Abundance and community structure of birds breeding in Kalahari woodland used  as  rangeland

G. Kopij1, Montse Ferrer2

1 University of Namibia, Oshakati, Namibia; 2 Arxius de Miscel·lània Zoològica, Museu de Ciències Naturals de Barcelona, Ps Picasso s/n, 08003, Barcelona, Spain

Corresponding author(s): G. Kopij (g.kopij@unam.na)

Received {date}; Revised {date}; Accepted {date}; Published {date}

Citation: Combination of authors, year of data paper publication (in parentheses), Title, Journal Name, Volume, Issue number (in parentheses), and doi of the data paper.

Resource Citation

Kopij, G., 2020. Abundance and community structure of birds breeding in Kalahari woodland used  as  rangeland. Museu de Ciències Naturals de Barcelona. Dataset/Occurrence: https://doi.org/10.15470/rova7r https://doi.org/10.15470/rova7r

Abstract

The line transect method was applied to assess the linear index of abundance and community structure of birds breeding in an area of Kalahari woodland used as range land for cattle. Four transects were designed along roads traversing the ranch. Each transect was 2.5 km long and was surveyed three times in 2014 and 2015. A total of 47 bird species were recorded but only 25-31 species were recorded on any particular transect. In the neighbouring pristine Kalahari woodland, the number of bird species on a12 km long transect was much higher (n = 88), and ranged in some sections (each 1.2 km in length) from 35 to 53. On any particular section, the number of dominant species ranged from 5 to 7, and their cumulative dominance on each section was similar, ranging from 53-56%, while the community dominance index ranged from 0.23 to 0.35.  The most numerous species were the Cape turtle dove and emerald-spotted wood dove, which were dominant on all sections. Together they comprised 28% of all breeding birds. The avian community in the Kalahari woodland in Sachinga LDC did not differ from the neighbouring pristine woodland either in terms of species diversity or evenness. However, it differed significantly in terms of species richness, the proportion of main ecological guilds, and linear index of abundance of particular species. These differences could be mainly due to the structure of woody vegetation, which is much thicker in Sachinga than in the pristine woodland  not used as pasture for cattle.  The thickening of this vegetation on the ranch could have been caused by heavy grazing pressure by the cattle.

Keywords: Community ecology, Population densities, Rangeland management, Occurrence, Occurrence

Project details

Project title: Abundance and community structure of birds breeding in Kalahari woodland used as rangeland
Personnel: G. Kopij
Study area descriptions/descriptor: The study was conducted in the Sachinga Livestock Development Centre of the Ministry of Agriculture of the Namibian Government. The centre is situated in NE Namibia, in the Zambezi region, about 40 km west of Katima Mulilo (fig. 1), between S17.39.40-S17.40.20 and E 24.23.55-E24.24.02. The Centre is a ranch of 3,243 ha. The aim of the centre is in situ conservation, livestock improvement programmes and provision of breeding animals to the farmers, and farmer education. The centre is surrounded by communal areas with subsistence farming.
Most of the Sachinga LDC is covered by teak woodland, with smaller portion of Burkea-Kisat-False Mopane woodland and Omuramba grassland. The natural vegetation is well-preserved and represented by three classes of Kalahari woodland: 1) Colophospermum mopane , with two dominant  associations: Nymphaea nouchali–Eragrostis rotifer which contains water species, and Combretum imberbe–Acacia nigrescens in association with sparse woodlands; 2) Baikiaea plurijuga woodland,  comprising Guibourtia coleospherma–Burkea africana Association and Combretum collinum–Boscia albitrunca association; and 3) Baikiaea plurijuga – Terminalia sericea class with Pterocarpus angolensis–Diploryhnchus condylocarpon association,  Dalbergia martinii–Berchemia discolor association, and Acacia fleckii–Baphia massaiensis association (Lushetile, 2009).
Design description: The American version of the transect line method (Bibby et al., 2012; Sutherland, 1996) was used to assess the population density and community structure of birds occurring in the ranch. A transect of  10 km in length and 100 m width (50 m on each side) was designed along roads traversing the ranch. The transect was divided into four equal sections (fig. 2). Each section was 2.5 km in length, and was surveyed three times (03/09/2014.  07/03/2015,  29/04/2015),  each time in the same direction.
Counts were conducted by the same observer, in the mornings, and in calm and cloudless weather conditions. Dominance is expressed as the percentage of the total number of pairs of a given species in relation to the total number of all pairs of all species recorded. A dominant species is defined as that comprising 5% or more of all individuals of all species recorded, and  a subdominant  species is defined as  that comprising 2-4.99%. 
All birds showing breeding (e.g. transporting nesting material, constructing nests, feeding chicks etc.) or territorial (e.g. singing males) behaviour were recorded. Special attention was paid to simultaneously singing males, as they were important in determining the number of occupied territories. Special care was taken not to count the same birds twice, as this could overestimate the number of territories. 
The number of breeding pairs was estimated for each section on each transect. The maximumnumber of breeding pairs at each survey and on each section was assumed as the real number of breeding pairs. The total number of breeding pairs of each species on a particular transect was calculated as the total of maximum numbers recorded on each section within the transect.   
The following guilds were distinguished: diet (G, granivorous; I, insectivorous; F, frugivorous; N, nectarivorous); and nesting (T, in trees or shrubs; H, in holes; G, on the ground; V, in herbaceous vegetation). 
The following indices were used to characterise diversity, evenness and similarity between  the communities: 
1)	Shannon’s diversity index: H’ = -∑ pi ln pi
where: pi is the proportion of breeding pairs belonging to the ith species 
2)	Simpson’s diversity index: D = ((∑n(n-1))/N(N-1)
where: n – total number of breeding pairs belonging to a given species, N – total number of breeding pairs of all species 
3)	Pielou’s evenness index: J’ =  (-∑ pi ln pi)/ln S
where pi is the proportion of breeding pairs belonging to the ith species; S – total number of species. J’ varies between 0 and 1. The lower the  variation between species in a community, the higher the J’. 
4)	Community dominance index: DI = (n1 + n2)/N
where n1, n2 – number of pairs of the two most abundant species, N – total number of pairs of all species. 
5)	Sörensen’s Coefficient: I = 2C/A+B 
where A – the number of bird species in one plot, B – the number of bird species in another plot, C – the number of bird species common to both plots.
Systematics and nomenclature of bird species follow Hockey et al. (2005). Scientific names of bird species are listed in appendix 1.

