‘Pecking orders’, or more correctly ‘dominance hierarchies’, have been described for a number of bird species, typically those that have been easy to study because of their domestication. The domestic fowl is perhaps the best example, but others include canaries, zebra finches and even oystercatchers.
Social rank is an important component of avian society, and the ability to identify a more dominant individual reduces the chances of an aggressive interaction with the potential for injury or even death. Such hierarchies are likely to be more common in birds that form social groups and, therefore, spend a lot of time together.
Linear hierarchies, where an individual is dominant over all of those below it in the pecking order, and subordinate to all those above it, tend to provide a stable group structure but only where the group size is small.
Stability breaks down in larger groups because it is more difficult for birds to recognise other individuals and determine their social position in relation to them.
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Main image: Oystercatchers. © Iolanda Frisina/Getty