They come in staggering, looking depressed. Sometimes they have ulcers on their eyes or in their stomachs.

Dr. Heather Barron’s patients range in size from sanderlings, tiny birds that can weigh as little as three and a half ounces, to loggerhead turtles that weigh hundreds of pounds. And the unusually long red tide hitting Sanibel Island in Florida has kept them coming in.

The Clinic for the Rehabilitation of Wildlife has seen a 25 percent increase in patients compared with this time last year, said Dr. Barron, the medical and research director. The clinic’s staff has been stretched thin, working 80-hour weeks to treat the large number of animals left sick by the red tide.