Nour Nadia, Currie David, Matthysen Erik, Van Damme Raoul, Dhondt André A
Laboratory of Animal Ecology, Department of Biology, University of Antwerp (UIA), Universteitsplein 1, B-2610 Antwerp, Belgium Fax: 32-3-820 22 77; e-mail:
Oecologia. 1998 May;114(4):522-530. doi: 10.1007/s004420050476.
The aim of this study was to examine the effects of forest fragmentation on the ability of parent birds to provide their young with an adequate food supply. To examine whether prey population densities of the great tit (Parus major L.) and the blue tit (P. caeruleus L.) vary between study areas in different forest size classes we compared provisioning rates and chick diet and related these parameters to breeding success. We filmed 217 nests over two breeding seasons and collected data on frass fall as a general estimate of caterpillar availability. Nests which were attended by none or one parent only during filming (n = 46) were excluded from the analyses. In both years and for both species feeding rates were highest in the smallest fragments and lowest in the large forest. There was also a suggestion that differences in feeding rates between areas vary between years. We found no consistent tendency for prey size to change with forest size, although both species brought slightly smaller prey items to the nest in the smallest forest fragments and feeding rates correlated negatively with prey size. Caterpillars were the main item fed to nestlings, in both species. We found no evidence to suggest that either frass fall or the proportion of caterpillars in the diet varied with forest size. There was also no correlation between mean frass fall and the total number of caterpillars brought to the nests, in either species. Breeding success, as measured by clutch size, brood size, fledging weight and fledging success, did not differ between the small fragments and the large forest, in either species. There was also no relationship between provisioning rate (as concerns volume of prey fed to nestlings and the quality of chick diet) and breeding success parameters. In conclusion, this study does not suggest suboptimal foraging or breeding conditions in small fragments compared to a nearby large forest, for either species.
本研究的目的是考察森林碎片化对亲鸟为雏鸟提供充足食物供应能力的影响。为了研究大山雀（Parus major L.）和蓝山雀（P. caeruleus L.）的猎物种群密度在不同森林面积等级的研究区域之间是否存在差异，我们比较了育雏率和雏鸟饮食，并将这些参数与繁殖成功率相关联。我们在两个繁殖季节拍摄了217个鸟巢，并收集了粪便掉落数据，作为对毛虫可获得性的总体估计。拍摄期间没有亲鸟或只有一只亲鸟照料的鸟巢（n = 46）被排除在分析之外。在这两年中，对于这两个物种来说，最小的碎片区域育雏率最高，而在大森林中最低。此外，有迹象表明不同区域之间的育雏率差异在不同年份有所不同。我们没有发现猎物大小随森林大小变化的一致趋势，尽管这两个物种在最小的森林碎片中带回巢的猎物略小，且育雏率与猎物大小呈负相关。毛虫是这两个物种喂给雏鸟的主要食物。我们没有发现证据表明粪便掉落量或饮食中毛虫的比例随森林大小而变化。对于这两个物种中的任何一个，平均粪便掉落量与带回巢的毛虫总数之间也没有相关性。以窝卵数、育雏数、离巢体重和离巢成功率衡量的繁殖成功率，在小碎片区域和大森林之间没有差异，这两个物种都是如此。在育雏率（涉及喂给雏鸟的猎物量和雏鸟饮食质量）与繁殖成功参数之间也没有关系。总之，本研究并未表明与附近的大森林相比，小碎片区域对这两个物种中的任何一个存在觅食或繁殖条件欠佳的情况。
