Animal Behaviour Lab
Dr Chris Evans
Acoustic communication in birds: cognition and function
Some animal calls encode specific information about environmental events such as the approach of predators or the discovery of food. This is important because it reveals a far more complex and sophisticated system than can be accommodated by traditional models, extending the parallels between animal communication and language. We have been exploring the information content of food calls and alarm calls produced by fowl (Gallus gallus). In playback experiments, these referential signals elicit specific responses that match the characteristics of the original eliciting event (e.g., looking upward as though to detect a soaring raptor or searching the substrate for food). Current experiments focus upon detection of deceptive signallers and the phenomenon of multi-modal signalling. This work aims to define the relationship between communication and cognition.
Parallel studies are concerned with the function. We are studying natural social groups to document individual variation in production of food calls and alarm calls. Molecular techniques are then used to determine paternity for each chick hatched, so that we can establish the relationship between vocal behaviour and reproductive success.
A related component of the project addresses the problem of signal design. Experiments with trained falcons reveal that aerial alarms have a ‘stealthy’ structure - they are much harder for avian predators to localize than ground alarms. In addition, males modify the structure of their alarms over the course of an encounter with a simulated predator, thus balancing individual risk against receiver benefit. These phenomena suggest that the costs of calling have shaped both signal structure and calling behaviour.
• Spectrograms and representative calls • Video clips from recent studies
• Calling and fitness • Multi-modal signalling
Recent news articles: Science News New Scientist Daily Telegraph Science News New Scientist
We are exploring the mechanisms responsible for behaviour of clear functional importance. Current projects focus on communication and cognitive processes in a wide range of organisms, including birds, lizards, and jumping spiders. Brief summaries of each project are presented below. Additional details are available on linked pages.
Dynamic visual signals: design and evolution
Current work focusses on the displays of Jacky dragons (Amphibolurus muricatus). These consist of a complex sequence of movements including tail-lashing, arm-waving and push-ups. We are using image analysis, neural network models and video playback to investigate signal design. In a recently completed study, we have shown that digital video sequences evoke the full gamut of social responses, including both aggressive and submissive displays. Experiments are now systematically exploring signal perception by receivers, using both natural and synthetic signals. Parallel projects use the same techniques to study predatory responses and recognition of aerial predators. Our goal is to understand the way in which the lizard visual system processes a wide range of ecologically-relevant events. We have also used comparative analyses to identify the ecological and social factors responsible for the evolution of complex visual displays in Iguanian lizards.
Recent news articles: Animal Behaviour Inside JEB: 2003 I 2007 Macquarie News New Scientist
The archive
Previous research topics have included mechanisms of mate choice in swordtail fish, perception of symmetry by humans, acquired predator recognition in tammar wallabies, and development of behaviour in megapodes. Click on the images to learn more.
Links
Visual processing in a unique modular system
Jumping spiders have achieved the seemingly impossible feat of achieving high acuity and large field of view, with only modest computational power. The key is a unique ‘modular’ design. Six secondary eyes function as motion detectors, functionally analogous to peripheral vision in vertebrates. When something interesting is detected, the spider spins around to bring its two large forward-facing primary eyes (analogous to a fovea) to bear. These animals have a body length of just 12 mm and brain only half the size of a honeybee’s, yet their sophisticated visual system attains a visual acuity that is almost an order of magnitude superior to their closest insect rivals and approaches that of primates. We are conducting an integrative analysis of the sensory processes underlying visual perception. This involves a multi-disciplinary team with complementary skills in behaviour, sensory processes and neurophysiology. In addition to staff at Macquarie, participants include Robert Jackson (University of Canterbury, NZ) and David O’Carroll (University of Adelaide).
• Spider project home page ARC media announcement
