Vol. 64, 2025
The Relationship Between
Relative Brain Size and Avoidance of Vehicular Collisions in Birds is
Subtle
Robert M. Zink1,* and Brittaney L. Buchanan1,2
doi:-
1School
of Natural Resources, School of Biological Sciences and Nebraska State
Museum, University of Nebraska-Lincoln, USA 56853. *Correspondence:
E-mail: rzink2@unl.edu (Zink)
2Biology Department, University of Florida, Gainesville, Florida, USA 32611. E-mail: buchananbl55@gmail.com (Buchanan)
(Received 15 November 2024 / Accepted 12 January 2025 / Published -- 2025)
Communicated by Jen-Pan Huang
Møller
and Erritzøe (2017) reported that birds killed by collisions with
vehicles had on average relatively smaller brains than birds killed by
other causes, which were not identified. Despite concerns about the
method used to assess brain mass, we reanalyzed the published data of
Møller and Erritzøe (2017) after excluding extraneous species and
confirmed a subtle tendency for birds killed by vehicular collision to
have somewhat small brains. Some groups of birds (owls, hawks, garden
birds and migratory species) did not reflect the overall result.
Surprisingly there was no effect of age or sex, whereas one would
expect inexperienced immature birds and females in breeding condition
to be vulnerable. Overall, plots of brain mass in birds killed by
vehicular collisions and other causes greatly overlap, and in some
species, individuals killed by collisions have relatively larger
brains. That is, the tendency for birds hit by vehicles to be
relatively smaller brained is not universal, nor in any species is
there an absolute difference in brain size between the two categories.
It is possible that in the short time birds have interacted with moving
vehicles that selection has acted on brain size to avoid collisions,
although we suggest that slightly larger brains might represent an
innate tendency to avoid rapidly approaching objects. An interesting
question from their study is what was the cause of mortality in the
birds not hit by vehicles. Likely sources of mortality of birds
post-nestling stage include depredation (natural and house cats) and
collisions with windows and other human structures. In fact, relatively
large-brained birds might be more susceptible to collisions with
windows or being caught by cats (i.e.,
the other sources of mortality), for which having a relatively larger
brain would not appear to mitigate these sources of mortality.
Key words: Bird brains, Brain mass, Cognitive ability, Vehicular collisions, Avian mortality
Citation:
Robert M. Zink RM, Buchanan BL. 2025. The relationship between relative
brain size and avoidance of vehicular collisions in birds is subtle.
Zool Stud 64:03.

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