Kaplan Rachel H, Rosamond Kristen M, Goded Sandra, Soultan Alaaeldin, Glass Alex, Kim Daniel H, Arcilla Nico
International Bird Conservation Partnership, Monterey, CA 93940, USA.
Crane Trust, Wood River, NE 68883, USA.
Animals (Basel). 2021 Sep 10;11(9):2661. doi: 10.3390/ani11092661.
Among the most rapidly declining birds in continental North America, grassland birds evolved with American bison () until bison nearly became extinct due to overhunting. Bison populations have subsequently rebounded due to reintroductions on conservation lands, but the impacts of bison on grassland nesting birds remain largely unknown. We investigated how bison reintroduction, together with other land management and climate factors, affected breeding populations of a grassland bird species of conservation concern, the Bobolink (). We quantified population changes in Bobolinks over an 18-year period in conservation grasslands where bison were reintroduced, compared with adjacent grasslands grazed by cattle and where hay was harvested after the bird breeding season. Four years after bison reintroduction, the bison population in the study area had doubled, while Bobolink abundance declined 62% and productivity declined 84%. Our findings suggest that bison reintroduction as a conservation strategy may be counterproductive in grassland fragments where overgrazing, trampling, and other negative impacts drive declines in grassland breeding birds. Where bird conservation is an objective, small grassland reserves may therefore be inappropriate sites for bison reintroduction. To maximize conservation benefits to birds, land managers should prioritize protecting grassland birds from disturbance during the bird breeding season.
在北美大陆数量下降最快的鸟类中，草原鸟类与美洲野牛共同进化，直到野牛因过度捕猎几乎灭绝。野牛种群随后因在保护区重新引入而有所反弹，但野牛对草原筑巢鸟类的影响在很大程度上仍不为人知。我们调查了野牛的重新引入，以及其他土地管理和气候因素，如何影响一种受保护的草原鸟类——食米雀的繁殖种群。我们量化了在重新引入野牛的保护草原上，食米雀在18年期间的种群变化，并与相邻的由牛放牧以及在鸟类繁殖季节后收割干草的草原进行了比较。野牛重新引入四年后，研究区域内的野牛数量翻了一番，而食米雀的数量下降了62%，繁殖率下降了84%。我们的研究结果表明，在过度放牧、践踏和其他负面影响导致草原繁殖鸟类数量下降的草原碎片中，将野牛重新引入作为一种保护策略可能会适得其反。因此，在以鸟类保护为目标的情况下，小型草原保护区可能不是适合重新引入野牛的地点。为了使对鸟类的保护效益最大化，土地管理者应优先保护草原鸟类在繁殖季节免受干扰。
