Fig. 5

Seasonal variation in New Caledonian crows’ tool-manufacture behaviour. a Manufacture sequences from Experiment 1 (as shown in Fig. 2a) reordered by calendar date, and with information added on incomplete behavioural actions and actions that were completed through multiple attempts. For a description of colour coding and manufacture stages, see Fig. 2. Sequences produced on the same day are grouped with a bracket underneath. Most-effective attempts and incomplete attempts are marked (/) and last attempts are marked (\); note that (/) and (\) can coincide (×). Temporal change in b the diameter of manufactured tools, and c the time taken to release the basic tool, with corresponding model fits (for further details, see main text)