[CT Birds] Eastern Kingbird Jekyll and Hyde Behavior

Anthony Zemba Anthony.Zemba at gza.com
Wed Mar 21 11:22:12 EDT 2012

Interesting, Thanks Paul
Yes, it makes no ecological sense to defend territory on their wintering grounds when their feeding guild changes to fruigivory as most tropical fruiting plants fruit asynchronously and therefore, they'd be defending territory that would be productive for just a short while. That is why they are nomadic on the wintering grounds, they are searching for the next fruit source.

Anthony Zemba CHMM
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-----Original Message-----
From: ctbirds-bounces at lists.ctbirding.org [mailto:ctbirds-bounces at lists.ctbirding.org] On Behalf Of paul cianfaglione
Sent: Wednesday, March 21, 2012 11:15 AM
To: CT Lists
Subject: [CT Birds] Eastern Kingbird Jekyll and Hyde Behavior


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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