Negotiation of territorial boundaries in a songbird

Abstract

How do territorial neighbors resolve the location of their boundaries? We addressed this question by testing the predictions of 2 nonexclusive game theoretical models for competitive signaling: the sequential assessment game and the territorial bargaining game. Our study species, the banded wren, is a neotropical nonmigratory songbird living in densely packed territorial neighborhoods. The males possess repertoires of approximately 25 song types that are largely shared between neighbors and sequentially delivered with variable switching rates. Over 3 days, boundary disputes among pairs of neighboring males were synchronously recorded, their perch positions were marked, and their behavioral interactions were noted. For each countersinging interaction between 2 focal males, we quantified approach and retreat order, a variety of song and call patterns, closest approach distance, distance from the territorial center, and female presence. Aggressors produced more rattle-buzz songs during the approaching phase of interactions, whereas defenders overlapped their opponent's songs. During the close phase of the interaction, both males matched frequently, but the key determinant of which one retreated first was song-type diversity-first retreaters sang with a higher diversity. Retreaters also produced more unshared song types during the interaction, and in the retreating phase of the interaction, they overlapped more. A negative correlation between song-type diversity asymmetry and contest duration suggested sequential assessment of motivational asymmetry. The use of this graded signal, which varied with distance from the center and indicated a male's motivation to defend a particular position, supported the bargaining model. The bargaining game could be viewed as a series of sequential assessment contests.

Female song and vocal interactions with males in a neotropical wren

“…However, females sometimes participate in boundary disputes with their mates (Molles and Vehrencamp, 1999) and respond to playback of male song . Response to playback of female song has never been tested in this species, but male-male counter-singing interactions have been characterized in detail, based on observations and experiments (Molles and Vehrencamp, 2001;Burt and Vehrencamp, 2005;Hall et al, 2006;Illes et al, 2006;Vehrencamp et al, 2007Vehrencamp et al, , 2014De Kort et al, 2009), as have male-female duets in many closely related species (Levin, 1996;Logue and Gammon, 2004;Gill et al, 2005;Marshall-Ball et al, 2006;Mennill and Vehrencamp, 2008). The singing style of banded wrens is similar to their congeners, rufous-and-white wrens (Thryothorus rufalbus) and sinaloa wrens (Thryothorus sinaloa), where rare female songs are occasionally loosely associated with the songs of their partner (Mann et al, 2009).…”

Direction-of-arrival estimation of animal vocalizations for monitoring animal behavior and improving estimates of abundance

“…Information regarding the location and movements of an animal can provide crucial context when examining variation in signaling behaviors that may vary according to the location of the signaler (Simpson 1985, Haff et al 2015, and to studies of vocal interactions involving multiple individuals (Vehrencamp et al 2014). To fully realize this potential, it will be necessary to estimate not only the DOA of a source, but also its absolute location.…”

Repertoire structure, song sharing, reproductive success, and territory tenure in a population of Canada Warblers (Cardellina canadensis) in central New Hampshire

“…Studies of female mate choice by song in Canada Warblers across a gradient of reproductive performance (e.g., whether females prefer local or shared songs versus large or complex repertoires in males with a greater range of pairing and fledging success) would be necessary to definitively test the relationship between song and fitness. Interactive playback studies to examine how song matching or varying patterns of song delivery are used in male-male interactions (e.g., Vehrencamp et al 2014) .1304. Bensch, S., Hasselquist, D., Nielsen, B., and Hansson, B.…”

“…Song sharing may increase reproductive success (Payne et al 1988) and length of territory tenure (Beecher et al 2000b), by allowing males to engage in aggressive intrasexual encounters using shared songs (Krebs et al 1981;Beecher et al 2000a;Vehrencamp 2001). Shared songs permit song matching between males, an aggressive signal, during territorial countersinging (Beecher et al 2000a;Vehrencamp 2001;Vehrencamp et al 2014). Indigo Bunting (Passerina cyanea (L., 1766)) males in their first breeding season who shared older neighbours' songs had higher pairing success than nonsharers (Payne et al 1988).…”