New World vultures as environmental sentinels
To measure effectively the penetration of ecological contaminants requires sensitive monitoring tools. Wildlife at high trophic levels, are often used to monitor the health of an ecosystem. Birds especially have served in this role, including eagles and vultures in Eurasia, Swainson’s Hawks in Argentina and suites of raptors in Canada and Italy. These species often are chosen as sentinels because of their sensitivity to environmental contaminants and after their populations have declined. As such, many of these species may be poor models for environmental monitoring because their population declines often serve as “trailing” rather than “leading” indicators of ecological change.
In this research we take a new approach to the use of birds as ecological sentinels, one based on the framework from the successful models applied to sentinel species monitored in marine systems. Rather than using species that are highly susceptible to contaminants, we will use species that effectively harbor contaminants they encounter in the wild but while being relatively resistant to their effects.
We focus our effort on the two most common vultures in the world: turkey vultures (Cathartes aura) and black vultures (Coragyps atratus). Both species are widespread in the Americas and both appear to be highly resistant to heavy metal poisoning. As such, these attributes form the basis of a stable sentinel for monitoring environmental contaminant levels before they become problematic and severely impact wildlife and ecosystems. Using novel individual aging techniques, we will also link contaminant levels in blood and tissue to age-specific demography of birds, thus opening up new avenues for both management and science.
Specifically, our work is geared to:
1) develop a novel conceptual model for environmental monitoring, based on a monitoring tool (New World vultures) that faithfully records the presence of environmental contaminants but that is relatively robust to mortality from their presence;
2) use this conceptual model to develop monitoring protocols for heavy metals specific to these species;
3) implement a large-scale region-wide environmental monitoring program that utilizes the conceptual framework and specific protocols developed above, to evaluate levels of heavy metals that may impact wildlife in natural ecosystems.
Graduate students Shannon Behmke and Julie Mallon are conducting research on one aspect of this problem and the work is in collaboration with Dr. Jesse Fallon of Cheat Lake Animal Hospital and Virginia Tech University and Keith Bildstein of Hawk Mountain Sanctuary Association.