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Measuring Stress Induced by Habitat Fragmentation and the Consequences for Populations of a Neotropical Migrant BirdEPA Grant Number: U916163
Title: Measuring Stress Induced by Habitat Fragmentation and the Consequences for Populations of a Neotropical Migrant Bird
Investigators: Morris-Porneluzi, Dana L.
Institution: University of Missouri - Columbia
EPA Project Officer: Cobbs-Green, Gladys M.
Project Period: January 1, 2003 through January 1, 2006
Project Amount: $108,193
RFA: STAR Graduate Fellowships (2003) Recipients Lists
Research Category: Fellowship - Terrestrial Ecology and Ecosystems , Academic Fellowships , Ecological Indicators/Assessment/Restoration
The overall objective of this research project is to determine whether predation-induced renesting causes stress and limits productivity and survival of Indigo Buntings (Passerina cyanea). The specific objectives of this research project are to: (1) measure predation rates between an unfragmented and fragmented landscape and between permanent and temporary habitat openings; (2) measure the effect of predation-induced renesting and landscape type on body condition and survival of female Indigo Buntings; and (3) measure the effect of maternal condition and landscape type on reproductive output. Habitat fragmentation studies have shown that a decline in reproductive success because of nest predation is an important factor limiting breeding populations of Neotropical migratory birds.
Data are collected from Indigo Buntings breeding in two habitat types (permanently disturbed openings: wildlife food plots and roadsides; temporary openings: even-aged and uneven-aged silvicultural openings) within a contiguously forested landscape in southeast Missouri and a fragmented landscape in central Missouri. Adults are captured at their nests when nestlings are 6 days old, at which time blood samples are collected from adults and nestlings (for corticosterone and DNA), individuals are measured (unflattened wing chord, tarsus, fat score), weighed (nearest 0.5 g), and banded with colored plastic and numbered leg bands. Body condition is determined by three indices: corrected mass, basal levels of plasma corticosterone, and hematocrit. Measures of reproductive output include clutch size, nestling condition, number of fledglings, and offspring sex ratio. Study sites are monitored throughout the breeding season to assess season-long reproductive output and to resight color-banded individuals for survival analysis. General linear models have been developed a priori (logistic, Poisson, or multiple linear regression) using biological variables (age, gender, number of nesting attempts, and distance to nearest neighbor) and environmental variables (habitat, landscape, predation rates, and interspecific brood parasitism rates) to assess their effects on body condition, reproductive output, and survival. I will use an information-theoretic approach to model selection and inference. Preliminary results from a contiguous forest show that female condition and reproductive output decline and basal levels of stress hormones increase with increased nesting attempts. Further work will determine whether female Indigo Buntings nesting in the fragmented landscape, where nest predation is more severe, suffer even higher energetic costs and lower survival. Ultimately, this research will determine if predation-induced renesting, brood parasitism, and other environmental factors elicit stress in female buntings and if this stress renders long-term effects on productivity, offspring quality, and adult survival.