|Patterns of butterfly,
bird and tree diversity in the Western Ghats
Krushnamegh Kunte*, Ajit Joglekar,
Ghate Utkarsh§,** and P. Pramod
*Swarmangal, 4024, Survey No.
14/4, Warje, Pune 411 029, India
Sinhagad Road, Pune 411 036, India
§Centre for Ecological Sciences, Indian
Institute of Science, Bangalore 560 012, India
Biodiversity Unit, Jawaharlal Nehru
Centre for Advanced and Scientific Research, Jakkur, Bangalore 560 064, India
We censused butterfly assemblages of the Western
Ghats of India in 15 localities and 8 vegetation types during 67 transects, each 600 m
long, and traversed in one hour. The natural vegetation types had relatively high
diversities compared to human impacted vegetation types such as scrub/savanna and
grasslands. The home gardens and paddy fields had very distinctive species composition,
coupled with very low levels of beta diversity. Their constituent species were more
widespread. Comparison of these patterns with those found amongst trees and birds reported
in similar studies threw up interesting parallels as well as contrasts. Species
dissimilarity in evergreen vegetation types were high for trees and butterflies, but low
for birds. Bird and butterfly assemblages in monoculture tree plantations had low species
richness, less distinctiveness and high levels of dissimilarity, being comprised of rather
widespread species. However, on the whole there was little relation between taxonomic
groups and vegetation types across diversity parameters. There could be important
implications of these patterns of diversity dispersion and their co-variation across
taxonomic groups for assigning conservation priorities. We emphasize the need for
classifying the landscape, both natural and manmade, on the basis of structural vegetation
types, followed by stratified sampling of multiple groups of organisms for monitoring the
status of and designing conservation strategy for biodiversity.
IN recent years, the focus of nature
conservation efforts has become more inclusive, broadening from an approach emphasizing
flagship species like cranes, sea turtles or tiger to embrace the entire diversity of
life. Thus, biological diversity is now increasingly recognized as a vital parameter to
assess global and local environmental changes and sustainability of developmental
activities1. As one of the worlds top twelve megadiversity countries, and
a signatory to the international Convention on Biological Diversity (CBD) it is important
for India to try and conserve the entire spectrum of biological diversity and to institute
an ongoing programme of monitoring the efficacy of conservation measures2.
The efforts needed for inventorying and monitoring
are enormous in magnitude. India harbours over 1,25,000 scientifically described and
perhaps another 400,000 undescribed species, over its 320 million ha of landmass and 200
million ha of exclusive economic zone3. Conservation strategies must therefore
be developed to maintain diversity levels in the entire range of natural as well as
managed ecosystems. This calls for extensive information, ideally on all groups of plants,
animals and micro-organisms across India's landscape and waterscape. Conservation
priorities should be decided on the basis of such information, and conservation measures
decided upon to translate these priorities into action4. The efficacy of the
conservation measures thus instituted would then have to be monitored on a periodic basis
to continually adjust the conservation actions to changing ground realities5.
Obviously this is a task that cannot be accomplished in its entirety; we must therefore
resort to sampling. Such sampling should be attempted along three axes: sampling a subset
of taxa; sampling in certain localities; and repeated assessments at certain time
intervals6,7. It must be clarified that this is to design a programme of
monitoring; side by side taxonomic inventorying of the entire spectrum of diversity has to
Such a monitoring programme must be designed on the
basis of an understanding of the diversity dispersion over space and time in different
groups of organisms. We have a broad understanding of such patterns over the Western Ghats
biogeographic province8. Very little is known about the diversity dispersion
across different vegetation types that constitute an intricate mosaic in this hill region.
Even in the United Kingdom where butterfly populations are being monitored for more than
two decades, understanding of the effect of compositional changes in habitats on butterfly
community structure and dynamics is far from being complete9. Since major
habitat transformation is a significant factor underlying erosion of diversity, it is
important to understand the patterns of diversity of various taxonomic groups across
different vegetation types10. Of course, habitats are defined from the
perspective of the organisms. Habitats for birds are evidently different from those for
earthworms or rotting fungi11. However, it is necessary to employ a standard
system of classification of habitats to organize a comprehensive programme of monitoring
biodiversity. For this purpose it is appropriate to focus on the dominant growth forms of
plants and to characterize habitats as vegetation types12.
