Association between song and a complex habitat transition in a Neotropical passerine, the Rufous-collared Sparrow

ATTINÁ, NATALÍ; LAVINIA OBLANCA PABLO DAMIÁN; TUBARO PABLO LUIS; LIJTMAER DARÍO A.

Virtual (Covid-19)

Congreso; VII North American Ornithological Conference; 2020

The acoustic adaptation hypothesis (AAH) proposes that song structure is adapted to minimize its degradation during transmission and predicts that notes should be more separated in closed than in open environments. The Rufous-collared Sparrow (Zonotrichia capensis) has been extensively studied in this regard because of the close association between its song and habitat structure, which generates song dialects that differ in the rate of their trill notes. However, previous studies have been rather simple with respect to the spatial assessment of song variation in this species. We studied the association between habitat and vocalizations in this species across a complex matrix of interdigitated steppe (open habitat) and espinal woodland (closed habitat) in central Argentina. We recorded 629 individuals in an area of 100 km x 170 km and used Raven 1.4 to measure temporal and frequency variables on each song. We found a reversed pattern of association between song and habitat compared to that expected under the AAH in the south of the study area, which could be the consequence of strong winds and a lower density of individuals in the steppe. The pattern was less clear in the north due to an overall reduction in trill note separation. Transitions between dialects were gradual across environments and vocalizations from one habitat were influenced by those from the neighboring one. Our results confirm that the song of Z. capensis is associated with habitat structure, even across intricated environmental transitions, but highlight that this association can be complex and difficult to predict.