Birds

“Best bet” Land-use Systems

Thematic reports

Impact of different land uses on biodiversity

An Intensive Biodiversity Baseline Study in Jambi Province,Central Sumatra, Indonesia

 

Unique id: 4

Source file: D:\Projects\ASB\ASB Country and Thematic reports - xml\Above ground biodiversity assessmet WG\C-Sec4-5.xml

 

Authors: By P. Jepson, Djarwadi

 

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4.1.      Introduction:

 

This report presents preliminary analyses and conclusions of the bird survey component of the Jambi base-line study. The analysis is largely descriptive and aims to provide an overview of the data to facilitate comparisons with findings from other disciplines and generate ideas for more detailed and multidisciplinary analysis. The conclusions section flags some areas which may merit further investigation.  A brief discussion on the sampling protocol suggests that for birds, an approach drawing on a landscape ecological framework may be more suitable for Rapid Biodiversity Assessment that aims to assess the impact of land use change.

 

4.2.      Aims and objectives:

 

To provide baseline data for above-ground biodiversity assessment based on bird species richness and functional (guild) type.

 

To investigate the changes in bird diversity across a disturbance gradient from natural forest to agricultural habitats.

 

To provide a sample reference point for other multi-disciplinary input.

 

4.3.      Personnel:

 

Paul Jepson, Ornithologist (University of Oxford)

Djawardi, Ornithologist (IPB, Bogor)

 

4.4.      Methods:

 

Review of existing methods:

 

For the purpose of measuring and comparing bird diversity there are two broad groups of methods: those which generate a species list, perhaps with an approximation of abundance, and those which generate a species list with a quantifiable measure of abundance.

 

For birds, abundance is enormously difficult to measure with any precision. A key problem is the difference between observed and real abundance. This can be a factor of a species’ habits and the openness of a habitat (distance at which birds can be seen and/or heard). The latter variable differs between habitat types and must be accounted for if the aim (such as in this study) is to compare diversity between habitats. A group of methods called Distance Sampling [Reynolds, 1980] which are supported by a sophisticated analytical statistics package (DISTANCE2) are available for comparing abundance in different habitats. One of these methods (Variable-circular Plot) has been employed by the BirdLife International-Indonesian Programme in Nusa Tenggara and Maluku to compare biodiversity values of different habitat types with proposed reserves. Although distance sampling is highly compatible with a plot-based protocol, it was not considered appropriate for the survey because BirdLife’s experienced has revealed that:

 

     while a density can be calculated with five contacts for a species, twenty contacts are usually required to generate densities within 5% confidence limits; this requires planning for at least 8 days sampling for each habitat type;

     data analysis is complicated and time consuming;

     it is questionable if the assumptions of Distance Sampling methodology are justified in tropical rainforest.

 

“Rapid” as defined by the time horizon of this study, constrained the choice to presence-absence methodologies and those which could yield useable data in one day's sampling per division.   Species accumulation curves were selected. This method is well known in Indonesia because it was described by John MacKinnon in his popular field guides. Counts of species are made during successive sampling units, and the cumulative number of species plotted. The rate at which the curve flattens gives an indication of total number of species and whether all species in the habitat have been observed.

 

MacKinnon defined the sampling unit as the first 20 species and envisaged an observer walking. This introduces a rough measure of relative abundance and increases the likelihood of meeting rare species. The need to link bird observations to a plot, as well as time constraints, required a variation of this methodology - observers stayed with the immediate vicinity of the plot and the sampling unit was a five minute time period. With this protocol an abundance measure is not possible, and rare species are likely to go unrecorded.

 

4.4.2    Field Methods used on this survey:

 

Twelve plots were sampled using a species accumulation methodology.  A species list of contacts was compiled for each five minute period between 16.30hrs and 18.00hrs and between 06.30 hrs. and 08.00 hrs. Audio-visual species contacts were made by the two observers named above in 'wooded' land use types and by a single observer in 'open' land use types.  The observers roved within 30m of the plot centre. 

