Multiple causes cited in whooping crane's death
by Pam Rotella
4 February 2013
Last October, a young whooping crane known as #10 died at the University of Illinois-Urbana's Wildlife Clinic during surgery to repair her broken leg. The crane was one of six being trained by Operation Migration's ultra-light program to migrate from Wisconsin to Florida.
The USGS National Wildlife Health Center in Madison, Wisconsin, has since performed a necropsy to determine why the bird died during routine wildlife surgery.
According to Dr. Barry Hartup, Director of Veterinary Services at the International Crane Foundation, the broken leg was likely caused by a hard landing, possibly due to windy weather conditions. The crane suffered a severe fracture to her tibiotarsus bone below her knee, with the bone broken into multiple fragments. Hartup said that multiple fractures aren't uncommon with birds because their bones are hollow.
The crane's leg was successfully repaired in surgery but she suffered a pulmonary hemorrhage before the operation was complete, according to the necropsy report. The lung damage may have been a reaction to anesthesia gas, but Hartup noted that other cranes have survived surgery under anesthesia before, for example the University of Illinois had successfully operated on another whooping crane who had been hit by a plow.
Hartup cited additional factors that may have stressed the crane, such as the physical demands of a long migration without time to recover, the painful fracture, transport to the veterinary hospital, and the surgery to fix her broken leg.
Dr. Anne Ballmann, a Wildlife Disease Specialist at the USGS-National Wildlife Health Center, noted that "Other than the fracture of the left tibiotarsus and evidence of mild bleeding in the lungs thought to be associated with the anesthetic death, no underlying infectious diseases or toxin exposures were identified. Bloodwork reported by the UIL vet school suggested this crane had low potassium levels which possibly contributed to its poor outcome while under anesthesia."
When asked whether a reaction to anesthesia had caused the crane's death, she denied that a single cause had been determined. "There are no definitive lesions or lab tests available that can confirm an anesthetic agent as the direct cause of death. The necropsy and subsequent tests ruled out other causes and supplemental information from UIL suggested an electrolyte imbalance may have predisposed this crane to acute heart and respiratory failure while under anesthesia. However, I stress that the precise cause of death in this crane could not be determined by the pathological evaluation."
Dr. Hartup of ICF added that the crane's last blood work before migration showed normal potassium levels. Hartup said that the bird had been "fed a quality diet," and that "there was no renal disease or dietary issues with this bird" known prior to her injury. He also noted that her potassium level at University of Illinois was "moderately low," but not far from the normal range for whooping cranes.
All original content including photographs © 2013 by Pam Rotella.