Always together: an extremely long pair bond in rufous horneros

Author(s)

Diniz, Pedro

• Document type: Journal article
• Source: ORNITHOLOGY RESEARCH; v. 33, n. 1, p. 7-pg., 2025-06-16.

Abstract

Prolonged pair bonds, commonly reported in long-lived non-passerines that reunite each breeding season, are often linked to enhanced reproductive performance through improved partner familiarity. However, such bonds are rarely described in year-round territorial birds, particularly those with low sexual conflict. Here, I report a rufous hornero (Furnarius rufus) pair that remained together for at least 10 years within the same urban territory. This surpasses known pair bond durations for passerines (2-7 years) and rivals the time the partners spent together in many non-passerines. Over time, I observed morphological and acoustic changes, with the female showing more signs of senescence (feather deterioration) and the partners tending to exhibit slower duet responses and reduced song synchronization. Conversely, duet-level vocal performance traits, such as minimum frequency, bandwidth, and frequency modulation, tended to improve. As a model of sexual cooperation and shared roles in reproduction and territoriality, rufous horneros likely represent other Neotropical ovenbirds (Furnariidae). Therefore, further research into the adaptive trade-offs of prolonged pair bonds in rufous horneros could shed light on the evolution of perennial monogamy in birds. (AU)

• FAPESP's process: 24/13237-3 - Does synchrony require practice? Ontogeny and evolution of duet coordination in birds
• Grantee: Pedro Diniz Alves
• Support Opportunities: Scholarships in Brazil - Post-Doctoral