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Group Size and Population Structure of Megaherbivores (Gaur Bos gaurus andAsian Elephant Elephas maximus) in a Deciduous Habitat of Western Ghats,IndiaAuthor(s): Tharmalingam Ramesh, Kalyanasundaram Sankar, Qamar Qureshi and Riddhika KalleSource: Mammal Study, 37(1):47-54. 2012.Published By: Mammal Society of JapanDOI: http://dx.doi.org/10.3106/041.037.0106URL: http://www.bioone.org/doi/full/10.3106/041.037.0106

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Mammal Study 37: 47–54 (2012)

© The Mammal Society of Japan Short communication

Group size and population structure of megaherbivores (gaur Bos

gaurus and Asian elephant Elephas maximus) in a deciduous habitat of

Western Ghats, India

Tharmalingam Ramesh*, Kalyanasundaram Sankar, Qamar Qureshi and Riddhika Kalle

Wildlife Institute of India, P.O. Box # 18, Chandrabani, Dehra Dun-248 001, Uttarakhand, India

Grouping is an important phenomenon influencing major

aspects of social animal lives, such as predation pres-

sure, pathogen pressure, aggression, foraging success,

metabolism and sexual selection in animal commu-

nity (Reiczigel et al. 2008). Moreover, group size is

likely to be an insightful reflection of the immediate

effect of important ecological parameters such as habitat

structure, spatio-temporal distribution of food and

predation pressure on group formation (Barrette 1991;

Sankar 1994; Raman 1997). Group size varies widely

within and between species (Altmann 1974; Geist 1974;

Jarman 1974; Clutton-Brock and Harvey 1977; Rodman

1981). Group size is experienced by an average indi-

vidual (Jarman 1974). Though average individuals come

from groups larger than the average group size, another

measure called “crowding” was used (Lloyd 1967;

Stokols 1972; Marsden 1972; Reiczigel et al. 2008) in

which an individual lives or is referred to group size

experienced by any individuals.

Age structure of a population is useful for understand-

ing dynamics of population growth and estimating life

history parameters (Spillet 1966; Stearns 1992). Age

structure of a population expressed as the distribution of

the number of individuals in each age group reflects

fecundity, mortality, reproductive status and population

increase. It is an important measure of demographical

change over time (Caughly 1977). Sex ratio is an indica-

tor of the reproductive potentiality of a species. A high

percentage of young as compared to adults generally

indicates a fast growing or thriving population in contrast

to a relatively smaller percentage of young that usually

indicates a sluggish rate of population increase. A popu-

lation with more females than males generally has a

higher reproductive potential than the one that is pre-

dominantly composed of male (Spillet 1966). De and

Spillet (1966) suggested that more or less 1:1 sex ratio

may usually be found in an area free from selective

shooting or predation. Poaching of adult male Asian ele-

phant (Elephas maximus) has significantly altered their

sex ratio in the Western Ghats (Arivazhagan 2005;

Sukumar 2006). Birth of calves is timed to minimize

environmental or energetic stress on mother or offspring

(Leuthold and Leuthold 1975).

The gaur (Bos gaurus) and Asian elephant popula-

tions co-occur in India with the exception of the Central

Indian highlands from where the Asian elephants have

become extinct (Krishnan 1972). Gaur belongs to the

group of wild oxen and Asia is home to them. It is the

largest member of the family Bovidae. The Wyanad-

Nagarhole-Bandipur-Mudumalai complex in Western

Ghats constitutes one of the most extensive strong-

holds of viable gaur and elephant populations in India

(Santiapillai and Jackson 1990; Ranjitsinh 1997; Sankar

et al. 2001; Sukumar 2006). Rapid loss and fragmenta-

tion of forests, diseases, illegal hunting, ivory poaching

of elephant, conflicts with people and escalating an-

thropogenic pressure seem to be the primary cause of

decline of the gaur and Asian elephant population in

India (Sankar et al. 2001; Sukumar 2006). Gaur and

Asian elephant are categorized as vulnerable and endan-

gered respectively by IUCN Red Data list (Duckworth

et al. 2008; Choudhury et al. 2008) and listed in Sched-

ule I of the Indian Wildlife Protection Act (1972). In the

Indian sub-continent, studies give detailed information

on group size and population structure of gaur (Schaller

1967; Sahai 1977; Chandiramani 1983; Moorthy 1989;

