Red Tide Cormorants

provided by Clinic for the Rehabilitation of Wildlife

Double-crested cormorant

Few people who stay for long on Florida’s West coast can fail to be aware of Harmful Algal Blooms (HABs) and, more specifically, red tides. Although more than 50 HAB species occur in the Gulf of Mexico, only about 2 percent of algal species worldwide are known to be harmful or toxic. One of the most well-known species is Karenia brevis, the Florida red tide organism. Despite their name, red tides are not always red. In high concentrations, they can discolor the water, but more often you will feel the effects and see the effects of the bloom rather than the bloom itself.

They are also not a new phenomenon, having been recorded in Florida since the 1800s. Not all algal blooms are harmful and while they are a natural phenomenon, the occurrence, severity, and duration of HABs is on the rise due to a confluence of human-driven factors. Red tides typically occur in the late fall and early winter months in the Gulf of Mexico, especially along the coastline adjacent to the outflows from the Caloosahatchee River.

The Karenia brevis organism produces sodium channel neurotoxins, called brevetoxins, that accumulate in the food chain when ingested. The accumulation can sicken or kill fish, sea turtles, sea birds, and marine mammals. Brevetoxins may also cause health problems in humans. These include respiratory irritation from breathing in airborne toxins near the coastline or Neurotoxic Shellfish Poisoning from consumption of the toxin in shellfish.

At the Clinic for the Rehabilitation of Wildlife (CROW), the “poster-child” for red tide is the double-crested cormorant. These seabirds are brown-black as adults while younger birds are browner overall with a paler neck and breast. They have an orange or yellow bill that has a characteristic hook at the tip. Since October 1 of this year, 59 of these birds have been admitted with signs of red tide.

A bird that is affected by red tide often shows a particular set of symptoms. Since it is a neurotoxin, it affects the birds nervous system. This results in the bird being unable to fly, appear wobbly or “drunk” when walking and they often lose their natural fear of humans. They can also lose their blink reflex and have gastrointestinal issues as a result of the toxin.

If you see a bird exhibiting these symptoms, contact CROW immediately, because the quicker it can receive help, the more likely it is to survive. The first 24-hours after being admitted to the hospital is often the most critical. In recent years, CROW has been at the forefront of developing a treatment for red tide poisoning in wildlife to help through this critical stage and on the road to recovery.

The treatment, known as intravenous lipid emulsion therapy, uses a lipid solution that is injected into the bloodstream using an IV catheter. The lipids bind to the toxins to prevent them from further affecting the bird while its body processes and removes them. Birds are also provided with fluid therapy to help support its liver and kidneys while they are working hard to remove the toxins along with plenty of toxin-free fish for it to eat. In severe cases that affect the birds digestive tract, a fish slurry fed using a tube inserted into the bird’s stomach is used because it is easier for the birds to digest before they are strong enough to eat whole fish on their own again.

This treatment protocol has shown great success in rehabilitating birds sickened by red tide. For those 59 birds admitted already this year, CROW has seen a 65 percent success rate in returning them to the wild. For those that made it through the critical first 24-hours, that rate jumps above 75 percent.

THIS WEEK AT CROW (12/16-12/22):
There were 79 new patients admitted to CROW’s Wildlife Hospital including 14 eastern cottontails, six double-crested cormorants, five gopher tortoises, a little blue heron, two white pelicans and a sharp-shinned hawk. Recent Releases include an eastern box turtle, five double-crested cormorants, a gopher tortoise and an eastern screech owl. Check out a full list of CROW’s current patients and recent releases!
Wildlife doesn’t have health insurance! Your donations help cover the costs of medical and rehabilitative care for over 5,000 patients admitted to CROW’s Wildlife Hospital each year!
Want to learn more about wildlife rehabilitation? Stop by CROW’s Visitor Education Center at 3883 Sanibel Captiva Road.

About Clinic for the Rehabilitation of Wildlife (CROW)
Established in 1968, the Clinic for the Rehabilitation of Wildlife (CROW) is a teaching hospital saving the sick, injured and orphaned native and migratory wildlife of Southwest Florida and beyond.  Through state-of-the-art veterinary care, public education programs and an engaging visitor center, CROW works to improve the health of the environment, humans and our animals through wildlife medicine. For more information, or to plan your visit, go to If you find an animal that is in need of help, call (239) 472-3644 ext. #222.

Comments (1)

  1. CROW constantly amazes me with how innovative their treatment plans are. I’ll be sending a donation soon.

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