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Research in Behavior, Ecology, and Physiology

Avian brood parasitism is a reproductive strategy in which birds lay their eggs into the nest of another bird, leaving the host to care for the parasitic offspring. Obligate avian brood parasites, birds which never care for their own young, represent 1% of the world's bird species. I am interested in the interactions between one North American obligate brood parasite, the Brown-headed Cowbird (Molothrus ater), and the hosts that it parasitizes. Most of my research involves one host of the cowbird, the prothonotary warbler (Protonotaria citrea), which always accepts cowbird eggs and offspring. By looking into social behavior, recognition, hormones, and more, I hope to better understand how brood parasites choose their hosts and how hosts are affected by brood parasites themselves.

Recent Projects:


Fledging in parasitized host nestlings

Fledging is an important milestone in a bird's life with repercussions on future survival and fitness. Competition between nestlings is one aspect of the nest envionment that may affect fledging phenology.  Recently published in Behavioral Ecology and Sociobiology, we experimentally parasitized nests with a cowbird (heterospecific parasite), warbler (conspecific parasite), or left non-parasitized as a control, to determine how parasitism status affects fledging phenology of hosts and how these fledging characteristics interact.


Host parent responses to parasitic nestling alarm calls

Many species of nestling birds give alarm calls when disturbed to alert their parents of danger so that parents may distract or attack predators. Cowbirds are no exception to this, but nothing was known about parasitic nestling alarm calls and if host parents that accept parasitic young learn these calls. Recently published in Animal Cognition, we used playbacks of nestling alarm calls to determine if adult warblers respond similarly to warbler and cowbird nestling alarm calls, and if this changes with parasitism experience.



Physiological responses of host nestlings to parasitism

It is well known that brood parasitism negatively affects the growth and survival of many species of host nestlings, but the effect that parasites have on the physiology of host nestlings is less well known. Published in Oecologia, our study on prothonotary warbler host nestlings parasitized by brown-headed cowbirds investigates how cowbirds affect the plasma corticosterone levels (a hormone involved in the stress response) and immune responses of these host nestlings.


Recognition of foreign eggs in acceptor hosts

Acceptance of parasitic eggs by hosts does not necessarily mean a lack of recognition. Hosts may choose not to reject parasitic eggs for a variety of reasons - such as physical constraints or enforcement of acceptance by mafia behaviors. Other methods can help elucidate recognition of parasitic eggs in hosts that accept. In our study, we looked at corticosterone responses (a hormone involved in stress response) of incubating female warblers in response to mimetic and non-mimetic model eggs.

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Signal detection theory

Signal detection theory is useful to model when an organism should accept or reject another organism or resource depending on the relative costs of acceptance errors, rejection errors, and rate of encounter. It has been widely applied across many biological fields, and in this special issue, we evaluated the use of SDT across subfields and study species, updated these models, and provided new data SDT in diverse systems.



Lateralization in a brood parasite host

To understand how hosts are able to identify and reject brood parasitic eggs, it is essential to determine how hosts view their clutches. In many ecological systems, eye use has shown to be lateralized, meaning that function is specialized  left vs. right hemispheres of the brain. Published in Biology Letters, we studied American robins, a host of the brown-headed cowbird, to determine if they preferentially use one eye over the other to recognize and reject foreign eggs in their nest.

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