Searching for April Migrants

Golden-winged Warbler

Each spring for as long as I can remember I have been fascinated by the dynamics and the mystery of spring migration among birds.  It probably began with my maternal grandfather who actually took the time to teach me a little bit of what he knew about nature.  He and I would go out for walks when I was 5 or 6 years old and we would traipse through the woods at the southern end of his farm  There he would point out the spring flowers that he knew, and where to find mushrooms, and show me how to recognize a Woodchuck foot print and about the birds that showed up abundantly in his trees.  Like it was yesterday I still remember the first Rose-breasted Grosbeak I ever saw and my grandfather showed it to me in those woods.

With the passage of time and the acquisition of knowledge I began to develop an even stronger interest in migrating birds.  In graduate school I applied for and received a Federal bird banding permit that allowed me to capture birds to place numbered aluminum bands on their legs.

Bird Bands

I had a study area near Mikana Wisconsin where I banded birds over four years in the mid-1970s.  There I chose a recently clear-cut forest with its rapidly re-growing quaking aspen trees and set up 15 mist nets on weekends to capture and band birds.  I still remember capturing a male Baltimore Oriole on May 15, 1975 in that clear cut forest.  I placed a numbered band on its leg, recorded other information about it, and tossed the bird back into the wild.  Given the abysmal return and recovery rates on banded songbirds I assumed that I would never see the bird again. However on May 16, 1976 and again on May 15, 1977, I captured the same Baltimore Oriole in the same net and on essentially the same day of the month.  Range maps for Baltimore Oriole show that they spend the winter south into South America and nest in summer well north into Canada. Where had the bird been before I captured it each year? Had it been dining in a palm tree near Cartagena, Colombia a week earlier?  Was it headed to central Ontario to build its nest?  These were questions I could never answer but they served to intensify my interest in birds and in bird migration.

The peak of spring songbird migration in my natal Wisconsin is from about May 1 through May 25.  The further south you travel the earlier the migration timing.  For instance when I lived in Virginia I could count on the most migrating warblers being around during April 15 through May 5.  Even further south, here on the west coast of Florida, migration never really seems to end, but the peak of spring migration for most songbirds is from the last week of March through about April 20. In other words, right now is the peak of the movement from tropical wintering habitats north to temperate and even boreal nesting areas.

Being a native of northern Wisconsin who grew up in the great north woods of that state, I'm well aware of what wilderness is like.  And having lived six years in Jamestown, North Dakota and another six years in Grand Island, Nebraska, I'm well aware of what "wide-open spaces" are like.  Living in the overly-developed west coast of Florida there is hardly anything remaining that resembles the north woods, and the only wide spaces are the areas from the north end of a mall parking lot to the south end.  Still despite this astonishingly human-dominated landscape there are small patches of habitat that allow me to think (very briefly) that I'm in the wilderness of northern Sawyer County Wisconsin.  That is if I can block out the sound of nearby Interstate 75, and I dont look at the massive 345 kilovolt powerline crossings and the din of honking cars on University Parkway dont distract me and the sight and sound of Delta Airlines 757 aircraft on final approach to the Sarasota airport dont interrupt me.

One little patch of habitat that some how miraculously has not been developed into endless condos lies just to the east of my home.  There among the sounds of civilization is a small area of artificial wetland and scrubby upland trees and the occasional Carolina pine tree and some willows at the wetland's edge.  Its far from wilderness but its just a few minutes walk from my house and by spending a couple of hours there each morning I can not only feel like I'm still a biologist but at this time of year I can also witness spring migration of birds.

A patch of relative normalcy in an overly developed landscape.  My "route" follows the jagged edge of the artificial wetland in the middle of the satellite image.  That wide road to the east (right) is Interstate 75 and University Parkway makes up the southernmost edge of the image

This morning dawned foggy with a very low cloud ceiling.   These conditions at this time of year are excellent for finding migrant songbirds and sometimes getting incredible views.  I remember well the morning of May 22, 1976.  My former wife and I were at Wisconsin Point, a patch of ground that geologically is known as a "baymouth bar" in Lake Superior, at Superior Wisconsin.  When we arrived at sunrise a pea-soup like fog had enveloped everything and it trapped migrant birds.  They were everywhere that morning; some like a Chestnut-sided Warbler we found hopped onto my arm and stood there looking at me as I looked at it.  Ruth and I spent 7 hours on the Point that morning and early afternoon and by the time we left we had recorded an astonishing 135 species of birds!  Included among them was every species of Warbler and every Flycatcher that nests or migrates through northern Wisconsin.  All this on a spit of land 5 miles long and no more than 100 yards wide.  Everything had been grounded by the fog and we were in birder heaven.

This morning's fog

A patch of subtropical hardwood forest in the fog

My luck this morning was nowhere near as good as what Ruth and I experienced that long ago morning in the fog but still it was obvious that spring migration is well underway.  My first indication was a Golden-winged Warbler, only the seventh one I've ever seen in Florida.  It was first heard singing and then eventually found hopping around in the trees as it foraged.  This bird nests at the edge of old fields and in early successional stage forests.  Both are rapidly disappearing from the landscape as more and more humans fill less and less space. In 1977 I banded eleven Golden-winged Warblers in my banding study area near Mikana Wisconsin.  That was the largest number of Golden-winged Warbler anyone banded anywhere in North America that year.  

Searching further a Worm-eating Warbler popped into view and off in the distance I heard a male Black-throated Blue Warbler, probably freshly arrived from the mountains of Jamaica, singing from the edge of the woods.  A male Northern Parula was busy doing its upward buzzy trill as a male Common Yellowthroat sang its distinctive "witchity-witchity-witchity" song from the willows at the edge of the wetland.  Palm Warblers and Yellow-rumped Warblers winter abundantly in this part of Florida and I was surprised to still find a couple of them sprinkled in with other birds freshly arrived from the tropics.  

Another star of the spring migration scene was Wood Thrush.  This bird with its fantasticly melodious voice is rapidly disappearing from the landscape as more and more people build more and more houses in fewer and fewer small patches of forest that remain in the eastern United States.  Seeing it freshly arrived, probably from Costa Rica, was another bit of evidence that spring migration is kicking into high gear.

I found 57 species of birds during my 2 1/2 hour walk through 2 1/2 miles of habitat.  Well 57 species of birds and one 8-foot alligator who decided that the dike surrounding the wetland was where he wanted to chill out in the fog and there was no way I was going to convince him to move.  He sat still and I sat still and eventually he moved. I didn't until he did!

Many of the 57 species this morning were resident birds like Sandhill Crane and Snowy Egret and Anhinga however 16 species were most definitely migrants and 10 of those were warblers.  Numbers of species and numbers of individuals will probably grow each day for the next 10 days or so. I will know that spring migration is winding down when species like Yellow-billed Cuckoo and Canada Warblers arrive. Until then however I'll be out on my 2 1/2 mile route each morning, binoculars in hand, looking for migrant birds just like I have done for 55 years since my grandfather first showed me that long ago Rose-breasted Grosbeak in his forest.