I am a behavioral ecologist interested in the mating systems, breeding biology, and conservation of birds. My specific areas of research interest include female extra-pair mating tactics, evolution of extra-pair mating systems, nest defense and nest predation, brood parasitism and the impacts of urbanization on birds.
Extra-pair Mating Behavior
Although most bird species form monogamous pair bonds, the use of DNA fingerprinting techniques have shown that many species engage in copulations outside the pair bond. This behavior is referred to as extra-pair mating. My research focus over the last ten years has been on the evolution of extra-pair mating systems in birds through study of the variation in levels of extra-pair mating among species and the benefits and costs of this behavior to males and females. Currently, my students and I have been studying the mating strategies of two common species in east Texas , the Carolina Wren ( Thryothorus ludovicianus ), which exhibits no extra-pair mating and the Northern Cardinal ( Cardinalis cardinalis ), a species that engages in extra-pair mating. Through quantifying both behavioral strategies (e.g. parental care) and ecological factors (e.g. nesting densities) for both species, we hope to understand the selective pressures for and against the evolution of extra-pair mating behavior in these species as well as other songbirds.
The main cause of nest failure in songbirds is predation. Nest defense involves one or more behaviors (e.g. alarm calls, displays, dives, strikes) used by parents to increase offspring survival when faced with a predator. However, nest defense can be costly, therefore parents are expected to make an optimal compromise between their own safety and that of their young. Costs may vary between the sexes. In many species of birds females defend the nest more than males, whereas in other species males contribute more to nest defense. Several hypotheses have been proposed to explain differences among species relating to differential costs and benefits to the sexes. I am currently investigating several of these hypotheses using a comparative method approach.
Effects of Urbanization on Nesting Success of Songbirds
A new area of study for me involves quantifying songbird nest predation in habitats with varying levels of urbanization. Urbanization involves modification of natural landscapes into human dominated landscapes. Levels of landscape modification can vary from moderate (e.g. parks, golf courses) to severe (e.g. housing developments). Research will involve quantifying predation rates and identifying predators of both artificial nests and natural nests of songbirds in different habitats.
Current Graduate Students:
Photo Guadalupe Quiroz
Project title: Recognition of alarm calls by nestling Carolina Wrens
Photo Sian Escobar
Project title: Genetic monogamy in the Carolina Wren
Photo Anne-Marie Prouty
Project title: Nest predation on natural and artificial songbird nests in two habitats
Former Graduate Students:
Sheena Humbird (2006)
Project title: Extra-pair mating tactics in the Northern Cardinal (Cardinalis cardinalis): a test of the ‘constrained female hypothesis'
Kelly D'Orazio (2003)
Project title: Nest defense in the Carolina Wren
Rebecca Bodily (2002)
Project title: Mate guarding and extra-pair paternity in the Northern Mockingbird
Hope McGaha (2000)
Project title: Effects of dual species brood parasitism on the nesting success of Northern Cardinals