ISRN ZoologyVolume 2012 (2012), Article ID 259695, 11 pagesdoi:10.5402/2012/259695

Research Article

Food Habit and Feeding Patterns of Great Indian One-Horned Rhinoceros (Rhinoceros unicornis) in Rajiv Gandhi Orang National Park, Assam, India

B. C. Hazarika¹ and P. K. Saikia²

¹Department of Zoology, Mangaldai College, Assam, Mangaldai 784125, India²Animal Ecology & Wildlife Biology Laboratory, Department of Zoology, Gauhati University, Assam, Guwahati 781014, India

Received 2 November 2011; Accepted 20 December 2011

Academic Editor: S. T. Boysen

Copyright © 2012 B. C. Hazarika and P. K. Saikia. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract.

Food and feeding patterns of great Indian one-horned Rhinoceros (Rhinoceros unicornis) has been studied in Rajiv Gandhi Orang National Park. Altogether 75 species of grasses, 27 species of herbs-shrubs, 27 species of trees, and 9 species of aquatic plants species were identified as a food-plant species of Indian Rhino in the study area. Of the total 75 species of grasses, 48 species had a relative dominance of <1.0. The Saccharum spontaneum was ranked as the highest relative dominance food-plant among grasses (relative dominance value, 8.45%), while the Cyperus pilosus ranked the lowest (relative dominance value, 0.08%). Among 27 herbs-shrubs species, three had a relative dominance of <1.0. The Diplazium esculentum was ranked the highest relative dominance food plants among herbs-shrubs food plants (relative dominance value, 13.83%), while the Solanum viarum was ranked the lowest (relative dominance value, 0.66%). All tree species had a relative dominance of >1.0. The Dalbergia sissoo ranked the highest among all trees (relative dominance value, 7.94%), while the Anthocephalus cadamba ranked the lowest (value, 1.19%). Grasses constituted 86.66% of the total annual diet of Rhino, while the aquatic and woodland species constituted only 13.34% of the total annual diet. Altogether 71 plants species were identified as the Rhino food plants at Rajiv Gandhi Orang National Park. Of which, grasses constituted the highest (42 species), followed by woodland species (trees, herbs-shrubs), (20 species) and aquatic plants (9 species). The grass species Hemarthria compressa contributed a highest of 11.63%, while the aquatic plant Polygonum hydropiper was the least of 0.01% in total annual diet. Out of total 42 food-plant species, 20 grass species had no selectivity. The Hemarthria compressa was the top ranking grass species that has been selected as food by the Indian Rhino. Altogether, 36 food-plants (24 grasses, 9 woodland species, and 3 aquatic species) were identified as the staple food that constituted 83.64% of the total annual diet. Study showed that ten top ranking food plants constituted 56.44% and 20 top ranking food plants constituted 72.19% of the total annual diet. Thus, the grass species alone have enough to provide food for Indian Rhino in Rajiv Gandhi Orang National Park. Soil licking and crop depredation by the Indian Rhino were common in the fringe villages in study area.

1. Introduction

Food is the primary requirement of an animal to survive and maintain its good health. Hence, the animal must acquire food that contains enough nutrients to fulfill its physiological needs. Again, the distribution pattern of food resources over the habitat guides the distribution of male and female individuals. [1]. Hence, the availability of food resource and its distribution pattern do not only affect the physiology of a species, but also the activity (or time budget) and the habitat utilization pattern of the wildlife species.

The study of species-specific food choice and the distribution pattern of food resources over the habitat are important prerequisites to improve the habitat quality and have a great value for in situ conservation of a species. It also helps to evaluate the habitat quality before initiating the species reintroduction programme. Hence, a number of keystone and flagship species [2, 3] are subjected to study to layout a holistic approach for conservation and management action plan. During conservation and management process, the feeding ecology is one of the best tools to understand the food choice of a species, which further helps to understand the reasons of habitat selectivity and variation in time allocation in different activities.

A number of studies on feeding ecology of Indian Rhino were conducted by several authors in India and Nepal, such as [4–13]. Apart from that, the studies on the chemical composition of food items [6, 14], feeding behaviour of Rhino [4, 5], analysis of Rhino dung, seed dispersal, germination of seed on Rhino dung [10, 15], and so forth were carried out in India and Nepal conditions. Among those, most studies were conducted in Terai grassland and on natural and introduced Rhino population. Although few studies were carried out in the Brahmaputra floodplain area, most of them were qualitative in nature. Hence, the present study was aimed to quantify the data on feeding ecology of Rhino, to analyze the food and feeding habits, food preference, and food selectivity of Rhino in Rajiv Gandhi Orang National Park.

The present study aimed to find out the food and feeding habit and food selectivity of Indian Rhinos in order to lay out a comprehensive conservation strategy in the Brahmaputra floodplain habitats. The study emphasizes following objectives: (1) to investigate the food habitat of Indian Rhino in study area to find out the seasonal feeding pattern, (2) to identify the food plants species and its characteristics in different habitat of study area, (3) to identify the staple food of  Indian Rhino, and (4) to find out the food selectivity and dietary spectrum of Indian Rhino in Rajiv Gandhi Orang National Park, based on gathered data.

2. Materials and Methods

2.1. Study Area

The Rajiv Gandhi Orang National Park (coordinates: 92°15′–92°27′E and 26°29′–26°40′N) is situated in the north bank of the river Brahmaputra and within the administrative boundary of Darrang, Udalguri and Sonitpur districts of Assam, India (Figure 1). The study area is located about 130 km apart from the state capital city Guwahati and included under the jurisdiction of Mangaldoi Wildlife Division, Department of Environment and Forests, Government of Assam, India. The area of the park is 78.81 sq.km. The park harbours 64 Rhinos (2009 Census).

