Monday, July 18, 2011

Black Oystercatchers, Some Closer Nest Views

We have been keeping track of the development of the Black Oystercatcher nest and used a different camera, lens and tripod set-up this weekend. These shots were all taken with a Nikon D7000 with a 500mm f/4 lens, a 1.7 teleconverter and a sturdy tripod. These were shot at 1/1000 @ f8, ISO ~ 500. We have done some cropping and sharpening of the images.

The weather was warm and sunny and the nest sitting was a quiet affair most of the time. We did capture an exchange of nest sitters as the mates loudly announced their need for a change and to get some exercise.

During the exchange of nest sitting.

 Checking to see if the eggs are OK.

 Time for a welcome stretch.
Getting settled again.

Tuesday, July 12, 2011

Black Oystercatchers Nesting; Another Day, Another Adventure

Today we checked back again and found a visiting Swiss family right at the base of the Oystercatcher nesting rock. We waited patiently for the three young boys to climb all over the neighboring rocks but fortunately they didn't disturb the nesting. The male and female didn't call attention to themselves by changing nesting duties or doing any of their typical loud calling.

We got a nice sequence from a slightly different angle and today we were able to see the eggs more clearly. We start with one of the nesting pair on the nest which was adandoned for a short time. The mate apparently didn't respond so the original nest "sitter" went back "on duty" until the family moved  on. This first shot is just before the eggs were exposed.

 The eggs were unattended only briefly.

The "sitter" went to the top of the nearby rock and called only once - got no reply and resumed the nesting duty. Nice Pose at the top of the rock.

Getting settled back onto the eggs - very carefully - this time for about 40 minutes.

Finally the mate arrives. The family were standing near me and I briefed them on the exchange of nesting duties that was about the happen.

And not to be disappointed, the nesting pair exchanged positions.

Finally we left with another nice pose. We will check often to see how thy are doing. By our count, the hatching could take almost two more weeks. We read that gestation can be from 24 to 28 days. We make this about day 10 so far.

Sunday, July 10, 2011

Black Oystercatchers Nesting Along the Monterey Shore

Every day when we are out walking along the Monterey Bay shore, it is likely that we will see Black Oystercatchers - or rather we can hear them coming and going first and then locate them blending into the dark colored sea grass covered rocks. Once you get accustomed to their call, it is quite unmistakable. A few days ago, a friend observed some nest building activity - a collection of pebbles and other "found objects" which may be used to disguise the eggs. Knowing the location, and finding the sun burning through the typical marine layer, we cautiously approached the nest site.

We immediately saw one of the Black Oystercatchers perched on the rocks where they often spend the afternoon soaking up the sun. Even the arrival of the second one wasn't unusual as they are often seen in pairs. The second Oystercatcher was out of this shot on the rocks above.

We saw the second Oystercatcher approaching from the right. The birds were communicating somehow but not with their usual high-pitched chatter.

We were then treated to the sharing of the nesting duties, as both the male and female take turns brooding of the eggs. We watched and photographed the pair as they exchanged positions. While this took place, we observed three eggs and some of their found object "nesting material".

The nesting exchange took place as shown in the following sequence of shots. I would guess that the eggs were exposed for less than 10 seconds. The Nikon D7000 with the effective 600mm lens captured the scene at about 6 frames per second. Some of these shots have been moderately cropped and sharpened.

With this shot, the exchange is complete and the second bird is carrying on the nesting duties.

During another exchange later in the afternoon, we were fortunate to get this shot of both the male and female birds and the exposed eggs. There is certainly some communication going on here - maybe it is one telling the other to get on the eggs fast. You can see that the eggs are quite exposed and there are always predators lurking along the ocean.

This second egg nesting exchange was also quickly accomplished.

And finally, we left the pair with one gone off in the search for food while the other struck one final nice pose. We will return often to see how the nesting is going. We read that the mortality rate of Black Oystercatcher chicks is very high. We certainly hope that some of this brood will make it.

We often find that the Washington State Audubon Society has some of the better information to be found on the web. The information here about the Black Oystercatcher is the best summary information we have found after looking at several books and many web sites. There is good nesting habitat information that describes the gestation period and how the parents bring the young food for several weeks after hatching.

Wikipedia also has excellent information on the Black Oystercatcher here.

We also found that California eBird held a Black Oystercatcher survey just a month ago. We missed it unfortunately but we have our own observations that help complete the local history for us. California eBird information can be found here.

We also would like to add our own clarifications about the Black Oystercatchers we see here in the Monterey Bay area. We frequently read that these birds are black - as you see here and in many other shots we have taken, particularly those in good sunlight, these birds have a black head but the main body color is dark brown.

With luck, we will be able to watch this nesting pair for weeks to come. Stay tuned.

Wednesday, July 6, 2011

Heermann's Gulls Return to Monterey Bay

Don Roberson in his excellent book "Monterey Birds" tells us that Heermann's Gulls do not breed in this area but migrate about 850 miles south to a small island (Isla Rasa) in Baja California each year and begin arriving back in this area in mid-June. Arriving gulls continue until there are thousands present from mid-July through November. Heermann's Gulls are strictly coastal and are rarely seen inland or more than a few miles offshore.

Our local expert, Brian Weed comments that I missed one of the local remarkable facts about Heermann's Gulls which I excerpt directly from Don Roberson's book. "Three pairs of Heermann's Gulls nested on two tiny man-made islets in Roberts Lake, Seaside, CA, beginning in 1999. Eight young were fledged in July 1999 and another eight in July 2000, but nesting failed in summer 2001. This tiny colony is the only one in the United States, and the 1999 fledglings represented the first successful nesting ever recorded of Heermann's Gull north of Mexico."

I also found a YouTube video of Isla Rasa that describes that it is the breeding ground for Elegant Terns and Heermann's Gulls. The video gives a nice perspective on the two breeding colonies Here.

Wikipedia always has excellent information on the local birds and we again read that there are very few Heermann's Gulls that "winter-over" on the Monterey Peninsula. Although we checked this location a week ago and didn't see any Heermann's Gulls - there were many to be seen today. You can find more complete information on the Heermann's Gull on Wikipedia Here.

This individual looks like he might have just completed his "trek" from Isla Rasa off Baja California in the Gulf of Mexico. It is certainly nice to see them returning but they usually look far more healthy than this individual. They will keep us company along the Monterey Bay shore from now through November. We saw perhaps a dozen or more birds from our fixed location today, many were in the kelp beds offshore and we did see a few more on their usual perches on the coastal rocks.

This is the same individual on one of the nearby rocks. We expect the population to "fill out" in the days ahead as this "ruffled" appearance isn't typical. We usually see them far more healthy looking.

The shot below isn't particularly good but it does show a group of Heermann's Gulls in the kelp beds maybe a half mile offshore. Today, we were using the Nikon D7000 with a 300mm f4 lens and a new Nikon 2x teleconverter. This is one of the the first times we have used this combination and haven't been disappointed with this configuration. It focuses well (in good light like today) although Nikon reports that they do not recommend this configuration. This shot is cropped and sharpened moderately.

We were also treated to this pair of Western Gulls that were chattering along the Rec. Trail rocks. We see the Western Gull throughout the winter and they are reported to breed at over 45 different sites along the Big Sur coast from Carmel Bay South. The Western Gull is strictly limited to coastal saltwater, moving inland only a few miles along the tidal Elkhorn Slough. Don Roberson tells us on page 230 of his book that Western Gulls are also scarce beyond 30 miles offshore.

It is nice to have our Heermann's friends return and now we can look forward to seeing them throughout the summer until they head south once again for Baja California in November.