Karanth and Sunquist 1992; Bhattacharya et al. 1997;

Prayurasiddhi 1997; Vairavel 1998, Sankar et al. 2001;

Kumar et al. 2004) and Asian elephant (Mckay 1973;

Oliver 1978; Shahi 1980; Ishwaran 1981; Sukumar 1985;

Karanth and Sunquist 1992; Easa and Balakrishnan 1995;

Kurt et al. 1995; Katugaha et al. 1999; Arivazhagan 2005;

Williams et al. 2007). Megaherbivores need more food

and space than smaller herbivores. Habitat loss and frag-

*To whom correspondence should be addressed. E-mail: ramesh81ngl@gmail.com

Mammal Study 37 (2012)48

mentation, poaching and other anthropogenic disturb-

ances commonly restrict these megaherbivores into

small protected areas (Sukumar 1989; Sankar et al.

2001). For conserving these species it is important to

know their grouping pattern and population structure

which would be useful in understanding their life history

parameters.

Materials and methods

Study area

Mudumalai Tiger Reserve (11°32'-11°43'N; 76°22'-

76°45'E) is situated at the tri-junction of Tamil Nadu,

Karnataka and Kerala states, at an elevation that varies

from 960 to 1,266 m. This 321 km2

tiger reserve

includes 100 km2

of national park bounded with

Wayanad Wildlife Sanctuary on the west, Bandipur

Tiger Reserve in the north and Nilgiri North Forest Divi-

sion in the south (Ramesh 2010). The present study was

carried out in the deciduous habitat of Mudumalai Tiger

Reserve covering 107 km2

(Fig. 1). The tiger reserve has

a long wet season and a short dry season. It receives

rainfall from south-west and north-east monsoons

(Ramesh 2010). The south-west monsoon starts by May

and ends by August while the north-east monsoon starts

by September and ends by December. Based on the

climate of the area, there are three distinct seasons recog-

nized; dry season (January to April), first wet season

(May to August) and second wet season (September to

December) (Varman and Sukumar 1993). The rainfall

has a marked east-west gradient, with the eastern areas

getting the least amount of the heaviest rains (1,000

to 2,000 mm). The temperature ranges from 8°C in

December to 35°C in April. In addition to gaur and

Asian elephant, ungulate species found in Mudumalai

are chital (Axis axis), sambar (Rusa unicolor), muntjac

(Muntiacus muntjak), wild pig (Sus scrofa), Indian

chevrotain (Tragulus meminna), four-horned antelope

(Tertracerus quadricornis) and black-buck (Antelope

cervicapra).

Fig. 1. Location of intensive study area and vehicle transects in Mudumalai Tiger Reserve, Western Ghats.

Ramesh et al., Social structure of megaherbivores 49

Data collection and analysis

Since Mudumalai experiences different seasons, data

was collected and analysed season wise. Vehicle tran-

sect method was chosen as it allows more sample area

coverage within a short duration. Major proportion of

the tiger reserve (>200 km2

) is dominated by deciduous

forest (dry and moist). Vehicle transect was systemati-

cally distributed within the deciduous patch of 107 km2

to cover the entire study area. Data on group size, sex

ratio and age structure of gaur and Asian elephant were

collected between February 2008 and December 2009

(dry season-January to April; first wet season-May to

August and second wet season-October to December).

Data for the present study were collected by the first

author who has been working in this study site for

several years. Sampling duration was longer during the

second wet season compared to the first wet and dry

season due to logistic constraints. Five vehicle transect

routes ranging from 15 to 23 km were monitored to

record gaur and Asian elephant sightings. Each transect

was monitored twice a month during the early morning

and late afternoon which resulted in a total effort of

3,740 km. The total length of transects amounted to

93.5 km. On each sighting of gaur and Asian elephant,

the following information was recorded; group size, sex

and age classes. Average mean group size was estimated

by taking the average of different group sightings and

group size was classified into different class intervals

for better interpretation between seasons. Age classifica-

tion of gaur was carried out based on Schaller (1967)

and Sankar et al. (2001), while Asian elephant was

classified based on Sukumar (1985). Male gaurs were

classified into; adult males (possess a shiny black coat

with heavy horns protruding sideways and upwards and

a large dewlap hanging below the chin, and gonad),

sub-adult males (dark brown coat with a conspicuous

dorsal ridge and a smaller dewlap, large drapes between

the fore legs, gonad) and yearling males (10–20 months

old, 25–50% in size of sub-adult male with gonad)

(Schaller 1967; Sankar et al. 2001). Female gaurs were

classified into; adult females (smaller than adult males,

pelage is dark brown with more upright horns corru-

gated inwards than in adult males), sub-adult females

(50–75% in size of adult female lacking a conspicuous

white stocking), yearling females (light brown coat were

25 to 50% in size of sub-adult females without gonad)

(Schaller 1967; Sankar et al. 2001). Calves were classi-

fied as small calves (light brown coloured coat, approx.

