|Mitchell, Robert - Rob|
Submitted to: Journal of Wildlife Management
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/12/2004
Publication Date: 4/1/2005
Citation: Abbott, W., Dabbert, B., Lucia, D., Mitchell, R. 2005. Does muscular damage during capture and handling handicap radiomarked northern bobwhites?. Journal of Wildlife Management 69(2):664-670. Interpretive Summary: Northern bobwhites are captured routinely for scientific study. Exertion during capture can lead to acidosis and free radical production that result in muscle damage, which shortens the life expectancy of the birds. There is anecdotal evidence that injections of vitamin E and selenium injections can treat avian species for this disorder. Our objective was to determine if injections of vitamin E and selenium would increase the survival of northern bobwhites following capture. We captured northern bobwhite in Northwest Texas in 2002 and 2003, and injected half of the birds with a vitamin E and selenium solution and the other half with a saline control, and obtained a blood sample from all birds. We then transported these birds to our study site in Lynn County and fitted them with radio transmitters prior to release. Birds were monitored to determine their status every three days. Survival was greater for treated birds during the first 70 days after capture in 2002, during all of 2003, and when treatments were pooled by year. Our results indicate that injecting wild northern bobwhites with vitamin E and selenium increased survival.
Technical Abstract: Northern bobwhites (Colinus virginianus) are captured routinely for scientific study. Extreme exertion during restraint and transport can lead to acidosis and free radical production that result in muscle tissue damage. This condition, termed capture myopathy, can result in dyspnea, hyperthermia, weakness, muscle rigidity, and collapse. These complications could lead to increased susceptibility of individuals to predation or contribute to death weeks or months after the capture event because of the scarring of cardiac and skeletal muscle that can occur. Death of radiomarked northern bobwhite caused by capture instead of natural causes could negatively bias mortality rate estimates if mortalities occur after traditional censor periods. We hypothesize that muscular damage incurred during capture handicaps northern bobwhites and causes their survival rates to be biased low. We evaluated our hypothesis by comparing survival of northern bobwhite that were treated for muscular damage with an injection of vitamin E and selenium with those that were not treated. There is anecdotal evidence that this solution can treat avian species, as it is recommended in veterinary avian medicine. We captured northern bobwhite in Northwest Texas during 2002 and 2003. After capture we intramuscularly injected half of the birds with 0.1ml of a vitamin E and selenium solution and the other half with a saline control, and obtained a blood sample from all birds. We then transported these birds to our study site in Lynn County and fitted them with radio transmitters prior to release. Birds were monitored to determine their status every three days. Survival rates were estimated using the staggered-entry Kaplan-Meier Product Limit Estimator. We attempted to evaluate the relationship between plasma enzyme levels that indicate muscle damage and survival using staggered-entry Cox regression analysis and T-tests. Survival curves were not different (X2 = 0.13, P = 0.71) between treatment and control groups during 2002 when considering the entire 175-day monitoring period. However, the survival curve of treated birds was greater (X2 = 5.75, P = 0.017) than the survival curve of control birds in 2002 during the first 70 days of monitoring; a time period after which sample sizes were very small. Treated birds exhibited a greater (X2 = 7.11, P < 0.008) survival curve than control birds during 2003 and when treatments were pooled by year (X2 = 4.75, P = 0.029). Thus, our data suggest that injection of wild northern bobwhite with vitamin E and selenium increased survival of transplanted birds as compared to control birds injected with saline. Enzyme levels in our study indicate that all birds suffered muscular damage. However, the lack of a strong relationship between the indicators of muscle damage and bird survival makes it unclear through what physiological pathway vitamin E and selenium increased survival.