MORTALITY OF BUTTERFLY FAUNA DUE TO VEHICULAR TRAFFIC AND THEIR CONSERVATION IN RIPU-CHIRANG RESERVE FORESTS OF WESTERN ASSAM, INDIA

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MORTALITY OF BUTTERFLY FAUNA DUE TO VEHICULAR TRAFFIC AND THEIR
CONSERVATION IN RIPU-CHIRANG RESERVE FORESTS OF WESTERN ASSAM, INDIA
(This paper was presentation in the 2nd Asian Lepidoptera Conservation Symposium 2008 at Penang, Malaysia).
Kushal Choudhury1and Sonali Ghosh2
1 Lecturer, Science College, Kokrajhar. Assam. India PIN 783370
e-mail: kushal.c8@gmail.com
2Divisional Forest Officer, Social Forestry Division. Kokrajhar. Assam. India
Abstract:
Road and traffic are the central features of human development, but a severe threat to forest and
wildlife. In this study road-kill of butterflies were enumerated along a 25 km stretch of road in Ripu-
Chirang Reserve Forest of western Assam. Butterflies were killed significantly more in monsoon
during the time of road crossing and mud-puddling. A total of 7431 butterfly deaths of 81 species were
recorded over one year (2007-2008). Mortality is more in case of Nymphalidae, Pieridae and
Papilionidae than Lycaenidae and Hesperiidae. This indicates the abundance of Nymphalids, Pierids
and Papilionids in the study site. To reduce mortality and also to attract tourists some artificial mud-
puddling sites were developed at a distance of mean 15m away from the main road and provided with
natural diet (cattle urine, fecal matter of certain carnivores, fruits, carcasses etc.) to lure butterflies. This
study highlights the impact of vehicular traffic on butterflies and the need for their conservation.
Key words: Butterflies, road-kills, Ripu-Chirang Reserve Forest, Mud-puddling sites
Introduction:
Roads are regarded as an integral part of human development. Roads have been recognized as a
source of various kinds of ecological consequences i.e. increased mortality of animals and plants due to
road kill, habitat loss from road construction, alteration of the physical and chemical environment and
changes in roadside wilderness (Orlowski et al. 2004; Rao at el. 2007). Road-kills can have a
significant impact on populations of threatened or endangered species (Kushlan, 1988; Foster and
Humphrey, 1995; Evink et al. 1996). For many such species, road mortality can serve as a limiting
factor, as their foraging and dispersal behaviors put them at risk of being struck on road ways (Gibbs
and Shriver, 2002: Aresco, 2005). Therefore, roads are considered as one of the growing threat to

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animal and plant populations (Forman and Alexander, 1998). Most of the road mortality studies have
centered on amphibian (Hels and Buchwald, 2001), reptiles (Haxton, 2000; Rosen and Lowe, 1994;
Sharma et al. 2007 and Gopi Sundar, 2004), birds (Gopi Sundar, 2004) and mammals (Gopi Sundar,
2004), but impact of road on invertebrates especially insects cannot be ignored as they play an
important role in pollination. Among the invertebrates, Order Lepidoptera is regarded as an indicator of
a healthy environment (Sparrow et al.1994 and Haribal, 1992) as well as a good pollinator which is
also highly influenced by the road ecology (Yves, 1998).
In India few studies were carried out on the issue of butterfly mortality on roads (Rao et al.,
2007), but considering northeastern India, which is a diversity hotspot for butterfly (Evan 1932, Winter
Blyth 1957), no study on such ecological loss is hitherto known.
Study objectives:
The aim of this study in the Ripu-Chirang Reserve Forest were: (1) To quantify the amount of
road-kill and its impact on the loss of butterfly diversity in Ripu-Chirang Reserve Forest. (2) To design
alternatives such as artificial mud-puddling sites away from points of heavy vehicular traffic and also
to provide economic incentive to local villagers.
Study area:
The study was carried out during the year 2006-2007 from April to September on a 25km stretch of
sand-gravel forest road of Ripu-Chirang Reserve Forest (89º55´- 90º30´E and 27º15´-26º35´N). Ripu-
Chirang Reserve Forest falls under Kochugaon and Haltugaon Forest Divisions of Kokrajhar district in
western Assam of India. It is a transitional zone between Manas Tiger Reserve and Buxa Tiger
Reserve. It also has strong linkages with the Bhutan Biological Conservation Complex because it is
located just at the foothills of Phipsu Wildlife Sanctuary in Bhutan. Ripu-Chirang Reserve forest is also
part of Manas Tiger Reserve and Ripu-Chirang Elephant Reserve. It is also considered as an IBA
(Important Bird Area) and is one of the last refuges for the highly endemic and endangered Golden
Langur (Trachepithecus geei). The elevation in the area varies from 60-150 msl. The average rain fall
is 3330 mm. The total area of both these Reserve Forests is 1197.81 sq km that is at present
administered under 8 forest ranges. The Reserve Forest is bounded by international boundary in the
North, Bhur river in the east, Saralbhanga river in the west and National Highway no. 31 in the south.
The forest type available in this Reserve Forest ranges from semi-deciduous with Sal (Shorea robusta)
as the dominant tree species to broad leaved wet evergreen forest and riparian forest. The Reserve

