Double-Crested Cormorant Arrives with Multitude of Symptoms

Editor’s Note: The juvenile double-crested cormorant is part of the CROW CAW (Case A Week) series, which tells the stories of the patients at the Clinic for the Rehabilitation of Wildlife on Sanibel Island, the dangers they face, and how we can help protect all of our wildlife. Read previous cases here.

A juvenile double-crested cormorant (Phalacrocorax auritus) (Patient 25-4729) was found on Fort Myers Beach, unable to fly, and brought to the Clinic for the Rehabilitation of Wildlife.

The patient was dull, fairly dehydrated, and emaciated, with burrs on its feet and small tears in the webbing between its toes. Furthermore, on radiographs, there was a minor chip fracture on the left humeral head.

The veterinarians suspected that the animal had sustained some unknown trauma, possibly accompanied by red tide toxicosis. To neutralize the toxin and facilitate its excretion, the cormorant was administered intravenous lipid emulsion (IVLE).

Bloodwork revealed significant inflammation, prompting the initiation of antibiotics for a possible infection. To address dehydration, intravenous fluids were started, and pain medications were administered to manage the fracture and webbing tears.

It’s common for patients to present to CROW with a variety of symptoms and injuries stemming from a larger underlying issue. In this case, it’s suspected that the red tide toxins caused neurological problems that led to the other injuries and symptoms. The double-crested cormorant’s red tide symptoms have already improved, and its fracture and feet are healing.

Double-crested cormorants are medium-sized waterbirds with a hooked beak and dark feathers. This juvenile patient has brown feathers that will be replaced with darker ones once it molts into its adult plumage.

Although these birds dive for their prey, they don’t have waterproof feathers and are often seen standing on rocks or trees, drying their wings after emerging from the water. This lack of waterproofing is thought to reduce buoyancy, allowing them to dive deeper to hunt fish more effectively.