To the Editor:

Re ''At Bronx Zoo, an Elephant Exhibit's End Plays Out in Elephant Time'' (news article, Feb. 7):

The world's largest land mammals suffer in captivity, and so do the smallest.

Despite their small size, mice are thinking, feeling creatures with wants and needs and a capacity to suffer. In the lab, racks of tiny ''shoe box'' cages are routinely supplied only with a water bottle, a sprinkle of sawdust and lumps of processed chow to be nibbled through the bars.

Studies find that mice and rats are highly motivated to perform important natural behaviors like foraging, running, burrowing, climbing and choosing social partners. Thwarting them has harmful physical and psychological effects.

About half of the hundred million mice kept in labs suffer from pathological repetitive movement patterns commonly seen in animals confined in zoos.

Jonathan Balcombe
Washington, Feb. 8, 2006

The writer is a research scientist with the Physicians Committee for Responsible Medicine.