DOI: 10.5061/dryad.m9p07
title: Data from: Drivers of bird species richness within moist high-altitude grasslands in eastern South Africa

description: Moist high-altitude grasslands in South Africa are renowned for high
 avifaunal diversity and are priority areas for conservation. Conservation
 management of these areas conflicts with management for other uses, such
 as intensive livestock agriculture, which requires annual burning and
 leads to heavy grazing. Recently the area has become target for water
 storage schemes and renewable electricity energy projects. There is
 therefore an urgent need to investigate environmental factors and habitat
 factors that affect bird species richness in order to optimise management
 of those areas set aside for conservation. A particularly good opportunity
 to study these issues arose at Ingula in the eastern South African
 high-altitude grasslands. An area that had been subject to intense grazing
 was bought by the national power utility that constructed a pumped storage
 scheme on part of the land and set aside the rest for bird conservation.
 Since the new management took over in 2005 the area has been mostly
 annually burned with relatively little grazing. The new management seeks
 scientific advice on how to maintain avian species richness of the study
 area. We collected bird occurrence and vegetation data along random
 transects between 2006 and 2010 to monitor the impact of the new
 management, and to study the effect of the habitat changes on bird species
 richness. To achieve these, we convert bird transect data to presence only
 data to investigate how bird species richness were related to key transect
 vegetation attributes under this new grassland management. First we used
 generalised linear mixed models, to examine changes in vegetation grass
 height and cover and between burned and unburned habitats. Secondly, we
 examined how total bird species richness varied across seasons and years.
 And finally we investigated which habitat vegetation attributes were
 correlated with species richness of a group of grassland depended bird
 species only. Transects that were burned showed a larger decrease in
 vegetation cover compared to transects that were not burned. Grass height
 increased over time. Bird species richness was highest in summer compared
 to other seasons and increased over time. Overall bird species richness
 increased over the three summer surveys but species richness of birds that
 prefer heavily grazed habitat showed little change over the three years.
 Changes in bird species richness were best explained by the model with
 grass height for combined species richness of grassland depended birds but
 also for birds that prefer heavy grazing when treated alone. On one hand
 birds that prefer moderate grazing were best explained by a null model.
 However, overall bird species richness was better positively correlated to
 grass height than grass cover or dead grass. We conclude that frequent
 burning alone with relatively reduced grazing led to higher but less dense
 grass, which benefited some species and disadvantaged others. We suggest
 that management of this grassland use combination of fire and grazing and
 leave some areas unburned to accommodates birds of various habitat needs.
description: avibaseline_PLOSGrassland bird data and vegetation data filesIngula vegtn transects 2006,2007,2010_PLOS2016