Chicken
The domestic chicken achieves a maximum sprint velocity of approximately 14.5 kilometres per hour, or 9 miles per hour, when sufficiently motivated by threat or opportunity. This represents a significant reduction from the capabilities of their wild junglefowl ancestors.
Flight capability exists but has atrophied considerably under domestication. Modern chickens achieve brief bursts covering 10 to 15 feet horizontally at modest heights, sufficient for reaching low perches but inadequate for sustained aerial travel. The broiler varieties bred for meat production have become so gravitationally challenged that even these limited flights prove difficult.
One must note, however, that the chicken's reduced velocity reflects deliberate human selection rather than evolutionary failure. Chickens have been bred for egg production, meat yield, and temperament. Speed has been actively discouraged in favour of docility and feed conversion efficiency. The chicken sacrificed velocity for other advantages.
Capybara
The capybara, despite its considerable bulk, demonstrates surprising terrestrial velocity when circumstances demand. Fully grown specimens achieve running speeds of 35 kilometres per hour across open ground, equivalent to approximately 22 miles per hour in imperial measurement.
This velocity proves particularly remarkable given the animal's physiology. The capybara is, fundamentally, a giant guinea pig optimised for aquatic environments. Its legs are short relative to body mass, its feet partially webbed, and its general disposition suggests that running is considered rather undignified. Yet when predators approach, the capybara can accelerate with surprising urgency.
In water, the species demonstrates even greater capability. Capybaras swim with grace and efficiency, remaining submerged for up to five minutes and using aquatic environments as their primary escape route. They have been observed sleeping while mostly submerged, with only nostrils protruding above the waterline. This amphibious versatility represents evolutionary sophistication that merits acknowledgment.
VERDICT
In matters of terrestrial velocity, the capybara holds a decisive advantage of approximately 140% over its gallinaceous competitor. The 35 kph maximum of Hydrochoerus hydrochaeris substantially exceeds the chicken's 14.5 kph ceiling.
The capybara's aquatic capabilities further extend this advantage. While the chicken demonstrates adequate swimming ability in emergencies, it approaches water with the enthusiasm of a creature that would prefer virtually any alternative. The capybara, meanwhile, treats water as a preferred medium for locomotion, thermoregulation, and social activity.
This category belongs to the capybara without controversy. The world's largest rodent has retained locomotor capabilities that domestic breeding has systematically removed from the chicken. In the fundamental biological metric of escape velocity, the capybara prevails.