The domestic chicken, Gallus gallus domesticus, is one of the world’s most widespread and diverse livestock species. The sheer number of “kinds” of chickens is difficult to quantify because they are classified in several different ways, reflecting centuries of selective breeding. This domesticated descendant of the red junglefowl exhibits an astonishing range of characteristics. Understanding the diversity of chickens requires acknowledging that the answer depends on whether one is counting distinct genetic lines, physical appearances, or functional roles. The number of recognized breeds worldwide is estimated to be over a thousand, with some organizations recognizing more than 1,600 different breeds.
Understanding Breeds, Varieties, and Strains
To structure the vast chicken population, formal systems of classification rely on the terms breed, variety, and strain. A breed is an established group of birds that share a common set of characteristics, such as body shape, skin color, and comb type, which are reliably passed down to their offspring. For instance, the Rhode Island Red is a recognized breed with a specific body conformation and color.
A variety represents a subdivision within a breed, distinguished by specific traits like plumage color, feather pattern, or comb type. The Plymouth Rock breed, for example, is split into varieties such as Barred, White, or Buff Plymouth Rock, all sharing the same fundamental body shape. This level of sub-classification greatly increases the total count of distinct chicken appearances.
A strain is a specialized term referring to a family or bloodline developed by a single breeder or organization for a specific, often commercial, trait. These lines are selectively bred for characteristics like superior egg production, rapid growth rate, or better feed efficiency. A strain of White Leghorn maintains the breed’s general characteristics but is uniquely uniform in its high egg-laying capability due to generations of focused breeding.
Classification Based on Primary Purpose
One of the most practical ways to categorize chickens is by their primary utility, which has driven much of their selective breeding. These functional classifications include Egg Layers, Meat Birds, Dual-Purpose, and Exhibition/Ornamental types.
Egg Layers
Egg Layers are typically lightweight and active, putting their energy into high egg output rather than muscle mass. They often lay over 250 eggs annually. The White Leghorn is the classic example, bred to be an efficient egg-producing machine.
Meat Birds
Meat Birds, or broilers, are bred for rapid growth and substantial body mass, with a high feed-to-meat conversion ratio. Modern commercial broilers are often hybrids, such as the widely used Cornish Cross. They reach market weight in a short period and have a heavy-bodied physique compared to the lean egg layers.
Dual-Purpose
Dual-Purpose breeds offer a moderate balance, providing a respectable number of eggs while also growing large enough to be used for meat. Breeds like the Wyandotte, Rhode Island Red, and Orpington are popular choices in this category, offering a sustainable option for small farms and homesteads. While they take longer to mature for meat than a broiler, they provide a steady supply of eggs and are often cold-hardy.
Exhibition/Ornamental
Exhibition or Ornamental birds are kept primarily for their unique appearance, such as specific feathering, crests, or unusual colors. These birds, like the Polish with its large crest or the Silkie, are valued for aesthetics rather than production efficiency.
Major Breed Classes by Geographical Origin
Formal poultry organizations categorize standard breeds into “Classes” based on their geographical origin. This system acknowledges the historical development of breeds influenced by local environments and human selection.
- American Class: Includes breeds developed in North America, such as the Plymouth Rock and New Hampshire, which tend to be robust and cold-hardy.
- Asiatic Class: Features large, heavy breeds that originated in Asia, exemplified by the Brahma and Cochin. These breeds are often characterized by feathered legs and a calm, deliberate temperament.
- English Class: Groups breeds originating in the British Isles, including the Orpington and Sussex. These breeds were developed to be substantial table birds, focusing on moderate size and meat production qualities.
- Mediterranean Class: Contains breeds like the Leghorn and Minorca, featuring birds that are generally more active and lighter-bodied, reflecting their origins in warmer climates.
The World of Bantam Chickens
Bantams represent a unique classification based purely on size, existing as miniature versions of standard fowl. They are roughly one-quarter to one-fifth the size of their standard counterparts, making them suitable for smaller spaces and urban environments. This category is divided into two types: miniature bantams and true bantams.
Miniature bantams are simply downsized versions of full-sized breeds, such as a Bantam Rhode Island Red or a Bantam Plymouth Rock. True bantams are naturally small breeds that do not have a large-fowl equivalent, like the Sebright or the Japanese Bantam. Bantams are often prized as ornamental birds or pets due to their manageable size and docile nature.