Noisy miners plan ahead: cryptic signalling of reward location impairs search for nectar, but not for invertebrates

Noisy miners, Manorina melanocephala (Australian honeyeaters, Meliphagidae) feed on both nectar and invertebrates. The spatiotemporal distributions of these two food resources differ: nectar is a static, visually signalled resource, and invertebrates are cryptic and mobile. In the present study, we investigated whether birds would forage more efficiently if they could plan their search path through a 'patch' of feeders, than if they could not. We predicted that the ability to plan would only increase the efficiency of nectar foraging. Wild-caught captive birds were allowed to forage through arrays of feeders containing both nectar (sucrose) and invertebrate (mealworm) prey. When foraging for nectar, birds made more search errors if they were unable to plan their foraging route, while search efficiency for invertebrate prey was not affected in this way. These results suggest that noisy miners make use of the advertised locations of nectar to plan their search route. Such route planning may be a type of planning that does not involve anticipation of future motivational states.