Figure 1: Location map of Rajiv Gandhi Orang National Park.

The eastern side of the study area is bounded by Borsola area and river Brahmaputra of Sonitpur district, southern side by the river Brahmaputra, western side by the tributary Dhansiri and Bagribari village area, and the northern side is bounded by Nalbari and Rangagora villages of Darrang district.

The study area comprises of alluvial floodplains of the river Brahmaputra. In fact, the complete study area is an alluvial terrace, and the entire Rajiv Gandhi Orang National Park could be divided into two halves, that is, lower Orang and upper Orang. The lower Orang portion is more recent origin, whereas the upper portion to its north is separated by high bank, traversing the park from east to west. The terrain is gently sloping from North to South. The altitude of the study area ranges between of 45–75 m MSL.

The entire protected area was a human habitat area till the last decade of the 19th century [16]. Prior to declaration of Orang as a “Game Reserve” in 1915, different ethnic groups occupied the entire study area. Two large tributaries of the river Brahmaputra, namely, Dhansiri and Panchnoi are associated with numbers of streams and nullah that criss-crosses the park and became the source of water for the entire habitat.

2.2. Methods

For the study of food and feeding ecology of Indian Rhino, the following methodologies were used for data collection.

2.2.1. Vegetation Sampling

For vegetation sampling, a total of 80 quadrats (1 m × 1 m in size) for grasses, 20 quadrats (5 m × 5 m in size) for shrub and herbs, and 20 quadrats (10 m × 10 m in size) for trees were taken covering all the habitats in Rajiv Gandhi Orang National Park. Since the Rajiv Gandhi Orang National Park is primarily a grassland habitat dotted with scattered forests and shrub land, more quadrats were placed on grasslands, compared to other habitats. During sampling, the number of each individual plant species found on the quadrats was recorded to calculate the relative dominance [2, 17].

2.2.2. Sampling for Food Habits

Scan animal sampling and ad libitum sampling [18] methods were used to collect the data of food and feeding habit at Rajiv Gandhi Orang National Park. During study, the seasonal variation of time spent on feeding in different food plant species was recorded to identify the staple food, food selectivity, and dietary spectrum of Indian Rhino in Rajiv Gandhi Orang National Park from dawn to dusk. The staple food referred to here is the food items eaten by Indian Rhino throughout the year, irrespective of seasons. The food selectivity is the ratio of the percent of time spent and percent of dominance of each plant species. The ratio “” indicated whether the consumed plant species had an effect on availability in the habitat or outcome of the food selection. If , then it suggests strong selection of feeding activity, and when , then it suggests that the feeding occurs due to availability of particular food items. Again, if  , then it indicated that the particular plant species is consumed as per its distribution and dominance in the sampling quadrate.

The formulae of food selectivity could be represented as The dietary spectrum was determined by quantifying the food dependency of Indian Rhino in study area.

The study was carried out from April 2000 to March 2003 covering random sampling points of the whole study area of 78.81 sq.km. in Rajiv Gandhi Orang National Park (92°15′–92°27′E; 26°29′–26°40′N). A total of 10 days per month was spent to visit each and every corner of the park. The field study was conducted using motor vehicles, bicycles, country boats, elephant back as well as on foot. During field visits, the sightings of Indian rhinos were recorded with their numbers, age-sex, GPS locations, and habitat types. The data were further analyzed to find out the daily range, home range, and habitat utilization pattern. The vegetation samplings were done covering all the habitats on seasonal basis. Again, the sightings of Rhino dung piles, and occurrences of any less frequent opportunistic behaviour (e.g., aggressive, reproductive, etc.) were also recorded in each and every visit.

The foraging tract was followed at the time of scan sampling, the grasses were identified if possible, and samples were collected to make herbarium sheet for identification of food plants. The plucked eaten food plants were confirmed by(a)direct observation of foraging rhino;(b)following the rhino food tracks;(c)by fresh Rhino dung analysis, that is, comparing undigested parts of food plants with herbarium sheet.

3. Results

3.1. Relative Dominance and Frequency

3.1.1. Grasses

The study revealed the presence of 75 grass species under Poaceae and Cyperaceae family in Rajiv Gandhi Orang National Park during sampling. Of the total 75 grass species, 48 had a relative frequency <1, 13 had relative frequency 1-2, and 14 had >2 (Table 1). The Saccharum spontaneum was the highest ranked relative dominance species, whose dominance value was 8.45%, while the Cyperus pilosus was the lowest ranked grass species with a dominance value of 0.08%.

Table 1: Frequency occurrence of grasses, shrubs, herbs, and tree species in Rajiv Gandhi Orang National Park.

Frequency class
Frequency of grass species
Frequency of shrub and herb species
Frequency of tree

0-1
48
3
0

1-2
13
8
7

2-3
5
6
5

3-4
1
2
4

4-5
6
3
4

5-6
1
0
1

6-7
1
1
4

7-8
0
0
2

8-9
0
2
0

9-10
0
0
0

10-11
0
0
0

11-12
0
1
0

12-13
0
0
0

13-14
0
1
0

Total
75
27
27

3.1.2. Herbs and Shrubs

A total of 27 herbs and shrubs species belonging to 16 families (see Appendix 6.2) were recorded during sampling in Rajiv Gandhi Orang National Park of which 3 species had a relative frequency <1, and 24 species had a relative frequency >1 (Table 1). The species Diplazium esculentum was the highest ranked species among shrubs and herbs with a relative dominance value of 13.83%, while the Solanum viarum was the lowest ranked species with a relative dominance value of 0.66%.

