Data for: Individual differences in song plasticity in response to social stimuli and singing position

Individual animals can react to the changes in their environment by
exhibiting behaviours in an individual-specific way leading to individual
differences in phenotypic plasticity. However, the effect of multiple
environmental factors on multiple traits is rarely tested. Such a complex
approach is necessary to assess the generality of plasticity and to
understand how among-individual differences in the ability to adapt to
changing environments evolve. This study examined whether individuals
adjust different song traits to varying environmental conditions in the
collared flycatcher (Ficedula albicollis), a passerine with complex song.
We also aimed to reveal among-individual differences in behavioural
responses by testing whether individual differences in plasticity were
repeatable. The presence of general plasticity across traits and/or
contexts was also tested. To assess plasticity, we documented 1)
short-scale temporal changes in song traits in different social contexts
(after exposition to male stimulus, female stimulus or without stimuli),
and 2) changes concerning the height from where the bird sang (singing
position), used as a proxy of predation risk and acoustic transmission
conditions. We found population-level relationships between singing
position and both song length and complexity, as well as social
context-dependent temporal changes in song length and maximum frequency.
We found among-individual differences in plasticity of song length and
maximum frequency along both the temporal and positional gradients. These
among-individual differences in plasticity were repeatable. Some of the
plastic responses correlated across different song traits and
environmental gradients. Overall, our results show that the plasticity of
bird song 1) depends on the social context, 2) exists along different
environmental gradients and 3) there is evidence for trade-offs between
the responses of different traits to different environmental variables.
Our results highlight the need to consider individual differences and to
investigate multiple traits along multiple environmental axes when
studying behavioural plasticity.