Journal: Biology Letters (Sept 2013)
This article focuses on animal behavioral adaptations to human intervention; it also expands upon potential natural selection reasonings in the discussion section of the paper.
This Biology Letters article focuses on the relationship between speed limit in regions of a road in western France (the human intervention) and a bird’s flight-initiation-distance or FID (behavioral adaptation). The main variable the researchers measured was FID on four road sections with speed limits of 20, 50, 90, and 110 km/hr. To differentiate between the variables of car speed and speed limit, three scenarios were set for each road section: a car would travel first under the speed limit, second at the speed limit, and third above the speed limit. The landscape was kept constant across these various road sections.
The researchers measured the following variables from each road section: speed limit, car speed, season, bird position, and bird mass. Linear mixed models showed that there was an increase in bird FID in response to increasing speed limit (see attached graph in link above). However, they found that the car speed (entering the road section) did not have any direct or indirect relationship with FID. The researchers thus concluded that birds are able to associate certain road sections with speed limits as a means to measure the risk of a collision. The researchers also found that increasing body mass index correlated with increasing FID; birds with larger body mass index are less agile and thus require a larger FID to escape collision.