3.1.3. Trees

The study found altogether 27 tree species belonging to 8 families in Rajiv Gandhi Orang National Park with a relative frequency >1.0 (see Table 1). The Dalbergia sissoo was the highest ranked species with a relative dominance value of 7.94%, whereas the Anthocephalus cadamba ranked the lowest was species with a relative dominance value of 1.19%.

3.1.4. Food Items and Food Selection

The study showed that, grass constituted the highest of 86.66% total annual food of Indian Rhino in Rajiv Gandhi Orang National Park, but the nongrass aquatic plants and tree species constituted only 13.34% of total annual diet, indicated the high selection of grasses by Indian Rhino in Rajiv Gandhi Orang National Park during foraging (Figure 2).

Figure 2: Annual uses of food items by Indian Rhino at Rajiv Gandhi Orang National Park.

The study also revealed that the Indian Rhino selected 89.13% grass species as food items during winter season and 83.50% during monsoon season (Figure 3). Of the total 42 grass species, 20 species had no selectivity but eaten during foraging time owing to availability in the grassland habitat of study area.

Figure 3: Seasonal use of food plant species by Rhinoceros unicornis in Rajiv Gandhi Orang National Park.

3.1.5. Food Items

Study showed that altogether 71 plant species have used by Indian Rhino as food items throughout the year in study area, of which 42 species were grasses, 20 species trees, herbs, and shrubs, and 9 species were other aquatic plant. Again, among all the 71 food plant species, the Indian Rhino consumed a total of 63 plant species as food during premonsoon, 49 species during monsoon, 57 species during retreating monsoon, and 58 species were used during winter season. Again, the Indian Rhino had consumed 36 grass species, 19 trees and aquatic plant species during premonsoon season, whereas consumed 32 grasses, 11 trees, and 6 aquatic plants species during monsoon season. During retreating monsoon, they consumed altogether 33 grass species, 17 trees species, and 7 other aquatic plants, whereas during winter season they consumed a total of 39 grass species, 15 trees species, and 4 other aquatic plants species (see Table 2).

Table 2: Seasonal use of food-plant species by Indian Rhino in Rajiv Gandhi Orang National Park.

Species
Premonsoon
Monsoon
Retreating Monsoon
Winter

Grasses
36
32
33
39

Tree species
19
11
17
15

Aquatic plant species
8
6
7
4

Total
63
49
57
58

3.1.6. Categories of Consumed Food Plant Species

Study revealed that there were altogether 12 different categories of food plants, that have been based on plant characteristics under three major habitat types, namely, grasslands, aquatic and woodland habitats in Rajiv Gandhi Orang National Park (Table 3). The Rhino consumed dissimilar categories of food items in various seasons of the year. The analysis of proportional use of food plant types by Indian Rhino showed that the plant types, namely, dry short grass (dsg), wet creeping short grass (wcsg), and wet tall grass (wtg) were consumed in maximum proportion during premonsoon compared to other types (Figure 4). Again, the proportional use of wet creeping short grass (wcsg), dry short grass (dsg), wet tall grass (wtg), and creeping aquatic beds (cab) were higher during monsoon season than other types of food-plant species (see Figure 5). Whereas, the wet creeping short grasses (wcsg), wet tall grasses (wtg), dry short grasses (dsg), submerged (sm), and creeping aquatic beds (cab) types of food-plants were consumed in higher proportion during retreating monsoon season (Figure 6). During winter season, the Indian Rhino consumed higher proportion of wet creeping short grass (wcsg), wet tall grass (wtg), dry short grass (dsg), wet short grass (wsg), dry tall tree (dtt), and creeping aquatic beds (cab) types of food plants than other types of species (Figure 7).

Table 3: The food plant species, in which habitat it occurs, feeding percentage, and major categories of food-plants of Rhinoceros unicornis in Rajiv Gandhi Orang National Park (PM: premonsoon; M: monsoon; RTM: retreating monsoon; WIN: winter; WSG: wet short grass; WCSG: wet creeping short grass; DSG: dry short grass; DST: dry short tree; DTT: dry tall tree; DH: dry herbs; DS: dry shrubs; EAB: emergent aquatic bed; CAB: creeping aquatic bed; FFAB: free-floating aquatic bed; SM: submerged; SV: swampy vegetation; GL: grassland; Aq: aquatic; WL: woodland).

Food plant species
Families
Types of food plants
Habitat category
Percent of feeding

