Jackrabbits’ long ears help detect sounds and release body heat. Blood vessels in the ears can widen to increase heat loss when the animal is hot.
A living heat exchanger
The ears have a large exposed surface and a rich blood supply. Bringing more warm blood close to that surface allows heat to pass to cooler surroundings. The National Park Service describes widening ear blood vessels as part of temperature regulation.
Cooling has physical limits
Ears cannot provide unlimited cooling in every environment. Heat transfer depends on surrounding conditions, so body regulation also involves behavior. A large ear is not the equivalent of an electric refrigerator.
Are jackrabbits actually rabbits?
Despite their common name, jackrabbits are hares. Their ears have more than one role: an anatomical feature can support both hearing and temperature control. Explaining them only as oversized hearing organs misses an important desert adaptation.
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Sources and evidence
- National Park Service — Black-tailed jackrabbit ↗
Scientific background for the explanation above.
Sources consulted: 16 October 2026. Written with AI assistance and checked against the linked references; not independently reviewed by a subject specialist. Sources do not endorse this article. See our editorial policy.
Revision: Initial publication with institutional sources and a direct answer.