Saturday, March 20, 2010

Exit, Winter

Canada Geese flying due north at sunset on March 18
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I have really enjoyed watching the clash of the seasons. For the moment, with 73 degree air temperatures and south winds, it appears that spring has won. But with a month left until growing season, anything can happen. Even if this is just a brief reprieve from snow, north winds, and icy roads, I'll take it.
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This year, we've been treated to a spectacular - and quite early - display of waterfowl staging and return migration. Early March showed us wave upon wave of northbound Canada Geese, Snow Geese, and even Tundra Swans. In the case of both species of geese, the return migration from Maryland's wintering grounds is often brief and urgent, typically after the first major storm in April. And suddenly, after a 6 month stay, they are gone. Instead, this year, the birds started staging - congregating in large numbers and feeding with a sense of urgency - as soon as our 48" snow pack began to receed from Maryland's wheat, barley, corn, and soybean fields, approximately February 20th or so. Around March 1st, hunting and birding bloggers began reporting "high flyers" in Maryland and Virginia. These reports grew in frequency and I believe we lost our last big flocks of geese last week. This is actually pretty important, because unlike the flight south, which can take weeks or months, the flight north lasts only a few weeks. A miscalculation on the part of the geese can result in their arriving at Canadian nesting grounds still covered with a foot or more of snow and ice. This was the case in 2009, which resulted in very poor reproduction for Atlantic Flyway Canada Geese. And I don't have to tell my hunting readers that fewer yearling geese means fewer geese harvested, if only because the geese who migrate south have already lived through one or more hunting seasons. If you review any of my goose hunting notes from last season, you'll note that I'm a believer of this theory.
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I've got some "swan notes" at the bottom of this note - the Tundra Swans' pattern this spring was highly unusual, and only received bottom billing because I could not get a good photograph.

Scaup feeding on the edge of a marsh in the Central Chesapeake Bay, early March
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We still appear to have our winter songbirds in the area - notably the northern chickadees and dark-eyed juncos - but the ducks appear to be headed out with the geese. My drive home from work is mainly up a peninsula that is south of the Patapsco River and north of the Patuxent River. My drive home, often at dusk or just afterward, has been peppered with flocks of wood ducks, mallards, and black ducks trying to build up their reserves before a fast push north. My only current construction management job is on the "open Bay," so I've been treated to some enormous rafts of Scaup who are also staging for their return trip to their nesting grounds in Alaska. You heard it right! These drakes (above) were feeding close to the marsh on what I hope was our last day of heavy north winds. They look pretty darn healthy, and are featuring their breeding plumage.



Nutrient-rich waters and a very high tide, pushed in by the season's first south wind,
March 18
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The spring rains have definitely begun in earnest, although it's been sunny for 5 days now. Rain is washing off a lot of raw soil, exposed by the freeze/thaw action of so much ice and snow. The tributaries look pretty disgusting, but to some extent (about 10% of the current nastiness), it's a natural process.
Flock of Tundra Swans headed north....over my neighbor's house. March 19.
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So now, the oddity of the Tundra Swan's migration this spring. Tundra Swans in the Atlantic Flyway generally winter from southeastern Virginia to northeastern South Carolina. A few flocks spend some time roosting and feeding on the eastern shore of Maryland and Delaware - that number has been increasing annually for at least 10 years. The dominant theory is that our current "warming climate pattern" is allowing them to stay farther north. This is consistent with a wider study of wintering birds conducted by Audubon which found that many bird species are wintering farther north every year. The link above points out the "outliers" or "we're trying to make a point here," showing an average of 300-400 miles of northward movement over the last 40 years.
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Maryland DNR biologists observed near-record numbers of Tundra Swans this past winter, and while the swans' return north is usually at night, over open water, I observed several flocks flying over the DC-Baltimore area earlier this month. Strange times are afoot!
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Whatever process is actually at work, I'm awful glad that it's masquerading as Springtime.


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