The effects of vehicle passage on foraging behavior of wading birds

Abstract

Protected lands contain a large proportion of existing critical habitat for many wading bird species, but human activities in these areas have the potential to adversely effect these species. The effects of passing vehicles on the foraging behavior of wading birds was studied using observational and experimental methods at the Merritt Island National Wildlife Refuge near Titusville, Florida. Foraging wading birds were more likely to be disturbed when vehicles slowed or stopped adjacent to them, than when vehicles continued driving by. In an area with a high rate of human visitation, some individual wading birds responded more strongly to passing vehicles than did others, suggesting that some were habituated to disturbance. Experimental disturbance by a vehicle caused a significant depression in the foraging rates of the Snowy Egret (Egretta thula) and the Great Egret (Ardea alba) and non-significant reductions in foraging rates in the Tricolored Heron (E. tricolor). Nineteen percent of the birds flushed following disturbance. The proximity of the disturbance vehicle influenced the probability of flushing in a species-specific manner with the Tricolored Heron being the most sensitive, the Great Egret intermediate, and the Snowy Egret the least sensitive. Recommendations to managers include concentrating ecotourism in certain areas and educating ecotourists about the effects of their behavior on wading birds.