Many species of the family Picidae, such as the woodpeckers, excavate the tree-cavities where they nest. Frequently the cavities are used during a single breeding season and subsequently abandoned, which allows their use by non-excavator species for nesting or roosting. Here we analyze the role of woodpeckers as providers of nesting and refuge places in two urban parks in the city of Madrid. The environmental characteristics of the woodpecker nest-sites were also studied. Prior to the breeding season 75 trees bearing woodpecker-excavated cavities and 142 control trees (i.e. without woodpecker cavities) were located, georeferenced and characterized by a set of variables relative to the tree and its environment. During the breeding season the cavities were monitored with an endoscopic camera to verify occupation and user identity. Additionally, 71 non-excavated tree-cavities were monitored to measure their occupancy and make comparisons with those excavated by woodpeckers. Woodpeckers showed a strong preference for trees of the genus Populus: 54 of 75 (72%) woodpecker-cavities were in poplars, which comprised only 7–10% of available trees. The excavated cavities were found mainly in the trunk of the trees, north oriented and away from paths. The occupancy rate by bird species was higher, although not significantly, for excavated cavities than for natural cavities (36.0% and 23.9% respectively). The richness and composition of cavity-user species also differed between types of tree-cavities. This work shows the importance of woodpeckers as providers of nesting and refuge places for other cavity-user birds and highlights their role as ecosystem engineers in urban parks. Finally, we consider that these results can guide biodiversity conservation efforts in urban planning.

Picidae家族的许多物种，例如啄木鸟，都在它们筑巢的地方挖掘树木。通常在单个繁殖季节使用型腔，然后将其丢弃，从而允许非挖掘机物种将其用于筑巢或栖息。在这里，我们分析了啄木鸟在马德里市两个城市公园中作为筑巢和避难所的提供者的作用。还研究了啄木鸟巢点的环境特征。在繁殖季节之前，对75棵啄木鸟开洞的树木和142棵对照树（即没有啄木鸟的洞）进行了定位，地理定位，并通过相对于树木及其环境的一组变量进行了表征。在繁殖季节，使用内窥镜摄像机对蛀牙进行监测，以验证其职业和使用者身份。另外，监测了71个未挖掘的树洞，以测量它们的占用并与啄木鸟挖掘的树洞进行比较。啄木鸟表现出对树属的强烈偏好杨树：75个啄木鸟洞中的54个（占72％）在杨树中，仅占可利用树木的7–10％。挖出的洞主要发现在树木的树干上，朝北且远离小路。采掘空洞中鸟类的占用率比自然空洞高（尽管不明显）（分别为36.0％和23.9％）。树木使用者在不同类型的树木洞中的丰富度和组成也有所不同。这项工作显示了啄木鸟作为其他使用腔鸟的鸟类筑巢和避难所的提供者的重要性，并强调了啄木鸟在城市公园中作为生态系统工程师的作用。最后，我们认为这些结果可以指导城市规划中的生物多样性保护工作。