Abstract
Causes of seabird "wrecks" are often unknown, but stormy weather,5 harmful algal blooms,2,4 poor food availability,3 and disease6 have been implicated in these mass stranding events. International Bird Rescue received large numbers of live Northern Fulmars (NOFU) during stranding events in 2003 (n = 94) and 2010 (n = 43). Strandings occurred primarily from late October through December. In 2003, CA Department of Fish and Game biologists necropsied 186 beach cast birds. Most were emaciated hatch-year birds with fluid in the lungs, were negative for Chlamydophila and heavy metals, and had small pieces of plastic commonly found in the ventriculus. Necropsies at International Bird Rescue (n = 29) showed emaciation, lung and/or air sac lesions in 25/29 (86.2%, 3 fungal, 22 unknown); foot lesions in 8/29 (27.6%), and fermented mash in many proventriculi. Live birds were housed in freshwater pools and tube fed grain-based mash if not eating fish. A small number of birds were treated with antibiotics for foot lesions (4 of the 94 birds, 3 of 4 survived to release). Itraconazole was given prophylactically against aspergillosis. Only six of 94 birds (6.4%) survived to release. In 2010 clinical signs included foot webbing lesions (nodules, hemorrhages, blistering, and distal necrosis) and abnormal respiratory sounds. Birds became increasingly lethargic once housed in pools and several birds died. Blood chemistry results showed extremely low plasma sodium (117–120 mg/dL), data from these birds were included in Frankfurter et al. (2012).1 Subsequently, salt supplementation was initiated once birds were housed in water full time at 1–2g NaCl/kg body weight every to every other day. Lethargy and inappetence ceased with supplementation, and birds became aggressive enough that they sometimes had to be separated due to fighting. Five cases were submitted for pathology. Significant findings: pneumonia in 4/5 (1 Gram+, 1 Gram-, 1 fungal, 1 unknown), necrotizing pododermatitis in 4/5 (1 Gram-, 3 unknown), 2/5 bursal cryptosporidiosis, 1/5 nephritis, 1/5 cerebral neuronal necrosis. Overall impression of pathologists: Probable viral foot lesions leading to opportunistic bacterial and fungal respiratory infections. Electron microscopic and metagenomic virus identification efforts have been unrewarding. Birds with abnormal respiratory sounds and/or foot lesions were treated with Clavamox at 125 mg/kg twice daily in combination with Baytril at 25 mg/kg once daily for a minimum of two weeks. All birds were also given itraconazole at 15 mg/kg once daily. Birds were housed in freshwater pools; nutritional tubings when inappetent were Emeraid CarnivoreTM (Lafeber Company), a diet better suited to obligate carnivores. Twenty-one of 43 birds (48.8%) survived to release. NOFUs have been known historically to be a difficult species to rehabilitate, with successful releases for only 5–10% of birds admitted for care. During the 2010 event, we improved this expected outcome through identification and management of two treatment challenges: hyponatremia likely due to freshwater housing and a still-unidentified primary pathogen with secondary opportunistic respiratory infections. Further investigation of future mass stranding events is planned to explore the role of disease in sometimes massive wrecks of NOFUs and other seabirds.
Acknowledgements
Thanks to Hannah Nevins and other staff at CADFW-MWVCRC, Beach COMBERS, Monterey Bay SPCA, Dr. Patty Pesavento at University of California Davis School of Veterinary Medicine, and International Bird Rescue volunteers for caring for the animals and patiently implementing our sometimes rapidly changing animal care protocols. Additional thanks to Henriette Jewell for data excavation and compilation.
* Presenting author
Literature Cited
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