<3 months old of <30 kg, golden yellow pelage) and

large calves (light brown to dark brown coloured coat of

approx. 30 to 100 kg and half the size of yearling

females) (Schaller 1967; Sankar et al. 2001). Asian ele-

phants were classified into various age-sex categories

based on relative height and morphological character-

istics (Sukumar 1989). Young elephants (<15 years)

were compared to the oldest adult female in the group

(Eisenberg and Lockhart 1972) based on their height,

while the older elephants were classified based on their

morphological characteristics like degree of ear fold,

depression of the buccal cavity, forehead and with the

aid of camp elephant age classes with tribal mahout’s

field experience. Asian elephants were placed in broad

age-classes; calves (<1 year old), juveniles (1–5 years

old), sub-adults (5–15 years) and adults (>15 years).

Males were identified by the presence of tusks while

females were tuskless and ‘Makhna’ (tuskless sub-adult

and adult males) was identified using morphological

characters (Arivazhagan 2005) such as trunk muscula-

ture, absence of tusks and presence of penis sheath. We

calculated the ‘crowding’ phenomenon and mean group

size using program Flocker 1.0 (Reiczigel and Rozsa

2006) following the crowding measure used by Reiczigel

et al. (2008). Vehicle transect sightings were pooled for

two years together and analyzed season-wise to estimate

frequency distribution of group size, sex ratio, mean

group size and age structure. Mann Whitney test between

two seasons and Kruskal-Wallis test for all three seasons

(Fowler et al. 1998) were used to determine significant

differences observed in group size and crowding of gaur

and Asian elephant between seasons.

Results

Group size of gaur ranged from 1 to 42 individuals

with a mean group size of 7.5 ± 0.4 and the crowding

value was 17.0 (n = 2,944 individuals) (Table 1). There

was a seasonal difference in mean group size (P = 0.025)

of gaur, while crowding rate (P = 0.010) increased in the

wet season (Table 2). There was not much difference

between the first wet and second wet season in the mean

group size and crowding. More than 70% of gaur groups

were observed between group size ranging from 1 to 10

individuals in all the seasons. 48% of adult males were

found solitary and 6.3% adult bulls were found in bache-

lor herds during the dry season. Calves were sighted

throughout the year. The average adult male:adult

female:calf ratio in gaur was 38.5:100:38.9 (n = 2,062

individuals) (Table 3). The average age composition of

Mammal Study 37 (2012)50

gaur consisted of more adult than sub adult, yearling and

calf in both the sex classes (Table 4).

Asian elephant group size varied from 1 to 22 individ-

uals. More than 92% of the group size ranged from 1 to

10 individuals. The overall mean group size and crowd-

ing was 4.6 ± 0.16 and 6.8 respectively (n = 1,710 indi-

viduals) (Table 1). The mean group size (P = 0.251) and

crowding value (P = 0.542) did not vary seasonally

(Table 2). The overall adult male:adult female:calf ratio

was 10.5:100:26.4 (n = 1,198 individuals) (Table 3). The

Table 1. Seasonal grouping patterns of gaur and Asian elephant in Mudumalai Tiger Reserve, Western Ghats, India (February 2008–December 2009)

Species/Season NG NA LGO MC MG MGS SE

Group size

1–5 6–10 11–15 16–20 >20

Gaur–Dry 138 957 41 6.9 3 6.9 0.72 65.2 10.9 5.1 10.1 8.7

Gaur–I Wet 141 1185 42 17.1 5 8.4 0.72 50.4 23.4 8.5 7.8 9.9

Gaur–II Wet 111 802 41 16 3 7.2 0.77 56.8 14.4 16.2 3.6 9.0

Overall data 390 2944 42 17 4 7.5 0.42 57.4 16.4 9.5 7.4 9.2

Elephant–Dry 118 552 22 7.3 4 4.6 0.32 72.9 19.5 5.9 0.8 0.8

Elephant–I Wet 147 714 21 7.0 4 4.8 0.26 66.7 26.5 6.1 0.0 0.7

Elephant–II Wet 105 444 12 6.2 6 4.2 0.22 70.5 26.7 2.9 0.0 0.0

Overall data 370 1710 22 6.8 4 4.6 0.16 69.7 24.3 5.1 0.5 0.3

NG, Number of groups; NA, Number of animals; LGO, Largest group observed; MC, Mean Crowding; MG, Median group size; MGS, Mean group

