Management factors affecting densities of common grassland birds of high elevation grasslands of eastern South Africa:Ingula as a case study

作     者：David H.Maphisa Hanneline Smit-Robinson Les G.Underhill Res Altwegg 

作者机构：South African National Biodiversity Institute Statistics in EcologyEnvironment and ConservationDepartment of Statistical SciencesUniversity of Cape Town Bird Life South Africa Applied Behavioural Ecological and Ecosystem Research Unit(ABEERU)UNISA Animal Demography UnitDepartment of Biological SciencesUniversity of Cape Town African Climate and Development InitiativeUniversity of Cape Town 

出 版 物：《Chinese Birds》 (中国鸟类（英文版）)

年 卷 期：2017年第8卷第1期

页      面：37-49页

核心收录：

学科分类：07[理学] 0713[理学-生态学] 

基　　金：supported in the position of Bird Life South Africa Ingula Project Manager with funding by Eskom through The Ingula Partnership Fund supported the first author with a vehicle for the duration of the project,while employed by Bird Life South Africa supported by the National Research Foundation of South Africa(Grant 85802) 

主　　题：Density and detection Grassland birds Grass height and cover Hierarchical distance sampling models 

摘      要：Background: World?wide grassland birds are in decline due to habitat loss and degradation resulting from inten?sive agricultural practices. Understanding how key grassland habitat attributes determine grassland bird densities is required to make appropriate conservation decisions. We examine drivers of bird densities in a South African grass?land area that has been managed for biodiversity conservation with reduced grazing ***: We estimated the density of the eight most common grassland bird species encountered in our area to evaluate the effects of recent grassland management changes on the avifauna. We collected data on birds and habitat from the austral summers of 2006/2007, 2007/2008 and 2010/2011. We used hierarchical distance sampling methods to estimate density of birds relative to two main habitat variables, i.e., grass cover and height. In addition, we used regression splines within these distance sampling models as a more flexible description of suitable ranges of grass height and cover for each ***: For most species, density is related to grass height and cover as expected. The African Quailfinch(Ortygospiza atricollis) and Common Quail(Coturnix coturnix) preferred relatively short and open grass. The Yellow?breasted Pipit(Anthus chloris), African Pipit(Anthus cinnamomeus) and Red?capped Lark(Calandrella cinerea) preferred short and relatively dense grass, while the Wing?snapping Cisticola(Cisticola ayresii) preferred grass of intermediate height and cover. The Cape Longclaw(Macronyx capensis) and Zitting Cisticola(Cisticola juncidis) preferred tall and dense grass. Our results agree with previous studies that grass height combined with grass cover are the most important habitat features that managers should manipulate in order to increase the density of target species. The regression splines show that the effect of these two habitat variables on density is well described by linear relationships for most ***: This