An Ecological study of peregrine falcons (Falco peregrinus) at Lake Mead National Recreation Area, 2006-2010

• Main Author: Barnes, Joseph Graham
• Format: Thesis
• Language: unknown
• Published: University of Nevada, Las Vegas 2011
• Subjects: Falco peregrinus
• Online Access: https://dx.doi.org/10.34917/2396891; https://digitalscholarship.unlv.edu/thesesdissertations/1028

Peregrine Falcons (Falco peregrinus) represent an encouraging conservation biology success story in North America during the twentieth century. Their distribution and population size suffered major restrictions after the initiation of widespread application of the synthetic pesticide dichloro-diphenyl-trichloroethane (DDT) within the U.S. in the 1940s. The species was federally listed as endangered in the U.S. in 1969 and was then delisted in 1999 after DDT was banned in 1972. Herein, I present my ecological research of peregrines within Lake Mead National Recreation Area (LMNRA), concentrating on the years 2006-2010. This thesis is comprised of two chapters. In the first chapter, I describe the development, testing, and utilization of a novel call-broadcast survey protocol to quickly establish territorial occupancy of peregrines. The first chapter represents an article being prepared for publication in early 2011, co-authored with Jef R. Jaeger, and Daniel B. Thompson, therefore I use plural pronouns throughout this chapter to keep it consistent with the future publication work. In Chapter 2, I present results of my ecological studies of peregrines, focusing on known breeding population size, reproductive efforts, spatial distribution, foraging ecology, and competition. In the second chapter, I also report on aquatic bird abundance data I collected during a separate inventory and monitoring project conducted within LMNRA from 2004-2009. The aquatic bird data indicates seasonal shifts of potential prey in relation to observed and collected peregrine diet composition. The ecological results presented in Chapter 2 are consistent with a healthy, still-increasing, breeding population of peregrines. The seemingly recent expansion of breeding peregrines in areas far from water, with their depressed level of reproductive success, indicate a likely habitat quality gradient that may act to limit future population growth in the region. Most compelling, are the abundant availability of aquatic birds, and the high dietary composition of those birds at peregrine territories in close proximity to permanent water. Additionally, I document an increased number of intraspecific agonistic interactions over time, which indicates density-dependent factors may begin regulating peregrine numbers in highly suitable breeding habitat.