Investigation of cognitive mechanisms and strategy on solving multiple string-pulling problems in Azure-winged magpie (Cyanopica cyanus)

Bumblebees attend to both the properties of the string and the target in string-pulling tasks, but prioritize the features of the string

Previous studies have demonstrated that associative learning and experience play important roles in the string-pulling of bumblebees (Bombus terrestris). However, the features of the target (artificial flower with sugar reward) and the string that bees learn in such tasks remain unknown. This study aimed to explore the specific aspects of the string-flower arrangement that bumblebees learn and how they prioritize these features. We show that bumblebees trained with string-pulling are sensitive to the flower stimuli; they exhibit a preference for pulling strings connected to flowers over strings that are not attached to a target. Additionally, they chose to pull strings attached to flowers of the same color and shape as experienced during training. The string feature also plays a crucial role for bumblebees when the flower features are identical. Furthermore, bees prioritized the features of the strings rather than the flowers when both cues were in conflict. Our results show that bumblebees solve string-pulling tasks by acquiring knowledge about the characteristics of both targets and strings, and contribute to a deeper understanding of the cognitive processes employed by bees when tackling non-natural skills.

Group intrusions by a brood parasitic fish are not cooperative

Brood parasites relegate all parental duties to unrelated hosts. Host resistance against brood parasitism is most effective during egg laying and is best countered by surreptitious oviposition. This may be aided through distraction of host attention by the male partner or a larger cooperative group. Cuckoo catfish (Synodontis multipunctatus) parasitize the broods of mouthbrooding cichlids, which collect their eggs immediately after oviposition. Cuckoo catfish must time their intrusion precisely, as the temporal window for parasitism lasts only a few seconds. As the cuckoo catfish typically intrude host spawning as a group, we tested whether groups of catfish distract spawning cichlid pairs more successfully than a single catfish pair. We found that larger catfish groups were not more effective in parasitism, as parasitism success by groups of three catfish pairs increased only proportionally to single catfish pairs. The number of cichlid eggs in host clutches decreased at high catfish abundance, apparently due to elevated cuckoo catfish predation on the eggs. Hence, group intrusions do not represent cooperative actions, but incur an increased cost to the host cichlid from greater egg predation by cuckoo catfish.