Work elsewhere has shown that songbird development is flexible in the face of predation risk. Another major selective pressure on nestlings and their parents is brood parasitism by Brown-headed Cowbirds. What are the direct and indirect effects of parasitism risk on nestling development and parental allocation?
This is the topic of Sarah Winnicki’s MS research. She studyied the effects of Brown-headed Cowbird (Molothrus ater) brood parasitism on the growth and development of nestlings of three grassland-obligate host species: Grasshopper Sparrow (Ammodramus savannarum), Dickcissel (Spiza americana), and Eastern Meadowlark (Sturnella magna). Using a combination of nest cameras, nestling measurements, and comparative analyses, we related skeletal growth, development (eyes opening, movement capacity), feather growth, and fat/muscle gain of the host nestlings to parasitism, predation, and parental feeding behavior. She also examined how being raised in the nests of different hosts affected cowbird nestling development. Sarah defended her thesis over the summer of 2019 and is preparing two manuscripts for publication. Stay tuned for the punchlines…!