同域分布3种啄木鸟冬季取食的生态位差异

为了掌握黑啄木鸟、三趾啄木鸟和大斑啄木鸟的冬季取食行为特征，特别是三者之间取食生态位的差异，于2016年1月5-13日，在黑龙江省凉水国家级自然保护区以样线法结合样方法对3种啄木鸟的取食生境和取食行为进行了系统调查，收集了15个生境和行为特征变量数据。共布设45条样线，484个对照样方，收集312组啄木鸟取食数据，其中黑啄木鸟73组，三趾啄木鸟97组，大斑啄木鸟142组。多变量回归树和多分类逻辑斯谛分析结果显示，3种啄木鸟在所调查的15项特征上存在显著分异。采用基于利用-可利用方法的Bailey''s方法和双因子方差分析，分别对3种啄木鸟的生境选择和行为特征进行分析，结果显示：黑啄木鸟和三趾啄木鸟偏好在郁闭度较高的原始云、冷杉林中取食，而大斑啄木鸟则随机地在各种林型、生境中取食。黑啄木鸟、三趾啄木鸟多在树干取食，黑啄木鸟更常在倒木上取食，而大斑啄木鸟则多在树冠层取食。黑啄木鸟基本只在主干上凿洞，其他两种特别是大斑啄木鸟则可以在侧枝上取食。与黑啄木鸟和大斑啄木鸟凿洞取食昆虫不同，三趾啄木鸟多通过扒去树皮获得食物。黑啄木鸟的取食树基本为死树，单树取食时间最长，大斑啄木鸟多在活树上取食，单树取食时间最短，经常更换取食树，而三趾啄木鸟的取食树则死活参半，单树取食时间也较长。黑啄木鸟的冬季取食行为节律表现为双峰形，日出后和日落前各有一个活动高峰，其他两种则于白天持续取食。3种啄木鸟取食生境和行为生态位的差异，使它们能够更有效地利用有限的食物资源，共存于同一森林。

Forage niche differentiation of three sympatric woodpecker species in winter

This systematic survey aimed to acquire knowledge about the foraging behavior of the woodpecker in broad-leaved Korean pine forests, and explore the coexisting features of sympatric woodpecker species, by investigating the foraging habitat and behavior characteristics of three woodpecker species. The species were black woodpeckers (Dryocopus martius), three-toed woodpeckers (Picoides tridactylus), and the great spotted woodpecker (Dendrocopos major) that are distributed in Liangshui nature reserve in the northeastern region of China. The survey was conducted from January 5 to 13, 2016 and 45 east-west direction parallel transects were set in the core area of the reserve, each with a length 1 km and each transect was surveyed two times. Furthermore, 25 and 20 transects were surveyed in the morning and afternoon, respectively. Except for the species and sex of the woodpeckers, 15 variables of the forage habitat and behavioral characteristics were measured, which were forest type, slope position, dominant tree species, crown density, tree density, snag density, forage tree species, height of the forage tree, diameter at breast height of forage tree, forage tree situation, forage height, forage position, drill type, and forage duration per tree. Furthermore, 312 forage quadrats of 20 m×20 m were investigated, which included 73, 97, and 142 quadrats of black, three-toed, and great spotted woodpeckers, respectively. We set 484 same area control quadrats in a grid to collect the available data on the habitat factors. The methods of multivariate regression tree and multinomial logistic regression were used to explore the pattern of the woodpecker''s forage niche partitioning. Bailey''s method and two-way analysis of variance (ANOVA) method were used to analyze the selectivity of the woodpeckers on special forage habitat factor or differences in their forage behavior. The results showed a clear niche partitioning pattern of the three woodpecker species. The virgin fir and spruce forests distributed in the mountain valley were the most favored forage habitat of the black and three-toed woodpeckers, whereas the great spotted woodpeckers randomly foraged in different forests. Furthermore, the great spotted woodpeckers foraged on different tree species, but the black and three-toed woodpeckers most often foraged on firs. Black and three-toed woodpeckers selected foraging spots in the forests with closer crowns, whereas the great spotted woodpeckers preferred to forage in the forests with higher tree density and lower crown density. The great spotted woodpeckers often foraged on bigger living trees, drilled among crowns, and on branches. The other two species spent more foraging time on trunks, especially, the black woodpeckers, which were often observed foraging on snags and logs. The three-toed woodpeckers stripped bark to get food while the other two species drilled holes into the trunks or branches to find xylophagous insects. Two peaks of forage activity in the morning and afternoon were found in black woodpecker, whereas the other two species foraged throughout the day. The black and three-toed woodpeckers usually spent a longer time ( > 20 min) foraging on the same tree than the great spotted woodpeckers, which often changed forage trees. Under conditions of limited food resources, the habitat and behavior niche portioning facilitated the efficient utilization of resources and coexistence of the three woodpecker species. To the best of our knowledge, this is the first report on the foraging behavior portioning of these three species of woodpeckers in winter, and the first report on the foraging behavior of Dryocopus martius.