Ecological specialists utilize a restricted range of resources and have evolved adaptations to exploit their specialized resources. For example, avian insectivores that feed nestlings with grasshoppers, beetles, or moths perform insect prey preparation before feeding nestlings so that the nestlings are able to swallow the prey. This behavior is generally not expected for soft prey such as earthworms. However, an overview of photographic evidence available online suggested that earthworms are sundered by parents before bringing the prey to the nestlings in a range of species from several families of vermivores worldwide. Reports on the provisioning of nestlings by the vermivores are relatively scant and no report on earthworm sundering has been published. We studied earthworm sundering performed by parents provisioning their broods at four nests of the Fairy Pitta in Korea. The birds sundered earthworms more often when nestlings were smaller and when the earthworm was longer. This is the first quantitative description of earthworm sundering in avian vermivores. We present and evaluate four hypotheses for the function of sundering: provisioning of small nestlings, decreased detectability, hunting multiple prey, and transport of prey. Among these, provisioning of small nestlings seems the most feasible explanation of sundering by the Fairy Pitta as sundering the earthworm allows parents to efficiently provision the younger/smaller nestlings who would have difficulties swallowing unsundered earthworms. This specialized prey preparation technique of vermivores suggests a tight adaptive match between their parental behaviors and their diet (vermivory).

Numerous non-avian dinosaurs possessed pennaceous feathers on their forelimbs (proto-wings) and tail (caudal plumage). Their functions remain unclear. We propose that the pennaceous feathers were used in displays to flush prey through stimulation of sensory-neural escape pathways in prey, and to provide higher speed and maneuverability during pursuits after prey. We evaluated escape behavior of grasshoppers to the hypothetical visual flush-displays by a robotic dinosaur, and neurophysiological responses of grasshoppers’ escape pathway to computer animations of the hypothetical flush-displays by dinosaurs. We confirmed that prey of small dinosaurs might have escaped more often when proto-wings were present, especially distally and with contrasting patterns, and when caudal plumage, especially of large area, was used during the hypothetical flush-displays. The reinforcing loop between flush and pursue functions could have contributed to the evolution of larger and stiffer feathers for faster running, maneuverability, and stronger flush-displays, promoting foraging based on the flush-pursue strategy. The flush-pursue hypothesis can explain the presence and distribution of the pennaceous feathers, plumage color contrasts, as well as a number of other features observed in early pennaraptorans. This scenario highlights that sensory-neural processes underlying prey’s antipredatory reactions may contribute to the origin of major evolutionary innovations in predators.