PM
M
RTM
WIN

(a) Grasses

Agrostis zenkeri
Poaceae
WSG
GL
1.0
0.0
0.0
0.89

Apluda mutica
Poaceae
DSG
GL
2.2
0.5
0.0
1.7

Arundinella bengalensis
Poaceae
WCSG
GL
1.8
2.3
1.06
0.9

Arundinella nepalensis
Poaceae
WCSG
GL
1.9
0.7
0.49
1.84

Arundo donax
Poaceae
WTG
GL
7.8
5.6
6.8
5.3

Axonopus compressus
Poaceae
WSG
GL
1.4
0.0
0.0
0.58

Brachiaria ramosa
Poaceae
WCSG
GL
2.4
6.8
3.45
2.66

Chrysopogon aciculatus
Poaceae
DSG
GL
4.0
5.8
4.46
4.13

Cynodon dactylon
Poaceae
WSG
GL
3.0
1.5
2.3
1.63

Cyperus cyperoides
Cyperaceae
WSG
GL
0.0
0.1
0.4
0.0

Cyperus rotundus
Cyperaceae
WSG
GL
0.0
2.4
1.6
1.53

Cyperus brevifolius
Cyperaceae
WSG
GL
0.0
0.4
1.8
0

Cyperus globosus
Cyperaceae
WSG
GL
0.0
0.2
0.47
0.23

Cyperus kyllingia
Cyperaceae
WSG
GL
0.0
0.9
0.4
0

Cyrtococcum accrescens
Cyperaceae
DSG
GL
1.7
0.0
0.0
0.94

Dichanthium caricosum
Poaceae
WSG
GL
1.7
0.0
0.0
1.89

Digitaria ciliaris
Poaceae
WSG
GL
0.8
0
0.8
2.4

Echinochloa crus-galli
Poaceae
WSG
GL
0.0
0.0
0.0
0.89

Eleusine indica
Poaceae
DSG
GL
1.8
0.3
1.75
1.92

Eragrostis japonica
Poaceae
WTG
GL
1.2
0.0
0.9
0.56

Eragrostis unioloides
Poaceae
WSG
GL
0.8
0.1
0.0
1.84

Eriochloa procera
Poaceae
WSG
GL
1.7
0.5
0.6
0.32

Hemarthria compressa
Poaceae
WSG
GL
7.9
13.0
14.3
11.8

Hemarthria protesna
Poaceae
WSG
GL
1.0
1.6
1.86
0.82

Hygroryza aristata
Poaceae
WSG
GL
1.8
2.3
2.48
1.34

Hymenachne pseudointerrupta
Poaceae
WCSG
GL
7.9
14
12.6
8.57

Sacciolepis interrupta
Poaceae
DSG
GL
2.2
1.0
0.74
2.06

Leersia hexandra
Poaceae
WCSG
GL
3.5
14
9.23
8.7

Leptochloa panicea
Poaceae
WSG
GL
1.8
1.0
1.7
1.56

Panicum walense
Poaceae
DSG
GL
1.3
0.0
0.0
0.84

Oplismenus burmannii
Poaceae
DSG
GL
1.3
1.0
1.6
0.87

Paspalidiumflavidum
Poaceae
WCSG
GL
0.6
0.0
0.56
1.61

Paspalum conjugatum
Poaceae
WSG
GL
0.7
1.3
1.33
0.89

Paspalum dilatatum
Poaceae
WSG
GL
0.9
1.1
1.5
0.6

Phragmites karka
Poaceae
WTG
GL
5.8
3.3
3.88
4.67

Saccharum procerum
Poaceae
WTG
GL
1.1
1.8
0.93
1.83

Saccharum ravennae
Poaceae
WTG
GL
2.6
1.8
0.8
2.31

Saccharum spontaneum
Poaceae
WTG
GL
3.7
1.0
0.68
2.89

Setaria pumila
Poaceae
WSG
GL
0.0
0.0
0.0
1.7

Themeda villosa
Poaceae
WTG
GL
2.4
0.8
1.06
2.62

Vetiveria zizanioides
Poaceae
WTG
GL
0.0
0.0
0.8
0.07

Imperata cylindrica
Poaceae
DSG
GL
1.6
2.5
2.6
1.2

(b) Aquatic plants

Ipomea aquatica
Convolvulaceae
CAB
Aq
1.0
1.5
1.9
1.26

Pistia stratiotes
Araceae
FFAB
Aq
1.7
1.6
0.74
0.89

Eichhornia crassipes
Pontederiaceae
FFAB
Aq
0.9
1.1
0.84
0.0

Vallisneria spiralis
Hydrocharitaceae
SM
Aq
0.7
0.0
1.66
0.0

Hydrilla verticillata
Hydrocharitaceae
SM
Aq
1.6
0.0
1.8
0.3

Nymphaea nouchali
Nymphaeaceae
EAB
Aq
0.0
1.0
0.87
0.0

Trapa bispinosa
Trapaceae
EAB
Aq
0.3
0.0
0.0
0.0

Enhydra fluctuans
Asteraceae
CAB
Aq
0.5
2.1
1.35
0.7

Alpinia allughas
Zingiberaceae
SV
Aq
0.1
0.2
0.0
0.0

(c) Herbs and shrubs

Ageratum conyzoides
Asteraceae
DS
WL
0.5
0.0
0.02
0.4

Mikania micrantha
Asteraceae
DH
WL
0.5
0.0
0.47
0.55

Melastoma malabathricum
Melastomataceae
DS
WL
0.6
0.0
0
0

Lantana camera
Verbenaceae
DS
WL
0.7
0.0
0.55
0

Xanthium strumarium
Asteraceae
DS
WL
0.7
0.0
0.53
0.16

Grewia sapida
Tiliaceae
DS
WL
0.9
0.7
0.61
0.53

Polygonum hydropiper
Polygonaceae
DH
WL
0.0
0.0
0.0
0.01

Diplazium esculentum
Dryopteridaceae
DH
WL
0.9
0.0
0.2
0.67

Amaranthus spinosus
Amaranthaceae
DH
WL
1.0
0.0
0.6
0.0

(d) Trees

Bombax ceiba
Bombacaceae
DTT
WL
0.9
0.0
0
0.78

Trewia nudiflora
Euphorbiaceae
DTT
WL
0.5
0.6
0.66
0.76

Dalbergia sissoo
Papilionaceae
DTT
WL
0.7
0.9
0.12
0.87

Cassia fistula
Caesalpiniaceae
DTT
WL
0.5
0.4
0.05
0.81

Mangifera indica
Anacardiaceae
DTT
WL
0.0
0.4
0.03
0.0

Ficus glomerata
Moraceae
DTT
WL
0.6
0.4
0.01
0.63

Streblus asper
Moraceae
DST
WL
0.0
0.0
0.01
0.0

Ficus rumphii
Moraceae
DTT
WL
0.1
0.4
1.03
0.9

Artocarpus heterophyllus
