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1. Graphical methods are presented for the simultaneous comparisons of group size and territory size (subsumed jointly under the term “social dispersion”), in organisms with exclusive but contiguous territories. The methods are applied to recently published data on five species of neotropical emballonurid bats with particular emphasis on identifying the(More)
In a variety of songbirds the production of trilled song elements is constrained by a performance tradeoff between how fast a bird can repeat trill units (trill rate) and the range of frequencies each unit can span (frequency bandwidth). High-performance trills serve as an assessment signal for females, but little is known about the signal value of vocal(More)
Recent experiments in divergent fields of birdsong have revealed that vocal performance is important for reproductive success and under active control by distinct neural circuits. Vocal consistency, the degree to which the spectral properties (e.g. dominant or fundamental frequency) of song elements are produced consistently from rendition to rendition, has(More)
Older males tend to have a competitive advantage over younger males in sexual selection. Therefore, it is expected that signals used in sexual selection change with age. Although song repertoire size in songbirds is often mentioned as an age-related trait, many species, including the banded wren (Thryothorus pleurostictus), do not increase their repertoires(More)
Conventional signals impose costs on senders through receiver retaliation rather than through investment in signal production. While several visual conventional signals have been described (mainly 'badges of status'), acoustic examples are rare; however, several aspects of repertoire use in songbirds are potential candidates. We performed interactive(More)
Using the responses of territory owners to playback to infer the territorial function of acoustic signals is common practice. However, difficulties with interpreting the results of such experiments have obscured our understanding of territorial signalling. For instance, a stronger response to playback is often interpreted as more aggressive, but there is no(More)
In many tropical animals, male and female breeding partners combine their songs to produce vocal duets [1-5]. Duets are often so highly coordinated that human listeners mistake them for the songs of a single animal [6]. Behavioral ecologists rank duets among the most complex vocal performances in the animal kingdom [7, 8]. Despite much research, the(More)
Climatic variability and unpredictability affect the distribution and abundance of resources and the timing and duration of breeding opportunities. In vertebrates, climatic variability selects for enhanced cognition when organisms compensate for environmental changes through learning and innovation. This hypothesis is supported by larger brain sizes, higher(More)
We studied the use of song types and their acoustic features in different social contexts in the banded wren (Thryothorus pleurostictus), a resident tropical songbird in which males possess about 20 distinctive song types varying in duration, bandwidth, note composition, and trill structure. We recorded six focal males intensively for four days each while(More)
Song-type matching is a singing strategy found in some oscine songbirds with repertoires of song types and at least partial sharing of song types between males. Males reply to the song of a rival male by subsequently singing the same song type. For type matching to serve as an effective long-distance threat signal, it must be backed up by some probability(More)