Cats
With their speed and agility, hummingbirds quickly entrance cats in the outdoors, whether domestic or feral. Cats enjoy stalking the evasive hummingbird before pouncing and using their sharp claws to bat at the animal, sometimes only snagging the tails. Cats also tend to carry hummingbirds in their mouths, proud of their capture, even if the hummingbird is not dead. Domestic cats likely won't eat the hummingbird, but feral cats do. The Hummingbird Society attributes cats for critically endangering such hummingbird species as the Juan Fernandez firecrown.
Birds
Large birds provide a serious threat to eggs, young and adult hummingbirds. Raptors, including hawks, kestrels and falcons, pursue hummingbirds and eat them, despite the high energy needed to capture prey too small to have much nutritional benefit. Despite fierce and seemingly fearless defense from the adult hummingbirds, nests prove particularly vulnerable to medium-sized birds, such as blue jays and crows. Other bird threats depend on the hummingbird's range and include owls, shrikes, roadrunners, flycatchers, orioles, grackles, gulls and herons.
Insects and Spiders
A common threat to hummingbirds, the praying mantis settles on tree branches and bushes to wait for prey to fly close enough to snag in their arms. Although similar in size or smaller than hummingbirds, the praying mantis consumes the entire bird. Large dragonflies also prey upon hummingbirds. Hummingbirds use parts of spider webs to adhere their nests to tree branches, but some individuals become ensnared in the webs, where they are wrapped up and slowly consumed like an insect.
Miscellaneous
Snakes and small mammals climb trees and raid the nests, eating the hummingbird eggs and young. Large frogs, such as the leopard frog, use their quick tongues to snag hummingbirds from the air and swallow them whole. However, the Hummingbird Society believes most of these frogs likely choke and die as well. A bass dissection once yielded a hummingbird in its stomach. Bees and wasps attack hummingbirds when provoked or threatened, killing the small bird with their venom, but they do not consume the body.