Sunday, July 15, 2012

The “Tropical” Birds of Our Local Forest

The male Scarlet Tanager perches below the forest canopy 
Many of the birds nesting at our nature preserve only reside with us from 3 to 4 months out of the year. The rest of their lives are spent in the tropical regions of Central and South America. While they are here with us, in a way, they bring the tropics to us in the form of their colorful plumage and exotic songs. Though many of these “neotropical” songbirds breed in a variety habitat types, the forest, or forest edges are the most common places to find them.
The male Rose-breasted Grosbeak sings from a treetop on the forest edge

At the nature preserve, our older forest is the most likely place to see or hear these birds. The most well-known tropical looking birds –the Scarlet Tanager, Rose-breasted Grosbeak and Baltimore Oriole are somewhat easier to see at this point in the season, as most are involved in feeding their young, which are now out of the nest. As you get close to them, they give sharp alarm calls, and fortunately for the observer, defensive parents will sometimes come in close to scold intruders.
The male Baltimore Oriole perches on a Red Oak in one of the reforestation fields

A male Hooded Warbler protecting his nest area
The Hooded Warbler nests in the brushy understory of our open-canopy  forest. The male of the species truly does look like a refugee from the tropics with his bright yellow body and black hood, which is interrupted by a bold yellow eye mask. His song is a strongly whistled short phrase that sounds to some like: “ta-weet…ta-weet…ta-weety-o”. This song varies little with different individuals, but the Hooded Warbler also sings an alternate song which is not as well recognized and is harder to translate into words.
The female Hooded Warbler with an insect to bring back to the nest

The Hooded Warbler most often breeds in small colonies where there is a substantial amount of suitable habitat. We are fortunate to have one such colony at our nature preserve.

The male Hooded returns to the nest where hungry chicks await
After the young leave the nest, only one infertile egg remains

As a nest site, the female chose a short Beech sapling that was shrouded by blackberry brambles. Only by getting very low to the ground, was I able to peer between the leaves and see what she was up to. That’s where I saw her weaving together relatively wide strips of bark and long pieces of grass. It really more resembled the nest of a Red-winged Blackbird than any creation by a member of the warbler clan. When finished, the sturdy looking nest looked like it would stand up well to any boisterous brood, and as things turned out, it did.

The male Mourning Warbler on the breeding grounds
Another, mostly tropical species, the Mourning Warbler, has almost exactly the same habitat requirements as the Hooded Warbler –nesting in the understory of open-canopy forests. This is another Yellow bird, but this one has a complete black hood over its head with no yellow eye mask. In male birds, the hood is darkest at the point where it meets the bird’s breast.

A female Mourning Warbler fluffs up her feathers and takes a sun bath
The species is shy and retiring –that is unless you get close to their active nest (most always hidden away in a low bramble), at that point both parents come out to scold you with harsh “witch…witch..witch” calls. It’s almost as if they are trying to accuse someone of practicing the dark arts.

The not very tropical looking Ovenbird
The song of the Mourning Warbler is a rapidly given phrase. It’s a series of 3 or 4 tight, almost gurgled trills, which are terminated by a low note. The male Mourning Warbler can sometimes be heard to give a rather extraordinary “flight song”. As is implied, the flight-song is given on the wing as the bird ascends over his breeding grounds. This song is very seldom heard –and there seems to be very little mention of it in the bird literature.  It sounds like a haphazard jumble of notes with the Mourning Warbler’s typical song incorporated into the middle of it. It can be compared to the evening flight song given by the Ovenbird (another warbler of the forest) and that given by the Common Yellowthroat. The latter species’ flight song is the most familiar to birders, since it is given at all times of the day in forest clearings and brushy meadows.
The male Common Yellowthroat or "Bandit Bird"

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