Stephen McDowell, M.S. Student, Stephen F. Austin State University
Dr. Warren Conway
Dr. David Haukos
U.S. Fish and Wildlife Service
U.S. Geological Survey
Stephen F. Austin State University
Cooperators: Texas Chenier Plain NWR Complex
Dr. Dan Collins
Example of coastal marsh habitat being sampled for lead availability.
Location: Anahuac NWR
Completion: December 2012
(1) Determine the availability of lead on the upper Texas Gulf Coast.
(2) Estimate the exposure of lead by mottled ducks.
(3) Evaluate pathways of lead exposure for waterbirds of the upper Texas Gulf Coast.
Progress and Results:
The mottled duck is a non-migratory waterfowl species that depends on the marshes
along the Gulf of Mexico. Since the mid-1980s the Texas breeding pair populations
have declined, where current population estimates hover around 17,000 individuals.
Though use of lead shot was banned nationwide for migratory waterfowl hunting in
1991, recent studies show mottled ducks continue to have elevated wing bone lead
concentrations. Such data indicate that mottled ducks continue to be exposed to
lead somewhere during the annual cycle. I am estimating blood lead concentrations
within local, hatch-year, and adult mottled ducks to isolate when mottled ducks
are initially exposed to lead. I am also estimating spent lead shot availability
and distribution, as well as soil lead concentrations on the Complex to determine
potential pathways by which mottled ducks obtain lead. Such research is important
to evaluate long term effects on mottled duck populations and as possible influences
on important vital rates, such as survival and fecundity.
McDowell, S.K., W. Conway, and D. Haukos. 2012. Potential exposure to environmental
lead in mottled ducks (Anas fulvigula) on the Texas Chenier Plains National
Wildlife Refuge Complex. 48th Annual Meeting, Texas Chapter of The
Wildlife Society, Fort Worth, Texas.