It is with this background that the Western Ghats
Biodiversity Network (WGBN) has organized a programme of sampling species level diversity
in a number of taxa in a series of 20 localities distributed over the length of the
Western Ghats. Each locality is viewed as a mosaic of several terrestrial vegetation types
and a variety of freshwater habitats. WGBN has then undertaken sampling of flowering
plants, bryophytes, birds, butterflies, ants, aquatic insects, freshwater mollusks, fish
and caecilians in representative landscape element types13. In this paper we
discuss the results of our studies through WGBN on butterfly communities and diversity,
and compare the patterns discerned with those for birds and trees published previously12,14.
In terms of indicator organisms for biodiversity
studies15, butterflies are an excellent choice. They are common almost
everywhere, attractive and easy to observe. Many species, both common and rare, can be
easily and reliably identified in the field, without killing. They are also amongst the
better-studied groups of organisms, with availability of field guides. Further, their
diversity and community composition are dependent on that of plants, as their caterpillars
have strict dependence on specific host plants. As they undergo metamorphosis,
ecologically they contribute more to local diversity because of their dual fundamental
role than monomorphic organisms. Therefore, they should be given more prominence in
diversity studies. India has a butterfly fauna comprising of 1501 species of which the
Western Ghats harbours 330 species including 37 endemic species and another 23 shared only
with Sri Lanka16. These 330 species belong to 166 genera and 5 families.
Materials and methods
The Western Ghats is a 1600 km long mountain
range, with a variable breadth of 5 to 25 km, lying parallel to the western coast of
India. In elevation it rises up to 2800 m. The present study was based on 67 line
transects from 14 localities in elevations below 1200 m. The landscape of each of the
14 localities was a mosaic of different vegetation types. We sampled the butterflies by
walking on line transects that traversed through homogeneous vegetation types. The
transects were assigned to the eight vegetation types on the basis of structure and
phenology of the vegetation, the rationale for which was discussed at length in Utkarsh et
al.12. The 5 natural vegetation types mentioned here broadly correspond to
the classification followed by Indian foresters17, the French institute at
Pandichery18 and UNESCO19. The typology followed in this study is
briefly described below:
Evergreen forests: These harbour
2030 m tall trees, with a dense canopy covering over 80% of the ground. More
than 80% of the trees are evergreen species. Here, we have recomputed the tree diversity
parameters by pooling three closely related evergreen vegetation types described in
Utkarsh et al.12 to achieve compatibility for the purpose of comparison12.
Semi-evergreen forests: These harbour
1525 m tall trees with 4080% evergreen species, having 6080% canopy
Deciduous forests: These have 1020 m
tall trees, closed but not with a very dense canopy covering 4070% of the ground.
About 040% trees are evergreen. The deciduous forests referred here mainly
correspond to moist deciduous forests, and not the dry ones.
Scrub/savanna: These are non-forest formations
with shrubby or grassy undergrowth and a scattered tree canopy (040%). Trees, if
present, are 515 m tall. Proportion of evergreen trees varies from place to
place, but generally the deciduous trees predominate.
Grasslands: These are devoid of trees, and
abound in grasses, sedges and other herbaceous flora during the
monsoon postmonsoon period. Occasionally, shrubs may be present.
Monoculture plantations: These comprise of
orchards or forestry plantations. The orchards we surveyed consisted of evergreen trees
with a shady canopy such as arecanut, coconut or semi-evergreen canopy like rubber. The
forestry plantations were made up of evergreen trees like Ailanthus, mahogany, or
deciduous trees like teak. A given patch usually comprises of a single species but there
may be regeneration of natural trees, varying in degree and composition from place to
place. Canopy cover in plantations surveyed was high-ranging from 60 to 95%. Tree heights
were uniform within and variable across plantations.
Home Gardens: These harbour a heterogeneous
vegetation structure in terms of canopy cover (4090%), evergreenness (4080%)
and tree heights.
Paddy fields: The fields harbour indigenous and
naturalized herbaceous species along the bunds, which spread all over the field after the
paddy crop is harvested.
