Avian Ecology
SURVIVAL OF MALE EASTERN WILD TURKEYS ACROSS A GRADIENT OF HUNTING PRESSURE
SREL Collaborators: Jim Beasley, Cody Tisdale, James Martin, Allie Rakowski
Outside Collaborators: Mike Chamberlain (UGA)
Wild turkeys are a popular game species across their range in North America. However, current population declines in the southeastern U.S. are not well understood and thus are a cause for concern for management agencies. To better understand recent population declines, we must understand the effects harvest has on population demographics such as survival. The Savannah River Site provides a unique opportunity to study a population of wild turkey with little to no hunting pressure We are deploying transmitters on adult male turkeys to estimate adult gobbler survival. We will then compare these data to survival data collected from hunted populations of turkeys across the southeast.
CONTAMINANT EXPOSURE IN EASTERN WILD TURKEYS AND RISKS TO HUNTERS
SREL Collaborators: Jim Beasley, Cody Tisdale, James Martin, Chris Leaphart
Due to their popularity as a game species, it is important to understand what contaminants wild turkeys may be exposed to in the environment, and in turn potential exposure risks to hunters. On the Savannah River Site (SRS) several areas exist with known radiocesium and trace element contamination, which is bioavailable to local wildlife. For this study we are capturing and sampling turkeys inhabiting contaminated areas on the SRS as well as nearby control areas for trace elements and radiocesium. We also are attaching GPS transmitters to captured turkeys to observe how often they use contaminated areas of site and how this influences contaminant uptake. From these data we will be able to determine whether wild turkeys inhabiting contaminated environments accumulate these contaminants within consumable tissues. These data will be used to inform potential risks to hunters.
SPATIAL ECOLOGY OF BLACK AND TURKEY VULTURES IN THE SOUTHEASTERN USA
SREL Collaborators: Jim Beasley, Larry Bryan, Amanda Holland, Mike Byrne, Gene Rhodes
Outside Collaborators: Travis DeVault (APHIS)
Black (Coragyps atratus) and turkey vultures (Cathartes aura) are scavengers commonly associated with areas of human development. Because vultures utilize anthropogenic resources frequently, they often face many hazards associated with human landscapes, such as collisions with airplanes, vehicles, wind turbines, and other structures (bird-strikes). The economic costs associated with bird-strikes are substantial and the problem is intensified with the fact populations of these species have been increasing in recent decades. However, this trend is in sharp contrast to the severe declines observed for vulture populations globally in recent years. The ecological implications of global vulture declines are considerable; vultures are capable of detoxifying pathogens incubated in rotting carcasses and play a significant role nutrient cycling. In the absence of vultures, transmission rates of infectious disease accelerate among mammalian scavengers. Considering the important ecological role of vultures and issues related to conflicts in human landscapes, improving knowledge of vulture spatial ecology will benefit conservation of these ecologically important species and provide managers with enhanced tools for predicting vulture presence and ultimately reducing economic costs of bird-strikes and other conflicts.
MECHANISMS OF COEXISTENCE IN TWO SYMPATRIC OBLIGATE AVIAN SCAVENGERS; BLACK AND TURKEY VULTURES
Despite high levels of dietary overlap, black and turkey vultures often coexist in large numbers. The focus of this research is in elucidating the mechanisms that allow for the sympatric occurrence of these obligate scavengers. Morphological differences between the species should precipitate behavioral characteristics that promote differentiation in foraging habitat, prey composition and activity patterns. For example, the lower wing loading of turkey vultures should enable them to expend less energy and fly in a more energetic fashion in a wider range of weather and atmospheric conditions than black vultures. Thus, turkey vultures may be expected to be able to actively search for food at times when black vultures are not able to foraging in an energetically efficient manner. Turkey vultures have well developed olfactory capabilities which they use to locate food, whereas black vultures are reliant on sight. Thus, turkey vultures should be able to locate small forage items, as well as carcasses under canopy cover in a more efficient manner than black vultures. While turkey vultures are commonly considered solitary foragers, black vultures are aggressive and highly gregarious. As a result, flocks of black vultures are able to displace turkey vultures from carcasses.
Specifically, we are testing the following hypotheses:
1. Black vulture flight behavior is more influenced by the occurrence of favorable atmospheric conditions (such as those that promote thermal formation), than turkey vultures.
2. Turkey vultures are able to locate small prey items faster than black vultures.
3. Turkey vultures are able to locate prey items under canopy cover faster than black vultures.
We are testing these hypotheses using a combination of data from camera traps placed at carcasses of different sizes in a variety of habitats across multiple seasons, and high resolution movement data collected by solar powered GPS units attached to a sample of individuals of both species.