Moraceae
DTT
WL
0.0
0.5
0.01
0.04

Ziziphus zuzuba
Rhamnaceae
DST
WL
0.5
0.3
0.02
0.26

Bauhinia purpurea
Leguminoseae
DTT
WL
0.0
0.0
0.02
0.35

Figure 4: Proportional use of food plants species by Indian Rhino in Rajiv Gandhi Orang National Park during premonsoon season (data was represented, Mean ± 2SE; wsg: wet short grass; wcsg: wet creeping short grass; dsg: dry short grass; dst: dry short tree; dtt: dry tall tree; dh: dry herbs; ds: dry shrubs; eab: emergent aquatic bed; cab: creping aquatic bed; ffab: free-floating aquatic bed; SM: submerged; sv: swampy vegetation).

Figure 5: Proportional use of food plants species by Indian Rhino in Rajiv Gandhi Orang National Park during monsoon season (data was represented, Mean ± 2SE; wsg: wet short grass; wcsg: wet creeping short grass; dsg: dry short grass; dst: dry short tree; dtt: dry tall tree; dh: dry herbs; ds: dry shrubs; eab: emergent aquatic bed; cab: creeping aquatic bed; ffab: free-floating aquatic bed; SM: submerged; sv: swampy vegetation).

Figure 6: Proportional use of food plants species by Indian Rhino in Rajiv Gandhi Orang National Park during retreating monsoon (data was represented, Mean ± 2SE; wsg: wet short grass; wcsg: wet creeping short grass; dsg: dry short grass; dst: dry short tree; dtt: dry tall tree; dh: dry herbs; ds: dry shrubs; eab: emergent aquatic bed; cab: creeping aquatic bed; ffab: free-floating aquatic bed; SM: submerged; sv: swampy vegetation).

Figure 7: Proportional use of food plants species by Indian Rhino in Rajiv Gandhi Orang National Park during winter season (data was represented, Mean ± 2SE; wsg: wet short grass; wcsg: wet creeping short grass; dsg: dry short grass; dst: dry short tree; dtt: dry tall tree; dh: Dry herbs; ds: dry shrubs; eab: emergent aquatic bed; cab: creeping aquatic bed; ffab: free-floating aquatic bed; SM: submerged; sv: swampy vegetation).

3.1.7. Feeding Frequency

The study revealed that the grass species Hemarthria compressa contributed the highest consumed (11.63%) food plant species of Rhino, while the marshyland plant species Polygonum hydropiper was the lowest consumed (0.01%) food-plant species, in their total annual diet. The annual feeding frequency of the ten top ranking plant species of Indian Rhino in their total annual diets were Hemarthria compressa, Hymenachne pseudointerrupta, Leersia hexandra, Arundo donax, Chrysopogon aciculatus, Phragmites karka, Brachiaria ramosa, Cynodon dactylon, Saccharum spontaneum, and Imperata cylindrica (Table 4).

Table 4: Shows the ten top ranking annual food plants of Indian Rhino in Rajiv Gandhi Orang National Park.

SL number
Species
Annual feeding frequency (%)

1
Hemarthria compressa
11.63

2
Hymenachne pseudointerrupta
10.64

3
Leersia hexandra
8.80

4
Arundo donax
6.38

5
Chrysopogon aciculatus
4.60

6
Phragmites karka
4.42

7
Brachiaria ramosa
3.83

8
Cynodon dactylon
2.11

9
Saccharum spontaneum
2.05

10
Imperata cylindrica
1.98

3.1.8. Staple Food

The analysis showed that altogether 36 plant species (Table 5) were selected by Indian Rhino as their regular food item. This 36 numbers constituted 83.64% of the total annual diet budget of Indian Rhino in Rajiv Gandhi Orang National Park. Among all the 36 plant species, 24 plant species were grasses that constituted 75.97% of the total selected annual food plant species; hence, it is referred to as staple food of Indian Rhino. But, among nongrass species, only 9 trees species and 3 aquatic plant species were also selected as annual food, which constituted only 7.67% of the total annual diet, that were also referred as staple food (Table 6).

Table 5: Staple food of Rhino in Rajiv Gandhi Orang National Park (a) grasses, (b) trees and (c) aquatic plants.