The butterflies were censused along 600 m long
transects, traversed in one hour. Transects were enumerated between 8.00 and 11.00 h
in the morning, when butterfly activity was usually at its daily peak. The sampling was
conducted during May and SeptemberOctober 1995. The species were identified on the
basis of field characters20,21. A total of 3294 individuals were assigned to
133 species. 267 individuals could not be identified to species level. Since these
belonged to more than one genus and formed a small fraction (7.5%) of the total
individuals recorded (3561) these have not been included in the present analysis. Each
vegetation type was sampled in localities scattered all over the Western Ghats, except
monoculture plantations and home gardens, which were sampled only in the southern half of
the Ghats, i.e. 13°N southwards, where they were plentiful. Details of distribution of
transects in habitat types, localities and latitudinal zones, are provided in Table 1.
This sampling scheme had certain limitations. The
evergreen forests are supposedly very rich in butterflies, many of which fly high in the
canopy, and some are specialized to this stratum (Harish Gaokar, pers. commun.). These
could not be sampled, leading to underestimation of abundance and perhaps also the
diversity of evergreen forest assemblages. The other types such as deciduous forests,
scrub or home gardens did not have a high and dense canopy that could obscure the sighting
of butterflies. Further, seasonal replicates in all vegetation types in all localities
would have been desirable, but could not be accomplished due to logistic constraints.
Hence, sampling was confined to the peak season of butterfly abundance. Each transect in a
locality was traversed only once. The number of transects taken per vegetation type varied
(Table 1). The distribution of sampling transects per vegetation type or locality broadly
reflects the frequency of occurrence of these vegetation types among the study sites, but
does not follow a systematic design. Hence, the patterns described here are exploratory in
Our basic data then consisted of the abundance of
133 species along 67 transects belonging to 8 vegetation types in 15 localities. The
number of butterflies per transect varied between 3 and 129 individuals with a mean of 51
and the number of species from 3 to 30 with a mean of 15. We employed these data to
compute various diversity parameters as follows.
(a) a -diversity of species encountered in a given
sample may be measured simply as species richness, or in terms of indices such as
ShannonWeaver or Simpsons index. We find that the values of such possible
indices are very strongly correlated to species richness14 and therefore stick
to the simpler measure in subsequent discussion. However, the number of species on a
transect was strongly influenced by the number of individuals sampled (r = 0.56,
p < 0.01) which varied from 9 to 129. We corrected for this variation
by rarefaction, through the average number of species amongst 9 consecutive individuals22.
(b) b -diversity is related to the unshared species
while comparing two sets of species samples. We measured b -diversity as dissimilarity of
species composition, djk, amongst two samples j and k. It
is defined in terms of the chord distance, which reflects the relative difference between
two transects as projected on to a circle of unit radius22.
where xij and xik
are the numbers of individuals of species i in transects j and k,
respectively, and S is the total number of species encountered over the two
transects j and k.
(c) We specify this dissimilarity in two ways, for
all pairs of transects assigned to a given vegetation type, and for all pairs in comparing
transects assigned to two different vegetation types. If the assignment of transects on
the basis of vegetation structurephenology is accompanied by occurrence of a
characteristic set of species then across type levels of dissimilarity should be greater
than those within types. We characterise this through the ratio of mean dissimilarity of a
type for all pairs across types to mean dissimilarity of all pairs within a given type.
This ratio has been termed as the distinctiveness of a given type.
(d) Individuals of a given species may occur on
several of the transects sampled. A particular set of species encountered on a given
transect may then be characterized in terms of the mean proportion of transects on which
members of the set are encountered. If the study involves n transects, then the
lowest value this index would take is 1/n. To facilitate comparison amongst studies
involving different numbers of assemblages sampled, we suggest an index called ubiquity,
and define it as
where pi is the ubiquity for
transect i, fij is the proportion of the total number of
transects, n, over which a species j present on the transect i is
encountered, and mi is the total number of species encountered on
transect i. Ubiquity will then vary between 0 and 1; a value of 0 implying none of
the species encountered on that transect were encountered elsewhere; a value of 1 implying
that all the species encountered on a given transect were found on all other transects.
