title: Laterality and flight: concurrent tests of side-bias and optimality in flying tree swallows.
abstract: Behavioural side-bias occurs in many vertebrates, including birds as a result of hemispheric specialization and can be advantageous by improving response times to sudden stimuli and efficiency in multi-tasking. However, behavioural side-bias can lead to morphological asymmetries resulting in reduced performance for specific activities. For flying animals, wing asymmetry is particularly costly and it is unclear if behavioural side-biases will be expressed in flight; the benefits of quick response time afforded by side-biases must be balanced against the costs of less efficient flight due to the morphological asymmetry side-biases may incur. Thus, competing constraints could lead to context-dependent expression or suppression of side-bias in flight. In repeated flight trials through an outdoor tunnel with obstacles, tree swallows (Tachycineta bicolor) preferred larger openings, but we did not detect either individual or population-level side-biases. Thus, while observed behavioural side-biases during substrate-foraging and copulation are common in birds, we did not see such side-bias expressed in obstacle avoidance behaviour in flight. This finding highlights the importance of behavioural context for investigations of side-bias and hemispheric laterality and suggests both proximate and ultimate trade-offs between species-specific cognitive ecology and flight biomechanics.
authors.affiliation: Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, United States of America. jtm39@cornell.edu
authors.forename: James T
authors.initials: JT
authors.lastname: Mandel
authors.forename: John M
authors.initials: JM
authors.lastname: Ratcliffe
authors.forename: David J
authors.initials: DJ
authors.lastname: Cerasale
authors.forename: David W
authors.initials: DW
authors.lastname: Winkler
mesh_terms: D000818:Animals; D005426:Flight, Animal; D046388:Swallows / Q000502:physiology*