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A 3.3-kg, juvenile brown pelican (Pelecanus occidentalis) of undetermined sex was presented to the Center for Rehabilitation of Wildlife (CROW) for lethargy and an inability to fly away from rescuers. On presentation, the bird was bright, alert, and responsive, and results of physical examination were unremarkable. The pelican's flight ability was not assessed on the initial examination. Results of baseline blood tests revealed a packed cell volume of 40% (reference mean value, 48 [+ or -] 8%) (1) and a total protein of 2.8 g/dL (reference mean value, 4.8 [+ or -] 0.7 g/dL). (1) Radiographs were taken to screen for traumatic injuries that would impair flight ability. The bird was induced with 5% isoflurane and 2 L of oxygen via a facemask and maintained on 3% isoflurane for radiographs.
A large, bony and soft tissue mass extending from the thoracic inlet to the cloaca was observed on radiographs (Figs 3 and 4). This mass was consistent with a teleost fish in the gastrointestinal tract.
After anesthesia was discontinued, the bird recovered with flow-by oxygen administered by facemask and a warm forced-air blanket was used for thermal support. During recovery, the bird regurgitated a large snook fish, consistent with the radiographic image. After regurgitating the fish, the bird weighed 2.2 kg, the normal average weight for immature brown pelicans in the area. The bird was fully recovered in 20 minutes, and 1 hour later, it was placed in a flight cage and was observed to fly. Because the bird had regurgitated the fish and was able to fly, no further treatment was needed. After 6 additional hours of observation, during which, no other abnormalities were observed, the bird was released in the same area in which it was found.
A pelican can hold up to 3 gallons of fish and water in its gular pouch, which is roughly 3 times the amount that will fit into the proventriculus. (2) Pelicans typically consume approximately 1.8 kg of fish a day; however, this usually comprises numerous fish and not one large catch. The pelican in this case was a juvenile and was theorized to have been given this oversized catch by fishermen in the area. The discomfort and weight of the fish, which was approximately 50% of the bird's body weight, was thought to contribute to this animal's inability to fly. Adult pelicans catch fish on approximately 66% of their dives, whereas immature pelicans are successful only about 30% of the time. Immature pelicans are, therefore, much more likely to resort to scavenging around docks and fish-processing locations. (3)
Gastric foreign bodies are seen often in pelicans, and improper disposal of fish remains by fishermen is a common cause. The remains can be hazardous not only because of size but also because of potential toxicosis from decomposition of the fish (Fig 5). Additionally, exposed bones in fish offal can, when swallowed, puncture or lacerate viscera. Ingested fish or fish offal can also contain hooks, line, or other gear.
Injuries related to fishing activities occur commonly in many species. In one report of pelicans in the Monterey Bay region of California, approximately 60% of pelicans admitted to a local rehabilitation center during a 6-year period had injuries related to fishing gear. (4) According to this report, "Derelict fishing gear--lost, abandoned or discarded sport and commercial line, nets, traps, etc--in the marine environment is a significant cause of injury in California coastal marine wildlife." (4(P355)) In 2011, 6% of 2617 birds admitted to CROW had fishing-gear related injuries (CROW, unpublished data, 2011).
One simple way to avoid those injuries is to educate fisherman to properly dispose of offal and fishing gear. In 2007, the California Lost Fishing Gear Recovery Project retrieved nearly 10 tons of fishing gear from around the Channel Islands. (5) According to the Seadoc Society, "Lost fishing gear is commercial and recreational fishing gear--nets, traps, pots, line--that becomes lost or is discarded in the water." (6) Discarded gear like those listed are hazardous to animals that can become entangled, can damage the habitat of the animals, and pose hazards to boats if line wraps around the propeller. Another problem with discarded fishing tackle is potential lead toxicity. (7) Radiographs should be routinely performed on sea birds admitted to rehabilitation centers, especially those known to scavenge from fisherman.
This case was submitted by Aundria West, DVM, and Heather Barron, DVM, Dipl ABVP (Avian), Center for the Rehabilitation of Wildlife (CROW), PO Box 150, Sanibel, FL 33957, USA.
(1.) Weber M. Pelecaniformes (pelicans, tropicbirds, cormorants, frigatebirds, anhingas, gannets). In: Fowler ME, Miller RE, eds. Zoo and Wild Animal Medicine. St Louis, MO: Elsevier Science; 2003:118-122.
(2.) Meet our animals: brown pelican. Smithsonian National Zoological Park Web site, http://nationalzoo.si. edu/animals/birds/facts/fact-brownpelican.cfm. Accessed September 8, 2012.
(3.) Willett E. The biogeography of California brown pelican (Pelecanus occidentalis californicus). http:// online.sfsu.edu/bholzman/courses/Fall01%20projects/ BPELICAN1.HTM. Published November 28, 2001. Accessed September 8, 2012.
(4.) Dau BK, Gilardi KV, Gulland FM, et al. Fishing gear-related injury in California marine wildlife. J Wildl Dis. 2009;45(2):355-362.
(5.) Pier cleanups and fishing-line recycling start next week. UCDavis Web site, http://news.ucdavis.edu/ search/news_detail.lasso?id=8094. Published March 16, 2007. Accessed September 8, 2012.
(6.) California lost fishing gear recovery project. The Seadoc Society Web site. http://www.seadocsociety. org/wp-content/uploads/p + pmanual2009.pdf. Accessed September 8, 2012.
(7.) Michael P. Fish and Wildlife Issues Related to the Use of Lead Fishing Gear. Olympia, WA: Washington Department of Fish and Wildlife FPT 06-13; 2006. ttp://www.statesmanjournal.com/assets/pdf/ J0147700121.PDF. Published December 2005. Accessed September 8, 2012.
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|Title Annotation:||gastrointestinal obstruction|
|Author:||West, Aundria; Barron, Heather|
|Publication:||Journal of Avian Medicine and Surgery|
|Article Type:||Clinical report|
|Date:||Sep 1, 2014|
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