Thornton, CO Animal Ordinances: Chickens & Livestock (2026)

City Code Chapter 6, Article I bans keeping horses, mules, sheep, cattle, swine, most fowl, pigeons, and other livestock in residential zone districts under Section 6-36(a), with narrow exceptions: up to two ducks per premises, and backyard chickens kept under Section 6-53. Section 6-53 permits up to six hen chickens (no roosters) on lots with detached residential dwellings in the Residential - Low Density, Mid Density, High Density, Planned Development Legacy, Transit-Oriented Development, and Eastlake Residential districts. A chicken coop is mandatory: it must sit in the backyard only, be set back at least five feet from side and rear lines, stay under 120 square feet and seven feet tall, and provide at least six square feet per bird.

Chickens must be confined to the coop from dusk to dawn and may free-range the fenced yard or a chicken run during the day. Feed and waste must be kept in resealable, pest-proof metal containers, and on-site slaughtering is prohibited. Separately, Section 6-54 lets residents keep miniature goats (100 pounds or less at maturity) in groups of exactly two, but only after obtaining a city permit that requires a site plan, an application fee, and a pre-issuance property inspection; unaltered males over four months old are barred, breeding is prohibited, and goats count toward the four-animal household cap in Section 6-37. Residents in the Agricultural or Residential Estate districts follow different limits under Section 6-36(b) instead of the citywide ban.