‘Quoth the Raven…’

Abstract

There's no doubt that Edgar Allen Poe did a first-rate job of increasing name awareness for Corvus corax (i.e. ‘The Raven’). But fame comes with a price – in this case, it was a full-blown character assassination! Fortunately, unwitting promoters of ravens are rescuing their maligned reputations. Researchers in comparative cognition are showing the raven to be a cognitively and socially sophisticated creature deserving of greater respect. An outstanding example of such efforts is a recent study by Bugnyar et al.1xFood calling in ravens: are yells referential signals?. Bugnyar, T. et al. Anim. Behav. 2001; 61: 949–958Crossref | Scopus (58)See all References1 that targeted the food-calling behavior of ravens residing near a wild game park in the Austrian Alps. One unanswered question is whether ravens’ food calls are functionally referential like the calls of vervet monkeys that alert other vervet monkeys to avian or terrestrial predators. Bugnyar et al. addressed this question in ravens by examining the kind of information about a food source that is communicated in ravens’ food calls.They focused on a group of wild ravens who were often spotted scavenging food at a wild boar enclosure. (The picture shows a possible study participant riding atop a wild boar – photo courtesy of Mareike Stowe). Over three summer months, the researchers varied the type of food (beef, kitchen leftovers, and wild boar chow) and the quantity of food (one, two and three buckets) to be offered to the wild boars – and consequently, to be eaten by the ravens – on any given day. They recorded the ravens’ vocal responses during different phases of the daily test sessions. In a ‘baseline’ phase, no food was visible. In the ‘presentation’ phase, ravens could see the food but did not have ready access to it. In the ‘availability’ phase, the food was thrown into the wild boar enclosure and the ravens (and the boars) commenced eating. Finally, in the ‘after feeding’ control phase, the food had been consumed but the ravens were still present. The critical question was whether the ravens modulated their food calling as a function of the food presented and across the different test phases.Bugnyar et al. found evidence of referential specificity in that ravens were more likely to produce ‘Haa’ yells in specific contexts: (1) for preferred food items (i.e. beef and leftovers) regardless of quantity, and (2) during the food presentation and availability phases but less so during the baseline phases. The authors also obtained evidence that juvenile ravens learnt the referential relationship between food calls and food items over the course of the summer.Although these results do not prove beyond doubt that ravens’ food calls are functionally referential (additional work examining ravens’ responses to food calls is necessary), they do provide a promising first step. And perhaps more importantly, elegant studies such as this reinforce the notion that finding intelligence in non-human animals is often more limited by an ability to devise methodologies worthy of the challenge than by cognitive limitations of the creatures themselves.