Recent well-documented cases of cultural evolution towards increasing efficiency in non-human
animals have led some authors to propose that other animals are also capable of cumulative cultural
evolution, where traits become more refined and/or complex over time. Yet few comparative
examples exist of traits increasing in complexity, and experimental tests remain scarce. In a previous
study, we introduced a foraging innovation into replicate subpopulations of great tits, the ‘slidingdoor puzzle’. Here we track diffusion of a second ‘dial puzzle’, before introducing a two-step puzzle
that combines both actions. We mapped social networks across two generations to ask if individuals
could: 1) recombine socially-learned traits, and 2) socially transmit a two-step trait. Our results show
birds could recombine skills into more complex foraging behaviours, and naïve birds across both
generations could learn the two-step trait. However, closer interrogation revealed that acquisition
was not achieved entirely through social learning—rather, birds socially learned components before
reconstructing full solutions asocially. As a consequence, singular cultural traditions failed to emerge,
although subpopulations of birds shared preferences for a subset of behavioural variants. Our results
show that while tits can socially learn complex foraging behaviours, these may need to be scaffolded
by rewarding each component.
