Mitigating the Effects of Live Trade in Endangered Species: Nutritional Rehabilitation of Grey Crowned Cranes in Rwanda
The grey crowned crane (Balearica regulorum) is the only species of crane in Rwanda and faces serious threat from domestic live trade. We conducted a study of the nutritional challenges of cranes coming from illegal captivity and the short-term effects of a balanced, formulated diet used to condition the cranes prior to release in the wild. Twelve cranes were randomly selected from 18 individuals that met inclusion criteria. Nutritional analyses from blood samples were conducted before and immediately following provision of Mazuri® Crane Diet for 6 weeks while in a quarantine holding facility. We analyzed serum chemistries (eight analytes), serum triglycerides and non-esterified fatty acids, plasma vitamin A (retinol) and vitamin E (α-tocopherol), and 12 whole blood trace element concentrations. Many cranes were hypoproteinemic or observed with deficiencies in vitamin A or E, selenium or zinc at the beginning of the trial. We observed statistically significant increases in serum total protein, uric acid, cholesterol, triglycerides, plasma vitamin A and E, copper, iron, selenium, and zinc by the end of the trial (Wilcoxon signed rank p<0.05). Blood lead declined to baseline levels in two cranes with elevated concentrations (>5 µg/dl) at the beginning of the trial. The results suggest that the current rehabilitation and biosecurity management process is effective in reversing nutritional deficiencies from captivity and improving the condition of cranes prior to release. We expect these effects will improve the success of assimilating the cranes to native habitat following their soft release.
The authors thank all staff and volunteers of the Rwanda Wildlife Conservation Association, Gorilla Doctors, and the Rwandan Development Board Conservation Department for their assistance with the cranes. ICF Veterinary Research Intern K. Rayment assisted greatly with data analysis. This research was funded in part by an AZA Conservation Fund Grant and the Disney Conservation Fund to B. Hartup.