The diet of parrots consists of seeds, fruit, nectar and pollen and to a lesser degree animal prey. Without question the most important of these to most true parrots and cockatoos are seeds. The evolution of the large and powerful bill can be explained primarily as an adaptation to opening and consuming seeds. All true parrots except the Pesquet’s Parrot employ the same method to obtain the seed from the husk; the seed is held between the mandibles and the lower mandible crushes the husk, whereupon the seed is rotated in the bill and the remaining husk is removed. A foot is sometimes used in order to help holding large seeds in place. Parrots are seed predators rather than seed dispersers; and in many cases where species are recorded as consuming fruit they are only eating the fruit in order to get at the seed. As seeds often have poisons to protect them parrots will consume clay in order to filter the toxic compounds. The lorikeets, Swift Parrot and Philippine Hanging parrot are primarily nectar and pollen consumers, and have tongues with brush tips to collect this source of food, as well as some changes in the gut. Many other species also consume nectar as well when it becomes available. In addition to feeding on seeds and flowers, some parrot species will prey on animals. Golden-winged Parakeets prey on water snails, and famously the Keas of New Zealand will scavenge on sheep carcases and even kill juvenile petrels. Another New Zealand parrot, the Antipodes Island Parakeet, enters the burrows of nesting Grey-backed Storm-petrels and kills the incubating adults. Some cockatoos and the Kākā will also excavate branches and wood in order to obtain grubs.