Bird species subjected to more variable environments should have greater phenotypic plasticity than those that are more restricted to specific habitat types leading to the expectation that migratory birds should be relatively more plastic than resident birds. For each bird species, we collected the following life-history data: Species body mass and habitat breadth were extracted from Sayol et al., 2020 while diet breadth, life span (max) were extracted from Sayol et al., 2018 and migratory status (resident or sedentary, partially migratory or migratory) was extracted from Tobias and Pigot, 2019. The main type of diet for each species was extracted from Wilman et al., 2014.

We calculated the mean, maximum, minimum and standard deviation of flight initiation distance for each bird species with > 5 observations, to avoid potential overinflated standard deviation estimates from species with only a few observations. Then, for each species, we calculated our metric of plasticity based on the coefficient of variation (CV) of FID. Because this is a ratio of the variance to the mean, plasticity is independent of body size.

Following standardised methods, trained observers identified a non-alarmed bird (i.e. resting or foraging) and directly approached at a measured pace of 0.5 m/s. With such data, we processed and estimated a surrogate of behavioural plasticity. The behavioural plasticity was calculated for each bird species, based on the coefficient of variation (CV) of FID.

The dataset include the following variables:

Variable Description

Species Scientific name of species

StartingDistance.mean Mean value of the starting distance measured during the approach to the bird

StartingDistance.sd Standard deviation value of the starting distance measured during the approach to the bird

StartingDistance.min Minimum value of the starting distance measured during the approach to the bird

StartingDistance.max Maximum value of the starting distance measured during the approach to the bird

FID.mean Mean value of the flight initiation distance measured during the approach to the bird

FID.sd Standard deviation value of the flight initiation distance measured during the approach to the bird

FID.min Minimum value of the flight initiation distance measured during the approach to the bird

FID.max Maximum value of the flight initiation distance measured during the approach to the bird

FID.count Number of flight initiation distance measures collected for each avian species

relative.sdFID Measure of behavioural plasticity calculated for each bird species. 

Plasticity  coefficient of variation (CV) of FID.

dif.SDFID "=StartingDistance.mean - FID.mean"

Country Country where the data were collected

Body.mass.g Species mean body mass, extracted from Sayol F, Sol D, Pigot AL. 2020 Brain size and life history interact to predict urban tolerance in birds. Front. Ecol. Evol. 8, 58. (doi:10.3389/fevo.2020.00058)

Main.diet The primary type of diet item used by each species, extracted from Wilman H, Belmaker J, Simpson J, de la Rosa C, Rivadeneira MM, Jetz W. 2014 EltonTraits 1.0: Species-level foraging attributes of the world’s birds and mammals. Ecology 95, 2027. (doi:10.1890/13-1917.1)

Lifespan.max Maximum recorded longevity for each species, extracted from Sayol F, Downing PA, Iwaniuk AN, Maspons J, Sol D. 2018 Predictable evolution towards larger brains in birds colonizing oceanic islands. Nat. Commun. 9, 2820. (doi:10.1038/s41467-018-05280-8)

MigratoryBehaviour Classification of species in "Sedentary", "PartiallyMigratory" or "Migratory", extracted from Tobias, J.A., Pigot, A.L., 2019. Integrating behaviour and ecology into global biodiversity conservation strategies. Philos. Trans. R. Soc. B Biol. Sci. 374, 20190012. https://doi.org/10.1098/rstb.2019.0012

Habitat.Breadth Degree of habitat specialization, extracted from Sayol F, Sol D, Pigot AL. 2020 Brain size and life history interact to predict urban tolerance in birds. Front. Ecol. Evol. 8, 58. (doi:10.3389/fevo.2020.00058)

Diet.Breadth Degree of diet specialization, extracted from Sayol F, Downing PA, Iwaniuk AN, Maspons J, Sol D. 2018 Predictable evolution towards larger brains in birds colonizing oceanic islands. Nat. Commun. 9, 2820. (doi:10.1038/s41467-018-05280-8)Species subjected to more variable environments should have greater phenotypic plasticity than those that are more restricted to specific habitat types leading to the expectation that migratory birds should be relatively more plastic than resident birds. We tested this comparatively by studying variation in flight initiation distance (FID), a well-studied antipredator behaviour.