Name of the food plant
Seasons

PM
M
RM
W

(a) Grasses

Arundinella begalensis (Spreng.) Druce.
1.8
2.3
1.06
0.9

Arundinella nepalensis Trin.
1.9
0.7
0.49
1.84

Arundo donax Linn.
7.8
5.6
6.8
5.3

Brachiaria ramosa (L.) Stapf.
2.4
6.8
3.45
2.66

Chrysopogon aciculatus (Retz.) Trin.
4.01
5.8
4.46
4.13

Cynodon dactylon (L.) Pers
3.02
1.5
2.3
1.63

Eleusine indica (L.) Gaertn.
1.84
0.25
1.75
1.92

Eriochloa procera (Retz.) C.E.Hubb.
1.71
0.5
0.6
0.32

Hemarthria compressa (L.f.) R.Br.
7.9
12.5
14.3
11.83

Hemarthria protesna Steud.
0.96
1.56
1.86
0.82

Hygroryza aristata (Retz.) Nees ex Wight and Arn.
1.81
2.26
2.48
1.34

Hymenachne pseudointerrupta
7.93
13.5
12.57
8.57

Imperata cylindrica (L.) Beauv.
1.6
2.5
2.6
1.2

Leersia hexandra Sw.
3.54
13.72
9.23
8.7

Leptochloa panicea (Retz.) Ohwi
1.8
1.03
1.7
1.56

Oplismenus burmannii (Retz.) P.Beauv.
1.3
1.01
1.6
0.87

Paspalum conjugatum Berg.
0.7
1.3
1.33
0.89

Paspalum dilatatum Poir.
0.86
1.08
1.5
0.6

Phragmites karka (Retz.) Trin.ex.Steud.
5.83
3.3
3.88
4.67

Saccharum procerum Roxb.
1.08
1.81
0.93
1.83

Saccharum ravennae (L.) Beauv.
2.61
1.8
0.8
2.31

Saccharum spontaneum Linn.
3.68
0.96
0.68
2.89

Sacciolepis interrupta (Willd.) Stapl.
2.2
0.95
0.74
2.06

Themeda villosa(Poir.) A.Camus.
2.4
0.83
1.06
2.62

(b) Trees

Artocarpus heterophyllus Lamk.
0.02
0.45
0.01
0.04

Bauhinia purpurea L.
0.02
0.01
0.02
0.35

Cassia fistula L.
0.49
0.37
0.05
0.81

Dalbergia sissoo Roxb.
0.67
0.85
0.12
0.87

Ficus glomerata Roxb.
0.57
0.36
0.01
0.63

Ficus rumphii Bl.
0.05
0.35
1.03
0.9

Grewia sapida Roxb.
0.94
0.66
0.61
0.53

Trewia nudiflora L.
0.52
0.62
0.66
0.76

Ziziphus zuzuba Lamk.
0.46
0.29
0.02
0.26

(c) Aquatic plants

Enhydra fluctuans Lour.
0.5
2.1
1.35
0.7

Ipomea aquatica Forssk.
1.03
1.48
1.9
1.26

Pistia stratiotes Linn.
1.73
1.6
0.74
0.89

Table 6: Percent use of Staple food by Indian Rhino in Rajiv Gandhi Orang National Park (PM: premonsoon; M: monsoon; RM: retreating monsoon; W: winter).

Groups of plants
Staple food plants species
Proportional use of the staple food

Number
Proportional use
PM
M
RM
W

Grasses
24
75.97
70.68
83.56
78.17
71.46

Woodland
9
3.85
3.74
3.96
2.53
5.15

Aquatic
3
3.82
3.26
5.18
3.99
2.85

Total
36
83.64
77.68
92.70
84.69
74.46

3.1.9. Dietary Spectrum

The food selection pattern of the Indian Rhino showed a distinct dietary spectrum during present study. The study showed that up to 10 top ranking food plants species of Rhino constituted almost 56.44% of the total annual diet, but it was 72.19% up to 20 top ranking food plants species, whereas the rest 41 food plants constituted only 28% of the total annual diet of the Rhinos in Rajiv Gandhi Orang National Park (see Figure 8). Again, among the 20 top ranking food-plant species, 19 species were grasses, and only one species was aquatic plant species (Ipomea aquatica). This clearly indicated that the grass alone was the sufficient food items, of Rhino, necessary for survival in Rajiv Gandhi Orang National Park.

Figure 8: Dietary spectrum of Indian Rhino in Rajiv Gandhi Orang National Park (based on actual collected data).

3.1.10. Cultivated Crop

The study revealed that the Indian Rhinos in Rajiv Gandhi Orang National Park had often visited in fringe villages for depredation of cultivated crops. There were altogether 10 cultivated crops and 10 vegetables eaten by Rhino as their food. No quantitative analysis of the cultivated crops were made, that have consumed in dark hours of the day (Table 7).

Table 7: Cultivated crop and vegetable species eaten by Indian Rhino as food in association with natural food items (name written in parentheses are in local vernacular names).

Crops
Vegetables and others

Zea mays (zea)
Cucurbita pepo (summer Squash)

Oryza sativa (paddy)
Cucurbita maxima (red Pumpkin)

Cicer arietinum (gram)
Luffa acutangula (ridged gourd)

Pisum sativum (peas)
Cucumis sativus (cucumber)

Cajanus cajan (pigeon pea)
Capsicum annuum (chilli)

Phaseolus mungo (black gram)
Abelmoschus esculentus (lady’s finger)

Phaseolus lunatus (lima bean)
Cucurbita maxima (sweet gourd)

Phaseolus aureus (green gram)
Solanum melongena (brinjal)

Triticum aestivum (wheat)
Ipomea batatas (sweet potato)

Lathyrus sativus (khesari dal)
Carica papaya (papaya)

3.1.11. Geophagy (or Soil Eating)

There were altogether seven soil eating (soil licking) sites of Indian Rhinos in Rajiv Gandhi Orang National Park during study period (Table 8). The Rhino frequently visited the soil eating sites during night hours. It was also reported by the forest personnel that the Rhino occasionally consumed soil near the forest camps.

Table 8: Shows the soil eating sites in Rajiv Gandhi Orang National Park with GPS locations.