size; SE, Standard Error; Dry, January to April; I Wet, May to August; II Wet, September to December.

Table 3. Sex ratio of gaur and Asian elephant in Mudumalai Tiger Reserve, India (February 2008–December 2009)

Table 4. Age structure of gaur in Mudumalai Tiger Reserve, India (February 2008–December 2009)

Species/Seasons Adult male Adult female Calves

Number of individuals

classified

Gaur–Dry 46.1 100 39.0 687

Gaur–I Wet 29.2 100 35.7 831

Gaur–II Wet 44.9 100 44.6 544

Overall data 38.5 100 38.9 2062

Elephant–Dry 12.7 100 22.5 384

Elephant–I Wet 8.4 100 28.9 508

Elephant–II Wet 11.3 100 27.1 306

Overall data 10.5 100 26.4 1198

Dry, January to April; I Wet, May to August; II Wet, September to December.

Seasons

Adult male Sub adult male Yearling male Adult female

Sub adult

female

Yearling

female

Calves

Total

No. % No. % No. % No. % No. % No. % Small % Large %

Dry 171 18 60 6 31 3 371 39 105 11 74 8 42 4 103 11 957

I Wet 147 12 65 6 43 4 504 43 134 11 112 10 58 5 122 10 1185

II Wet 129 16 55 7 37 5 287 36 78 9.7 88 11 41 5 87 11 802

Overall 447 15 180 6 111 4 1162 40 317 11 274 9 141 5 312 11 2944

Dry, January to April; I Wet, May to August; II Wet, September to December.

Table 2. Comparison of group size and crowding of gaur and Asian

elephant between seasons in Mudumalai Tiger Reserve, India (Febru-

ary 2008–December 2009)

Seasons

Gaur–P value Elephant–P value

Group size/Crowding Group size/Crowding

Dry × I Wet 0.009/0.012 0.353/0.609

Dry × II Wet 0.581/0.018 0.461/0.721

I Wet × II Wet 0.065/0.721 0.102/0.284

Overall data 0.025/0.010 0.251/0.542

Dry, January to April; I Wet, May to August; II Wet, September to

December.

Ramesh et al., Social structure of megaherbivores 51

average age composition of elephant had more adult than

sub adult and juvenile in both the sex classes while the

percentage of calves exceeded over adult male (Table 5).

Discussion

Gaur is a group living animal (Sankar et al. 2001). A

typical group includes cows, calves, one or two adult

bulls and sub-adults (Schaller 1967). Group size of gaur

in Mudumalai varied over seasons, and the crowding rate

Table 5. Age structure of Asian elephant in Mudumalai Tiger Reserve, India (February 2008–December 2009)

Table 6. Mean group size, group range, sex ratio and female: calf ratio of gaur and Asian elephant from protected areas in Indian sub-continent

Seasons

Adult male Sub adult male Juvenile Adult female

Sub adult

female

Juvenile Calves

Total

No. % No. % No. % No. % No. % No. % No. %

Dry 36 6.5 22 4.0 18 3.3 284 51.4 53 9.6 75 13.6 64 11.6 552

I Wet 31 4.3 35 4.9 22 3.1 370 51.8 64 9.0 85 11.9 107 15.0 714

II Wet 25 5.6 18 4.1 15 3.4 221 49.8 48 10.8 57 12.8 60 13.5 444

Overall 92 5.4 75 4.4 55 3.2 875 51.2 165 9.6 217 12.7 231 13.5 1710

Dry, January to April; I Wet, May to August; II Wet, September to December.

