Java sparrow song conforms to Menzerath’s Law but not Zipf’s Law of Abbreviation

Abstract

AbstractLinguistic laws, which describe common statistical patterns in human language, are often studied in animal communication systems. Despite good evidence for the existence of these laws in non-human primates, data is still limited for other taxa. Birdsong is often used as a model for human language development due to similarities in vocal learning and production. Therefore, it is useful to explore features of human language in birdsong to determine the value and limitations of such comparisons. Here, we looked for patterns consistent with Menzerath’s law, the tendency for longer sequences to be made up of smaller constituent parts, and Zipf’s Law of Abbreviation, the tendency for more frequently used elements to be shorter in length, in the songs of Java sparrows (Padda oryzivora). We found that songs conformed to Menzerath’s law at both the population and individual level; longer sequences were made up of shorter notes, and this pattern was achieved through note selection, rather than shortening existing notes. This adherence to Menzerath’s law may reflect species-specific constraints on song durations. However, we found no evidence to support adherence to Zipf’s Law of Abbreviation, either at population or individual level; more frequently used notes were not shorter in length. As they are used in courtship, songs may experience different selection pressure to other parts of the vocal repertoire, which could act against compression. Whilst there may be some limitations in applying linguistic laws designed for human language to birdsong, especially Zipf’s Law of Abbreviation, these laws may still provide insights into animal and human communication systems.