Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

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

Hulthén, Kaj LU ; Martel, Cornelia ; Nilsson, Dan E. LU ; Brönmark, Christer LU ; Nilsson, P. Anders LU orcid ; Langerhans, R. Brian ; Hansson, Lars Anders LU orcid ; Brodersen, Jakob LU ; Baktoft, Henrik LU and Skov, Christian LU (2025) In Journal of Animal Ecology 94(5). p.874-883
Abstract

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, antipredator benefits or navigational requirements. Yet, it remains elusive whether variations in eye morphology and corresponding visual capabilities are associated with migratory... (More)

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, antipredator 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 (also known as 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 field study tracking the migration decisions of over 2000 individuals in two different lake systems, we found that relative pupil size was positively associated with individual migration propensity. Computational simulations of the visual ecology associated with the observed differences in pupil size show that migrants have an extended visual detection range and that the performance gain is most pronounced for viewing small targets (e.g. planktonic prey) under low-light conditions. These results suggest that the larger pupils of migrants represent an adaptation for increased foraging efficiency to aid in the accumulation of critical pre-migratory energy reserves. Together, our anatomical and functional findings provide new perspectives on visual system design in relation to individual-level migratory decision-making.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
animal migration, eye size, partial migration, pupil size, vision, visual ecology, visual range, visual system design
in
Journal of Animal Ecology
volume
94
issue
5
pages
10 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:85219638133
  • pmid:40017146
ISSN
0021-8790
DOI
10.1111/1365-2656.70015
language
English
LU publication?
yes
id
e45ff983-4875-428d-9bba-d850386964ff
date added to LUP
2025-06-26 10:45:00
date last changed
2025-07-24 14:46:11
@article{e45ff983-4875-428d-9bba-d850386964ff,
  abstract     = {{<p>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, antipredator 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 (also known as 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 field study tracking the migration decisions of over 2000 individuals in two different lake systems, we found that relative pupil size was positively associated with individual migration propensity. Computational simulations of the visual ecology associated with the observed differences in pupil size show that migrants have an extended visual detection range and that the performance gain is most pronounced for viewing small targets (e.g. planktonic prey) under low-light conditions. These results suggest that the larger pupils of migrants represent an adaptation for increased foraging efficiency to aid in the accumulation of critical pre-migratory energy reserves. Together, our anatomical and functional findings provide new perspectives on visual system design in relation to individual-level migratory decision-making.</p>}},
  author       = {{Hulthén, Kaj and Martel, Cornelia and Nilsson, Dan E. and Brönmark, Christer and Nilsson, P. Anders and Langerhans, R. Brian and Hansson, Lars Anders and Brodersen, Jakob and Baktoft, Henrik and Skov, Christian}},
  issn         = {{0021-8790}},
  keywords     = {{animal migration; eye size; partial migration; pupil size; vision; visual ecology; visual range; visual system design}},
  language     = {{eng}},
  number       = {{5}},
  pages        = {{874--883}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Journal of Animal Ecology}},
  title        = {{Will I stay or will I go? Eye morphology predicts individual migratory propensity in a partial migrant}},
  url          = {{http://dx.doi.org/10.1111/1365-2656.70015}},
  doi          = {{10.1111/1365-2656.70015}},
  volume       = {{94}},
  year         = {{2025}},
}