Diet of Montagu's Harriers Circus pygargus Wintering in India: Analysing Seasonal, Regional and Sex Differences Using Web-Sourced Photographs and Pellet Contents

IF 0.8 4区 生物学 Q3 ORNITHOLOGY Acta Ornithologica Pub Date : 2023-06-14 DOI:10.3161/00016454AO2022.57.2.004
A. Kannan, S. Thalavaipandi, Deven Mehta, A. Saravanan, M. Prashanth, T. Ganesh
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Abstract

Abstract. Studies on the diet composition of bird species provide valuable insights on their habitat use, trophic interactions and prey selection. Prey abundance can drive movements of raptors in their wintering grounds. But such links have been difficult to establish due to the lack of dietary information for most raptor species. Estimating the wintering diet of raptors is a challenge that requires extensive fieldwork across a large geographical area which is often not possible. The methods used in breeding sites such as nest observations are not available in the non-breeding regions. Recently, several studies have demonstrated the use of web-sourced photographs as a tool for understanding the diet of raptors and also the need for combining multiple approaches to get a comprehensive overview of diet. In this study, we use a novel approach by using web-sourced photographs and pellets to estimate the variations in the diet of Montagu's Harrier Circus pygargus, a species in decline, across its wintering range in India. A total of 232 photographs and 391 pellets collected across western India, Deccan and south India during autumn, winter and early spring seasons were analysed. About 53% of photographs and 71% of pellets contained orthopterans, forming the major component of the harrier's diet. The proportion of reptiles, eggs and birds in the diet were similar across both methods. Presence of other insects in the diet was better estimated by photographs (23%) than pellets (8%) while rodent presence was higher in pellets (17%) than photographs (4%). Pellet analysis and photographs showed similar variation in diet across seasons while only pellets showed variation in diet across regions. Photographs also showed that there is significant variation in diet between the sexes of the species, with higher presence of insects and reptiles in the diet of males than females. Our results suggest that a combination of photographs and pellet analysis provide better estimates of wintering diet of Montagu's Harriers.
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蒙塔古鹞在印度越冬的饮食:利用网络图片和颗粒含量分析季节、地区和性别差异
摘要对鸟类饮食组成的研究为它们的栖息地利用、营养相互作用和猎物选择提供了有价值的见解。猎物的丰富可以驱动猛禽在越冬地的活动。但由于缺乏大多数猛禽物种的饮食信息,这种联系一直很难建立。估计猛禽的越冬饮食是一项挑战,需要在大的地理区域进行广泛的实地调查,而这通常是不可能的。在繁殖地使用的方法,如巢穴观察,在非繁殖区是不可用的。最近,几项研究表明,使用网络来源的照片作为了解猛禽饮食的工具,还需要结合多种方法来全面了解饮食。在这项研究中,我们使用了一种新的方法,使用网络来源的照片和颗粒来估计Montagu的鹞马戏团蟒蛇(一种正在衰退的物种)在印度越冬期间的饮食变化。对秋季、冬季和早春期间在印度西部、德干和南部收集的232张照片和391粒颗粒进行了分析。大约53%的照片和71%的颗粒含有直翅目昆虫,它们是鹞饮食的主要成分。两种方法中爬行动物、蛋和鸟类在饮食中的比例相似。照片(23%)比颗粒物(8%)更好地估计了饮食中其他昆虫的存在,而颗粒物中啮齿动物的存在(17%)比照片(4%)更高。颗粒分析和照片显示,不同季节的饮食变化相似,而只有颗粒显示不同地区的饮食变化。照片还显示,该物种的性别在饮食上存在显著差异,雄性饮食中昆虫和爬行动物的数量高于雌性。我们的研究结果表明,结合照片和颗粒分析,可以更好地估计蒙塔古鹞的越冬饮食。
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来源期刊
Acta Ornithologica
Acta Ornithologica 生物-鸟类学
CiteScore
2.10
自引率
0.00%
发文量
14
审稿时长
>12 weeks
期刊介绍: Publishes scientific papers (original research reports, reviews, short notes, etc.) and announcements from all fields of ornithology. All manuscripts are peer-reviewed. Established in 1933 as Acta Ornithologica Musei Zoologici Polonici, since 1953 continued under the present title. Published twice a year by the Natura Optima Dux Foundation under the auspices of the Museum and Institute of Zoology, Polish Academy of Sciences.
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