DOI: 10.5061/dryad.n02v6wx09
title: Individual repeatability of avian migration phenology: a systematic review and meta-analysis

description: Changes in phenology and distribution are being widely reported for many
 migratory species in response to shifting environmental conditions.
 Understanding these changes and the situations in which they occur can be
 aided by understanding consistent individual differences in phenology and
 distribution and the situations in which consistency varies in strength or
 detectability. Studies tracking the same individuals over consecutive
 years are increasingly reporting migratory timings to be a repeatable
 trait, suggesting that flexible individual responses to environmental
 conditions may contribute little to population-level changes in phenology
 and distribution. However, how this varies across species and sexes,
 across the annual cycle and in relation to study (tracking method, study
 design) and/or ecosystem characteristics is not yet clear. Here, we take
 advantage of the growing number of publications in movement ecology to
 perform a phylogenetic multilevel meta-analysis of repeatability estimates
 for avian migratory timings to investigate these questions. Of 2,433
 reviewed studies, 54 contained suitable information for meta-analysis,
 resulting in 177 effect sizes from 47 species. Individual repeatability of
 avian migratory timings averaged 0.414 (95% confidence interval: 0.3–0.5)
 across landbirds, waterbirds and seabirds, suggesting consistent
 individual differences in migratory timings is a common feature of
 migratory systems. Timing of departure from the non-breeding grounds was
 more repeatable than timings of arrival at or departure from breeding
 grounds, suggesting that conditions encountered on migratory journeys and
 outcome of breeding attempts can influence individual variation.
 Population-level shifts in phenology could arise through individual
 timings changing with environmental conditions and/or through shifts in
 the numbers of individuals with different timings. Our findings suggest
 that, in addition to identifying the conditions associated with individual
 variation in phenology, exploring the causes of between-individual
 variation will be key in predicting future rates and directions of changes
 in migratory timings. We, therefore, encourage researchers to report the
 within- and between- individual variance components underpinning the
 reported repeatability estimates to aid interpretation of migration
 behaviour. In addition, the lack of studies in the tropics means that
 levels of repeatability in less strongly seasonal environments are not yet
 clear.
description: The methods for collecting and
 analysing the data are presented in the manuscript and supporting
 information.
description: Here, we share the systematic search
 results, data, and code from Franklin et al. (2022). Individual
 repeatability of avian migration phenology: a systematic review and
 meta-analysis. Journal of Animal Ecology. You can also find all materials
 on GitHub at https://github.com/kirstyfranklin/Avian_migration_meta-analysis. WoS_tidy.csv: A tidied version of the Web of Science search results. scopus_tidy.csv: A tidied version of the Scopus search results. Rayyan_tidy_with_decisions.csv: A tidied version of the output from Rayyan abstract screening software. This includes the decisions made from abstract screening. Full_text_screening.csv: List of full texts screened, decision of whether to include or exclude, and reasons for excluding. meta-analysis_data-2022.csv: data extracted from the papers and used in the analyses. This can also be found in Table S1 in the Supporting Information. meta-analysis_descriptions.csv: Full description of the extracted data. This can also be found in the Supporting Information. Hackett.tre: Phylogenetic tree used in our analyses (provided by Benedikt Holtmann). Franklin_etal_Supporting_Information.html: Code for the exploration, processing and analyses in a user-friendly, self-contained knitted format. We recommend the reader to navigate this document if interested in the code. Franklin_etal_Supporting_Information.Rmd: R markdown file containing the processing and analyses code (to build the above .html file). Missing values are indicated as "NA" in all datasets.