Vocal sexual dimorphism in three Antbird (Aves, Passeriformes) species in a Cerrado fragment in southeastern Brazil

• Grant number: 22/04384-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2022
• End date: June 30, 2024
• Field of knowledge: Biological Sciences - Zoology
• Principal Investigator: Reginaldo José Donatelli
• Grantee: Enrico Lopes Breviglieri
• Host Institution: Faculdade de Ciências (FC). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil
• Associated scholarship(s): 23/09512-6 - Applying machine learning methods to detect vocal sexual dimorphism in antbirds, BE.EP.IC

Abstract

Communication is an important field in animal behavior, as social interactions between individuals are based on information exchange. The majority of vocalizations is distinct for each species, and many studies have documented a wide range of vocal signals in different taxonomic levels, including species, populations, and individuals. Therefore, bird vocalizations are crucial not only for avian reproduction but also for their evolution, since compatibility between individuals in a population is a minimal condition for species maintenance. However, studies exploring vocal differences betweenbird sexes are rare. This study will analyze the sexual dimorphism in the vocalization of Thamnophilidae (Aves: Passeriformes) species in the Cerrado of São Paulo state. Thamnophilidae is a taxonomic family composed of Neotropical species, with approximately 235 insectivorous taxa, which are found in the understory and midstory of tropical forests. They are ideal to evaluate the many roles played by selective pressures that induce male and female signal evolution. The antbirds have a species-specific song, emitted by both sexes, that can be involved both in territorial defense and breeding, even more when produced in duets. The methods used will be: (1) selection of five antbird species that have external sexual dimorphism (Herpsilochmus atricapillus, Herpsilochmus longirostris, Thamnophilus doliatus, Thamnophilus pelzelni e Taraba major); (2) search for couples of these species, mainly during the breeding season, followed by the recording of the couples´ song; (3) analysis of vocal parameters [delta time (s); number of sylables; song pace (sylables/s); maximum frequency (kHz); minimum frequency (kHz); peak frequency contour (kHz); peak time average (s); average entropy (bits)], which will be compared between males and females. To verify if there is vocal sexual dimorphism between coespecific individuals, generalized linear mixed models (GLMM) will be conducted, using binomial distribution. Models will be tested for each of the species separately, which include each of the vocal parameters as response variables; sex and environmental variables will be included as predictor variables. From this study, it´s expected to be proven that there is vocal sexual dimorphism in Thamnophilidae (Aves: Passeriformes), and, as a consequence, it is expected to infer about the role of female vocalizations in the evolution of birds.