DOI: 10.5061/dryad.6q573n5w4
title: Evidence of repertoire sharing and stability despite a high turnover rate in a duetting neotropical wren

description: In songbirds, the spatial pattern of song sharing among individuals is
 influenced by the song learning and dispersal strategies within each
 species. In birds where females and males sing and create joint acoustic
 displays (duets), the processes defining the patterns of song sharing
 become more complex as there might be different selection pressures
 shaping the behaviour of each sex. To provide further insight into the
 vocal development and the dispersal strategy of duetting tropical species,
 we investigated the patterns of individual and pair repertoire sharing, as
 well as the stability of these repertoires, in a colour-marked population
 of riverside wrens, Cantorchilus semibadius, located in the Osa Peninsula,
 Costa Rica. Using data collected over a five-year period, we found
 considerable variation in the sharing levels of phrase and duet type
 repertoires among neighbouring individuals coupled with a general decline
 of repertoire sharing as distance increased between birds’ territories.
 These results are consistent with a pattern predicted in age-restricted
 learners that establish preferentially near their tutors. Furthermore, we
 found no evidence of individuals changing their phrase type repertoires
 over time, including after remating events. Duet type repertoires were
 also stable when pairs remained together. However, we observed a
 surprisingly high turnover rate. When individuals remated, even though the
 majority of the previous duet type repertoire remained, several new duet
 types were included. Taken together, our findings suggest that riverside
 wrens might create their individual repertoires by copying their same-sex
 parent and neighbouring individuals before dispersal. Additionally, we
 speculate that even though birds were able to create new duet types after
 changing partners, a substantial portion of their duet type repertoire
 might also be copied from their parents and neighbouring pairs during the
 initial critical period of song learning.
description: We conducted observations and recordings of 37 pairs (61
 individuals) in 23 territories within a population of riverside wrens,
 Cantorchilus semibadius, for four years during a five-year period (2013,
 2015-2017) in Osa Peninsula, Costa Rica. From our recordings, we isolated
 all phrase and duet types using Syrinx and created sound spectrograms and
 a library of phrase types for each individual and a library of duet
 types for each pair. The ID of each pair includes the name of the
 territory and the year when the pair was recorded in that territory. The
 duet types present in the repertoire of each pair are composed by a female
 phrase type and a male phrase type. The first female and male phrase types
 and the first duet type recorded were categorized as following: PF1, PM1,
 and PF1PM1 respectively. To investigate the spatial
 patterns of song sharing, we performed the following analyses: first,
 we quantified repertoire sharing by using the song sharing
 index, <i>S </i>=
 2<i>N</i><sub>s</sub>/(2<i>N</i><sub>s</sub><i> </i>+ <i>a</i> + <i>b</i>), in which <i>N</i><sub>s</sub> is the number of shared phrase/duet types between two individuals/pairs and <i>a</i> and <i>b</i> are the non-shared phrase/duet types of each individual/pair (McGregor and Krebs 1982). Then, we performed permutation-based Mantel tests, which assess the correlation between matrices of song sharing (song sharing coefficient, <i>S</i>) across territories and the corresponding matrices of the geographical distance between them. Distances were measured in meters between territories’ centres. We only included the three years in which we had 10 or more territories with complete or near complete repertoires of phrase and duet types (2015, 2016, 2017).  To investigate repertoire stability in pairs that remained together across years and in individuals that changed mates, we used the Chao-1 index estimates of phrase and duet types richness (number of different phrase/duet types in a repertoire). Reference years and pairs were defined for comparison purposes, to test stability across years and across territories, respectively. For these references, asymptotic estimators of phrase/duet type richness (repertoire sizes), as well as the corresponding 95% confidence intervals, were obtained. For the remaining years/pairs, i.e. those compared to the reference years/pairs, the number of different phrase types and duet types recorded that were not recorded in the reference were registered. Additions to the estimated reference repertoire that exceeded the upper 95% confidence interval of the Chao index were considered to be evidence of a change in individuals and pairs repertoires and, therefore, lack of stability. We only included pairs for which we had nearly complete repertoires. As a result, 11 pairs were considered in the analysis for individuals that remained together in the same territory and 8 pairs were considered in the analysis for individuals that changed partners.