"Concatenated series of simple phrases" is a concise way to describe the assembly rule for the
songs of many wood-warbler (Family Parulidae) species. These songs of the Rufous-capped Warbler
are good examples, but this bird manages to sing with considerable variety despite his adherence to
that rule. In his first song of this sequence he deploys two phrase-types. In the second, he inserts another, at
position six. He then alternates these two configurations, never altering the order seen in the second song.
Then, just when you think you have him figured out, he drops the first and third phrase-types and gives
a series of long one-part songs. What do you want to bet that he does the same with the other
phrase-types from time to time? Check out
all the recordings from this territory to find out.
Our songster is well-studied and often-recorded, because his species is so local in the U.S., its range barely
penetrating southeastern Arizona and south-central Texas. He and his mate were stake-outs in 2019, when Alan Schmierer
took me to see and record them. Unfortunately, the have not been reported since Al found
four birds in their territory September 28, 2019. I hope those were parents and their offspring of the year. I also hope
they are nesting somewhere else successfully this year.
This is an attractive species, and a welcome addition to the avifauna of the U.S.,
not least because it introduces its genus, Basileuterus, and its different way of
doing things, to birders accustomed to northern warblers. Basileuterus warblers are
nonmigratory, and the sexes do not differ in plumage. They build covered nests on the ground, and
like dense vegetation, like the thickets of Hunter Canyon. The genus has numerous species, occupying brushy places from Mexico into
South America. Several have attractive patterns of yellow and rufous on their faces, like the
Rufous-capped. Several have extremely small ranges, automatically putting them in danger of
extinction. It would be a wonderful group to specialize in.