By biologists' rules, a bird eating seeds counts as a predator
Predation sounds simple: one creature kills and eats another. But a mouse eating seeds is technically a predator, since each seed is a whole living organism, while a deer browsing leaves is not, because the plant survives. Fleas, wasp larvae and albatrosses all test where the line falls.
At heart, predation means one organism killing and eating another. It sits in a family of feeding styles alongside parasitism and micropredation, which usually spare the host, and parasitoidism, which eventually kills it. An ichneumon wasp lays eggs inside a host that its larvae then consume; zoologists call that parasitism, reasoning that a predator takes many victims over its life while a parasitoid larva gets just one. Mosquitoes, fleas and sap-sucking aphids are micropredators, now often grouped with parasites since their hosts survive. Scavengers eat only the already dead, though jackals, hyenas and yellowjacket wasps hunt and scavenge alike.
The borderlines produce surprises. Animals grazing on phytoplankton or microbial mats are predators, because their food dies, and so are seed eaters and egg eaters, from specialist snakes to opportunistic foxes and badgers. Predators span mantids, dragonflies, spiders, centipedes, sea stars, jellyfish and barnacles. Pitcher plants, Venus flytraps and sundews trap insects, some fungi snare nematodes with constricting rings, and single-celled protozoa and bacteria have evolved to prey on microbes many times over.
Every hunt runs through a cycle of searching, deciding, chasing or ambushing, and handling. Sit-and-wait tactics suit low-energy hunters facing dense, mobile prey, as with web-building spiders, mantises and kestrels, whereas sharks, shrews and insect-eating birds keep moving. Prey tends to cluster, so predators hunt for rich patches; breeding black-browed albatrosses range up to 3,000 km to feed their chicks. Many search paths resemble a Lévy walk, bursts of short steps punctuated by long jumps, seen in bacteria, honeybees, sharks and human hunter-gatherers. Insect-eating birds grab nearly every palatable morsel, while lions and falcons, facing costly chases, choose more carefully.
Hunters rely on keen senses, claws, jaws, strength, stamina, cooperation and sometimes aggressive mimicry. Prey answers with warning colours, alarm calls, camouflage, copycat patterns, spines and chemicals, and the two sides can lock into an evolutionary arms race. This pressure has shaped life since at least the Cambrian.
Source: Predation
