Will I stay or will I go? Eye morphology predicts individual migratory propensity in a partial migrant

Billions of animals undertake migratory journeys every year, with powerful consequences for ecosystem dynamics. Key behaviours that enable successful migration are often guided by the visual system. The amount and quality of information that animals can extract from visual scenes are directly related to structural eye size — larger eyes can house larger pupils, enhancing light-gathering capacity and vision by improving visual acuity and contrast sensitivity. Migration should exert strong demands on individual visual performance, for example via foraging, anti-predator benefits or navigational requirements. Yet, it remains elusive whether variations in eye morphology and corresponding visual capabilities are associated with migratory propensity. Here, we capitalize upon intra-population variation in migratory propensity (a.k.a. partial migration) in roach, a common freshwater fish, to directly test for migration-associated variation in image-forming eyes within a species. In a multi-year..., Data for this study consists of measurements of relative eye and pupil size extracted from digital photographs, as well as migration propensities of individual roach (Rutilus rutilus) migrating between lakes and connected streams. Data was collected for multiple years and from two different lakes (Loldrup and Søgård Sø) using passive biotelemetry with stationary and continuously operating antenna arrays., , # Will I stay or will I go? Eye morphology predicts individual migratory propensity in a partial migrant

[https://doi.org/10.5061/dryad.dncjsxm9d](https://doi.org/10.5061/dryad.dncjsxm9d)

## Description of the data and file structure

Data Collection Methods:

Data for this study consists of measurements of relative eye and pupil size extracted from digital photographs, as well as migration propensities of individual roach (Rutilus rutilus) migrating between lakes and connected streams. Data was collected for multiple years and from two different lakes (Loldrup and Søgård Sø) using passive biotelemetry with stationary and continuously operating antenna arrays.

See text for further details.
### Files and variables

#### File: Dryad\_Eyes\_JAE.xlsx

**Description:** Data used to test for associations between eye morphology and individual migration propensity as well as to perform computational simulations of the visual ecology associated with observed differences in pupil size.

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