Diversity and Habitat Selection of Papilionidae in a Protected Forest Reserve in Assam, Northeast India Dissertation zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultäten der Georg-August-Universität zu Göttingen vorgelegt von Kamini Kusum Barua aus Assam, Nord-Ost Indien Göttingen 2007 D7 Referent: Prof. Dr. Michael Mühlenberg Korreferent: Prof. Dr. Rainer Willmann Tag der mündlichen Prüfung: 23.01.2008 SUMMARY ZUSAMMENFASSUNG EXTENDED SUMMARY The Eastern Himalayas covering entire Northeast India is located at the confluence of the Oriental and Palaearctic realms and exhibits a high level of endemism in the flora and fauna. The region has a high diversity of butterflies as reported from the first documentation on the butterfly fauna of this region. However there has hardly been any focus on research studies for butterflies in this biodiversity rich zone. The butterfly family Papilionidae is associated with pristine forests and their abundance is directly associated with loss of forest cover due to logging and human disturbance. A review of the past records of Papilionidae from this region and comparison with recent checklists have brought into the limelight, some important questions pertaining to the probable extinction of many species and the need for further monitoring of some of the still existing species. There are also several Eastern Himalaya endemic Papilionidae at sub-species level and we need to investigate their status and distribution at both regional and local levels. The habitat association by forest type and distribution pattern, seasonal abundance, correlation between mean abundance and geographic range and the feeding guild and indicator properties of swallowtail butterflies (Lepidoptera: Papilionidae) were studied in a disturbed secondary protected forest reserve in Assam, Northeast India. The method of multivariate analysis by constrained canonical correspondence ordination (Ter Braak, 1986) was used for examining the effects of some independent, continuous environmental variables like altitude, rainfall, year, geographical position (latitude and longitude) on the swallowtail butterfly group and species assemblages during the two-year study period. The separating effects of season and forest type as categorical variables were examined for observing their effects on the abundance and distribution of the Papilionidae within the study area. We used the indicator (IndVal) method of Dufrene & Legendre (1997) to detect some characteristic indicator taxa within the study area by defining the indicator values of the group and species assemblages for the transects by forest types and mean seasonal abundances. The analyses were done separately for the three study sites of Garbhanga range and two study sites of Rani range based on the pooled abundance data. All the five study sites were moderately to heavily disturbed as observed from the land-use satellite imageries and actual field observations. Line transect method (Pollard, 1977, 1984; Thomas, 1983; i Pollard & Yates, 1993) was followed for sampling the butterflies within a 50 ha study area. Permanent line transects were laid within the study sites on the basis of habitat type - scattered forest and closed forest, which were selected on the basis of canopy openness and observed levels of disturbance. A total sample effort of 131 days across the five study sites during dry and wet seasons of the two-year study period resulted in 18,371 individuals identified from 28 species of Papilionidae. Our sampling effort was not equal across the study sites of both the ranges within the Reserve. For the three study sites in Garbhanga range, we walked 24 kms amounting to two transect counts in nine hours of sampling per day in the 12 transects. For the two study sites of Rani range we walked 16 kms amounting to two transect counts in six hours of sampling per day in the eight transects. As the study area experiences a tropical monsoon type of climate, therefore the different diversity parameters including species richness, evenness and rarefaction estimates were examined by forest type and season. As the host-plant specificity of the swallowtail butterflies is confined to a few tropical plant families, we therefore tried to document the availability of some of the important larval food-plants of the swallowtail butterflies within the study area. We identified 28 species of Papilionidae within the protected reserve during the 2- year study period. In the study sites of Garbhanga and Rani ranges, 28 and 26 species were recorded respectively. Vegetation study relating to estimation of the species diversity and richness conducted in each of the two study sites of Garbhanga and Rani ranges showed a near similarity in the floral composition and could be considered to represent the overall vegetation profile of the study area. The total plant family representation in the study area was 65 which included a total of 197 species out of which 99 species were represented by trees, 63 species were herbs/shrubs and 35 species were represented by climbers. Seven plant families represented the larval host-plant resources and 29 plant families represented the potential adult nectar sources of the swallowtail butterflies. The monophagous feeding guild recorded the highest number of species (12) and the correlation between the mean abundance and feeding guild of the Papilionidae was significant, showing a marked increase in the mean abundance of the Papilionidae from ‘specialist’ to generalist’ feeders and monophagy to polyphagy. The correlation between the mean abundance and the pre-defined geographic range of the species assemblages in the three study sites of Garbhanga range was weak but significant and positive indicating a marked increase in the mean abundance of the ii Papilionidae with the widest geographic range. For the two study sites of Rani range, the correlation was not significant but still positive. Species with the widest range did not show a large variation in their mean abundance as observed in the correlation results for the study sites of Garbhanga range. Canonical Correspondence Analysis (CCA) showed that the swallowtail butterfly species assemblage could be divided into two groups with respect to habitat association and abundance by forest types was highly significant for all the five study sites. In Garbhanga range, 16 species were closed forest restricted and nine species were open/scattered forest dependent while another three species could be classified as intermediate as they were encountered in both gaps and closed forests. In Rani range, only 14 species were found to be confined to the closed forest while the number of species associated with gaps and the intermediate species was the same as in Garbhanga range. In Garbhanga range, higher abundances of butterflies from the genera Graphium (Jays and Bluebottles), Papilio (Common Mormon and Great Mormon) and Pathysa (Swordtails and Zebras) were encountered in the open forest transects while the abundances of the butterflies from the closed forests and particularly from the genera Atrophaneura (Windmills and Batwings), Troides (Birdwings) and Papilio castor (Common Raven) were lower. Peacocks and Helens (Papilio sp.) from the closed forests and the gap species like Pachliopta aristolochiae (Common Rose) and Lamproptera sp. (Dragontails) recorded moderate abundances. However in Rani range, the abundance trend for the group (genus-wise) assemblages were found to be different – closed forest confined groups like the Birdwings (Troides sp.), Peacocks and Helens (Papilio sp.) and open forest dependant groups like the Jays and Bluebottles (Graphium sp.), Swordtails (Pathysa sp.) as well as the Dragontails (Lamproptera sp.) were recorded in higher abundances. The site scores in the ordination plots for both Garbhanga and Rani ranges simply showed the changing abundances of swallowtail butterflies across the open and closed forest transects throughout the study period. However they could not be considered as strong predictors of butterfly seasonality. Therefore in our study we only tried to observe the changing patterns of species abundances through dry and wet seasons of the study period between the two forest types. The effects of independent variables were studied separately for Garbhanga and Rani ranges and the results of the CCA ordination showed the significant effects of some of these variables on the species assemblages. The significant effect of the amount of rainfall as an iii independent variable on the abundances of different species assemblages within Garbhanga and Rani ranges clearly indicated the influence of the monsoon climate on plant phenology and the resultant high wet season abundances. However the effect of rain on butterfly abundances indicated a larger variation between the dry and wet season abundances in Rani range and this could be attributed to favourable microclimatic conditions within this range. In the constrained ordinations for both Rani and Garbhanga ranges, the influence of the monsoon rain on the seasonality of some species like particularly the Limes (Papilio demoleus), Jays (Graphium sp.) and Common Rose (Pachliopta aristolochiae) was strongly predicted. Again some of the closed forest restricted species like the Crimson Rose (Pachliopta hector) and Common Raven (Papilio castor) were found to be highly seasonal in their association with the monsoon period. To examine the continuum of seasonal abundance of the swallowtail butterflies, the effect of year as