Status, distribution and habitat use of Tibetan Gazelle in Upper Mustang , Nepal
( Procapra picticaudataHodgson, 1846)
Introduction
Tibetan Gazelle ( Procapra picticaudata Hogdson, 1846) is a
new species to Nepalrecorded by the Upper Mustang Biodiversity Conservation Project during 2001
(Shah 2001). Until that time no information on population status, distribution
and habitat use pattern of the species were known in Nepal. The species has been listed as Insufficient Known Category in the IUCN Red
Data Book. The population of the species throughout its distribution ranges has
been reported as depleted to an endangered level due to illegal hunting for
flesh and skin (Schaller, 1998). However, till date no such information is
available from Upper Mustang, Nepal. Literature survey reveals that there have been many studies else where but
all are related to Mongolian gazelle Procapra gutturusa (Wang et al. 2002;
Leimgruber et al. 2001; Jiang et al. 1998, 2002; Milner-Gulland 1998; Reading
et al. 1998). In this paper an attempt has been made to assess its population
status, distribution and habitat use in Dhalung Rangeland. Drive count and
vantage point count were used to know the status and a comparison of the
pellets/dung sample along well defined transects was the key basis for the
comparison of the habitat use.
This study is a part of the biodiversity status survey
undertaken in August 2004 by the Upper Mustang Biodiversity Conservation
Project (UMBCP) implemented by the National Trust for Nature Conservation
(KMTNC) through its Annapurna Conservation Area Project (ACAP).
Dhalung pasture
Dhalung pasture is located towards the north of Upper
Mustang. Dhalung is an important summer pastures for nomads. The nomads use the
pasture for nearly four months to graze their livestock which comprises of
sheep, goat, yak and horses. A total of 38.5 sq km. area is covered by Dhalung
pasture. This is the pasture where Tibetan Gazelle breeds during the summer
seasons and this pasture is also an important refuge habitat of Tibetan Wild
ass which uses this pasture during April to early July (Chetri and Gurung
2004).
The climate of the area can be characterized as cold desert,
desiccated by strong winds and high solar radiation. The maximum and minimum
temperature recorded during July and in January is 18°C and -12°C. The whole
pasture remains under snow for 4 – 5 months from November to March. Total
annual rainfall is less than 200 mm and more than half of the total
precipitation occurs as snow during winter. The region falls under the
Dhaulagiri–Annapurna mountain rain-shadow zone. The vegetation represents high
altitude grasslands that are Tibetan in characters (Stainton 1972).
Population status and
distribution in Dhalung Rangeland
A total of 46 Tibetan Gazelle (male to female ratio 3:4,
female to lamb 4:1) with ecological density of 0.84 animal/sq km. (Chetri 2005)
was recorded in Dhalung Rangeland (Figure 1). This indicates a healthy
population which encompasses the whole Dhalung Rangeland (38.5 sq km.).
However, the high variation of female to lamb ratio may indicate a loss due to
predation from golden eagle ( Aquila chrysaetos ), grey
wolf ( Canis lupus ) and red fox ( Vulpes vulpes ). While conducting the survey
a pair of red fox was observed chasing a herd of 11 gazelle. Interview with the
Nomads reveals that high predation by grey wolf occurs during the winter where
the movement of the Gazelle was limited due the snow. The altitude range of the
gazelle in Dhalung Rangeland ranges from 4822 to 5119m. 73 % of the gazelle
were recorded (based on direct sighting and pellets) at an altitude range of
5000-5119m and rest 27% were recorded at an altitude of 4822-4999m. The mean
altitude range is 5032 m.
Habitat Use: Transect
Survey for pellets/dung
The habitat of Tibetan Gazelle in Upper Mustang is located
along the border between Tibetan Autonomous Region of China and Nepal(Figure 1). Three transects were fixed covering the main habitats of Tibetan
gazelle with the help of Global Positioning System (GPS). 10 m2 (1.78 m radius)
circular plots were placed at 50m intervals along the well defined transect
lines and observations were made whether the pellets samples were present in
the plots. Habitat preference (HP) of the species was calculated as:
HP = Pellets/dung present in each habitat type/Total
pellets/dung present in all the habitat types X 100
A comparative assessment was made with regard to slope,
aspect and vegetation types. Analysis of the data with respect to slope showed
that gazelle prefers mostly 0-5 ° slope to graze. This finding is also
supplemented by the direct observation of the gazelle during the time of
counting (see Chetri 2005) as well as from Habitat Preference value (Table 1).
