Saturday, September 5, 2009

The Migrants Are Coming - And I Dont Mean Tourists

There has been an obvious increase in the number of tourists already returning to coastal Florida. In the last week I've seen more Ohio and Michigan license plates than since they went back north in April. Most telling was the four (count them, four!) Ontario license plates seen just yesterday while on my bicycle ride. These are all definite signs that organisms are leaving the more northerly climes and headed for the warmth and tranquility of subtropical Florida.

Despite the apparent ingress of less-than-desirable humans, there has also been an increase this week in the number of bird species making their way south.

Bird migration is an almost 12-month a year process but most of us think only of spring migration when birds return from littler latitudes decked out in the breeding plumage and singing to attract a mate. Most think of April and May as the peak of spring migration although "fall" migration can begin as early as June when some male shorebirds first arrive from the Arctic.

Warblers (my most favorite group of birds) generally begin their southward movements in late July (Louisiana Waterthrush immediately comes to mind) and they are joined by other species throughout August. Some species like Canada Warbler pass through Florida on their way to South America. Others get here and stay until next spring.

Palm Warbler is one of those species.

Yesterday while on my bike ride I heard and then saw my first Palm Warblers of the winter. There were two birds, apparently post-breeding males, calling vigorously from a large tree in the parking lot of the British Pub on University Parkway. I pass through here daily and would have heard Palm Warblers earlier had they been here. Yesterday's sighting says that our "winter" birds are here and will be around until next April or so.

Palm Warblers nest in bogs and similar wet forest habitats in and near the boreal forest of the northern United States and Canada. Although rare in Wisconsin in summer there are a few places where this species can be found in the Badger State during summer. I remember well my first trip to Maine when I flew to Bangor in June 1984 to capture some Palm Warblers for an experiment we were doing on fitting a radio transmitter on the back of a bird like Kirtland's Warbler that wags its tail constantly. With the help of the Maine Cooperative Fish and Wildlife Research Unit myself and some graduate students caught 12 Palm Warblers in a bog near Bangor and I transported them back to Laurel Maryland for the research effort. Almost predictably good old Delta Airlines lost the birds in the baggage of a 727 I rode back to Baltimore. A day later the birds were found and amazingly they were all still alive.

Despite them being a species of rich, wet, boreal bogs in the summer, Palm Warblers spend their winter in many habitats - including palms in Florida. In the West Indies they are most abundant in xeric scrub habitats - the antithesis of their summer nesting habitat.

You can learn more about the ecology of Palm Warblers here and here.

Now that Palm Warblers are back on the west coast of Florida its safe to say, at least ornithologically, that fall is here and that means winter with its frigid 60 degree temperatures can't be far behind. There's hardly a cloud in the sky today and the temperature is currently in the pleasant mid-70s. It seems like a perfect day to find some coastal scrub habitat and go look for migrants. And I think that is exactly what I'm going to do.