Monday, August 13

Sedge Wrens, Montgomery County, PA

This morning I discovered a pair of Sedge Wrens in a hayfield just north of Philadelphia. The male began singing more or less incessantly at dawn and as I approached him a second bird called nearby, perhaps a female.
North American Sedge Wrens have interesting breeding behavior, nesting in the spring in the upper mid-west, then moving south and/or eastward to produce a second, late summer brood, with little site fidelity. Their songs are unusual too, in that the trills are unique to each individual, not learned from other birds, each male having more than a hundred improvised versions.
Sedge Wrens are rare birds in Pennsylvania and are designated an endangered species.

Male singing.

The non-singing second bird, two different calls:
raspy alarm

chip, similar to the introductory notes of the song.

Addendum September 20th

The male continued to sing, especially in the early morning hours before sunrise, until September 1st, after which no singing was heard. A nest was located by watching the (presumed) female visit a big bluestem tussock with food on September 6th. The fledglings left the nest September 9th or 10th, but returned to the nest each evening during the following week to roost. They remained close to the nest during the day, making calls similar to the adult chip. The adult female would occasionally use the raspy alarm.

Juvenile call

This recording starts with juvenile Sedge Wrens and ends with a nearby Common Yellowthroat, which has a similar call to the young Sedge Wren.

Common Yellowthroat call

Two eggs remained unhatched in the nest.

The breeding habitat, a 30 acre dry grassland of mostly big and little bluestem, without bushes or sedges.

A map showing the three song locations of the male. Singing was mainly at location 1, where the male would sing for hours at night, location 2 was also frequently used. Rarely, the male would sing at location 3. The white square is the site of the nest.

Update October 6th
One of the fledgling Sedge Wrens was heard singing a plastic song, a bird that had fledged only four weeks previously (Oct, PA).

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