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A raven's call tells its age, sex, and foraging opportunities

Ravens may be able to identify the age, sex, and specific details of a nearby foraging opportunity just by listening to another raven’s call, according to a new study.

Common ravens use calls to alert other ravens of available food, but these calls serve a range of purposes.

Researchers from the University of Vienna and the University of Cambridge say these calls are used as calling cards and nearby ravens can assess the specifics of a feeding situation.

Some feeding spots are dominated by competing ravens, or there may be predators nearby which poses an unnecessary risk.

The study, published in the journal Frontiers in Zoology, is the first of its kind to examine how raven food calls are interpreted by ravens who aren’t familiar with each other.

“The majority of previous research on call characteristics in ravens focused on recognition of known individuals,” said Markus Böckle, the corresponding author. “However, to our knowledge, no experiments have tested for features in food calls that might provide ravens with information about unknown individuals.”

The researchers studied a population of free-ranging common ravens that gathered for feedings on wild boar at the Cumberland Wildpark Grünau from 2009 to 2010.

The feeding sessions were videotaped, and audio recordings of 418 calls made by 12 different ravens were also analyzed.

The results showed that each raven’s call differed depending on age and sex, which could mean that the calls are a way to inform nearby strangers of more than just the specifics of foraging opportunities.

“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),” said Böckle. “This gives ravens the opportunity to use information about the caller in decision-making processes, such as whether to join or avoid foraging groups.”

The calls could also be used to help ravens recruit allies to help them in tricky food situations such as dominant ravens competing for the same food source.

According to the researchers, the different calls may determine age and sex because of several factors such as size differences between sexes and age groups as well and hormones that create different resonances and timbres.

By Kay Vandette, Staff Writer

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