The lower the value of ubiquity then the more restricted in distribution is the set of
species found on a given transect. The index of ubiquity used here was first demonstrated
by Pramod et al.14. Then, it was simply expressed in terms of the number
of transects. Utkarsh et al.12 used the term prevalence for
the same, but after normalizing it over the sampling effort, as in this paper, so that
samples across taxonomic groups or different studies could be compared efficiently.
(e) We use the term cohesiveness to characterize the
extent of cohesion of species in any particular assemblage. We compute it in relation to
the affinity, i.e. departure of the mean of overlap for all pairs of species in that
assemblage, from the overlap expected on the basis of chance alone. The overlap Aij
between any pair of species may be computed as:
Aij = Tij/(
Ti + Tj Tij) ,
where Tij is the number of
transects over which i and j occur together, and Ti, Tj
are the number of transects over which species i and j occur, respectively.
Thus, computed overlap is dependent on sampling effort, being underestimated by low levels
of sampling. The value of overlap expected by chance alone, Cij = pipj/(pi + pj pipj);
where Pi = Ti/T and Pj = Tj/T;
T being the total number of transects. The departure of the overlap from that
expected on the basis of chance is therefore Aij Cij.
This correction renders the overlap measure independent of level of sampling effort. The
expected value of this quantity, affinity, is 0 if the probability of occurrence of
species i on any transect is independent of the probability of occurrence of
species j on that transect. If there is a positive tendency for the two species to
occur together, then Aij will take a positive value between 0 and 1; if
the occurrence of i implies a lower than random chance of the presence of j,
then it will take a negative value between 0 and 1. It should be noted that the second
term correcting for expected co-occurrence on the basis of chance alone would have a high
value if both species are widespread, and a low value if both are rare. Cohesiveness is
then defined as:
where n is the total number of species
present on the transect. It would then take a low value if the constituent species have a
high degree of affinity amongst themselves, constituting a cohesive set of species. It
will take a high value if the constituent species are derived as if by chance from many
different assemblages, and have little affinity for each other. Cohesiveness is opposite
of the hospitality index coined by Pramod et al.14 to assess diversity
of species assemblages.
These two indices, ubiquity and cohesiveness attempt
to capture properties relating to diversity at the level of sets of species assemblages,
namely, how widespread and cohesive are the species constituting the assemblages. This
goes beyond the normal measures of diversity such as species richness characterizing
single assemblages. Cohesiveness is not a trivial consequence of diversity, but an
independent property negatively correlated to ubiquity. It is useful to examine whether
the cohesiveness of the observed data differs significantly from those of simulated random
assemblages. We have done so on the basis of three kinds of simulations:
- All 133 species have an equal chance of occurring on any of the
transects, with the total number of species per transects fixed between 3 and 129, with 10
simulations of each level of species richness.
- One hundred simulations setting the distribution of species richness
per transect as observed.
- One hundred simulations setting the distribution of ubiquity per
species as observed.
It turns out that the observed range as well as
standard deviation of cohesiveness is significantly different from that of random
assemblages created in any of these three ways. The observed mean is higher than in
simulated assemblages, implying that real life butterfly assemblages do exhibit a measure
of cohesion. Furthermore, the standard deviation of cohesiveness in observed assemblages
is significantly greater, implying that the variation in extent of cohesion, is of real
ecological significance. We also carried out one further check, namely, deleting the
species which occur on only one or two transects. It turns out that the computed
cohesiveness values do not differ significantly from those computed by retaining the whole
Unlike species diversity or evenness, cohesiveness
has no meaning as a property of single assemblages. Instead, it depends on the
distribution of butterfly species over a number of assemblages. It is then necessary to
check the minimum number of assemblages for which the value of cohesiveness stabilizes. To
do so we computed mean cohesiveness for different numbers of assemblages for assemblages
drawn randomly from the pool of observed assemblages. It is seen that the value of
cohesiveness quickly rises up to 15 transects and reaches an asymptote around 50
transects. With a sample of 67 assemblages, we are above this limit.
