Population Size and Habitat Occupancy by the Endangered Mariana Crow

IF 0.7 4区 生物学 Q4 MARINE & FRESHWATER BIOLOGY
Pacific Science Pub Date : 2023-04-26 DOI:10.2984/76.4.1
R. J. Craig
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引用次数: 0

Abstract

Abstract: I present data on the Mariana Crow for an extensive but previously unavailable set of population and habitat surveys from 1992 to 1993. From these, I (1) compute a series of population estimates from that period during which Mariana Crow numbers were first entering a precipitous decline, (2) quantitatively assess the habitats occupied by individual birds and thereby provide a view of the range of habitats occupied during a time when the species was still widespread, and (3) provide the first direct wet-dry season comparisons of populations and habitat occupancy. Surveys yielded significantly different wet (943) and dry season (459) population estimates, which suggested wet season courtship activity preceding dry season nesting when birds became more secretive. Moreover, they indicated that the critical turning point in population decline was after 1995. Forest was the principal habitat type occupied during both wet and dry seasons, with savanna present less than half as often as forest, although birds occupied a range of additional habitats. The species was more versatile in habitat use than is often assumed, as rates of habitat occupancy and availability were similar. Versatility is an advantage for populations confined to small islands that periodically suffer catastrophic habitat damage due to typhoons.
濒危马里亚纳乌鸦的种群规模和栖息地占用
摘要:本文提供了1992年至1993年马里亚纳乌鸦种群和栖息地调查的大量数据。从这些数据中,我(1)计算了马里亚纳乌鸦数量首次进入急剧下降时期的一系列种群估计,(2)定量评估了单个鸟类所占据的栖息地,从而提供了该物种仍然广泛分布的时期所占据的栖息地范围的观点,(3)提供了第一次直接的种群和栖息地占用的干湿季节比较。调查结果显示,湿季(943只)和旱季(459只)的种群数量估计存在显著差异,这表明湿季的求偶活动在旱季筑巢之前,此时鸟类变得更加隐秘。此外,他们指出人口下降的关键转折点是在1995年以后。在湿季和旱季,森林都是主要的栖息地类型,尽管鸟类占据了一系列额外的栖息地,但稀树草原的出现频率不到森林的一半。由于生境占用率和可得性相似,该物种在生境利用方面比通常认为的更加多样化。对于生活在小岛屿上的人口来说,多功能性是一个优势,因为这些岛屿上的人口周期性地遭受台风造成的灾难性栖息地破坏。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Pacific Science
Pacific Science 生物-动物学
CiteScore
1.40
自引率
14.30%
发文量
17
审稿时长
3 months
期刊介绍: Pacific Science: A Quarterly Devoted to the Biological and Physical Sciences of the Pacific Region The official journal of the Pacific Science Association. Appearing quarterly since 1947, Pacific Science is an international, multidisciplinary journal reporting research on the biological and physical sciences of the Pacific basin. It focuses on biogeography, ecology, evolution, geology and volcanology, oceanography, paleontology, and systematics. In addition to publishing original research, the journal features review articles providing a synthesis of current knowledge.
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