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Forest is provided with a good number of water sources. The Saralbhanga and Bhur river are the major
sources of water along with their tributaries, viz Laopani, Dholpani, Ultapani and Samukha.
Majbhander is the only perennial lake located inside the Saralpara Forest Block, and during the dry
season it is one of the only places where the butterflies are always visible at mud-puddling.
Figure-1 Location of Ripu Chirang Reserve Forest in India
Methodology:
We followed ‘slow driving method’ to find out the road-kill butterflies. In this method the entire
road was considered as transect and was covered by slow riding on bike. The vehicle was driven at 10-
20km speed depending on visibility and when road-kill butterflies were seen, they were collected from
the road for identification and removed from the road to avoid multiple counts. At the same time the
road side habitat and the location of the road-kills were recorded. The road was covered twice every
week between 1500-1800 hr. The species were identified in the field with the help of field guide of
Evans (1932), Haribal (1992) and Kunte (2000) up to the species level whenever possible otherwise

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upto the Genus level for partially damaged species. Traffic load was also enumerated from 0800 to
1600hr.
To reduce the mortality of road-kill butterflies, 14 artificial mud-puddling sites were
constructed at a distance of 1.5 km interval from each other and also on either side of the road. Mud-
puddling sites were constructed at the open areas to access sufficient sun light. The ideal dimension of
mud-puddling sites were 10 X 20 feet and were demarcated by betel nut branches or logs with a height
of 6” from the ground (Fig-2). The mud-puddling sites were first provided with rocks then it was filled
with sand and gravels and
Figure-2 An ideal soil texture of the artificial mud-puddling site for butterflies
then a thin layer of soil was spread over the sand and gravels. The composition was similar to the soil
texture of the road (Fig-1) with high moisture (water) holding capacity. To lure butterflies a regular
scattering of urine of cattle, fecal matter of certain animals including dead meat of occasionally found
road kills, fruits and carcasses etc. were provided.
Result:
During the study period a total of 7431 individuals of 81 species of butterflies belonging to 6
families were recorded. The total smaplng days was 96 (two days in a week) that was undertaken from
April 2007 to March 2008. Among the 6 families Nymphalidae with highest mortality (36.72%
(n=38)), Pieridae (35.84% (n=12)), Papilionidae (16.33% (n=13)), Lycaenidae (10.79% (n=10)) and
Heperidae (.24% (n=8)) were recorded (Table-1). There was no representative recorded from the
family Radionidae; certain daymoths (Theretra sp.,Arctiidae sp. Erebus sp., Cyclosia sp. and
Dysphanis sp.) were also recorded as road-kills. Among the 5 families Princeps nephelus, Gandaka
harina, Charaxes marmax, Caleta elna and Cupitha purreea were more frequently encountered than