(f) To provide an idea of characteristic and
commoner species of various vegetation types we present a matrix (Table 2) depicting
occurrence of selected species in various vegetation types. For this purpose, the
percentage of transects of each vegetation type on which a given species is recorded was
computed. This matrix was subjected to reciprocal averaging type of ordination23
and scores for species and sites on the first axis were used for further analysis. The
species were grouped into those confined to a single vegetation type, shared between two,
three and so on up to all the eight types. From each of these eight groups of species,
eight species were chosen such that each had its peak frequency of occurrence in a
different type. Of course, there were fewer than 8 species that occurred in 6 or 7 or 8
types. Thus from 8 groups of species based on frequency of vegetation types inhabited, a
total of 51, and not 64, species could be selected such that each vegetation type was
represented by most frequent species from each of the 8 groups. These 51 species and the
vegetation types were sorted on the basis of their reciprocal averaging scores.
(g) Our interest also lies in understanding the
patterns of covariation of diversity across various taxonomic groups. We had computed
similar indices of diversity for bird14 and tree12 communities,
sampled in nearby areas. The bird and tree surveys cover all but one of the 15 localities
where butterflies were sampled. However, bird and tree data from some other neighbouring
localities have also been used here, as our focus is more on characterizing habitat types
than the localities. A total of 9987 birds belonging to 212 species were sampled using 132
belt transects on an average 550 ´ 100 m in size, representing 21
localities and 8 different vegetation types. A total of 20,785 trees belonging to 398
species were recorded from 108 transects on an average measuring 400 ´
20 m from 30 localities and 4 vegetation types. All the tree transects belong
to natural vegetation, although with varying levels of human impact. Since the vegetation
classification schemes for the three taxonomic groups are compatible and most of the
sampling localities are the same; we compare average per transect values for various
diversity parameters across taxonomic groups and vegetation types. For this purpose, we
normalize the values for a given taxonomic group on a given diversity parameter on a 0 to
Results and discussions
Patterns of butterfly diversity
Table 3 summarizes the diversity parameters for
butterflies, as well as for trees and birds discussed in two earlier papers12,14.
Table 2 provides a glimpse of occurrence of the common and characteristic species of the
various vegetation types. The butterfly species richness levels as computed on basis the
of rarefaction, were relatively higher for the natural forests which harboured a diversity
of tree species, although we had not sampled the manmade habitats for tree diversity
estimates (Table 3). The butterfly densities were highest in the deciduous forests.
Although they appeared rather low in the evergreen and semievergreen forests, those may be
underestimates due to under representation of butterflies flying higher up in the canopy.
Natural vegetation types also had high beta diversity but moderate to low species
ubiquity. Although these natural types harboured many localized and some widespread
species, generalist species had invaded along paths and canopy openings. The forests
exhibited low to moderate levels of cohesiveness. The distinctiveness of the species
composition of the semievergreen forests communities was low, only next to scrub/savanna.
This is, probably because these forests may lack their own distinctive species and by the
very nature of their floristic characters draw the species from deciduous and evergreen
forests as well as attract generalists. The high alpha and beta diversity in the
semievergreen forests was also to be expected in view of the possibilities of shared,
widely distributed species.
The home garden butterfly assemblages had moderate
species richness but the lowest beta diversity, i.e. they comprised of a relatively
constant set of species. The gardens had considerable canopy heterogeneity and a variety
of cultivated and naturalized plants, including several important nectar sources. They
therefore attracted shade-loving forest species and open habitat dwelling butterflies
alike, but had no exclusive species of their own, and hence turned out to be less
cohesive. Highly ubiquitous species dominated the garden assemblages. Although the forest
species also entered the home gardens, these were not very common. The ubiquity of garden
species was therefore very high.
It must be noted however, that our sampling
localities present transition zones from manmade ecosystems of coastal lowlands to forest
and grasslands of the hills. The gardens and plantations that we have sampled represent
assemblages enriched by species drawn from neighboring natural ecosystems. This may not be
the case of villages or towns situated away from the forests and grasslands. Natural
ecosystems located at more remote places in the mountains may also harbour more
distinctive assemblages, in comparison with more human influenced ecosystems sampled for
Monocultures of economic tree speciesteak,
rubber, arecanut, coconut, ailanthus and mahoganyharboured assemblages of low
alpha diversity, moderate beta diversity and moderate levels of cohesiveness. These
however, included species with highest ubiquity. Although plantations were similar to home
gardens in some respects, they were much less distinctive than the latter, since their
composition was determined much more by that of the neighbouring forests, while gardens
shared species with other pools also, for instance, grasslands. This explains the higher
beta diversity of the plantations than the home gardens.
Grasslands supported moderate alpha and low beta
diversities, and lowest levels of abundance, ubiquity and cohesiveness. This suggests that
they harboured a set of species specially adapted to these sunny, hot, dry and open
vegetation types. However, due to some geographical species dissimilarity, their
distinctiveness was moderate. Scrub/savanna constituted the other secondary vegetation
type, but it differed from the grasslands in the vegetation structure and several
diversity parameters. Thus, it supported lower levels of alpha and beta diversities but
higher levels of species ubiquity and cohesiveness, besides least distinctive of all the
Lastly, paddy fields supported butterflies at
moderate densities, but lowest levels of alpha diversities and very low levels of beta
diversities. These species exhibited moderate levels of ubiquity, very high levels of
distinctiveness and very high cohesiveness value. This suggested that the paddy fields
were inhabited by a set of more ubiquitous species adapted to open conditions.
Distinctiveness of species assemblages
A distinctiveness value of less than one implied
that the species assemblages of that vegetation type differed more amongst each other when
compared to assemblages belonging to other vegetation types. Semievergreen forests and
scrub/savanna exemplify this in case of butterflies (Table 3). On the other hand, the
values of distinctiveness measures were above one for all the vegetation types in case of
trees and birds. There was nevertheless a reasonable degree of correspondence between
tree, butterfly and bird communities, so that the distinctiveness values of a majority of
bird and butterfly communities were above one for most vegetation types. The strategy of
classifying the vegetation types based on the structural parameters, and not the floristic
composition may then indeed provide a reasonable basis for organizing a sampling scheme
for a programme of monitoring biodiversity.
Patterns of covariation
Tables 4 and 5 bring out notable contrasts and
parallels in the patterns for tree, bird and butterfly diversities. Table 4 recasts the
data in Table 3 after normalizing the values on a 0 to 100 scale, for each of the groups.
This makes possible the inter-group comparisons by judging the values themselves which are
now on a single, directly comparable scale. Consider the deciduous forests, for instance.
They supported low levels of densities as well as alpha and beta tree diversities but
moderate to high values of these attributes for the birds and butterflies. Their
distinctiveness, on the other hand, is highest for the tree communities while moderate for
birds and low for the butterflies. In terms of cohesiveness, the values for the bird
communities were highest, that for the trees lowest, and moderate for butterflies. Bird
species from deciduous forest assemblages were most ubiquitous, while trees and
butterflies were least ubiquitous. Other vegetation types and assemblages also differed
from one organism group to the other.
There were then no simple correlations of patterns
of diversity from one taxonomic group to the other, across diversity parameters or
vegetation types as indicated in Table 5. Out of the 18 correlations between these 3
groups on the basis of 6 diversity parameters, 15 were insignificant and only 3 were
significant (p < 0.05). Because of limited sample size and spatial
overlap, some of the patterns might have been obscured and need further investigations.
Nevertheless, the investigations into these patterns across taxonomic groups were both
interesting and exciting, as they provided newer insights for conservation planning. The
lack of correlation or negative correlation between diversity levels or parameters across
taxonomic groups was also reported at the scale of geographic regions24,25.
Therefore, conservation prioritization based only on rare or charismatic mammal or bird
species has certain limitations. However, our study questions the soundness of the hot
spots approach based on analysis of single taxon, of prioritizing a few geographical areas
or vegetation types for conservation based on the presumption that other taxonomic groups
or diversity parameters26 are also well represented or correlated with the
These are rather preliminary results but we believe
that they indicate directions along which we must work further to organize comprehensive
programmes of monitoring biodiversity. Such a programme must follow a landscape
perspective27 and not only investigate major environmental gradients, such as
the gradient of increasing number of wet months as one progresses south on the Western
Ghats. The patterns of diversity dispersion within a mosaic of landscape elements or
vegetation types in a given locality must be explored. Further, it should encompass a
broad range of representative types of organisms, not just flagship species or groups like
large mammals15 and birds. Finally, a broad programme of biodiversity
monitoring has to be based on a network approach as with the WGBN (ref. 13). It will be
our endeavour to build upon these preliminary results and develop a sound programme of
monitoring biodiversity in the Western Ghats region identified as one of the 18
biodiversity hotspots of the world13.
Lovejoy, T. E., in Biodiversity Measurement and Estimation,
Chapman and Hall, London, 1995, pp. 8187.
UNEP-CBD, Convention on Biological Diversity (CBD), Secretariat on
CBD, United Nations Environment Programme, Montreal, 1991.
Gadgil, M., Curr. Sci., 1994, 66, 401406.
Daniels, R. J. R., Hegde, M., Joshi, N. V. and Gadgil, M., Conserv.
Biol., 1992, 5, 464475.
Gadgil, M., Curr. Sci., 1996, 71, 688697.
Goldsmith, B. (ed.), Monitoring for Conservation and Ecology,
Chapman and Hall, London, 1991.
Noss, R., Conserv. Biol., 1990, 4, 355364.
Gadgil, M., J. Indian Inst. Sci., 1996, 76, 495504.
Pollard, E., Moss, D. and Yeats, T. J., J. Appl. Ecol., 1995,
Daniels, R. J. R., Joshi, N. V. and Gadgil. M., Proc. Natl. Acad.
Sci. USA, 1992, 89, 53115315.
Harper, J. L. and Hawksworth, D. L., in Biodiversity Measurement
and Estimation (ed. Hawkshworth, D. L.), Royal Society and Chapman and Hall, London,
Utkarsh, G., Joshi, N. V. and Gadgil, M., Curr. Sci., 1998,
Gadgil, M., Curr. Sci., 1996, 70, 3644.
Pramod, P., Joshi, N. V., Utkarsh, G. and Gadgil, M., Curr. Sci.,
1997, 73, 122127.
Pearson, D. L., in Biodiversity Measurement and Estimation
(ed. Hawskworth, D. L.), The Royal Society and Chapman and Hall, London, 1995, pp.
Gaokar, H., Butterflies of the Western Ghats, India; including Sri
Lanka: Biodiversity Assessment of a Threatened Mountain System, Centre for Ecological
Sciences, IISc, Bangalore and the Natural History Museum, London, 1996.
Champion, H. G. and Seth, S. K., A Revised Survey of Forest Types
in India and Burma, Manager of Publications, New Delhi, 1968.
Pascal, J. P., Wet Evergreen Forests of the Western Ghats of India,
Institut Francais, Pondicherry, 1988.
Mueller-Dombois, D. and Elleinberg, H., Aims and Methods of
Vegetation Ecology, John Wiley and Sons, New York, 1974.
Wynter-Blyth, M. A., (Repr.). Butterflies of Indian Region,
Today and Tomorrows Printers and Publishers, New Delhi, 1982.
Evans, W. H., The Identification of Indian Butterflies, Bombay
Natural History Society, 1932, 2nd edn., p. 454.
Ludwig, J. A. and Raynolds, J. F., Statistical Ecology: A Primer
on Methods and Computing, John Wiley and Sons, New York, 1988.
Gauche, H. G. Jr., Multivariate Analysis in Community Ecology,
Cambridge University Press, Cambridge, 1982.
Prendergast, J. R., Quinn, R. M., Lawton, J. H., Eversham, B. C. and
Gibbons, D. W., Nature, 1993, 365, 335337.
Gaston, K. J., in Aspects of Genesis and Maintenance of Biological
Diversity (ed. Hochberg, M. K. et al.), Oxford University Press, 1996, pp.
Myers, N., Environmentalist, 1990, 10, 243256.
Forman, R. T. T. and Godron, M., Landscape Ecology, John Wiley
and Sons, New York, 1987.
ACKNOWLEDGEMENT. We are grateful to all
the members of the Western Ghat Biodiversity Network, for their local support. We are
indebted to Prof. Madhav Gadgil and Dr N. V. Joshi for their support and encouragement. We
thank the Ministry of Environment and Forest, Government of India and the local forest
department officials for their continued co-operation. The PEW Foundation is acknowledged
for providing flexible financial support.
Received 7 August 1997; revised accepted 14 June