Figure 1.

(a) Male great tits feed chicks nearer the playback speaker in response to playback of great tit chick begging calls, but not in response to zebra finch song or no playback, but (b) do not feed chicks nearer to a speaker broadcasting chick begging calls at their previous nest visit. Points are means + s.e.'s of the proportions for males at different nests (n = 13) (i.e. are from the original data, not model estimates). p-Values are from generalized linear mixed models with binomial errors for the difference between the proportion of feeds to the left when playback is from the left or right (see text; triangles, playback from left; inverted triangles, playback from right; circles, playback from either).