Mortality in Aransas-Wood Buffalo Whooping Cranes: Timing, Location, and Causes

• Main Authors: Pearse, Aaron T., Brandt, David A., Hartup, Barry K., Bidwell, Mark T.
• Format: Text
• Language: unknown
• Published: DigitalCommons@University of Nebraska - Lincoln 2019
• Subjects: Animal Sciences; Behavior and Ethology; Biodiversity; Ecology and Evolutionary Biology; Environmental Policy; Life Sciences; Recreation; Parks and Tourism Administration; Terrestrial and Aquatic Ecology; Wood Buffalo
• Online Access: https://digitalcommons.unl.edu/usgsnpwrc/417; https://digitalcommons.unl.edu/context/usgsnpwrc/article/1416/viewcontent/Pearse_WCBC_2019_Mortality_in_Aransas.pdf

The Aransas-Wood Buffalo Population (AWBP) of Whooping Cranes (Grus americana) has experienced a population growth rate of approximately 4% for multiple decades (Butler et al., 2014a; Miller et al., 1974). Population growth for long-lived species of birds is generally highly sensitive to variation in adult mortality rates (Sæther and Bakke, 2000). A population model for endangered Red-crowned Cranes (Grus japonensis) in Japan conforms to this pattern, where growth rate is most sensitive to adult mortality (Masatomi et al., 2007). Earlier analyses observed that the AWBP growth rate increased in the mid-1950s and that this increase was likely caused by reduced annual mortality rates, even while the population experienced slightly decreasing natality (Binkley and Miller, 1988; Miller et al., 1974). A more contemporary analysis of the AWBP determined that approximately 50% of variation in annual population growth could be explained by variation in annual mortality (Butler et al., 2014a). Therefore, as a vital rate, mortality is critical to the maintained growth of the AWBP.