Location
GPS location
Remark

Camp/Beat
Location
Latitude and Longitude

Katasali Beat
(1) In front of the beat
92°15′13.43′′E 26°31′02.54′′N
Located under Acacia catechu tree

(2) North of the Katasali Beat
92°15′32.24′′E 26°31′02.73′′N
Located under Acacia catechu tree

(3) North-west of the Katasali Beat
92°15′05.59′′E 26°31′13.64′′N
Located under Acacia catechu tree

(4) West of the Katasali Beat
92°15′01.21′′E 26°31′57.47′′N
Located under Palm tree

Chandanpur Camp
(5) Near camp approaching point
92°15′13.43′′E 26°31′15.37′′N
Located under Acacia catechu tree

Satsimalu Beat
(6) South of the Guest house
92°18′34.02′′E 26°33′14.84′′N
Located under Lagerstroemia speciosa tree

Bantapu Camp
(7) In between Bantapu and Hatiputa camps
92°18′35.69′′E 26°32′21.87′′N
Located under Acacia catechu tree

4. Discussion

In present study, the consumption of 86.66% grass species followed by 6.68% aquatic plants and 6.66% woodland species (browse) by Indian Rhino indicates that, the grasses are the key food-plant species of Rhino in Rajiv Gandhi Orang National Park. This is also evident from the seasonal diet pattern, where 89.13% grasses were consumed during winter and 83.50% during premonsoon season. Laurie [4, 5] also reported that Indian Rhino at Nepal also consumed 86.4% grasses, 5.2% aquatic plants, and 3.4% browse from February–May (spring season), while 88.7% grasses, 5.7% aquatic plants and 5.6% browse from June–September (monsoon season) and 70.4% grasses, 8.0% aquatic plants and 21.6% browse from October–January (winter season). Those results supported the present findings of grass as the most preferred food items of Indian Rhino. Similar types of findings were also observed by Jnawali [19] in Bardia National Park and Chitwan National Park in Nepal. He suggested that a highest proportion of 92% grass species has used as the diet of Indian Rhino during monsoon in Bardia National Park and 86% in Chitwan National Park during hot season and lowest of 42–57% during winter season. Fjellstad and Steinheim [20] also suggested that the diet of Indian Rhino has consisted of 63% grass and 28% browse. This clearly indicates that, the Indian Rhino has mostly depended on grasses rather than browse or other aquatic plants. Hence, it could be opined that the Indian Rhino is more habitat specialized than any other large herbivore mammals. Fjellstad and Steinheim [20] also found in their study that Rhino depends on quality of food rather than quantity. They also found that Indian Rhino spent 85% total feeding time on three vegetation types, while there were six vegetation types for Asian elephant to reach the same habitat occupancy. Hence, the numbers of habitat types are limited for Indian Rhino.

Again, the number of food plant species of Indian Rhino varies from habitat to habitat, which was suggested by other studies. Laurie [4, 5] has stated that Indian Rhino fed on 183 food-plants species under 57 families in Chitwan National Park. Ghosh [12] has stated that the Rhino consumed 82 plant species belonging to 34 families in Jaldapara Wildlife Sanctuary. So, it is varied in all occasions. The present study indicates that the Indian Rhino of Rajiv Gandhi Orang National Park confined to 71 plant species of which 42 are grasses, 20 are woodland, and nine are aquatic species. This type of food composition is almost the same in different seasons of the year; hence, grasses play a major role in diet composition of Indian Rhino.

The mostly preferred 10 top ranking food plants are such as Hemarthria compressa (11.63%), Hymenachne pseudointerrupta (10.64%), Leersia hexandra (8.80%), Arundo donax (6.38%), Chrysopogon aciculatus (4.60%), Phragmites karka (4.42%), Brachiaria ramose (3.83%), Cynodon dactylon (2.11%), Saccharum spontaneum (2.05%), and Imperata cylindrica (1.98%), of which six species were positively selected for feeding. All these 10 species are confined to grasses and growing in wet grassland habitat. These findings of top ranking species are contradictory with the findings of Laurie [4, 5] and Ghosh [12] in Chitwan National Park of Nepal and Jaldapara Wildlife Sanctuary, West Bengal, respectively. But the study conducted by Bhattacharyya [11] in Kaziranga National Park of Assam is almost similar to our present study. This clearly indicates that the wet grassland habitat plays a vital role in the food selection by Indian Rhino in the Brahmaputra floodplain habitat of Rajiv Gandhi Orang National Park and as well as other protected areas of Assam, India, in comparison to other Rhino habitats of south-east Asia. Again, the present findings of 83.64% annual diet of Indian Rhino’s staple food in Rajiv Gandhi Orang National Park indicate that the Indian Rhino has a strong preference on certain food choice. Again the dietary spectrum of Indian Rhino further supports the strong selection of definite food plant species and the only 20 top ranking preferred food items constitutes 72.19% of the total annual diet of Indian Rhino in Rajiv Gandhi Orang National Park.

Crop depredation by wild elephant [21, 22] is a common phenomenon in India. But, the crop depredation caused by Indian Rhino in fringe village around the study areas is a new dimension of this aspect. Laurie [4, 5] Jnawali [23] and Bhattacharyya [11] has mentioned the crop depredation behaviour of Indian Rhino in India and Nepal. Like other large mammals, Indian Rhino in Rajiv Gandhi Orang National Park is also found to occasionally lick (eat) the soil in some specific locations. This is mainly due to compensation of mineral deficit of Indian Rhino in their regular diets. Gee [24], Laurie [4, 5], Ghosh [12], Dutta, [25] and Bhattacharyya [11] also suggested that soil licking behaviour of Rhino is mainly related to mineral deficiency of Indian Rhino in its feeding habitat. However, chemical analysis is suggested to find out physical need. These results are suggestive to limitations and requirements of different food items to fulfill the daily requirements of nutritional and energy supplement. The limited plant species in the diet of Indian Rhino, though a variety of plant species available to feed on, suggest that they obtain certain preferred food to fulfill the nutritional and energy requirements to survive and reproduce. In order to survive and reproduce, an animal depends on diet that should contain adequate and balanced essential nutrients. Larger species like elephant and Rhino tend to feed more because they need more energy. The age and sex variation also have some relationship with food intake. Females of some species tend to feed more on foliage than males because of greater protein requirement. Pregnant and lactating females tend to feed more on foliage because of an increase in metabolic rate.

