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Thursday, March 25, 2010

March can be subtle...

I've been musing on early spring over the last few days and, you know, March is a devil for playing tricks on us! The first Osprey or Laughing Gull turns up (ALWAYS found by someone else of course!!!) and immediately we expect the flood gates to open. We go out (wrapped up in cold weather gear!!), all excited at the prospect of finding a whole host of summer migrants and find - nothing! For days on end!!! And that's spring for you. We know in our heart of hearts that it will be another month before birds are really a-hopping, but we fall for it every year.

So this year, I've hung back and looked for more subtle changes that are taking place, and signs of things on the move. The first thing I noticed just a few days ago was that, whilst there are still plenty of White-throated Sparrows around Cape May Point, the ratio of adults to first-winters has changed dramatically. I've still got 15 or so White-throated Sparrows coming to my feeder at home and there's a similar number at the CMBO store feeders, but amongst those 30 birds there's just three adults. Mid-winter, zebra-headed adults were plentiful and easy to find, yet now, they're mostly gone. And this is typical for many migrant species; the brightest, butchest adult males will be first back on territory, claiming the best locations and already in full song by the time the females arrive. Young birds, breeding for the first time, will usually arrive after the vanguard and settle for sub-optimal habitats, unless they can claim an unoccupied territory where last year's occupant has not made it through the winter. The same scenario is apparent in the reduced number of American Wigeon on Lighthouse Pond; a month ago, the vast majority of birds were paired up (most duck species display and pair up on the wintering grounds, then head north together), now there's a much higher percentage of loners floating around, and many of these - if you look hard for traces of old feathers - are first-year birds.

Another sign of spring is the urgency of migration, which is usually far greater than in the fall; birds are in a hurry to get to the breeding grounds and chasing after a reported bird of interest can be more frustrating than in the fall - more often than not, it's gone before you get there! Sitting and watching a single spot over a period of time (or repeatedly visiting the same spot) can demonstrate this nicely. Yesterday I paid three visits to the Willow Pond at The Beanery, following on from Scott Whittle's original report of swallows and martins feeding there. It would be easy to assume that the same birds were present throughout the day, yet each visit provided different counts. At lunch time, nine Purple Martins, 12 Tree Swallows and one Barn Swallow were present. When I passed by after work, I found eight Purple Martins, three Tree Swallows and a single Cliff Swallow. Returning in the evening, I watched birds coming and going and came up with 10 Purple Martins, six Tree Swallows, two Barn Swallows, one Cliff Swallow and one Northern Rough-winged Swallow. A nice example of similar species with similar requirements drifting through and ending up at the same spot.

Finally, Don touched on the fact that Ospreys have been 'in' for a while now, yet many of us birding at Cape May Point hadn't seen one until yesterday. This is another feature of spring, where some species have individuals that seem capable of sneaking in straight to breeding sites without being seen on the way through! Ospreys are typical of this; in the UK where I come from, the first Osprey records are almost always of breeding birds at nest sites in Scotland, which somehow move up through the Brtitish Isles undetected. It can be several weeks before birds are then seen on passage further south in England and these later birds are probably heading further north, perhaps to Scandinavia. The same seems to hold at Cape May, where local breeding birds get sighted on their nest platforms before migrants are reported at the point. Indeed, yesterday was clearly a good migration day for Ospreys as I saw a total of seven birds during the course of the day - all heading in the same direction, north-east, on a south-westerly wind and clearly cutting across Cape Island and heading for the shore.

I wonder what will be next....

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