Individual vocal recognition across taxa: a review of the literature and a look into the future

Individual vocal recognition (IVR) has been well studied in mammals and birds. These studies have primarily delved into understanding IVR in specific limited contexts (e.g. parent–offspring and mate recognition) where individuals discriminate one individual from all others. However, little research has examined IVR in more socially demanding circumstances, such as when an individual discriminates all individuals in their social or familial group apart. In this review, we describe what IVR is and suggest splitting studies of IVR into two general types based on what questions they answer (IVR-singular, and IVR-multiple). We explain how we currently test for IVR, and many of the benefits and drawbacks of different methods. We address why IVR is so prevalent in the animal kingdom, and the circumstances in which it is often found. Finally, we explain current weaknesses in IVR research including temporality, specificity, and taxonomic bias, and testing paradigms, and provide some solutions to address these weaknesses. This article is part of the theme issue ‘Signal detection theory in recognition systems: from evolving models to experimental tests’.

New records and range extension of Black-goggled Tanager, Trichothraupis melanops (Vieillot, 1818) (Passeriformes, Thraupidae), in extreme southern Brazil

We describe new records of Trichothraupis melanops in five municipalities of Rio Grande do Sul, Brazil. The birds were detected in sporadic expeditions in the Serra do Sudeste and Campanha Gaúcha regions by direct visualization and vocal recognition. One of these records, next to the border with Uruguay, is the southernmost known location for the species in Brazil. This record expands the geographic range of the species in Brazil south by 170 km. We believe that these occurrences are seasonal displacements and do not represent a colonization front with resident populations.