Data from: Identifying ecological drivers of interspecific variation in song complexity in songbirds (Passeriformes, Passeri)

A diversity of selective pressures and stochastic processes have likely
created substantial variation in song structure, creating difficulties in
quantifying the influence of specific ecological factors. This problem is
further compounded by differences in study taxa and methods of data
analysis between studies. Large comparative studies offer the potential to
mitigate some of these methodological difficulties by maximizing the power
of statistical analyses and minimizing the probability of misidentifying
the magnitude and direction of relationships between independent and
dependent variables. In this study, we quantified song complexity for 367
species of globally distributed songbirds (Passeriformes, Passeri). We
quantified eight individual acoustic variables that have previously been
linked to audio complexity which we analyzed independently, and after
applying multivariate statistics to the variables. We used Bayesian linear
mixed effect models to test multiple hypotheses regarding song complexity:
that it should be greater in open habitats, in migratory species, for
sexually monomorphic species, at higher latitudes and altitudes, and that
it should co‐vary with clutch size characteristics. Our results challenge
perceptions of the effect of habitat structure on song complexity; for
instance, counter to expectation, we found songs in closed environments to
have reduced syllable diversity. Additionally, our results suggest song
complexity may not be ubiquitously a means of communicating male quality,
with no significant difference between recordings from monomorphic and
dimorphic species. By estimating song complexity in multiple ways, and
quantifying these over large taxonomic and spatial scales, we are able to
gain a more nuanced understanding of how song complexity is potentially
affected by a range of biotic and abiotic factors. Our results also
suggest that caution is required when making generalized statements about
the relative influence of different factors on song complexity; more
densely‐sampled, group‐specific studies are necessary complements to this
taxonomically broad analysis.