(1) Within the context of a formal risk assessment, evaluate the risk of environmental lead for mottled ducks and other waterbirds.
(2) Model factors determining lead availability and resulting mottled duck species distribution.
(3) Develop a body condition model for predicting non-breeding season fat stores in mottled ducks.
(4) Analyze lead isotope ratios in soil, vegetation, and mottled duck blood samples to determine past and ongoing sources of lead deposition.
Progress and Results:
Currently, ongoing studies on the Texas Chenier Plain and Midcoast NWR Complexes are quantifying spatial
availability of lead pellets and lead concentrations in the soil, birds, and plants. In addition, that study
is also relating environmental lead concentrations with concentrations in blood of mottled ducks and other
species. This project combines all of those data in conjunction with unique analyses and data collection to
conduct a formal risk assessment of lead exposure for mottled ducks. We used interpolation techniques in ArcGIS
to produce maps for all NWRs that predict probability density functions of lead availability in all sampled
habitats used by mottled ducks. To determine potential sources of lead in these samples (i.e., natural or
anthropogenic), ratios of stable lead isotopes following the methods of Saint-Laurent et al. (2010) were
evaluated and modelled spatially as well. Using the model being developed for predicting the influence of
environmental lead on population demography of mottled ducks on the Texas Chenier Plain NWR, we have
additionally estimated the effects of available lead on mottled duck species distribution using MaxENT models,
which includes elucidation of landscape-level environmental covariates that may be contributing to lead "hot-spots"
and where areas of increased lead concentration may overlap with areas of high mottled duck usage. This
information may, in future, be used in conjunction with the non-breeding season fat index developed herein,
which produced an equation that will allow managers to predict fat from age class, mass, and a length metric.
Finally, these data will be used to conduct a cumulative risk assessment for lead exposure in these ecosystems,
determining the quantitative value of risk related to a concrete situation and a recognized threat. Risk
assessment consists of an objective evaluation of risk in which assumptions and uncertainties are clearly
considered and presented. Part of the difficulty of risk management is the measurement of both of the quantities
in which risk assessment is concerned - potential loss and probability of occurrence. The collected data
will provide these quantities. We will follow the EPA framework for ecological risk assessment, including
the following three general phases: (1) problem formulation, (2) analysis, and (3) risk characterization.
Kearns, B., P. Walther, W. Conway, and D. Haukos. 2014. A body condition index for non-breeding mottled ducks on the upper Texas Gulf Coast. Mottled Duck Symposium, Annual Conference of the Southeastern Association of Fish and Wildlife Agencies, Destin, Florida.
Brian Kearns, Stephen McDowell, Jena Moon, Elizabeth Rigby, and David Haukos. 2014. Identifying Landscape-level indicators of environmental contaminants that affect wildlife: a species distribution approach. Graduate Student Research Forum, Division of Biology, Kansas State University.
Kearns, B., P. Walther, and D. Haukos. 2014. Developing a body condition index for mottled ducks on the upper Texas Gulf Coast. Annual meeting of the Texas Chapter of The Wildlife Society, Austin, TX.
Kearns, B., S. McDowell, J. Moon, W. Conway, and D. Haukos. 2014. The legacy of lead: developing new methods for assessing lead contamination and wildlife exposure risks in Gulf Coast wetland habitats. Annual meeting of the Texas Chapter of The Wildlife Society, Austin, TX.
Kearns, B.V., McDowell, S., Moon, J., Rigby E., Haukos, D. 2014. Identifying landscape-level indicators of environmental contaminants that affect wildlife: a species distribution approach. Midwest Fish and Wildlife Conference, Kansas City, MO.
Kearns, B., D. Haukos, J. Moon, and E. Rigby. 2013. Species distribution in environmental decision-making: characterizing the efficacy of different models for use in habitat and wildlife management. Annual Meeting of the Society for Conservation GIS. Monterey, California.
Kearns, B., S. McDowell, J. Moon, and D. Haukos. 2013. Spatial analysis and ecological risk assessment for lead exposure in Gulf Coast waterfowl: does environmental lead represent an ecological trap? Annual Meeting of the Ecological Society of America. Minneapolis, Minnesota.