Species Study site and Source

Mean group

size ± SE

Group range

Adult female:

calf ratio

Adult male: adult

female ratio

Gaur Mudumalai, India (Present study) 7.5 ± 0.40 1 to 42 1:0.39 0.39:1

Mudumalai, India (Kumar et al. 2004) 8.1 ± 0.63 1 to 47 1:0.16 0.25:1

Kanha, India (Schaller 1967) 8.8 ± 0.74 1 to 40 1:0.40 0.38:1

Nagarahole, India (Karanth and Sunquist 1992) 6.9 ± – 1 to 47 1:0.43 0.18:1

Bandipur, India (Johnsingh 1983) – 1 to 60 – –

Palamau, India (Sahai 1977) 5 to 7 – – –

Parambikulam, India (Vairavel 1998) 6.0 ± – 1–19 1:0.16 0.45:1

Pench, India (Sankar et al. 2001) 4.6 ± 0.29 1 to 19 1:0.24 0.60:1

Bhadra, India (Jathanna et al. 2003) 2.3 ± – – – –

Jaldapara, India (Bhattacharya et al. 1997) – 1 to 70 – –

Tadoba, India (Dubey 1999) – – – 0.47:1

Burma (Peacock 1933) 10 to 20 – – –

Elephant Mudumalai, India (Present study) 4.6 ± 0.16 1 to 22 1:0.26 0.11:1

Mudumalai, India (Arivazhagan 2005; Varman and

Sukumar 1995)

5.3 ± 0.73 – 1:0.19 0.04:1

Bandipur, India (Johnsingh 1983) 7.8 ± 0.16 1 to 39 1:0.37 0.40:1

Nagarahole, India (Karanth and Sunquist 1992;

Arivazhagan 2005)

3.5 ± – – 1:0.20 0.18:1

Hasanur-Biligiri Ranga Hills, India (Sukumar 1985) 7.6 ± 0.91 1 to 34 1:0.20 0.20:1

Periyar, India (Arivazhagan 2005; Easa and Sabu

Jahas 2002)

– 1 to 19 1:0.16 0.02:1

Parambikulam, India (Easa and Balakrishnan 1995) 7.9 ± 0.55 1 to 18 1:0.32 0.14:1

Rajaji, India (Williams et al. 2007) 6.8 ± 0.92 – 1:0.41 0.54:1

Maduru Oya, Sri Lanka (Dissanayake and

Santiapillai 2001)

11 to 20 1 to 65 1:0.18 0.42:2

Ruhuna, Sri Lanka (Katugaha et al. 1999) 3.9 ± – 1 to 21 1:0.35* 0.42:2

Gal Oya, Sri lanka (Mckay 1973) – 1 to 41 1:0.21 0.40:1

Lahugala, Sri Lanka (Mckay 1973) – >25 1:0.23 0.42:1

Yala, Sri Lanka (Kurt 1974) – – 1:0.35 0.53:1

– = Information not available, * = Calf and juvenile combined.

Mammal Study 37 (2012)52

increased in the wet seasons probably due to the increase

in food availability during monsoon. Kumar et al.

(2004) observed high forage biomass available for gaur

during the wet season compared to the dry season in

Mudumalai. Similarly other two studies in India

(Vairavel 1998; Sankar et al. 2001) observed major dif-

ference between seasons (Table 6). Group size range

of gaur was one of the largest in the present study

compared to other parts of the Indian sub-continent.

The estimated mean group size of gaur in Mudumalai

was also comparable to other parts of India (Table 6).

The largest group of gaur frequented mostly grasslands

dominated by Themeda species staying close to water

sources in the morning and evening and near teak plan-

tations where they fed mainly on fallen leaves and bark.

Calving season of gaur in Mudumalai indicated that

there was no distinct seasonality but a slight peak ob-

served in the first year in February, July and October to

December and for the second year in January, March,

April, July and December. Earlier study (Kumar et al.

2004) in Mudumalai also showed no definite peak season

in calving. In Jaldapara Wildlife Sanctuary, young gaur

calves were observed with the herd mostly during

November and December (Bhattacharya et al. 1997) and

in Kanha, calving period occurred from early Sepem-

ber to mid-March with a peak in December and January

and sometime in April, May, June and July (Schaller

1967). In Pench, gaur calving season was observed

throughout the year with a peak between March and May

(Sankar et al. 2001) and in Parambikulam, the highest

proportion of calves was reported during the second wet

season (Vairavel 1998). Morris (1937) recorded the rut-

ting period of gaur from November to March in southern

India. Twice a cow with two calves was seen separately

from the herd and once two calves were seen suckling

milk from a cow in a herd in Mudumalai. The present

finding in Mudumalai indicates the adaptability of gaur

to ascertain successful calf birth and survival throughout

the year. The adult female:calf ratio in Mudumalai is

similar to Kanha (Schaller 1967) and Nagarahole

(Karanth and Sunquist 1992) but higher than Pench

(Sankar et al. 2001), Mudumalai (Kumar et al. 2004)

