Large mammalian herbivores regularly encounter noxious insects on their food plants. Recent evidence revealed that goats efficiently avoid insect ingestion while feeding, yet it is unknown whether this ability is innate. We experimentally examined the behavioural responses of naïve goat kids to a common insect, the spring-webworm (Ocnogyna loewii). We filmed and analysed the kids’ behaviour while feeding and compared it to the behaviour described in adults. Naïve kids sorted the webworms apart from the food without ingesting them (all webworms survived). They exhibited behaviours similar to those displayed by adults, demonstrating an innate ability to avoid insect ingestion. The kids detected webworms using tactile stimulation, obtained by repeatedly touching the leaves with their muzzles. This enabled them to pick webworm-free leaves (leaving 93% of webworms behind). While adults frequently shook or discarded leaves with webworms or spat out webworms, these behaviours were rare in kids. The kids’ mean feeding rates doubled over the trials, indicating that their feeding efficiency on plants with and without insects improved with experience. Since ingesting noxious insects could be fatal, innate avoidance is critical. These findings highlight the importance of direct interactions between mammalian and insect herbivores.
Supplementary movie 1
A naive kid presented with a choice between control (left bowl) and webworm leaves (right bowl). The kid began feeding from the webworm leaves (first bite) yet, proceeded to feed from the control leaves. Once the control leaves were completely consumed, the kid fed on the webworm leaves while efficiently avoiding webworm ingestion. Video speed increased by ×5.
Supplementary movie 2
Probing behaviour while feeding on leaves with webworms (right bowl). By repeatedly touching the leaves with its muzzle (probing), the kid was able to pick webworm-free leaves. Video speed increased by ×5.
Supplementary movie 3
A feeding kid (not naïve) avoiding the ingestion of numerous webworms (non-choice trial). All six webworms remain intact. Video speed increased by ×5.
Non-choice experiment- webworms (kid #2609)
An example of a non-choice experiment- we presented a kid with one bowl at a time (control or webworm leaves) in randomized order. This bowl contains leaves with webworms.
Non-choice experiment-no webworms (kid #2609)
An example of a non-choice experiment- we presented a kid with one bowl at a time (control or webworm leaves) in randomized order. This bowl contains leaves without webworms.
Dual-choice experiment- Trial 1 (kid #2639)
We presented naive kids with a choice between two bowls (in randomized order) containing leaves alone and leaves with three webworms. We repeated this experiment over three consecutive days, in order to examine whether the kids learn to avoid webworms and feed more efficiently with experience. This video shows trial number 1.
Dual-choice experiment- Trial 2 (kid #2639)
We presented naive kids with a choice between two bowls (in randomized order) containing leaves alone and leaves with three webworms. We repeated this experiment over three consecutive days, in order to examine whether the kids learn to avoid webworms and feed more efficiently with experience. This video shows trial number 2.
Dual-choice experiment- Trial 3 (kid #2639)
We presented naive kids with a choice between two bowls (in randomized order) containing leaves alone and leaves with three webworms. We repeated this experiment over three consecutive days, in order to examine whether the kids learn to avoid webworms and feed more efficiently with experience. This video shows trial number 3.