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the other individuals. The least encountered species were Princeps protenor (Papilinidae), Leptosia
nina (Peiridae), Phalanta phalantha (Nymphalidae), Surendratodara distorta (Lycaenidae) and
Iambrix salsala, Udaspes folus (Hesperidae) families. The mean traffic load was calculated as 21
vehicles/day and the average road-kills density came out to be 20.35 /day. The road-kill mortality rate
peaked at 38.4 / day in 51.33 July witth the lowest in January 0.22/day. .
Figure 3. Location of the road-kill survey route (route highlighted in red) in Chirang RF
Vehicular traffic causes negative impact on butterfly density and results in high rate of
mortality. There is a very high incidence of mud-puddling by butterflies along roads in Ripu-Chirang
RF that can be attributed to the following possible reasons: (1) Roads are crucial openings in a forest
environment that provide a place for basking and therefore a place for thermoregulation. (2) In case of
the Ripu-Chirang forest road it is gradually inclined towards

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Figure 4. Family wise mortality of butterflies due to road kill in Ripu-Chirang RF
Bhutan foothills and therefore is an important habitat for all winter migrants coming to Assam plains.
(3) The road is also an excellent source of minerals perhaps due to the soil condition and also because a
lot of wild and domesticated animals use the road for dropping their feacal matter.It is also a good
source for the carrion feeding butterflies such as Charaxes polyxena, Charaxes marmax, Polyura
athamas, Princeps nephelus, ,Chliaria othona, Caleta elna etc. (4) During rainy season the entire forest
and banks of the river are coverd by vegetation and that particular road is the only place of mud-
puddling. (5) The studies reveal that certain generalised species of road-kill butterflies were observed
throughout the year. But certain species flourish during their peak-season i.e. summer. Therefore,
weather and season influence road-kill numbers. (6) Monthly mean temperature and rainfall have a
great influence on the amount of road mortality. Road-kills were high in the summer season than in the
winter and attained its peak in the month of July. Whereas the intensity of the road-kill mortality was
recorded the least (n=7) in the month of January. (7) The study also reveals that the highest
representative of road-kills were recorded from Nymphalidae followed by Peiridae and Papilionidae.
Though Lycanidae and Hesperidae were abundant in the study site their casualty is comparatively less
due to their swift movement. (8) Among the road-kills there were certain species which are also listed

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under Schedule I part IV (species of special conservation concern in India) of the Wildlife Protection
Act, 1972 (Princeps clytia, Chliaria othona, Castalius rosimon) and road-kills may have a significant
role in their extinction. (9) Most of the butterfly road-kills occurred after rain on sunny days or when
wild animals like elephant, wild cat, fox, etc. used to lay feacal matters or urine on the road, which
made them vulnerable to traffic. Though it is advocated that vehicle speed of 30-40km/hr is safe for
flying insects and speeds between 50-60km/hr serves strock/trauma to the insects (Rao et al. 2007).
Figure 5. Incidence of roadkilled of butterflies due to vehicular traffic during the year 2007-2008
Figure 6. Number of butterfly road kills encountered in a year 2007-2008

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Figure 7. Rainfall, relative humidity and mean temperature in a year 2007-2008
But here the scenerio was found quite different because most of the butterflie died during the time of
mud-puddling activity. During mud-puddling they never scattered even though they were touched (per.
obvs). In such cases vehical speed may not be a vital factor for there mortality.
Discussion and Alternatives suggested
Road-kills can pose serious threats to a variety of species. Vehicle traffic on roads can be the
direct source of wildlife mortality and, some instances, can be catastrophic (Langton 1989). For many
species, road mortality can serve as a limiting factor for their population because their foraging and
dispersal behaviour put them at risk of being struck on roadways (Gibbs and Shriver 2002). Road
mortality may not affect abundant population but it can have a significant impact on populations of
threatened and endengered species (e.g., Kushlan 1988; Foster and Humphrey 1995; Evink et al. 1996)
To minimize the road-kill of butterflies certain artificial mud-puddling sites were developed to
distract the population from the road. The mud-puddling sites were maintained by providing cattle
urine, occassional road killed carcasses, fruits and fecal matters. It was recorded that a good number of
butterflies belonging to the family Nymphalidae, Peiridae and Papilionida were attracted towards the