and Parambikulam (Vairavel 1998). The present study

indicates high percentage of females breeding in the

population. The overall skewed female sex ratio in

Mudumalai is much similar to the estimates from many

parts of India (Table 6). The skewed female ratio is

probably because solitary male gaurs dispersing from

mixed herds experience greater mortality and is more

vulnerable to predation by tiger (Karanth and Sunquist

1995; Ramesh et al. 2009; Ramesh 2010). In most ungu-

late populations the intensity of intra-male competition

results in greater male mortality (Berger and Gompper

1999). According to Klein (1970), North American male

deer appears to be more susceptible to mortality when

food becomes limited and this could be due to their large

bodies and higher metabolic rate resulting from greater

growth rate, activity, curiosity and independence than

the females. So the reproductive fitness strategies tend

to skew the population sex ratio towards females. Such

factors could also be responsible for the skewed sex ratio

among gaur in Mudumalai. Increased adult male ratio

of gaur was seen during the second wet and dry season

and this may be related to their breeding activities. Com-

monly two or more gaur bulls were seen in a herd of

>20 individuals in Mudumalai. In contrast to this,

Krishnan (1972) did not record two or more mature bulls

in a gaur herd in south India. Calf ratio did not differ in

gaur population between seasons in the study area.

The basic unit of Asian elephant is the family con-

sisting of an adult cow and her immature offspring

(Sukumar 2006). The Asian elephant lives in matriar-

chal groups of five to 20 individuals that interact with

other family units in the area (Sukumar 2006). The

similar observation of elephant group size was made

during the present study. Group size and crowding

rate of elephant did not vary much between seasons in

Mudumalai. This may be attributed to the high year-

round availability of Themeda cymbaria, T. triandra

grasses, water, swamps and woody plants in the

study area. Sivaganesan and Johnsingh (1995) reported

that deciduous forest is a prime elephant habitat in

Western Ghats. Sukumar (1985) observed a difference

in the mean group size between seasons especially in

the first wet season. Since the present study area holds

high density of elephant (Ramesh et al. 2009; Ramesh

2010) such difference was not noticed in seasonal group

size. From other studies, mean group size of elephant is

comparable to the present study (Table 6). Sukumar

(1985) observed a higher mean group size and seasonal

difference. It is possible that the study covered dry

and wet regions especially in drier parts where large

congregations take place towards water holes. The mean

calving ratio is considered to be the most important

parameter influencing growth rate in megaherbivores.

Williams et al. (2007) and Easa (1989) observed no

major difference in mean group size of Asian elephant

between seasons in Rajaji and Parambikulam, India,

Ramesh et al., Social structure of megaherbivores 53

respectively. The overall calving ratio of Asian ele-

phant in Mudumalai is similar to reports from most of the

earlier studies in the Indian sub-continent (Table 6).

This higher recruitment rate showed the reproductive

potential of females in Mudumalai. During the present

study, 10 ‘Makhnas’ were sighted. The reported adult

male ratio was low in Mudumalai as compared to other

study sites. The reason for this could be attributed to the

increased vulnerability of males to poaching for ivory.

The juvenile stage to male elephants particularly the age

class from 5 to 7 yrs in southern India are severely

affected by ivory poaching and have declined sharply in

the last two decades in the Nilgiris—Eastern Ghats

(Sukumar 1989; Arivazhagan 2005). This species is in

serious threat due to poaching, habitat loss throughout

their South Indian range (Sukumar 2006). There is a

possibility of difference in recruitment and chance devia-

tion from an equal sex ratio at birth (Sukumar 1985).

Acknowledgment: We would like to thank the Director

and Dean, Wildlife Institute of India and the Chief Wild-

life Warden, Tamil Nadu for granting permission to

work in Mudumalai. We thank the editor and the two

anonymous reviewers for their critical review and sug-

gestions which improved this manuscript. We thank our

field assistants C. James, M. Kethan, M. Mathan and

forest department staff for their assistance and support

during field work.

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Received 1 April 2011. Accepted 3 October 2011.