Bird Conservation International

Table of Contents - 2007 - Volume 17, Issue 01  


Articles

Vines and canopy contact: a route for snake predation on parrot nests

SUSAN E. KOENIG a1c1, JOSEPH M. WUNDERLE, JR a2 and ERNESTO C. ENKERLIN-HOEFLICH a3
a1 Windsor Research Centre, Sherwood Content P.O., Trelawny, Jamaica
a2 International Institute of Tropical Forestry, USDA Forest Service, Sabana Field Research Station, HC 02 Box 6205, Luquillo, Puerto Rico 00773, USA
a3 Centro de Calidad Ambiental, Tecnológico de Monterrey, Garza Sada #2501 Sur, Monterrey, Nuevo León, 64859, Mexico

Article author query
koenig se   [PubMed][Google Scholar] 
wunderle jm   [PubMed][Google Scholar] 
enkerlin-hoeflich ec   [PubMed][Google Scholar] 

Abstract

Ornithologists have hypothesized that some tropical forest birds avoid snake predation by nesting in isolated trees that do not have vines and canopy contact with neighbouring trees. Here we review two complementary studies that support this hypothesis by demonstrating (1) that an abundance of vines and an interlocking canopy characterized Jamaican Black-billed Parrot Amazona agilis nest-trees that failed due to chick loss, presumably to snakes, and (2) that such trees were used preferentially by an arboreal snake congeneric to the snake implicated in the parrot losses. Evidence strongly suggested that losses of nestling Black-billed Parrots were due in substantial part to predation by the Jamaican (yellow) Boa Epicrates subflavus (Boidae). Studies of the closely related Epicrates inornatus on Puerto Rico revealed that trees used by boas had more vine cover and more crown or canopy contact with neighbouring trees than did randomly selected trees. Moreover, the boas had relatively large home ranges and were most active during March to July, which corresponds with the breeding season of parrots as well as other bird species. We suggest that nest failure due to snakes may be reduced in endangered bird species through isolating the nest-tree by eliminating vines and canopy contact with neighbouring trees and shrubs and by placing barriers on the nest-tree trunk.

(Published Online March 13 2007)
(Received October 10 2005)
(Accepted March 15 2006)


Correspondence:
c1 Author for correspondence; e-mail: windsor@cwjamaica.com