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artificial mud-puddling sites. During the study period volunteers of Aaranayak and Discovery club
(NGO) made the locals and the vehicle drivers aware about the road-kill of butterflies.
Conclusion:
Road kill due to vehicular traffic and the choice of road as mud puddling site by butterflies is
inevitable in Ripu-Chirang RF. The road is a boon as it provides an excellent site for butterfly watching
and therefore has immense potential to become an eco-tourism spot but at the same time it is a bane as
it like a ‘suicide point’ for several butterflies. Since the prime factor for butterfly swarming is mud-
puddling, alternatives such as artificial mud-puddling sites can be designed to prevent any serious
mortality. Further, a long term reaserach and conservation needs to be initiated to study this butterfly
‘hotspot’.
Acknowledgement:
This project was funded by the Forest and Tourism Department of Bodoland Territorial Council
(BTC), Assam, India. We are grateful to Mr. Kampa Borgoyari, Deputy Chief, for his kind cooperation
throughout this study. Special thanks to Mr. G.C. Basumatary, CHD, Department of Forest and
Tourism, Mr. Rajen Choudhury, DFO, Dr. Hilloljyoti Singha, Mrs. Tribeni Mandal, Mr. Tarapada.
Mandal, Mrs. Manashi Choudhury and Jaydev Mandal for their constant encouragement in this study

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TABLE 1. List of Road-kill butterfly species with scientific name recorded from April 2007 to March
2008. Overall total= 7431 (* indicates species of special conservation concern in India)
Sl
No. Scientific Name APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FAB MAR TOTAL
Papilionidae
1Pachliopta aristolochiae 7 15 29 17 0 3 0 0 0 0 0 5 76
2Graphium agammemnon 10 4 3 0 0 4 2 0 0 0 2 9 34
3Graphium doson 6 17 3 9 2 0 0 0 0 0 5 3 45
4Pathysa antiphates 7 12 9 7 0 0 0 0 0 0 0 2 37
5Princeps clytia * 3 12 7 4 0 3 0 0 0 0 0 3 32
6Princeps polytes 33 39 32 22 5 2 1 1 0 0 2 1 138
7Graphium sarpedon 27 1 15 17 1 3 2 0 0 0 6 7 79
8Princeps memnon 18 22 27 18 0 1 0 0 0 0 0 12 98
9Princeps protenor 0 1 1 0 0 0 0 0 0 0 0 0 2
10 Princeps helenus 6 14 22 24 0 1 0 0 0 0 0 1 68
11 Princeps castor 34 58 61 41 3 6 2 0 0 0 8 15 228
12 Princeps nephelus 38 43 72 42 17 8 7 3 0 0 12 19 261
13 Princeps paris 22 29 32 21 2 1 2 0 0 0 0 7 116
Pieridae
14 Leptosia nina 5 0 3 0 0 0 0 0 0 0 0 7 15
15 Appias lyncida 52 44 70 33 12 9 8 3 4 2 4 19 260
16 Appias indra 13 79 61 41 32 8 0 0 0 0 7 17 258
17 Cepora nadina 24 92 51 39 21 12 2 0 0 0 0 33 274
18 Cepora nerissa 11 21 32 29 18 19 12 0 0 0 7 19 168
19 Hebomoia glaucippe 11 19 22 17 7 0 3 1 2 0 0 10 92
20 Ixias pyrene 42 88 38 52 32 0 5 6 5 0 0 5 273
21 Catopsilia pyranthe 3 19 37 25 21 11 21 2 0 0 0 20 159
22 Delious aglaia 9 0 1 5 0 12 7 2 0 0 0 1 37

