Liisa Hämäläinen

Macquarie University · Department of Biological Sciences

Animals gather social information by observing the behavior of others, but how the intensity of observed cues influences decision-making is rarely investigated. This is crucial for understanding how social information influences ecological and evolutionary dynamics. For example, observing a predator’s distaste of unpalatable prey can reduce predati...

Predators can learn to avoid toxic prey by observing strong distaste responses of others. We show that the intensity of responses varies among blue tits. Weaker distaste responses were found to be more common, but in contrast to strong responses, they did not elicit prey avoidance in observing birds. This demonstrates that predators pay attention t...

Social information use is well documented across the animal kingdom, but how it influences ecological and evolutionary processes is only just beginning to be investigated. Here we evaluate how social transmission may influence species interactions and potentially change or create novel selection pressures by focusing on predator–prey interactions,...

Social transmission of information is taxonomically widespread and could have profound effects on the ecological and evolutionary dynamics of animal communities. Demonstrating this in the wild, however, has been challenging. Here we show by field experiment that social transmission among predators can shape how selection acts on prey defences. Usin...

Colours are commonly used as visual cues when measuring animals’ cognitive abilities. However, animals can have innate biases towards certain colours that depend on ecological and evolutionary contexts, therefore potentially influencing their performance in experiments. For example, when foraging, the colour red can advertise profitable fruits or a...

Ever since Alfred R. Wallace suggested brightly coloured, toxic insects warn predators about their unprofitability, evolutionary biologists have searched for an explanation of how these aposematic prey evolve and are maintained in natural populations. Understanding how predators learn about this widespread prey defence is fundamental to addressing...

To make adaptive foraging decisions, predators need to gather information about the profitability of prey. As well as learning from prey encounters, recent studies show that predators can learn about prey defences by observing the negative foraging experiences of conspecifics. However, predator communities are complex. While observing heterospecifi...

Many prey species contain defensive chemicals that are described as tasting bitter. Bitter taste perception is, therefore, assumed to be important when predators are learning about prey defenses. However, it is not known how individuals differ in their response to bitter taste, and how this influences their foraging decisions. We conducted taste pe...

Video playback provides a promising method to study social interactions, and the number of video playback experiments has been growing in recent years. Using videos has advantages over live individuals as it increases the repeatability of demonstrations, and enables researchers to manipulate the features of the presented stimulus. How observers res...

Explaining the origin and maintenance of aposematism has remained a challenge for evolutionary biologists because conspicuous warning signals are predicted to have a high initial predation cost before predators learn to avoid them. Most previous work has assumed that predators need to sample prey individually (personal information) to learn about t...

1.Aposematism is an effective antipredator strategy. However, the initial evolution and maintenance of aposematism is paradoxical because conspicuous prey are vulnerable to attack by naïve predators. Consequently, the evolution of aposematic signal mimicry is also difficult to explain. 2.The cost of conspicuousness can be reduced if predators learn...

Video playback is becoming a common method for manipulating social stimuli in experiments. Parid tits are one of the most commonly studied groups of wild birds. However, it is not yet clear if tits respond to video playback or how their behavioural responses should be measured. Behaviours may also differ depending on what they observe demonstrators...

Demonstrator encountering aversive prey The video shows a demonstrator encountering aversive prey (mealworm injected with bitter-tasting Bitrex).

Results of the GLM models More comprehensive presentation of the results from all GLM models described in the results section.

Observer?s response to video playback The video shows an observer?s response to different sections of video playback: (i) a control section (a cup in an empty cage) before a demonstrator (30 s), (ii) a demonstrator encountering aversive prey (45 s), and (iii) a control section (a cup in an empty cage) after a demonstrator (30 s).

Demonstrator encountering palatable prey The video shows a demonstrator encountering palatable prey (mealworm).

Raw data used in the analyses

The maintenance of multiple morphs in warning signals is enigmatic because directional selection through predator avoidance should lead to the rapid loss of such variation. Opposing natural and sexual selection is a good candidate driving the maintenance of multiple male morphs but it also includes another enigma: when warning signal efficiency dif...

Several antipredator strategies are related to prey colouration. Some colour patterns can create visual illusions during movement (such as motion dazzle), making it difficult for a predator to capture moving prey successfully. Experimental evidence about motion dazzle, however, is still very scarce and comes only from studies using human predators...