 

Bird species contacts were scored: “H” = heard, “L” = seen, “T” = fly-over.  In open habitats a list was made of species actually recorded in the land use.

 

Data were entered into a spread-sheet after each morning count.  Entering data while a count is within immediate memory is an integral part of the overall methodology, because it:

     assisted with learning\confirming identity of calls;

     ensured both observers gave the same name to the same contact.

 

In additional to the above, bird species lists were complied for three landscape elements of the logged forest land-use not sampled in the plots, namely : access road edge; camp; and log pond.

 

4.4.3    Analysis:

 

4.4.3.1 Data storage and access:

 

The following two data sets are annexed to this report and contained in the Excel file name 'Jambird.xls':

     A matrix of species recorded in each 5-min count.

     A total species list by plot and also by additional “landscape elements”. (Annex III, Table 4)

 

Data set 1 is a combined and agreed record taken from the field notebooks of the two observers.  The second data set is compiled from the first. Additional values attributed to each species in order to facilitate investigation of the data sets are as follows:

 

     Species number code according to [Andrew, 1992 p.147];

     Species number code specific to this study.  i.e. the number of the species in the total species list for the study ordered according to [Andrew, 1992 p.147];

     Status i.e. resident ( R ), migrant (M);

     Diet guild sensu [Thiollay, 1995 p.199]

     Feeding site guild sensu [Thiollay, 1995 p.199]

     Body size category sensu [Thiollay, 1995 p.199]

 

4.4.3.2 Dataanalysis:

 

The methods used resulted in a presence-absence data set.  Although species were recorded by five minute count, it is not possible to analyse for relative abundance because counts are not independent, i.e.  a bird recorded in one count may or may not be the same bird recorded in subsequent counts.

 

Three species flying over the plot and unlikely to utilise the LUT in which the plot is embedded, were omitted from the analysis (see Appendix 4.1 for list).

 

To explore the question of the impact of disturbance on forest bird diversity the following analyses were made:

 

     Species richness. Species accumulation curves were plotted to compare species richness between plots. The intention is to re-analyse this data using the BritishMuseum program “Curves” which optimise the curve. This analysis will be submitted as an update to this report.

 

     Functional diversity. Species were assigned to diet guilds, foraging site guilds  and body size classes sensu [Thiollay, 1995 p.199]. Counts of number of species per class are graphed.  Unidentified species were omitted from the analysis. A table of number of species according to taxonomic family is also presented.

 

     Resident\migrant status. A simple count of migrant species by plot was made to ascertain whether numbers differed between plots.

 

     Differentiation in b diversity between sites. Sørenson’s similarity indices were calculated using the Multivariate Statistical Package (MVSP), 1987. This is a simple measure suitable for presence and absence data; it treats all species as equal irrespective of whether they are abundant or rare. [Magurran, 1988 p. 200]

 

     Clustering of sites.  A nearest neighbour cluster analysis was performed on the Sørenson’s similarity indices with randomised data input.

 

Preliminary results:

 

Descriptive analysis:

 

4.5.1.1  Species richness:

 

 

Figure 4.1  Species accumulation curves

 

 

Figure 4.1 shows species accumulation curves for each plot. The rate at which the curve flattens is crucial to comparing such curves, and it is regretted that it is not possible as yet to present smoothest-fit curves.

 

The richest plots were the natural forest plots (BS2 & BS5) and the heavily disturbed logged forest plot (BS3). The two industrial plantation plots (BS7 & BS8) were the most depauperate. The 'wooded' plots appear to show increasingly depauperate sub-sets with increased intensity of management. The 'non-wooded' plots have a largely open-country species assemblage distinct from the 'forest' plots. The Chromolaena plot (BS16) has some forest species and represents the change-over point.

