Vultures & Condors: Vultures and Condors aren't necessarily a threat to a healthy chicken. Vultures and Condors may attack sick or wounded chickens but rarely attack healthy ones.

DeerSurprisingly, deer may kill chicks. Deer are mostly Herbivorous but will snack on baby birds (or rarely small adult birds) if there is a lack of plant matter in the area. Deer mainly go for the bones if they attack a chick as the bones are rich in Phosphorus and Calcium that they need for strong bones or in Stags, Strong antlers.

Dogs: Coyotes and Foxes are notorious for attacking chickens. Young Foxes that go for chickens may be a death wish as there are accounts of hens killing young foxes. Domestic dogs may also attack chickens if not properly trained.

Cats: Cats are also a pesky chicken hunter. Feral cats are known for attacking and killing hens. A lot of cat species have an innate climbing ability so they may climb fences. Sometimes cats may form a bond with chickens such as protecting them in exchange for warmth in the winter.

Weasels: Weasels, like cats are notorious for hunting chickens. Although Weasels mainly go for the eggs. Which if you are raising chickens for eggs is a problem. Weasels are naturally flexible so some fences don't protect chickens from them.

Hawks and Falcons: Hawks and Falcons are known to attack chickens. Hawks and Falcons mainly attack by swooping down to grab their prey so if chickens go into a roofed area, they are safer than in the open.

Cats: Chickens may hold their ground against domestic cats and they may get injured while defending themselves.

Dogs: Most Dog breeds don't really do anything with chickens.

Non-Fowl Birds: Silkies are sometimes used to hatch other species' eggs.Broody hens may get injured when Territorial Parents find a chicken hatching their eggs. Chickens may do well with other bird species such as Parrots and Pigeons. Chickens and parrots are both susceptible to PBFD (Psittacine Beak and Feather Disease)

Small Mammals: Most small mammals such as mice and Ferrets are usually kept away from chickens in hamster cages or ferret cages. However ferrets do like to eat whole eggs, raw or cooked.

Rabbits: Chickens and rabbits are perfect for people raising animals in small spaces but Rabbits and Chickens carry diseases that can spread to each other. Rabbits may also seriously injure chickens and even kill them if they become territorial

Ducks: Ducks and chickens go very good together! Having a mixed coop is difficult though, due to the different health and dietary needs for chickens and ducks.

Turkeys: When Raising Turkeys and chickens together, histomoniasis or Blackhead disease, is a concern since Turkeys are susceptible to Blackhead unlike their Chicken counterparts

Peafowl: Like Turkeys, Peafowl are susceptible to histomoniasis and chickens may carry worms and protozoa that spread histomoniasis in their droppings.

Dealing with predators can be tough as many predators can get through traditional defenses like fencing. For predators with a natural climbing ability, fences made of thin mesh that are too small for predators to climb over or get through are ideal for keeping your coop safe from predators that climb or fly. If thin mesh doesn't prevent birds of prey from attacking them, put a net over the fenced area around the coop. However chickens may find their own ways of deterring birds of prey such as taunting them or pecking them when they swoop down. At night close up coop doors to keep Opossums or nocturnal Mustelids out