Durrell Wildlife Conservation Trust, Les Augrès Manor, , Trinity, Jersey JE3 5BP, Channel Islands.
Philos Trans R Soc Lond B Biol Sci. 2010 Apr 12;365(1543):1019-30. doi: 10.1098/rstb.2009.0288.
Habitat destruction and predation by invasive alien species has led to the disappearance of several island populations of Darwin's finches but to date none of the 13 recognized species have gone extinct. However, driven by rapid economic growth in the Galápagos, the effects of introduced species have accelerated and severely threatened these iconic birds. The critically endangered mangrove finch (Camarhynchus heliobates) is now confined to three small mangroves on Isabela Island. During 2006-2009, we assessed its population status and monitored nesting success, both before and after rat poisoning. Population size was estimated at around only 100 birds for the two main breeding sites, with possibly 5-10 birds surviving at a third mangrove. Before rat control, 54 per cent of nests during incubation phase were predated with only 18 per cent of nests producing fledglings. Post-rat control, nest predation during the incubation phase fell to 30 per cent with 37 per cent of nests producing fledglings. During the nestling phase, infestation by larvae of the introduced parasitic fly (Philornis downsi) caused 14 per cent additional mortality. Using population viability analysis, we simulated the probability of population persistence under various scenarios of control and showed that with effective management of these invasive species, mangrove finch populations should start to recover.
栖息地破坏和入侵外来物种的捕食导致了达尔文雀的几个岛屿种群消失，但迄今为止，这 13 种公认的物种没有灭绝。然而，由于加拉帕戈斯群岛经济的快速增长，引入物种的影响加速了，并严重威胁到这些标志性鸟类。极度濒危的红树林雀（Camarhynchus heliobates）现在仅局限于伊莎贝拉岛的三个小红树林中。在 2006 年至 2009 年期间，我们评估了其种群状况，并监测了在灭鼠前后的筑巢成功率。在两个主要繁殖地，种群规模估计约为 100 只鸟，而在第三个红树林中可能有 5-10 只鸟存活。在控制老鼠之前，孵化阶段有 54%的巢被捕食，只有 18%的巢产生幼鸟。在灭鼠后，孵化阶段的巢捕食率下降到 30%，有 37%的巢产生幼鸟。在雏鸟阶段，引入的寄生蝇（Philornis downsi）幼虫的侵袭导致了 14%的额外死亡率。通过种群生存力分析，我们模拟了在各种控制情景下种群持续存在的概率，并表明通过有效管理这些入侵物种，红树林雀的种群应该开始恢复。
