Eye size across avian lineages covaries with participation in a specialized foraging behavior
Data files
Nov 28, 2025 version files 2.26 MB
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README.md
1.78 KB
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Supplement.zip
2.26 MB
Abstract
Foraging ecology and visual ability are often strongly related across animal lineages, as many organisms identify food sources by sight. Birds particularly rely upon vision to seek out prey or other food items, leading to the correlated evolution of eye size and foraging behavior. Here, we focus on a specialized foraging tactic termed ‘disturbance foraging’, whereby a responding species exploits prey items flushed by a disturbing species. Using global databases of disturbance-responder species and eye size measurements from museum specimens, we tested the prediction that relative eye size accounting for body mass allometry (a proxy for visual acuity and sensitivity) would be larger in disturbance foragers that require enhanced visual performance to locate escaping prey (N = 463) compared to other species (N = 2840). As predicted, disturbance foragers possessed larger relative eye sizes. Residual eye size was correlated with a gradient in avian foraging behavior, such that species with the smallest and largest relative eye sizes were near-sighted and far-sighted non-disturbance foragers, respectively, while disturbance foragers had intermediate eye sizes. Birds appeared to invest similarly in acuity and sensitivity in relation to foraging behavior as measured by their respective anatomical proxies (residual axial length (AL) and cornea diameter (CD)), although there was partial evidence that some species groups invested more in acuity based upon the eye shape ratio (CD/AL). These patterns imply that even highly specialized behavioral tactics may evolve in concert with their respectively linked neurological and sensory systems.
Dataset DOI: 10.5061/dryad.kkwh70shq
Description of the data and file structure
Files and variables
File: Supplement.zip
Description:
The archived folder includes:
(1) Species x trait matrix including all variables informing the analysis ("traits_all.csv") using the Jetz et al. (2012) Nature taxonomy:
- species_jetz: species name based on the Bird Tree from Jetz et al. (2012) Nature
- family_jetz: family name based on the Bird Tree from Jetz et al. (2012) Nature
- group: species is terrestrial, aquatic, or a raptor
- hab.bin: species specializes in forests (1) or does not specialize in forests (0)
- for.bin: stereotypic foraging behavior - near-sighted/myopic (0) vs. far-sighted/hyperopic (1)
- dist.bin: displays disturbance foraging behavior (1) or does not (0)
- Diet.Carn: From Elton Traits (Wilman et al. 2014). Sum of invertebrate and vertebrate foraging percentages. Equals the percent of diet composed of invertebrates and vertebrates (non-plant)
- Trophic.Level: trophic group based on the Avonet database (Tobias et al. (2024) Ecology Letters)
- Trophic.Niche: trophic niche based on the Avonet database (Tobias et al. (2024) Ecology Letters)
(2) Phylogeny used for analyses (see manuscript for details) ("MCC_AllBirdsHackett1.tre")
(3) R script for analyses ("distfor_FINAL.R")
External Files
The eye size data can be accessed here: https://datadryad.org/dataset/doi:10.5061/dryad.3xsj3txq7.
Code/software
All analyses were done in R 4.4.2. All files required to run the code are referenced in this Read Me file.
