In spring, thoughts turn to sex, and three-spined stickleback females set about finding the most attractive mate. Their method of selection is to choose the male with the most attractive red belly, so it’s not surprising that Dr. Victoria Braithwaite (University of Edinburgh) has discovered that female sticklebacks become more sensitive to red during the breeding season. What is surprising is that the males do too! “This actually makes good sense” says Dr. Braithwaite. “Sticklebacks are very territorial and need to defend their territory from sneaky male competitors. Being able to assess competitors by their red coloration could help them do this more effectively.” Dr. Braithwaite will discuss how fine-tuned an animal’s cognitive ability is to its current physiological state on Monday 29th March at the annual SEB meeting (29th March – 2nd April 2004, session A3.6) at Heriot-Watt University, Edinburgh.

During the breeding season, male sticklebacks develop a red throat and belly and build a nest. They become highly territorial and attack anything red that comes near their breeding site. Dr. Braithwaite and her colleague Dr Philip Boulcott tested the fish for a shift in sensitivity to the red end of the spectrum before, during and after the breeding season and found that both male and female sticklebacks were particularly sensitive to red only during the breeding season. Previously scientists had assumed that only female sticklebacks increase their sensitivity to red during the breeding season, in order to select the best mates with the brightest bellies. It is likely that sex hormones cause this shift in perception, but this remains to be tested.

Dr. Braithwaite investigates how the breeding season of these fish impacts on learning as well as perception. Sticklebacks appear to change their spatial strategy during the breeding season. While these fish do not normally use landmarks to navigate, Dr. Braithwaite’s group has discovered that they do use landmarks during the breeding season. This heightened spatial awareness may reflect the need to accurately locate breeding territories. This research illustrates how cognitive abilities are influenced by the environment and by an animal’s physiological state.