ABSTRACT

We investigated the pre-breeding intersexual foraging habitat preferences of the great spotted woodpecker Dendrocopos major in six old, unmanaged riparian forest stands in Central Hungary, which are composed mainly of the invasive North American green ash Fraxinus pennysylvanica and boxelder Acer negundo, and native poplar Populus sp. and willow Salix sp. trees in lower abundances. With the influence of river management, the two invasive species have usurped native tree species in numerous Central European riparian forests. We studied the intersexual utilization of tree species, tree condition, stem diameter, foraging height, horizontal sections, substrate diameter, substrate condition, and foraging technique. The birds showed intersexual segregation in numerous studied variables despite the high niche overlap between sexes. Similar patterns were also found in other woodpecker species as well. We think that the most important part of this segregation could be the difference revealed in the choice of tree species, as males tended to be more specialized for native softwood tree species with rougher bark structure. Despite the high abundance of invasive tree species, neither sex preferred them. The further population decrease of native tree species could increase within-species competition and negatively affect the studied bird species.

摘要

我们调查了匈牙利中部六个古老的、未管理的河岸林分中大斑啄木鸟Dendrocopos 主要的繁殖前双性觅食栖息地偏好，这些林分主要由入侵的北美绿灰Fraxinus pennysylvanica和 boxelder Acer negundo以及本地杨树组成。杨藻。和柳柳sp. 丰度较低的树木。在河流管理的影响下，这两种入侵物种在众多中欧河岸森林中侵占了本地树种。我们研究了树种的间性利用、树体状况、茎粗、觅食高度、水平截面、基质直径、基质条件和觅食技术。尽管两性之间存在高度的生态位重叠，但这些鸟类在许多研究变量中都表现出两性分离。在其他啄木鸟物种中也发现了类似的模式。我们认为这种隔离最重要的部分可能是树种选择中所揭示的差异，因为雄性往往更专注于树皮结构较粗糙的本地软木树种。尽管入侵树种数量众多，但男女双方都不喜欢它们。