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23 Catopsilis Pomona 31 47 105 57 32 41 18 3 0 0 4 47 385
24 Eurema spp. 12 92 71 35 14 8 9 8 7 0 5 8 269
25 Gandaka harina 49 67 120 78 69 42 14 3 9 0 9 18 478
Nymphalidae
26 Charaxes polyxena 3 5 14 18 4 0 2 4 2 0 0 0 52
27 Charaxes marmax 28 37 32 35 21 12 26 48 22 0 0 8 269
28 Polyura athamas 36 13 11 5 18 0 4 4 6 0 0 3 100
29 Polyura arja 6 3 2 3 0 0 0 2 0 0 0 1 17
30 Cirrochroa aoris 12 3 12 21 27 18 5 7 0 0 0 1 106
31 Cirrochroa tyche 0 7 0 1 0 0 0 0 0 0 0 0 8
32 Moduza procris 0 3 5 3 0 1 8 0 0 0 0 0 20
33 Tirumala limniace 31 42 21 37 14 9 14 2 0 0 0 28 198
34 Tirumala septentrinis 19 15 32 12 8 14 2 3 2 0 0 8 115
35 Euploea sylvester 5 5 3 0 2 2 0 0 1 0 0 2 20
36 Ariadne ariadne 0 0 0 0 0 0 1 0 2 0 0 1 4
37 Precis hierta 3 12 5 17 0 0 0 0 0 2 1 4 44
38 Precis almanac 18 11 1 13 0 0 0 0 0 0 2 0 45
39 Neptis spp. 19 34 28 33 44 36 8 3 7 0 3 5 220
40 Danaus chrysippus 28 34 29 32 4 0 0 0 0 0 0 22 149
41 Danaus genutia 14 27 22 4 0 0 0 0 0 0 0 0 67
42 Phalanta phalantha 0 1 0 0 0 0 0 0 0 0 0 0 1
43 Euploea radmanthus 33 29 31 29 13 3 0 0 0 0 0 3 141
44 Tanaecia julil 0 2 0 1 0 0 0 0 0 0 0 1 4
45 Acraea violae 0 32 23 0 0 0 0 0 0 0 0 0 55
46 Penthema nefte 23 12 8 22 18 3 27 4 3 0 0 7 127
47 Orsotrioena medus 5 7 0 8 2 8 0 0 0 0 0 7 37
48 Euripus helitheres 0 0 0 0 1 0 0 0 0 0 0 2 3
49 Vanessa indica 0 1 0 1 0 0 1 1 0 0 0 0 4

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50 Hypolimnas bolina 13 27 12 13 8 14 0 0 0 0 0 3 90
51 Cyrestis thyodamas 3 0 5 0 5 8 5 3 5 0 0 0 34
52 Euploea midamus 13 21 12 14 3 2 2 0 0 0 0 5 72
53 Euploea algea 7 3 4 2 0 0 0 0 0 0 0 2 18
54 Euploea mulciber 4 11 23 13 2 0 2 0 0 0 0 0 55
55 Euploea core 6 21 20 15 6 4 0 0 0 2 3 7 84
56 Vindula erota 37 28 3 20 2 4 8 2 0 0 0 4 108
57 Pantoporia horodinia 21 33 23 27 33 39 29 9 0 0 0 15 229
58 Symbrenthia lilaea 18 14 25 12 22 2 6 0 0 0 0 22 121
59 Precis iphita 4 7 3 7 2 5 3 0 0 0 3 12 46
60 Cethosia bibles 6 7 9 3 4 3 2 0 0 0 0 5 39
61 Cethosia cyane 0 0 0 3 0 2 0 0 0 0 0 1 6
62 Elymnias hypermnestra 2 5 2 1 0 1 2 0 0 0 0 3 16
63 Ariadne merione 0 0 1 0 1 0 0 0 0 1 0 2 5
Lycaenidae
64 Curetus dentate 2 0 1 0 0 1 0 0 0 0 0 0 4
65 Surendratodara distorta 0 0 1 0 0 0 0 0 0 0 0 0 1
66 Heliophorus epicles 0 5 2 0 0 0 0 0 0 0 0 3 10
67 Caleta elna 29 22 140 82 49 11 14 12 17 0 2 17 395
68 Castalius rosimon * 0 2 1 0 0 0 0 0 0 0 0 2 5
69 Nacaduba hermus 0 12 22 32 39 42 32 43 12 0 0 4 238
70 Hypolycaena erylus 21 18 19 16 12 17 19 9 2 0 0 3 136
71 Chliaria othona* 0 1 1 0 1 0 0 0 0 0 0 1 4
72 Zeltus amasa 3 0 2 0 1 0 0 0 0 0 0 0 6
73 Spindasis vulcans 0 0 1 0 0 1 0 1 0 0 0 0 3

