St. Maarten Private Eye

According to Wiki and Dictionary.com an animal is any member of the kingdom Animalia, comprising multicellular organisms that have a well-defined shape and usually limited growth, can move voluntarily, actively acquire food and digest it internally, and have sensory and nervous systems that allow them to respond rapidly to stimuli: some classification schemes also include protozoa and certain other single-celled eukaryotes that have motility and animal-like nutritional modes.

Wikipedia says that birds are bipedal, endothermic (warm-blooded), vertebrate animals that lay eggs.
Dictionary.com confirms that.
Brittanica is on the same page mentioning that the feathers are the major characteristic that distinguishes them from all other animals.

A bird is not a mammal but I I think it is fair to say that a bird is an animal.

Rackham