Abstract
The International Crane Foundation has captured greater sandhill cranes (Grus canadensis tabida) in Wisconsin for long-term ecologic research using oral delivery of alpha-chloralose (AC).1 The goals of this study were to assess the efficacy of modest changes implemented in 2002 in drug deployment (regimented baiting limited to early fall) and post-capture treatments (fluid administration) intended to reduce capture-associated morbidity and mortality, especially exertional myopathy (EM). 317 captures made between 1990 and 2011 were reviewed. Capture efficacy (the proportion of capture attempts where all cranes in a targeted social group were successfully immobilized) improved from 65 to 72% following the aforementioned changes in 2002; however, there was no statistically significant difference in sedation scores. The proportion of cranes that were diagnosed with EM decreased from 7/188 (3.7%) to 3/129 (2.3%), and the overall mortality observed among the captured cranes decreased from 9/188 (4.8%) to 4/129 (3.1%). Time in confinement (elapsed time between capture and release, including processing and recovery in a portable pen) was reduced by 3 to 4 hours in birds that received subcutaneous fluids compared to those that did not (F2,213=6.6, p=0.002), but no preventive association was found between fluid administration and the development of EM. The findings of this follow-up study suggest that these management changes in bait deployment resulted in modest improvement in the efficacy of the field capture technique and were associated with decreased morbidity and mortality rates with little change in sedative effect. This method is associated with very low morbidity compared to alternative practices used to capture groups of cranes.
Literature Cited
1. Hayes, M.A., B.K. Hartup, J.M. Pittman, and J.A. Barzen. 2003. Capture of sandhill cranes using alpha-chloralose. J. Wildl. Dis. 39:859–868.