Abstract
North American populations of Black Vultures (Coragyps atratus) and Turkey Vultures (Cathartes aura) are steadily increasing and their ranges are expanding, and both species are common in southwest Florida. Success of these species in the United States has led to a rise in conflicts between humans and vultures and an increased need for effective vulture management. The occurrence of a problematic vulture roost at the Guadalupe Center of Immokalee, an early childhood education center in southwest Florida, was the focal point for a conflict between humans and vultures. The Center had up to 250-300 vultures on their property on a daily basis throughout most of the year. Vultures were observed perching on the Center building and surrounding structures, as well as using an associated retention pond for bathing and drinking, and adjacent mowed areas for social interactions. The primary objective of this study was to evaluate and determine site-specific solutions to a vulture roost location problem. In order to provide site-specific solutions to vulture roost problems, an understanding of vulture behavior and roost habitats used by vultures was essential to determine why the Guadalupe Center and areas surrounding it were attractive as a roost site. A secondary objective included the evaluation of management techniques that were initiated by the Center and were not site-specific. The overall goal was to evaluate vulture management techniques available, to reduce and disperse the vultures on the property, and reduce vulture-caused damage. The Guadalupe Center roost was compared to 26 vulture roosts in the United States. Of the 15 roosts observed in Florida, all were associated closely with water suggesting an importance of water to vulture roost location. Air currents, such as obstruction currents were present in over 70% of the roosts analyzed suggesting the importance of air current production to the proximity of roost sites. After the implementation of site-specific management techniques, the total population of vultures on the property decreased significantly. The total population of vultures did not decrease significantly after the initiation of non-site-specific management techniques. The areas of the property the vultures occupied differed between pre- and post-management. During roof-area management, vultures used the forested area north of the Center's property more often than expected and used the fences, pond, and building less often than expected, suggesting that site-specific management efforts were effective at dispersing the birds and reducing their impact on the property. Non-site-specific Center-initiated management did not have a long-term effect on the population; birds readily habituated to the strategies (deployment of vulture carcasses and pinwheels) and were observed more often than expected on all areas of the Center's property. The behavior of the birds at the Guadalupe Center did not differ significantly when comparing pre-management to any management strategy suggesting that management did not prevent vultures from engaging in behaviors essential for survival. Consistency and persistency are keys to effectively managing a problematic vulture roost. When the Center initiated non-site-specific management techniques, the vultures did not alter their use of the property. Since the management initiated by the Center was not consistent, vultures were able to readily habituate to the deterrents. Management of vultures should be a site-specific gradual process. Understanding behavior and roost habitat parameters is essential to developing effective management strategies for vultures.