In our recent paper (1) we showed that zebra finches, like starlings (2), can learn to discriminate between stimuli generated by two simple formal grammars, but argued that neither study provided a “convincing demonstration” of recursive language learning. Gentner et al. (3) criticize this conclusion and the design of our experiment. Their comments underscore our point that it is critical to exclude that seemingly complex syntactic tasks are solved by applying relatively simple rules. Gentner et al. (3) correctly point out that both studies differ in how the stimulus sets were created (Tables 1 and 2). They criticize our training set for the presence of bigrams shared between stimuli. Surprising in the light of this criticism and their statement in ref. 3, bigram sharing within and between training and transfer stimulus sets is also present in Gentner et al.’s starling experiment (see the legend of Table 1).