Comparative neuroanatomy and sensory abilities in birds. (#447)
Determining the sensory acuity and sensitivity of a species is a key component to understanding animal behaviour. Sensory systems allow species to derive information from the environment and make decisions related to foraging, mating and all other behaviours. Determining the acuity and sensitivity of the sensory pathways generally requires physiological or behavioural testing, but these techniques not always feasible. In contrast, the anatomy of sensory systems can provide comparable information on sensory system acuity and sensitivity with small sample sizes and without the logistical problems associated with testing. In birds, we have used this principle to gain insight into the sensory abilities of many different species. One example is the kakapo (Strigops habroptilus), a critically endangered nocturnal parrot. Most of the research on this species has focused on captive breeding and reintroduction efforts, with little known about how they perceive their environment. Through analyses of its anatomy, we determined that the kakapo has a visual system that combines the traits of parrots, owls and nightjars to result in good low light vision, but with poor visual acuity. A second example is New World vultures, which are thought to vary in their reliance on olfactory cues to find carrion. An anatomical comparison across species revealed similarities in visual acuity, but major differences in olfactory sensitivity. In fact, the turkey vulture (Cathartes aura) likely has the most sensitive olfactory system of any bird. Finally, we have applied our knowledge of brain-behaviour relationships to gain insight into the behaviour of extinct species. The neuroanatomy of an extinct Hawaiian duck uncovered suite of behavioural adaptations that enabled this species to occupy a unique ecological niche that is somewhat similar to that of kiwi (Apteryx spp.). These three examples, and many others, highlight the potential importance of neuroanatomy to understanding how birds sense and perceive their environment and has implications that extend to management and conservation strategies.