The Study Of Understory Birds In Nonggang Karst Forest

A study of understory birds in Nonggang karst forst was conducted fromMay 2006 to February 2007. The Forest structure and the Avifauna, community,mixed-species flock and adaptive syndromes of understory birds were studied inthis paper.Forest stand differed markedly in the availability of structural components.The density of trees, logs, snags and the canopy cover was lowest in shrub forest,but it was maximal in mature forest. The understory volume was lowest inmature forest, but it was maximal in shrub forest. The structural elements wasvery important for birds habitat in karst forest.66 species belonging to 22 families and 9 orders was detected in this study.And the Passeriformes were 57 species which about 73.1% of total birds.Among this birds, 46 species about 69.7% of total birds was resident bird, 19species about 28.8% of total birds was latitudinal migrant, only one speciesabout 1.5% of total birds was elevational migrant. 51 species about 77.4% oftotal birds was insectivore, 6 species about 9.1% of total birds was frugivore.And 55 species about 83.3% of total birds was bred in Nonggang karst forest. 39 species belonging to 17 families and 4 orders were represented in 320captures: 19 species in 109 captures in rainy season; 31 species in 211 capturesin dry season; Among these birds, 34 species and 308 individuals werePasseriformes, about 96.3% of the total captures and 87.2% of the total species.The captures less than 25g in mass constituted the largest component. Theunderstory birds were grouped into four habitat-use guilds: ground species,understory species, large-tree users and the vertical-profile generalists.34 bird species and two mammal species were detected in 102 flocks inNonggang karst forest. All the participants were insectivore. Most participantswere resident species (24 species and 1511 individuals), some were latitudinalmigrants (9 species and 185 individuals) and only one species was elevationalmigrant (17 individuals). There often were four to nine bird species inmixed-species flocks, and eleven to forty individuals were often foraging inflocks. Flocks averaged (±se) 5.97±2.08 species and 24.81±10.52 birds. TheGrey-cheeked Fulvetta plays a core species in the Nonggang karst forestmixed-species flocks. The bird species and individuals will increase from shrubto mature forest.The morphological characteristics, component of food and forage of 19understory insectivorous birds was analysed by clustering analysis. It showedthat all this birds use resources efficiently in different dimension at theecological niches level. Some birds which use similar resources will enhancefood and new forage space to avoid competition. This paper also concluded some threats for Nonggang karst understorybirds. It suggested that it was necessary for the conservation of understory birdshabitat to protect the forest structural components.