Bellamy P E, Brown N J, Enoksson B, Firbank L G, Fuller R J, Hinsley S A, Schotman A G M
NERC Institute of Terrestrial Ecology, Monks Wood, Abbots Ripton, Huntingdon, Cambridgeshire, PE17 2LS, UK Fax: +44-1487-773467; e-mail:
Department of Ecology, Lund University, S-22362 Lund, Sweden, , , , , , SE.
Oecologia. 1998 Jun;115(1-2):127-136. doi: 10.1007/s004420050499.
The nuthatch, Sitta europaea L., is a small (23 g), cavity-nesting woodland bird which, since the 1970s, has been expanding its range in Britain. However, within this range, the species is notably scarce in an area of eastern England. This gap in the species distribution could arise for several reasons including habitat quality, local landscape structure, regional landscape structure and climate. Field surveys and logistic models of breeding nuthatch presence/absence were used to investigate the relative influences of habitat quality, landscape structure and climate on the prevalence of nuthatches in eastern England. Field surveys of woods in the study area indicated that habitat quality was sufficient to support a nuthatch population. A model of habitat occupancy in relation to local landscape structure, developed in the Netherlands, was applied to the study area. The number of breeding pairs predicted for the study area by the model was lower than expected from habitat area alone, suggesting an additional effect of isolation. However, observed numbers were even lower than those predicted by the model. To evaluate the possible roles of climate and large-scale landscape structure on distribution, presence/absence data of breeding nuthatches at the 10-km grid square scale were related to variables describing climate and the amount and dispersion of broadleaved woodland. While climate in the study area appeared suitable, models including landscape variables suggested that the study area as a whole was unlikely to support nuthatches. Although suitable habitat was available, woodland in the study area appeared to be too isolated from surrounding nuthatch populations for colonisation to be successful. This situation may change if current increases in both national and regional populations continue, thus increasing the number of potential colonists reaching the study area.
坚果雀（Sitta europaea L.）是一种小型（23克）、在树洞中筑巢的林地鸟类，自20世纪70年代以来，其在英国的分布范围一直在扩大。然而，在这个分布范围内，该物种在英格兰东部的一个地区明显稀少。物种分布的这种差距可能由多种原因引起，包括栖息地质量、当地景观结构、区域景观结构和气候。通过对繁殖坚果雀存在与否的实地调查和逻辑模型，来研究栖息地质量、景观结构和气候对英格兰东部坚果雀分布的相对影响。对研究区域内树林的实地调查表明，栖息地质量足以支持坚果雀种群。在荷兰开发的一个关于栖息地占用与当地景观结构关系的模型被应用于研究区域。该模型预测研究区域内的繁殖对数低于仅根据栖息地面积预期的数量，这表明存在隔离的额外影响。然而，实际观察到的数量甚至低于模型预测的数量。为了评估气候和大规模景观结构对分布的可能作用，将10公里网格尺度上繁殖坚果雀的存在/不存在数据与描述气候以及阔叶林数量和分散程度的变量相关联。虽然研究区域的气候似乎适宜，但包含景观变量的模型表明，整个研究区域不太可能支持坚果雀生存。尽管有合适的栖息地，但研究区域内的林地似乎与周围的坚果雀种群过于隔离，以至于无法成功殖民。如果目前全国和区域种群的增长持续下去，从而增加到达研究区域的潜在殖民者数量，这种情况可能会改变。
