate molt is what the birds go through to get ready for breeding because this brings them into the breeding plumage. For birds to attract mates, they usually have to have intricate and glamorous patterns to entice the opposite sex. For Piping Plovers this means that they need to molt body plumage in the crown, nape, and breast.

We can examine these features in the photos provided and I will note some things I look at to come to my determination of the age of this female plover. First, let’s take a look at the crown. Females usually show a shorter and less thick forehead band than males. In second-year females, we usually see a short, thin band with a mix of white worn juvenile feathers. Here we see this female has a pretty thick band, but also a few white feathers in it, leading me to believe that she has had PA1 and PA2 (prealternate) molt and came back with a DPA (definitive prealternate) molt, but still has a few feathers left over from one of the other PA molts. When we see her next year, she will have no worn feathers, just a complete black forehead, making her very difficult to tell apart from males until she is lying on a nest.

Next, let’s look at the breast. On younger females the band on the breast doesn’t meet, but has a gap. This female’s band almost meets, but is not quite there yet especially when she moves as you can see there are white feathers making a minute gap.  Now taking all of these criteria together I would age her as a third year bird meaning that she is in her third calendar year. When we use the term calendar year it means when it turns to January 1st the bird goes to the next age class. So a bird born in June we classify as a HY (hatch year) and a soon as January 1st comes its becomes a SY (second year) bird. In conclusion, you need a to look at a multitude of variables to try to sex and age these tricky birds. I will be putting together a more in depth explanation of how to sex and age Piping Plovers in the future.

Audubon Alliance for Coastal Waterbirds, Audubon Connecticut and the Connecticut Audubon Society partnering to improve conditions for coastal waterbirds in Connecticut.

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