Competitive interactions of two sympatric raptors affecting their spatial distribution in an island environment

IF 1.4 4区生物学 Q2 Agricultural and Biological Sciences Journal of Ornithology Pub Date : 2024-01-04 DOI:10.1007/s10336-023-02124-1

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Abstract

Competition within and between species affects community structure and is well documented in raptors. We investigated the spatial distribution of two sympatric raptors in Cyprus, the Bonelli’s Eagle (BE) and the Long-legged Buzzard (LLB). Both species are facultative tree/cliff nesters, with overlapping nesting and foraging areas. In 2021, the BE population consisted of 40 pairs with a density of 1,3 pairs/100 km², and the LLB population of 113 pairs with 2,9 pairs/100 km². About 80% of BE nesting sites and 43% of LLB nesting sites were situated within the Natura 2000 (N2K) protected areas network while 97% of BE nesting sites and 91% of LLB’s were situated within 2.5 km from N2K areas. The spatial distribution was compared between and within species based on Nearest Neighbour Distance (NND) analysis. Average intraspecific NND for BE was 6.158 ± 2.207 m (SD), almost double compared to LLB which was 3.151 ± 1.730 m (SD). The distribution of BE nesting territories showed a regular spacing, indicating a stronger effect of intraspecific competitive interactions, whereas LLB nesting territories did not differ significantly from random. Average interspecific NND for BE was 5.339 ± 3.719 m (SD) and for LLB 5.673 ± 3.931 m (SD). Only the LLB had a regular pattern, suggesting that LLB pairs take into account neighbouring BE active territories when establishing their own, while the opposite is not the case. Therefore, the LLB, which is the smaller of the two raptors, avoids BE nesting sites by placing its nests further than to conspecifics. NNDs in 2021 were lower compared to previous studies in Cyprus, in 2005 for LLB and 2009 for BE, indicating an increase in both species’ densities.

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两种同栖猛禽的竞争互动影响它们在岛屿环境中的空间分布

摘要物种内和物种间的竞争会影响群落结构，这在猛禽中得到了充分的证实。我们调查了塞浦路斯两种同栖猛禽的空间分布情况，它们是博内利鹰（BE）和长腿鵟（LLB）。这两种猛禽都在树上/悬崖上觅食，筑巢和觅食区域相互重叠。2021 年，BE 种群数量为 40 对，密度为 1.3 对/100 平方公里；LLB 种群数量为 113 对，密度为 2.9 对/100 平方公里。约80%的BE筑巢地和43%的LLB筑巢地位于Natura 2000（N2K）保护区网络内，97%的BE筑巢地和91%的LLB筑巢地位于N2K保护区2.5公里范围内。根据近邻距离（NND）分析，比较了物种之间和物种内部的空间分布。BE 种内平均近邻距离（NND）为 6.158 ± 2.207 米（SD），与 LLB 的 3.151 ± 1.730 米（SD）相比几乎翻了一番。BE筑巢区的分布呈规则间距，表明种内竞争相互作用的影响较强，而LLB筑巢区的分布与随机分布无显著差异。BE和LLB种间平均NND分别为5.339 ± 3.719 m（SD）和5.673 ± 3.931 m（SD）。只有 LLB 有规律可循，这表明 LLB 配对在建立自己的活动领地时会考虑到邻近 BE 的活动领地，而情况恰恰相反。因此，在两种猛禽中体型较小的杓鹬通过将其巢穴置于比同类更远的地方来避开BE的巢穴。与之前在塞浦路斯进行的研究相比，2021年杓鹬的巢穴密度低于2005年，而杓鹬的巢穴密度低于2009年，这表明这两种猛禽的密度都有所上升。

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来源期刊

Journal of Ornithology 生物-鸟类学

自引率

7.70%

发文量

审稿时长

3-8 weeks

期刊介绍： The Journal of Ornithology (formerly Journal für Ornithologie) is the official journal of the German Ornithologists'' Society (http://www.do-g.de/ ) and has been the Society´s periodical since 1853, making it the oldest still existing ornithological journal worldwide.