March 12, 2018, BioMed Central
Common ravens (Corvus corax) use food associated 'haa' calls to recruit other individuals of the same species (conspecifics) to food foraging sites which may be dangerous because of predators or territorial breeding pairs. These calls provide clues about the age and sex of the caller, according to a study published in the open access journal Frontiers in Zoology.
Researchers at the University of Vienna and the University of Cambridge found that vocal signals emitted by ravens to alert conspecifics to feeding sites varied in frequency, call duration and amplitude, according to their age and sex. These differences may enable ravens to extract information about the caller and use this knowledge to aid in decision-making processes.
Dr. Markus Böckle, the corresponding author, said: "The majority of previous research on call characteristics in ravens focused on recognition of known individuals. However, to our knowledge, no experiments have tested for features in food calls that might provide ravens with information about unknown individuals."
Dr. Böckle adds: "Our results suggest that ravens have the necessary variation in their food calls and the cognitive means to distinguish between specific classes of sex and age (class-recognition). Thus, we show for the first time that ravens can potentially use food calls to tell other ravens apart, according to these categories. This gives ravens the opportunity to use information about the caller in decision making processes, such as whether to join or avoid foraging groups."