22 June 1999

68 Active Pairs This Season

I have just spent a week on the Island visiting the nest poles and it looks like a good year for Ospreys on the Vineyard in 1999. We have 64 breeding pairs and four housekeepers (young birds that are not quite ready to breed, but do build, or begin to build, nests). (Click here for a nest-by-nest summary of the active poles.)

Even though our highest pole number is 113, we began the year with 110 poles. One nest was taken down and not replaced, one (on Poucha Pond on Chappy) was actually a tree nest site (the only time that we know of Vineyard Ospreys trying to nest in a tree since the Mink Meadows pair moved from a dead pine to one of our poles) and one (the old Deep Bottom nest) seems to have disappeared as the surrounding forest has grown up around it.

The population seems to be almost identical to last year, when we had 65 breeding pairs and 4 "housekeepers."

Changes

There were 10 pairs where we had a change of status this year. Two breeding pairs from last year (the Getsinger’s birds on Chappy and the Trapp Pond nest) were housekeepers this year, and the Ames’ nest on the north shore was inactive after the male was electrocuted on a power transformer early in the breeding season last year. We don’t know what happened to the Getsinger’s birds—perhaps one or both died over the winter—but we did find a dead adult below the nest at Trapp Pond, so that pair presumably has at least one sub-adult bird in it this year. In fact, this may be the same pair that has been housekeeping on the neighboring pole #97 in Cow Bay this spring.

None of last year’s four housekeeping pairs returned to the same poles this year, but a new pair is nesting on Swan Neck at the Kohlberg’s, and a pair is once again housekeeping at the Stephen’s nest overlooking Katama Bay on Chappy.

Young in the Nests

Most pairs have hatched their young and several pairs have young that are getting really big—Mink Meadows (always an early nesting pair) and Ernie Bock’s pole in Edgartown being the oldest young that I saw this week. Several pairs seemed to have gotten a late start—perhaps young birds, or pairs whose nests blew down over the winter and had to rebuild in the spring. The females of the Cressy’s and Self’s pairs on Chappy are still lying low in their nests, suggesting that they are still on eggs or very small young.

We’ve already had one spectacularly unfortunate failure. One of the nest poles at Scrubby Neck was hit by lightning early in the month. This was an active nest before a bolt of lightning blew the pole into smithereens! Bree McDonald showed me what was left of the pole—a stump about three feet high and a bunch of splinters about four feet long and three inches in diameter. (After seeing that, you won’t catch me out in a thunderstorm!)

Despite this dramatic failure, the fishing seems to have been good so far this season. I was able to count heads in 24 nests, and Mike Syslo just emailed me his count from the Lobster Hatchery pair (3 young). In these 25 nests we saw 59 youngsters! Eleven pairs had three young, with the average young per nest being a healthy 2.36. At many nests I saw the adult male lazing around in the afternoon—a sure sign that the family had already had enough food for the day. Throughout the early and mid 90s, Gus Ben David reports that the adult males (and often the females) were so hard pressed to catch enough fish that they were rarely seen around the nest except to feed the young and would often hunt into the early evening in the last light of dusk.

Get Your Binoculars and Scopes Out!

By the time you all receive this update, the young should be pretty easy to see. For the late nests, watch the nest closely at feeding time. For the nests with more advanced young, the chicks should be moving around quite a bit, so if you watch the nests in the morning you should be able to count the young. Make sure you watch for a while, as often when there are three young, they won’t all have their heads up at the same time. Be patient and you’ll often see a third head pop up. In a couple of weeks most of the young will be big enough that they’ll be easy to see without missing any.

The most important information we want is the number of young that fledge, or fly out of the nest. This should happen in July. Some of the nests with large young now will probably take their first flights in early July, while some of the late bloomers may not take their first flight until early August.

I’ll send a data form, which I hope will make it easy for you (or y’all, as we’d say down here in North Carolina) to anyone who hasn't received one yet [click here to send me an email requesting one]. On it you can summarize what happened at your nests this year. I’m getting it to everyone late in the season, so you may only be able to fill in a few week’s worth of data, but remember that the most important numbers are the fledging count. If any of you happened to have taken notes, or can otherwise reconstruct what happened at your nests early in the season, please fill in what you can.

More details.

For the internet surfers amongst us, you can see the full list of occupied nests and how many young I was able to count in each nest at my website: http://www.bioweb.uncc.edu/bierregaard.

Help needed:

There are still a couple of nests where I need someone to check from time to time. Any volunteers?

Thanks for you help, and have a great summer,

Rob Bierregaard