Sex and Geographic Variation in Grey-Faced Petrel (<i>Pterodroma gouldi</i>) Morphometrics

Bourgeois, Karen; Dromzée, Sylvain; Welch, Jemma R.; Russell, James C.

doi:10.1675/063.040.0206

Cited by 5 publications

(2 citation statements)

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“…Chick wings and tarsi grow consistently across a season and provide a conservative measure of chick condition over an extended period of nourishment. In contrast, chick body masses fluctuate significantly based on time since last provisioning, and thus are a less reliable measure of long-term chick condition, until they grossly differ from growth curves [25].…”

Section: Discussionmentioning

confidence: 99%

“…Around egg hatching and chick fledging, weekly visits were increased to twice a week to obtain more accurate estimates of these dates. We took five morphological measurements of chicks at each inspection: body mass (grams) using a 1000-g Pesola scale, maximum flattened chord wing length (mm) using a steel butt-stopped rule, and false tarsus length (mm), bill culmen length (mm) and bill depth at nostrils (mm) using a pair of calipers (see [25]), although bill measurements were not subsequently used in analysis. From 2011 to 2013, we also measured unmonitored chicks on Te Hāwere-a-Maki once only at the end of the breeding season as a control to determine whether our regular handling of chicks may have negatively affected their growth rates.…”

Section: Field Methodsmentioning

confidence: 99%

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Climatic Effects on Grey-Faced Petrel (Pterodroma gouldi) Chick Growth and Survival

Russell

Welch

Bourgeois

et al. 2022

Birds

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Grey-faced Petrels (Pterodroma gouldi) are a colonial burrowing seabird predominantly nesting on offshore islands of the upper North Island of New Zealand. We studied their annual breeding biology and the impact of Southern Oscillation Index climatic effects by measuring colony productivity and chick growth rates from 2011 to 2015 on Te Hāwere-a-Maki as unfavorable warmer La Niña conditions changed to favorable cooler El Niño conditions. Across all five years, annual chick hatching consistently occurred within a one-week period at the end of August but fledging variably occurred over a three-week period following Christmas. Because ship rats are pest controlled on Te Hāwere-a-Maki, we found only a slight reduction in breeding success with nearby predator-free islands. However, chick growth and fledging rates were significantly higher under El Niño conditions occurring towards the end of our study, rather than La Niña conditions at the start of our study. Our regular handling of chicks for monitoring had no discernible impact compared to a set of control chicks. The combined impacts of annual variation in predation and climate mean the Grey-faced Petrel colony on Te Hāwere-a-Maki maintains a constant population size of around 100 burrows.

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Section: Discussionmentioning

confidence: 99%

Section: Field Methodsmentioning

confidence: 99%