Wintering area DDE source to migratory whitefaced

Authors: Michael A Yates Mark R Fuller Charles J Henny William S Seegar Jaqueline Garcia

Publish Date: 2009/08/21

Volume: 19, Issue: 1, Pages: 153-

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Abstract

Locations of contaminant exposure for nesting migratory species are difficult to fully understand because of possible additional sources encountered during migration or on the wintering grounds A portion of the migratory whitefaced ibis Plegadis chihi nesting at Carson Lake Nevada continues to be exposed to dichlorodiphenyldichloroethylene DDE with no change which is unusual observed in egg concentrations between 1985 and 2000 About 45–63 of the earliest nesting segment shows reduced reproductive success correlated with elevated egg concentrations of 4 μg/g wet weight ww Local prey primarily earthworms near nests contained little DDE so we tracked the migration and wintering movements of 20 adult males during 2000–2004 to determine the possible source At various wintering sites we found a correlation r 2 = 0518 P = 00125 N = 11 between DDE in earthworm composites and DDE in blood plasma of whitefaced ibis wintering there although the plasma was collected on their breeding grounds soon after arrival The main source of DDE was wintering areas in the Mexicali Valley of Baja California Norte Mexico and probably the adjacent Imperial Valley California USA This unusual continuing DDE problem for whitefaced ibis is associated with the longterm persistence in soil of DDE the earthworms’ ability to bioconcentrate DDE from soil the proclivity of whitefaced ibis to feed on earthworms in agricultural fields the species’s extreme sensitivity to DDE in their eggs and perhaps its life history strategy of being a “capital breeder” We suggest surveying and sampling whitefaced ibis eggs at nesting colonies especially at Carson Lake to monitor the continuing influence of DDEPrimary funding was provided by the Department of Defense’s Legacy Resource Management Program Linda Schueck and Branden Johnson of the USGS and Jim Dayton Blake Henke and Jack Cibor of Earthspan provided invaluable assistance in many ways The US Fish and Wildlife Service USFWS provided funding for some chemical analyses The Stillwater National Wildlife Refuge USFWS and the Nevada Department of Wildlife provided considerable resources time and capture expertise We wish especially to recognize Bill Henry of the former and Larry Neel Gary Herron Pete Bradley and Jenni Jeffers of the latter Eduardo Santana and Rodrigo Esparza assisted with the critical task of collecting invertebrates and recording other avian species associated with the ibis in Mexico Mary Gustafson of the Bird Banding Laboratory USGS graciously accommodated our request for the PTT/body weight ratio under our auxiliary marking permit Capture and processing expertise was also generously provided by Ali Chaney and Jennifer Newmark of the Nevada Natural Heritage Program and by Bob Goodman and Brian McDonald Eric Kelchlin kindly shared his expertise on the species during the planning stage We thank Susan Earnst Miguel Mora and two reviewers for useful suggestions to improve our manuscript

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