Sunday, April 10, 2011

Vacationing Birds

Just like humans, when birds go on vacation they often behave very differently from when they are engaged in domestic duties. Two weeks ago I wrote about the Wood Thrush on its wintering grounds in Belize where its behavior is positively robin like. The thrush’s behavior is a sharp contrast to its behavior on its breeding grounds in Vermont where it is shy, secretive, and elusive.

Here are a few more examples of bird behavior on wintering grounds that is different from behavior on breeding grounds.

Northern Waterthrush (Belize)
When I was surveying for the Vermont Breeding Bird Atlas, I found a Northern Waterthrush in a beaver pond in Stratton. It was singing, and I listed it as a probable breeding bird. I have returned to the beaver pond during June every year since. I have circled through the forest to the back end of the pond where the water is shallow and still, the favored habitat for the Northern Waterthrush. By contrast, it cousin, the Louisiana Waterthrush, likes fast moving mountain streams. Both waterthrushes are are warblers which look like thrushes (Wood, or Hermit) - brown birds with spotted white breasts. They bob their tails, like a Spotted Sandpiper, as they walk along the ground.

One June, I saw the Northern Waterthrush in the beaver pond for an extended time. At the the shallow end of the pond, I sat on a log and fed the mosquitos. While the male sang somewhere in the swampy pond, the female bobbed along the muddy edges a couple dozen feet from me, feeding. Then I suppose she gathered nesting material, because she flew off with something in her beak.

Every quest I have made for this warbler during June has required patience and luck. In our  swampy forest neighborhoods, the Northern Waterthrush is shy, secretive, and elusive, like the Wood Thrush. It carefully balances the need to advertise its presence in order to attract a mate and warn off rivals against the need to protect its nest, eggs, and young from dangers.

Along the shallow edges of a small pond in Belize, I watched a pair of Northern Waterthrushes as they foraged through leaf debris. It was the dry season, and many trees dropped their leaves. Large brown leaves covered the forest floor and the muddy pond edge. The waterthrushes walked along, tails bobbing. Systematically they flipped over the large leaves looking for food. Walk, bob, flip, feed ... walk, bob, flip, feed. They were cautious about any movement in their direction on my part. After all, I was a huge intrusive presence. But they were not the shy and elusive birds I knew in Vermont.

Hooded Warbler (male - Belize)

For many years I lived in Delaware Water Gap, Pennsylvania. The sides of the mountain ridges were covered with rhododendron, prime nesting habitat for the Hooded Warbler. On many occasions, I sat along the trail for long periods trying to get a good look at the male. He is a bright yellow bird with a bold and striking black hood. A good look is worth the wait. He often chose a mid-level branch as his singing perch. Picking that tiny spot of yellow out of filtered sunlight in a forest always included a dollop of luck. If a second male sang nearby, fast flights in defense of territory might provide a glimpse.

The first day we were in Belize, I caught my breath and said, “Oh my, a Hooded Warbler.” Then it happened again ... and again ... and again. The Hooded Warbler’s frequent appearance never became humdrum, but it was not the breath-catching experience that I had been accustomed to.

Botanical gardens adjoined our jungle lodge in Belize. One morning in an open orchard section, I watched a male Hooded Warbler feeding. He went from tree to tree, working the branches and gleaning the leaves. While he never allowed me to get too close, he did not hide in thick foliage where he was a mere flitting and fleeting presence. Back and forth he went, pausing from time to time to pose and allow me to marvel at the black cowl framing his yellow face.

The Hooded Warblers I saw were all males. The females, which lack the prominent black hood, were absent. That typified the experience with the “northern” birds which I saw on their wintering grounds.

Black-throated Green Warbler (female - Belize)
Magnolia Warbler (female - Belize)

Where we were staying in Belize, I saw lots of Black-throated Green Warblers - all female. In a much different location, I saw males. The Black-and-White Warblers were male. The Magnolia Warblers were female.

Parenthetically, last year I struggled to get reasonable pictures of the Magnolia Warbler. They were high in tree branches, moved rapidly, and rarely presented a good photo opportunity. I had several good opportunities to photograph the female Magnolia Warbler in Belize and the male in Tikal, Guatemala.

Continuing. I saw lots of American Redstarts with the black and orange plumage of the male and the gray and yellow plumage of the female. But, one year old male redstarts look like the female; they do not acquire the adult male’s black and orange plumage until they are two years old. I suspect that the American Redstarts were all male.

You see the pattern. In addition to very different behavior from what we see when these birds are in our neighborhoods during their breeding season, the sexes also vacation separately. With many species, males and females occupy different habitats during the winter.

Another striking behavioral difference in these wintering birds was the lack of song. They did not sing. Bird song is such a key component to knowing what birds are present, but singing is an activity largely confined to the breeding season. Local guides relied on voice for identification, but that voice was not song, it was call - the chip notes that birds use to communicate with one another.

On the wintering grounds, there is no singing, no displaying, and no rivalry among the males. There is no need for such behavior until the birds begin their journey northward when they are driven by hormonal changes and the urgency of species propagation.

Gray Catbird (Belize)

The Gray Catbird presented something of an exception. I heard some catbird mimicry, though not nearly as much as I hear during the summer in my yard. Otherwise, the catbird on vacation behaved like the catbird I see in Vermont. It came to the feeder on the veranda for fruit. It picked berries from the ground and off branches. It hoped about with friendly curiosity, cocking its head when listening to my silly sounds or when some other movement caught its attention.

In summary, it was fun seeing old friends on vacation.


Bill S. said...

Sounds like you had a wonderful time. I enjoyed the post as I will probably never get there. Great pictures.

Chris said...

Well I would prey to get nice pictures like that during my vacation... Not that I'm not trying but I never have enough time to find them and find a good spot for pictures. This is a beautiful set of pictures Chris.

Warren and Lisa Strobel said...

Very interesting post, Chris. We are waiting for our Wood Thrushes to return - it is almost clockwork. April 22 or 23. That is a song I would deeply miss hearing if I saw one in the winter.

eileeninmd said...

Beautiful shots, Chris! I love the Hooded Warbler. I would love to go birding in Belize. I enjoyed your post.


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