4.5.2.1     Trophic diversity:

 

4.5.2.1.a   Proportion of diet guilds:

 

Figure 4.5.2.1i.  Percentage of species diet guilds

Figure 4.5.2.1b.  Number  of species diet guilds

The gramnivore guild is represented in disturbed forest habitats and constitutes the largest percentage of species richness in the most highly modified habitats: Imperata; Cassava and Chromolaena (plots BS12, BS13 and BS16).   Plantation rubber (BS8) and jungle rubber (BS10) have similar proportions of each guild, as do the three logged forests.  The two Paraserianthes plots are dissimilar - BS6 has gramnivores and no nectarivores, whereas for BS7 it is the reverse (species numbers are low).

 

 

 

 

 

 

 

4.5.1.2b  Proportion of feeding site guilds:

 

Figure 4.5.1.2i.  Percentage of species in each  feedings site diet guilds

 Figure 4.5.2.2a.  Number of species in each feedings site diet guilds

The tree canopy feeding guild constitutes over 45% of species in natural forest plots (BS1-BS5) and in the jungle rubber (BS10) and plantation rubber (BS8). The proportion of this guild is less than 35% of species total in all other plots.  Species adapted to feeding from grasses and shrubs are present in all non-natural forest plots, but not in natural forest plots (with the exception of one species in Plot BS5). 


Proportion of body size classes:

 

Figure 4.5.2.3 a.  Percentage of species by size class

Figure 4.5.2.3 b.  No of species by size class

No clear patterns differentiate the plots.  Both the unlogged natural forest site (BS1) and Imperata (BS12) have the largest percentage of species in the heaviest weight class.

 

 

Species diversity by taxonomic family:

 

Natural forest plots are characterised by higher numbers of bird families and passerine bird families, compared with non-natural forest families (with the exception of BS1), see Table 4.1.  Five families are only present at natural forest plots, namely: Hemiprocnidae; Trogonidae; Muscicapidae; Monarchidae; Zosteropidae.

Table 4.1

Summary of species in each taxonomic family by plot

 

 

NaturalForest Plots

 

 

 

 

 

 

 

 

 

BS1

BS2

BS3

BS4

BS5

BS6

BS7

BS8

BS10

BS12

BS13

BS16

Ardeidae

 

 

 

 

 

 

 

 

 

 

1

 

Accipitridae

 

 

1

 

1

 

1

1

 

 

 

 

Falconidae

 

 

 

 

 

1

1

 

 

 

 

 

Anatidae

 

 

 

 

 

 

 

 

 

1

 

 

Phasianidae

 

 

 

 

 

 

 

 

 

1

1

 

Turnicidae

 

 

 

 

 

1

 

 

 

1

1

1

Rallidae

 

 

 

 

 

 

 

 

 

 

1

 

Charadriidae

 

 

 

 

 

 

 

 

 

 

 

 

Scolopacidae

 

 

 

 

 

 

 

 

 

 

 

 

Glareolidae

 

 

 

 

 

 

 

 

 

 

 

 

Columbidae

 

1

1

1

1

 

 

1

2

3

2

3

Psittacidae

2

2

2

2

2

2

 

2

 

1

1

 

Cuculidae

1

 

 

2

3

2

3

1

4

2

2

4

Strigidae

 

 

 

 

 

 

 

 

 

 

 

 

Caprimulgidae

 

 

 

 

 

 

 

 

 

 

 

 

Apodidae

 

 

1

1

 

3

 

 

 

 

 

 

Hemiprocnidae

 

 

 

 

 

 

 

 

 

 

 

 

Hemiprocnidae

 

1

1

1

1

 

 

 

 

 

 

 

Trogonidae

1

1

 

1

1

 

 

 

 

 

 

 

Alcedinidae

1

1

 

 

1

 

1

1

 

1

1

 

Meropidae

 

1

 

1

2

1

1

1

1

1

1

1

Capitonidae

1

1