Browsing by Subject "nesting ecology"

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    Nesting Ecology Of Red-Headed Woodpeckers (Melanerpes Erythrocephalus) In Central Minnesota
    (2017-12) Yohannes, Brittney
    The nesting ecology of Red-headed Woodpeckers (Melanerpes erythrocephalus) has not been well studied anywhere in the species’ range, and the few studies that have addressed nest success have not monitored nests through the entirety of the nesting cycle. The objectives of my study include estimating nest success, documenting the extent and timing of brood reduction, and detailing developmental milestones of Red-headed Woodpeckers in central Minnesota. Using a cavity camera, I monitored 61 nests throughout the nesting cycle in 2014 and 2015 and estimated nest success (from initiation to fledging) was 78.0% with logistic exposure modeling. Daily nest survival rate was higher for nests initiated earlier in the season and for nests in cavities in dead branches, as supported by lowest Akaike information criterion (AIC) scores among candidate models. Of nests found during the egg laying stage, 100% experienced some amount of brood reduction. On average, nest contents were reduced by 48.1% between egg laying and fledging with reduction occurring at all points in the nesting cycle. I documented the ages at which nestlings reach developmental milestones, which had previously been lacking from the literature, and included images of nestlings at various ages in Appendix 1 so that future investigators can determine approximate nestling ages based on visual inspections. Adult Red-headed Woodpeckers on the study site were color banded, and using Program MARK, I analyzed mark-resighting data using a Cormack-Jolly-Seber (CJS) model to estimate annual apparent survival and detection probability. In the most parsimonious model, apparent survival varied by year and detection probability differed by sex. Annual apparent survival ranged from 0.38-0.70 among years, and averaged lower than other apparent survival studies. Estimated detection rates were high, and averaged 0.72 for females and 1.00 for males. A small sample size of banded pairs was used to analyze mate-fidelity across breeding seasons and I found a positive association between individuals pairing with new mates and failed nesting during the previous breeding season (Fisher exact test: p = 0.095). Although Red-headed Woodpecker populations have declined for decades, my study is one of the few to measure both fecundity and survival.