Estación Biológica Cocha Cashu
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Ecology of obligate ant-following birds and army-ants

Principal Investigator: Susan Willson

Assistant Professor of Conservation Biology
Office: Johnson Hall of Science Room 231
Phone: (315) 229-5846, fax: 315-229-7429

Web page:

I am studying the community of obligate army-ant following birds at Cocha Cashu, as well as the two army ant species they follow. I have worked at Cashu from 1997-2001 for my Ph.D thesis, and will continue my work there after completion of my dissertation at the University of Missouri in 2002.

Five focal species of birds (Thamnophilidae: Phlegopsis nigromaculata, Myrmeciza fortis, Rhegmatorhina melanosticta, Gymnopithys salvini; Dendrocolaptidae: Dendrocincla merula) have been color-banded over a 200 ha. area. The main question I am asking about the birds is:

How do birds make foraging choices? given:

    A. quantifiable interference competition
    B. mobile food resource which is
    • a) superabundant
    • b) of variable size
    • c) spatially heterogeneous
Connected questions I am investigating are:
  • Do different species make foraging choices using different strategies?
  • Do all individuals within a species use the same foraging strategy?

Due to four years of intensive capture/ resight data and extrememly high recapture rates, I can estimate yearly survival of ant-following birds at Cashu. I am using the program MARK to analyze data, and believe that the results will contribute to the current debate over tropical vs. temperate avian survival rates.

I am also studying the population dynamics of the two army-ant species followed by obligate ant-followers at Cashu: Eciton burchelli and Labidus praedator. Does E.burchelli minimize re-exploitation of recently raided areas? Most work on army ants has occurred on Barro Colorado Island where E.burchelli density is much lower than at Cocha Cashu, so it will be interesting to compare results with those found on BCI.

Funding has been provided by an Exxon Teagle Foundation Scholarship, Trans World Airlines Grants, an Organization of American States PRA Training Grant, the MU Div. of Biological Sciences, and a GAANN Dept. of Education Fellowship.





Phlegopsis nigromaculata

female Myrmeciza fortis

Rhegmatorhina melanosticta

male Gymnopithys salvini

Dendrocincla merula