Spontaneous learning of pine cone opening behavior by black rats (Rattus rattus)

Black rats inhabit the Jerusalem Pine forests in Israel. These rats feed on pine seeds extracted from the cones. To strip the cone's scales, the rat has to employ an adept and sequential technique without which the energy gained from the seeds would be less than the energy spent. The stripping technique was found to be culturally transmitted from mothers to their pups only. Hungry adult rats could not acquire the technique even after 2 months. In the present study we explored the conditions that could facilitate the acquisition of pine cone stripping behavior by trial-and-error learning. Satiated rats were given pine cones for 60 days in various social and environmental conditions (unisex groups, pairs, and solitary rats, in cages and semi-natural conditions). The results of this study demonstrate that, given the right conditions, a small portion of the black rat population is capable of learning the complicated technique of pine cone stripping. In the wild, these rats can originate the local tradition of pine cone opening. The results are discussed with respect to their implication for problem solving, and for the occurrence of cone stripping in the natural rat population in the pine forests.