If you're interested in using any of these photographs in any way, please contact me. Send an e-mail to naturalhistoryphotos(at)gmail.com. Thanks!

Friday, August 17, 2012


This year I volunteered to assist Audubon California with monitoring a Black Oystercatcher nest on Bodega Head.  Below is a chronological series of photos from egg to fledging (first flight).  [These pictures were taken from far away so as not to disturb the birds.]

10 June 2012
Although barely visible, one egg (mostly in shadow) is present below the tail of the lower adult.  The pair started out incubating three eggs.  The nest is a shallow scrape or bowl lined with rock flakes and shell fragments.  Average incubation period is 26-28 days (both parents incubate).

23 June 2012
One young chick is visible to the right of the uppermost adult.  It's very small, gray and downy, sitting near the shadow of the inner vertical wall. Chicks are precocial and can walk 72 hours after hatching.  The female does most of the brooding, while the male does most of the provisioning (bringing food).  I saw adults feeding the chick limpets, mussels, and a live crab.

Here's one more from 23 June 2012 when the chick was up and walking.  Although quite adept at this time, we saw it tumble and do a complete somersault.  We called the chick "Summersalt" from then on (for its acrobatics, growing up during the summer, and a salty home.)

(You may have noticed one egg in the foreground.  Unfortunately, it never hatched.)

4 July 2012
The chick is larger now, but still mostly downy gray.  It's at the lower edge of the photo directly below the adult.

23 July 2012
Most growth occurs between 14-21 days after hatching.  Now the chick is looking similar to an adult with a black head, brown back, and pink legs, but note the shorter bill with an orange base and black/gray tip.

9 August 2012
Summersalt has now fledged!  (Average time to fledging is ~38-40 days.)  Note the tawny edges to the upper feathers, producing a gold-flecked appearance.  The eye is dark (rather than orange in adults).  The bill is still orange at the base and black/gray at the tip (the tip will retain dark coloration through the second year).

On 17 August 2012, we believe we saw Summersalt and parents foraging in a mussel bed just south of the nest site.  Remarkably, parental feeding of juveniles can continue for more than 120 days.

No comments: