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."
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