Data published through GBIF: https://ipt.gbif.es/resource?r=birds_kalahari_woodland

Taxonomic coverage

Taxonomic ranks
Family: Alcedinidae, Bucerotidae, Buphagidae, Caprimulgidae, Cisticolidae, Columbidae, Coraciidae, Dicruridae, Emberizidae, Estrildidae, Laniidae, Leiothrichidae, Macrosphenidae, Malaconotidae, Meropidae, Monarchidae, Muscicapidae, Nectariniidae, Numididae, Oriolidae, Paridae, Phasianidae, Phoeniculidae, Picidae, Platysteiridae, Pycnonotidae, Sturnidae, Trogonidae, Vangidae, Vangidae

Spatial coverage

General spatial coverage: The study was conducted in the Sachinga Livestock Development Centre of the Ministry of Agriculture of the Namibian Government. The centre is situated in NE Namibia, in the Zambezi region, about 40 km west of Katima Mulilo, between S17.39.40-S17.40.20 and E 24.23.55-E24.24.02. The Centre is a ranch of 3,243 ha. Most of the Sachinga LDC is covered by teak woodland, with smaller portion of Burkea-Kisat-False Mopane woodland and Omuramba grassland. The natural vegetation is well-preserved and represented by three classes of Kalahari woodland: 1) Colophospermum mopane , with two dominant  associations: Nymphaea nouchali–Eragrostis rotifer which contains water species, and Combretum imberbe–Acacia nigrescens in association with sparse woodlands; 2) Baikiaea plurijuga woodland,  comprising Guibourtia coleospherma–Burkea africana Association and Combretum collinum–Boscia albitrunca association; and 3) Baikiaea plurijuga – Terminalia sericea class with Pterocarpus angolensis–Diploryhnchus condylocarpon association,  Dalbergia martinii–Berchemia discolor association, and Acacia fleckii–Baphia massaiensis association (Lushetile, 2009).
Coordinates: 24°14'24''S and 24°13'48''S Latitude; 17°23'24''E and 17°23'60''E Longitude 

