Data and code for "Decoding the chaffinch "rain" call: a specialized alarm signal for nest predation"

Summary of the project : The chaffinch *Fringilla coelebs* is a very common passerine in Europe. One of the chaffinche's vocalisations, called "rain-call", is very common and conspicuous, however, it's function is still not well understood. Three hypotheses have been postulated as to what chaffinches rain-call are for: (1) the rain-call could be used in territorial context by males as a substitute for the song when the bird is in stressful conditions, (2) the rain-call is an alarm call, and (3) the rain-call is a mate-directed signal for communication within the pair. We tested these three hypotheses using two playbacks and behavioural observations in the wild. - In the first playback, we broadcasted rain-calls, chaffinch songs and the song of balckbirds as a control. We measured if chaffinch males reacted to rain-calls similarely to a simulated territorial intrusion. - In the second playback, we simulated the presence of predators (hawk and crows, compared to a balckbird's song as a control) and observed  if chaffinches started rain-calling. - Third, we closely followed five chaffinch males in the field, and took good note of the social and environemental context of rain-calling behaviour. We find that chaffinches did not react to rain-calls with the same agresive response than to territorial intrusion, wich does not support the hypothesis of a song substitute. We found that chaffinches started rain-calling consistently when we broadcasted predator calls, as well as when we saw real predators, which supports teh alarm call hypothesis. Finaly, we found that male chaffinches reain-called much more often when a femal chaffinch was around, which might hint that females are intended recievers of the rain-call alarm. We provide here the complete dataset for all thre experiment as well as the R code used to run statistical analyses. Variables and software versions are described further.