Friday, April 20, 2007

Rising Sea Levels Seem Likely to Doom Some of Long Island Sound's Marsh-Nesting Birds

I've been avoiding the subject of global warming and climate change here mainly because you can read about it just about everywhere else. But I noticed a story this morning about how ornithologists in Connecticut are looking into how climate change, and in particular the expected rise in sea level, will affect a local species, the salt marsh sharp-tailed sparrow.

The results of the research, in short, are this: if you're interested in birds and you haven't seen and observed a salt marsh sharp-tailed sparrow, don't wait around too long because they're likely to be gone (as will, it seems likely, much of Long Island Sound's salt marshes). Higher tides and bigger storm surges will flood salt marshes more frequently, destroying habitat where it doesn't actually kill nestlings.

This story, from the Greenwich Time, does a good job explaining things (although it makes the hard-to-believe assertion in the first sentence that Connecticut is home to 20 percent of the population of salt marsh sharp-tailed sparrows, and then fails to mention or account for that assertion again).

There are two species of sharp-tailed sparrows -- Nelson's and salt marsh. Until about a dozen years ago they were considered one species. The salt marsh sharp-tailed nests from the Delmarva Peninsula north to Maine, a small range which I suppose could mean that 20 percent of them do live in Connecticut. The Nelson's is an inland marsh species.

The New York State Breeding Bird Atlas project found salt marsh sharp-tailed sparrows in eight locations in Westchester and the north shore of Long Island (and in about 50 on the south shore, Peconic Bay and Staten Island). For comparison, here's the map for the early 1980s. I could find no comparable data for Connecticut though.



Blogger Sam said...

If I may play Devil's Advocate, in the short-term some coastal flooding of about 5-10 inches might be a good thing. Of course we know that much more than that we're in deep kimchee, but a little sea level rise might actually be a good thing for the salt marsh ecology.

Let me explain: ever since the 1940's the Army Crops of Engineers and local governments have been DRAINING the swamps at an alarmning rate. From Maine to the Everglades and on down the Gulf to the Bahia Grande, what used to be a semi-flooded riparian ecology was essentially dried up and killed off. All this was to control the mosquito and promote development, of course.

But nowdays we have been learning that maybe except for New Orleans, it is best to re-flood these areas and let nature have its way. Not only are we finding that re-flooding works, but improved water flow must be maintained or species diversity will suffer. The reason is because seawater should be around 30 ppt (parts per thousand) but in some areas without adequate flows and heavy drying, salt concentrations could go up over 100 ppt, which basically makes the swamp revert to an inselct-only ecology. Some areas must be evaluated for freshwater inflows, too.

It is interesting stuff and I hope more people become involved in un-doing the mess the Army Corps of Engineers created over the decades. A little sea rise, some dynamite, and some properly designed inflow channels (such as under highways) would be a good thing in my opinion.
/Sam Wells

2:00 PM  

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