Hernández-Brito Dailos, Carrete Martina, Ibáñez Carlos, Juste Javier, Tella José L
Department of Conservation Biology, Estación Biológica de Doñana (CSIC), Avda. Américo Vespucio, 41092 Sevilla, Spain.
Department of Physical, Chemical and Natural Systems, University Pablo de Olavide, Ctra. de Utrera, km. 1, 41013 Sevilla, Spain.
R Soc Open Sci. 2018 May 9;5(5):172477. doi: 10.1098/rsos.172477. eCollection 2018 May.
The identification of effects of invasive species is challenging owing to their multifaceted impacts on native biota. Negative impacts are most often reflected in individual fitness rather than in population dynamics of native species and are less expected in low-biodiversity habitats, such as urban environments. We report the long-term effects of invasive rose-ringed parakeets on the largest known population of a threatened bat species, the greater noctule, located in an urban park. Both species share preferences for the same tree cavities for breeding. While the number of parakeet nests increased by a factor of 20 in 14 years, the number of trees occupied by noctules declined by 81%. Parakeets occupied most cavities previously used by noctules, and spatial analyses showed that noctules tried to avoid cavities close to parakeets. Parakeets were highly aggressive towards noctules, trying to occupy their cavities, often resulting in noctule death. This led to a dramatic population decline, but also an unusual aggregation of the occupied trees, probably disrupting the complex social behaviour of this bat species. These results indicate a strong impact through site displacement and killing of competitors, and highlight the need for long-term research to identify unexpected impacts that would otherwise be overlooked.
由于入侵物种对本地生物群具有多方面的影响，因此确定其影响具有挑战性。负面影响通常更多地体现在个体健康状况上，而非本地物种的种群动态方面，而且在低生物多样性栖息地（如城市环境）中这种影响较难被预期。我们报告了入侵的玫瑰环鹦鹉对位于城市公园内的、已知最大的濒危蝙蝠物种——大棕蝠种群的长期影响。这两个物种对用于繁殖的相同树洞都有偏好。在14年里，鹦鹉巢穴数量增加了20倍，而被大棕蝠占据的树木数量减少了81%。鹦鹉占据了大多数以前被大棕蝠使用的树洞，空间分析表明大棕蝠试图避开靠近鹦鹉的树洞。鹦鹉对大棕蝠极具攻击性，试图占据它们的树洞，常常导致大棕蝠死亡。这导致了大棕蝠种群数量急剧下降，同时也导致了被占据树木的异常聚集，这可能扰乱了这种蝙蝠物种复杂的社会行为。这些结果表明，通过占据栖息地和杀死竞争者会产生强烈影响，并突出了进行长期研究以识别那些否则就会被忽视的意外影响的必要性。