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Hesperidae
74 Cupitha purreea 1 0 2 0 0 1 0 1 0 0 0 0 5
75 Odontoptilum angulata 1 0 0 0 0 0 0 0 0 0 0 1 2
76 Oriens gola 0 0 0 1 1 0 0 0 0 0 0 0 2
77 Ochus atkinsoni 0 0 0 1 1 0 0 1 0 0 0 0 3
78 Coladenia dan 0 0 1 0 0 0 1 0 0 0 0 0 2
79 Iambrix salsala 0 0 0 0 0 0 0 1 0 0 0 0 1
80 Udaspes folus 0 0 0 1 0 0 0 0 0 0 0 0 1
81 Bibasis sp. 0 0 2 0 0 0 0 0 0 0 0 0 2
Total spp. 947 1407 1540 1191 656 457 338 192 108 7 85 503 7431
REFERENCE:
Aresco, M.J. (2005). Mitigating measures to reduce highway mortality of turtles and other
herpetofauna at a north Florida lake. Journal of Wildlife Management 69:549-560.
Evink, G.L., Garrett, P., Zeigler, D., and Berry, J. (Eds.)(1996). Trends in addressing transportation
related wildlife mortality. FL-ER- 58-96. Florida Dept. of Transportation, Tallahassee, Florida, USA.
Evans, W.H. (1932). The Identification of Indian Butterflies. BNHS, Bombay. 454pp.
Forman, R.T.T and L.E. Alexander (1998). Roads and their major ecological effects. Annual Review
of Ecology and Systematics 29:207-231.
Foster, M.L. and S. R. Humphrey (1995). Use of highway underpasses by Florida Panthers and other
Wildlife Society Bulletin 23: 95-100.
Gibbs, J.P., and W.G. Shriver (2002). Estimating the effect the road mortality on turtle populations.
Conservation Biology 16: 1647-1652.
Gezegorz Orlowski & Lech Nowak (2004). Road mortality of hedgehogs Erinaceus spp. In farmland
in Lower Silesia (South-western Poland). Polish Journal of Ecology 523:377-382.
Hels T. and E. Buchwald (2001). The effect of road kills on amphibian populations. Biological
Conservation 99: 331-340.

14
Haribal, M. (1992). The butterflies of Sikkim Himalayas and their natural history, Sikkim Natural
Foundation, Gangtok. 217pp.
Haxton, T. (2000). Road mortality of snapping turtles, Chelydra serpentine, in central Ontaria during
their nesting period. Canadian Field Naturalist 114:106-110.
Kushlan, J.A. (1988). Conservation and management of the American Crocodile. Environmental
Management 12: 777-790.
Kunte, K. (2000). India - A Landscape: Butterflies of Peninsular India, University Press. 254pp.
Langton, T.E.S. (1989). Amphibians and Roads. ACO Polymer Products, Ltd. Bedfordshire, England.
Rosen P.C. and C.H. Lowe (1994). Highway mortality of snakes in the Sonoran desert of southern
Arizona. Biological Conservation 68:143-148.
Rao, R. Shyama Prasad and M. K. Saptha Girish (2007). Road kills: Assessing insect casualties
using flagship taxon. Current Science.
Sundar, K.S. Gopi (2004). Mortality of herpetofauna, birds and mammals due to vehicular traffic in
Etawah District, Utterpradesh, India. JBNHS 101(3):392-398.
Sparrow, H.P., T.D. Sisk, P.R. Ehrlich and D.D. Muray (1994). Techniques and guidelines for
monitoring Neotropical Butterflies. Conservation Biology, 8:800-809.
Sharma, P., M.F. Ahmed, B. Lahkar and A.Das (2007). A preliminary report of reptilian mortality
on road due to vehicular movements near kaziranga national park, Assam, India. Zoos’ Print Journal
22(7): 2742-2744.
Yves Basset, Vojtech Novotny, Scott E. Miller and Neil D. Springate, 1998). Assessing the impact
of forest disturbance on tropical invertebrates: some comments. Journal of Applied Ecology 35:461-
466.
Winter Blyth, M. A. (1957). Butterflies of Indian region. BNHS, Bombay.523pp.

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Figure-8. First two rows depict mud-puddling on the road. Second two rows indicats the road-
kill of butterflies and thired two rows indicates the Conservation Activity

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