Data from: Parental overproduction allows siblicidal bird to adjust brood size to climate-driven prey variation
Abstract
Parental overproduction is hypothesized to hedge against uncertainty over food availability and stochastic death of offspring and to improve brood fitness. Understanding the evolution of overproduction requires quantifying its benefits to parents across a wide range of ecological conditions, which has rarely been done. Using a multiple hypotheses approach and 30 years of data, we evaluated the benefits of overproduction in the Blue-footed booby, a seabird that lays up to three eggs asynchronously, resulting in an aggressive brood hierarchy that facilitates the death of last-hatched chicks under low food abundance. Results support the resource-tracking hypothesis, as low prey abundance (estimated from sea surface temperature and chlorophyll-a concentration) led to rapid brood reduction. The insurance hypothesis was supported in broods of three, where last-hatched chicks’ survival increased after a sibling’s death. Conversely, in broods of two, results suggested that parents abandoned last-hatched chicks following first-hatched chicks’ deaths. No direct evidence supported the facilitation hypothesis: the presence of a last-hatched chick during development did not enhance its sibling’s fitness in the short or long term. The value of last-hatched offspring to parents, as “extra” or “insurance” varied with indices of food abundance, brood size, and parental age. Ninety percent of overproduction benefits came from enabling parents to capitalize on favorable conditions by fledging additional offspring. Our study provides insight into the forces driving overproduction, explaining the adaptiveness of this apparently wasteful behavior and allowing us to better predict how overproduction’s benefits might be modified by ocean warming.
README: Parental overproduction allows siblicidal bird to adjust brood size to climate-driven prey variation
Climatic and biological data used in the article.
Description of the data and file structure
The data is a zip file containing two Excel files
File list:
- DATA.xlsx
- ReadME_DATA.xlsx
File descriptions
The DATA.xlsx file contains all the data utilized in the article. It comprises 16 sheets, each containing a distinct set of data utilized for the analyses. Correspondingly, the ReadME_DATA.xlsx file mirrors this structure, also consisting of 16 sheets. Each sheet in the ReadME_DATA.xlsx file offers a description of the columns' meanings within the associated dataset, along with a brief explanation of the data provided in that particular dataset.
"NA" stands for non-available values when climatic and oceanic data were missing, or biological data could not be registered.
Methods
Every year, from 1989 to 2019, all nests in our study areas (2.6 ha) were monitored over the breeding season from February through July. During nest inspections, every 3-6 days, breeders were identified and sexed based on vocal dimorphism (females grunt, males whistle), and chicks were marked with colored plastic bands after hatching, then measured (ulna length, mm), weighed and fitted with numbered steel bands at 70 days, when they fledged.