3,000-5,000 healthy zoo animals euthanized yearly in Europe alone

European zoos euthanize an estimated 3,000 to 5,000 healthy animals per year as 'surplus' — animals that are no longer needed for breeding programs and for whom no space exists at other facilities. These are not sick or suffering animals; they are healthy individuals killed because the zoo system overproduces animals it cannot house. The most visible case was Marius, a healthy 18-month-old giraffe publicly dissected at Copenhagen Zoo in 2014, but the practice is routine and largely hidden. This matters because zoos justify captive breeding as conservation, yet the system structurally produces animals it then kills, undermining both the ethical and conservation rationale. Some surplus animals are quietly transferred to unaccredited facilities, dealers, or even hunting ranches — Missouri's Dickerson Park Zoo transferred a giraffe, a greater kudu, and five red kangaroos to a dealer known to sell to hunting ranches. The problem persists because zoos need baby animals to drive visitor attendance and revenue, breeding programs produce more offspring than the captive population can absorb, and contraception is underused because it can complicate future breeding recommendations.