At localities above 20 ° slopes, no sign of gazelle was recorded. Although no
significant difference was observed in the used of slopes ( c 2=2.25; p>
0.05, df=3), the preference to slopes are in the sequences: 0-5° > 6-10°
>11-15° > 16-20°. Maximum number of time gazelle utilized the 0-5 º slope.
A significant difference was observed in the used of aspect ( c 2=16.57; P<
0.05, df=8). However, the preference to west slope is higher (see Table 1).
Possible reasons are: a) less human disturbances in comparison to East and
North and b) high distribution of palatable species and waterholes nearby. The
sequences of preference to aspect are: West>Gentle >East >Northwest
>North >South >Southwest >Southeast. Of the three types of
vegetation compared, a Chi-square test did not show any significant difference
among the use of three dominated vegetation communities ( c 2 =1.67; P>
0.05, df=2). Habitat preference value indicated that gazelle prefers to graze
in the graminoids dominated grassland compared to other vegetation communities.
The sequences of preference to three vegetation communities are: graminoids>
forbs>shrubs.
More than 53% of the vegetation is dominated by Kobressia
species which is the favorable food items of both gazelle and domestic animals.
The preferences of food items of Gazelle are quite similar with that of goat
and sheep (Chetri 2005). Campos-Arceiz et al. (2004) found a high degree of
food overlap between Mongolian gazelle and sheep/goat in Mongolia. In the case of the Tibetan gazelle, an increase in the livestock population
could lead to overgrazing and food shortages, under these conditions, a food
overlap is likely to lead to competition (Schoener 1983; de Boer & Prins
1990; Putman 1996). During summer, the nomads from Chinashift from Yakra towards the Dhalung pasture and settle near the border area.
Yakra is their winter pasture located approximately 120 km. from the boarder
area towards the North. Similarly, one nomad family from Chhunjung area used to
shift the camp to graze in the Dhalung during the summer. The habitat of the
species is in pressure due to overstocking of livestock. Wang et al. (2002)
reported that overstocking has recently produced a serious degradation of
semiarid grassland in Inner Mongolia . The same cannot
be ruled out in case of Dhalung rangeland considering the overflow of livestock
from the border areas.
Table 1: Distribution of pellets of Tibetan gazelle
according to vegetation communities, slope and aspect (the number in
parenthesis indicate Habitat Preference value, total no of plots observed, N =
157)
Vegetation Communities
Slope
Aspect
Forbs – 22 (31.2)
Graminoids - 27 (38.6) Shrubs – 21 (30.0)
0-5 ° - 35 (50.0)
6-10 ° - 19 (27.1)
11-15 ° - 13 (18.6)
16-20 ° - 3 (4.3)
21-25 ° - 0 (0.0)
26-30 ° - 0 (0.0)
East – 5 (7.1)
North – 8 (11.4)
Northeast – 14 (20.0)
Northwest – 1 (1.4)
South – 6 (8.6)
Southeast – 1 (1.4)
Southwest – 1 (1.4)
West – 20 (28.6)
Gentle – 14 (20.0)
Conclusion
Dhalung pasture is one of the hotspots of Tibetan gazelle as
it has high quality pasture, preferable forage and abundant waterholes. The
grazing pressure/disturbance in the pasture is high during the summer season.
The nomads were also found concerned over the disturbances to wild animals.
Gazelle herds were found grazing together with goats and sheep implying a fact
that Gazelle was adapted to a level of human disturbances. However, there is an
urgent need to find out whether there is a competition or plausible
relationship among the livestock and wildlife. During the summer season, forage
will presumably be nutritious and abundant, so the possibility of strong
competition will be minimal but during the time of food scarcity competition is
likely to take place. Thus, the management and controlled grazing of this
grassland is crucial but equally challenging.
(by Madhu Chetri)
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