[CT Birds] Eastern Kingbird Jekyll and Hyde Behavior

paul cianfaglione pgcianfaglione at gmail.com
Wed Mar 21 11:15:08 EDT 2012


Here is something I read recently in Steve Hilty's Book, *Birds of Tropical
America, *that I found fascinating about Eastern Kingbirds and elaborates
on Frank Gallo's remarks about the flycatchers winter fruit eating diet,

*The Eastern Kingbird is highly territorial and pugnacious and feeds only
on insects during the months when it breeds in North America. But during
the other half of the year, it does a behavioral about-face that would do
justice to Jekyll and Hyde. Its pugnacity is traded for docile
subordination to virtually all of its tropical relatives, and its
territoriality is traded for a period of nomadic wandering. Gathering in
large, nervously acting waxwing-like flocks that wheel and turn on dime and
plunge into giant fruiting trees, Eastern Kingbirds roam the floodplain and
river-edge rainforests of southwestern Amazonia in search of ripened
fruits. *

     *Why do Eastern Kingbirds have split personalities? If the Eastern
Kingbird’s off-breeding-season behavior of gathering in flocks seems
peculiar, consider that in western Amazonia, where most of them spend the
northern winter, there are at least eight other species of large-bodied
flycatchers – all of them potential competitors – that also consume fruit.
They include Great Kiskadees, Social and Gray-capped Flycatchers and
Tropical Kingbirds, which all have well-deserved reputations for pugnacity.

* *

*     Archbold Biological Station scientist, who studied flycatchers in
Peru, noted that these species persistently chase Eastern Kingbirds as well
as other birds in fruiting trees, but the kingbirds overwhelm them by their
sheer numbers. When a flock of Eastern Kingbirds descends on a fruit tree,
they may outnumber the resident species ten to one. A few kingbirds are
forced to flee the attacks of dominant resident flycatchers, but these
individuals return as soon as their attackers turn their attention to other
individuals. In this way, each kingbird, playing a game of averages, is
likely to be harassed only occasionally by resident flycatchers, and flock
members as a whole are able to feed. *


Paul Cianfaglione



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