BARRED ANTSHRIKES
 The
other day I found the feather shown at the right.
Not many bird species possess the spectacular black- and-white, Zebra-stripe barring such
feathers impart. I could think of just two local candidates. One is the Golden-fronted
Woodpecker, closely related to the North's Red-bellied Woodpecker, whose back is bared
with narrow, black and white stripes. The other possibility is the Barred Antshrike. Since
Barred Antshrikes were calling like crazy that morning with their 6-8 nasal kyow notes,
rising then falling, my guess is that that's a Barred Antshrike feather in the picture.
As feathers go, it's an impressive one. Note the black streak at the feather's upper,
left. Just think of the evolutionary trial-and-error needed to position that streak
perpendicularly to all the others. Nature employs all kinds of tricks for creating
ornamentation in systematic ways, but coming up with something running counter to already
existing patterns can be an extra challenge.
Antshrikes themselves belong to the neotropical Antbird Family, the Formicariidae. In
Mexico the family is represented by four antshrike species, one antvireo species, four
antbird species, one antthrush, and one antpitta. The "ant" part of the names
comes from the tendency of some of the family's species to accompany army-ant swarms and
prey upon fleeing insects.
Evolutionarily the family appears to specialize in "radiating" -- emulating
species in other birds groups, thus eventually looking and behaving somewhat like shrikes,
vireos, thrushes, etc. Many families specialize in efficiently exploiting just one general
niche, such as woodpeckers on tree trunks, or wood warblers foraging for insects among
tree branches, thus a certain conformity of appearance and behavior unites the whole
family. The Antbird family takes the opposite approach.
One of the most striking features of our Barred Antshrike species is its sexual
dimorphism; males and females look so unlike one another that it's hard to believe they're
they same species. The male has his intense Zebra-striping, but the female is mostly a
plain, rusty-red or rufous bird, with only modest striping on her cheeks.
The species is distributed in second growth, forest edges, thickets and such from Mexico's
north-central Gulf lowlands south to northern Argentina.
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