Heliconiini butterflies can learn time-dependent reward associations

For many pollinators, flowers provide predictable temporal schedules of
resource availability, meaning an ability to learn time-dependent
information could be widely beneficial. However, this ability has only
been demonstrated in a handful of species. Observational studies of
Heliconius butterflies suggest that they may have an ability to form
time-dependent foraging preferences. Heliconius are unique among
butterflies in actively collecting pollen, a dietary behaviour linked to
spatiotemporally faithful ‘trap-line’ foraging. Time-dependency of
foraging preferences is hypothesised to allow Heliconius to exploit
temporal predictability in alternative pollen resources. Here, we provide
the first experimental evidence in support of this hypothesis,
demonstrating that Heliconius hecale can learn opposing colour preferences
in two time periods. This shift in preference is robust to the order of
presentation, suggesting that preference is tied to the time of day and
not due to ordinal or interval learning. However, this ability is not
limited to Heliconius, as previously hypothesised, but is also present in
a related genus of non-pollen feeding butterflies. This demonstrates that
time learning likely pre-dates the origin of pollen-feeding and may be
prevalent across butterflies with less specialized foraging behaviours.