and they were unable to learn to avoid this prey type based on
visual signals. During the memory test there was no difference in
the proportion of grey prey consumed by any of the groups, indicating
that blueheads respond to colour and pattern comparably.
This result is contrary to a response observed in domestic chicks,
Gallus gallus domesticus, in which the chicks attended to colour and
not to pattern during avoidance learning (Aronsson & Gamberale-
Stille 2008).
For some birds,
a prelearned bias against colour appears to be innate, as demonstrated
in a study of naïve and wild-caught great tits, which both
avoided similar colours of prey (Lindström et al.1999).
the cleaner wrasse, Labroides dimidiatus, shows a high
level of learning flexibility in performing a reverse reward contingency
task, an ability previously demonstrated only in mammals
(Danisman et al. 2010). Zebrafish, Danio rerio, also show a high
capacity for reversal learning, demonstrating an ability to rapidly
learn and relearn to attend to a reinforced stimuli after switching
the reinforced stimuli with a previously unreinforced stimuli
(Parker et al. 2012).
The foregoing
study provides evidence that, while coral reef fish have the ability
to learn to avoid unpalatable prey using visual cues, they adapt to
changes in the appearance of defended prey much more rapidly
than terrestrial predators, such as birds. This may help to explain
why the often brilliant colours of tropical sponges are unrelated to
tissue palatability (Pawlik et al. 1995).