Temporal coverage: September 3, 2014 - April 29, 2015

Methods

Method step description: The following indices were used to characterise diversity, evenness and similarity between  the communities: 
1)	Shannon’s diversity index: H’ = -∑ pi ln pi
where: pi is the proportion of breeding pairs belonging to the ith species 
2)	Simpson’s diversity index: D = ((∑n(n-1))/N(N-1)
where: n – total number of breeding pairs belonging to a given species, N – total number of breeding pairs of all species 
3)	Pielou’s evenness index: J’ =  (-∑ pi ln pi)/ln S
where pi is the proportion of breeding pairs belonging to the ith species; S – total number of species. J’ varies between 0 and 1. The lower the  variation between species in a community, the higher the J’. 
4)	Community dominance index: DI = (n1 + n2)/N
where n1, n2 – number of pairs of the two most abundant species, N – total number of pairs of all species. 
5)	Sörensen’s Coefficient: I = 2C/A+B 
where A – the number of bird species in one plot, B – the number of bird species in another plot, C – the number of bird species common to both plots.
Systematics and nomenclature of bird species follow Hockey et al. (2005). Scientific names of bird species are listed in appendix 1.
Study extent description: The study was conducted in the Sachinga Livestock Development Centre of the Ministry of Agriculture of the Namibian Government. The centre is situated in NE Namibia, in the Zambezi region, about 40 km west of Katima Mulilo (fig. 1), between S17.39.40-S17.40.20 and E 24.23.55-E24.24.02. The Centre is a ranch of 3,243 ha. The aim of the centre is in situ conservation, livestock improvement programmes and provision of breeding animals to the farmers, and farmer education. The centre is surrounded by communal areas with subsistence farming.
Most of the Sachinga LDC is covered by teak woodland, with smaller portion of Burkea-Kisat-False Mopane woodland and Omuramba grassland. The natural vegetation is well-preserved and represented by three classes of Kalahari woodland: 1) Colophospermum mopane , with two dominant  associations: Nymphaea nouchali–Eragrostis rotifer which contains water species, and Combretum imberbe–Acacia nigrescens in association with sparse woodlands; 2) Baikiaea plurijuga woodland,  comprising Guibourtia coleospherma–Burkea africana Association and Combretum collinum–Boscia albitrunca association; and 3) Baikiaea plurijuga – Terminalia sericea class with Pterocarpus angolensis–Diploryhnchus condylocarpon association,  Dalbergia martinii–Berchemia discolor association, and Acacia fleckii–Baphia massaiensis association (Lushetile, 2009).
Sampling description: The American version of the transect line method (Bibby et al., 2012; Sutherland, 1996) was used to assess the population density and community structure of birds occurring in the ranch. A transect of  10 km in length and 100 m width (50 m on each side) was designed along roads traversing the ranch. The transect was divided into four equal sections (fig. 2). Each section was 2.5 km in length, and was surveyed three times (03/09/2014.  07/03/2015,  29/04/2015),  each time in the same direction.
Counts were conducted by the same observer, in the mornings, and in calm and cloudless weather conditions. Dominance is expressed as the percentage of the total number of pairs of a given species in relation to the total number of all pairs of all species recorded. A dominant species is defined as that comprising 5% or more of all individuals of all species recorded, and  a subdominant  species is defined as  that comprising 2-4.99%.
Quality control description: All birds showing breeding (e.g. transporting nesting material, constructing nests, feeding chicks etc.) or territorial (e.g. singing males) behaviour were recorded. Special attention was paid to simultaneously singing males, as they were important in determining the number of occupied territories. Special care was taken not to count the same birds twice, as this could overestimate the number of territories. 
The number of breeding pairs was estimated for each section on each transect. The maximumnumber of breeding pairs at each survey and on each section was assumed as the real number of breeding pairs. The total number of breeding pairs of each species on a particular transect was calculated as the total of maximum numbers recorded on each section within the transect.

Datasets

Dataset description
Object name: Darwin Core Archive Abundance and community structure of birds breeding in Kalahari woodland used  as  rangeland
Character encoding: UTF-8
Format name: Darwin Core Archive format
Format version: 1.0
Distribution: https://ipt.gbif.es/archive.do?r=birds_kalahari_woodland
Publication date of data: 2022-06-08
Language: English
Licences of use: Creative Commons Attribution (CC-BY) 4.0 License

Metadata language: English
Date of metadata creation: 2020-08-19
Hierarchy level: Dataset

References
Kopij, G., 2020. Abundance and community structure of birds breeding in Kalahari woodland used  as  rangeland. Arxius de Miscel·lania Zoologica, 18: 101-112, Doi: https://doi.org/10.32800/amz.2020.18.0101 https://doi.org/10.32800/amz.2020.18.0101