Acknowledgments

The authors hereby acknowledge the help and support provided by the officials and forest guards of Rajiv Gandhi Orang National Park. They also acknowledge the help and support provided by the director of Manas Tiger Project Mr. Abhijit Rabha. They also acknowledge the support provided by Bhrigu Prasad Saikia and Sandipan Das, Research Scholar, Department of Zoology, Gauhati University.

References

P. O. Mary, G. S. Solanki, D. Limbo, and K. Upadhya, “Observation of feeding and territorial behaviour of Rhinoceros unicornis in Kaziranga National Park,” Tigerpaper, vol. 25, no. 4, pp. 25–28, 1998.

C. J. Krebs, Ecology: The Experimental Analysis of Distribution and Abundance, Harper and Row, New York, NY, USA, 1985.

R. E. Ricklefs, The Economy of Nature, W. H. Freeman & Company, New York, NY, USA, 5th edition, 2001.

W. A. Laurie, The Ecology and Behaviour of the Greater One-Horned Rhinoceros, Ph.D. dissertation, University of Cambridge, 1978.

W. A. Laurie, “Behaviourial ecology of the greater one-horned rhinoceros (Rhinoceros unicornis),” Journal of Zoology, vol. 196, pp. 307–341, 1982.

R. J. Deka, N. K. Sarma, and K. K. Baruah, “Nutritional evaluation of the principal forages / feed consumed by Indian rhino (Rhinoceros unicornis) in Pobitora Wildlife Sanctuary and Assam State Zoo-cum-Botanical Garden, Assam,” Zoos' Print Journal, vol. 18, no. 3, pp. 1043–1045, 2003.

A. Bairagee and J. Kalita, “Imperata cylindrica (Linn.) Raeusch in the grasslands of Pabitora Wildlife Sanctuary, Assam, India,” Zoos' Print Journal, vol. 19, no. 4, pp. 1432–1434, 2004.

K. C. Patar, Behavioural Patterns of the One Horned Indian Rhinoceros: Observations in Kaziranga National Park, Spectrum Publications, Guwahati, India, 2005.

R. L. Brahmachary, B. Mallik, and B. C. Rakshit, “An attempt to determine the food habits of the Indian Rhinoceros,” Journal of the Bombay Natural History Society, vol. 67, pp. 588–560, 1969.

R. L. Brahmachary, B. Mallik, and B. C. Rakshit, “Further attempts to determine the food habits of the Indian Rhinoceros at Kaziranga,” Journal of the Bombay Natural History Society, vol. 71, no. 2, pp. 295–298, 1971.

B. K. Bhattacharyya, Studies on certain aspects of the biology of the Great Indian One-horned Rhinoceros (Rhinoceros unicornis), Ph.D. thesis, Gauhati University, 1991.

D. Ghosh, Studies on the Eco-Status of the Indian Rhinoceros Rhinoceros unicornis with special reference to altered habitat due to human interference in Jaldapara Sanctuary, West Bengal, Ph.D. thesis, University of Ranchi, India, 1991.

B. C. Hazarika and P. K. Saikia, “Man Rhino Conflicts in Rajiv Gandhi Orang National Park, Assam. Abstract,” in National Seminar on Biodiversity Conservation and Future Concern, Gauhati University, 2005.

G. Banerjee, Habitat use by Rhinos and other sympatric species in Kaziranga National Park, M.S. dissertation, Wildlife Institute of India, 2001.

E. Dinerstein, “Seed dispersal by greater one-horned rhinoceros Rhinoceros unicornis and the flora of Rhinoceros latrines,” Mammalia, vol. 55, no. 3, pp. 355–362, 1991.

B. N. Talukdar and P. Sharma, Orang-Check List of the Birds of Orang Wildlife Sanctuary, Self Publication, 2nd edition, 1995.

T. R. E. Southwood and P. A. Henderson, Ecological Methods, Blackwell Science, London, UK, 3rd edition, 2000.

J. Altmann, “Observational study of behavior: sampling methods,” Behaviour, vol. 49, no. 3-4, pp. 227–267, 1974.

S. R. Jnawali, Population Ecology of Greater One Horned Rhinoceros (Rhinoceros unicornis) with particular emphasis on habitat preference, food ecology and ranging behaviour of a reintroduced population in Royal Bardia National Park in Lowland Nepal, Doctor Scientiarum thesis, Agricultural University of Norway, 1995.

J. I. Fjellstad and G. Steinheim, Diet and habitat use of Greater Indian one horned Rhinoceros (Rhinoceros unicornis) and Asian elephant (Elephas maximus) during the dry season in Babai Valley, Royal Bardia National Park, Nepal, M.S. thesis, Agricultural Unversity of Norway, 1996.

R. Sukumar, The Asian Elephant: Ecology and Management, Cambridge University Press, Cambridge, UK, 1989.

S. C. Dey, “Depredation by Wildlife in fringe areas in North Bengal with special reference to elephant damage,” Indian Forester, vol. 117, no. 10, pp. 901–908, 1991.

S. R. Jnawali, Park-people conflict: Interaction between Greater One horned Rhinoceros and people adjacent to the Royal Chitwan national Park in Sauraha area, M.S. thesis, Agricultaural University of Norway, 1988.

E. P. Gee, Wildlife of India, Coliins, London, UK, 1964.

A. K. Dutta, Unicornis, Konark Publishers, New Delhi, India, 1991.