by Yadav Sharma Bajagai
Area under consideration
Animals under consideration
Figure 2: Trend of kangaroo population in Australia .
Grazing behavior and diet selection
Sheep in rangelands are generally more selective feeder than cattle and goat but tend to eat range of plants as far as possible  to fulfill their nutrient requirement and have ability to choose feed according to their need . The range of acceptance widens during drought . Generally large and small sheep eat 23.5 g and 37 g DM per kg body weight daily .
They tend to graze more in the area of water hole especially in arid climate zone avoiding hottest part of the day to eat and go for the shelter . Sheep grazing on good quality lush pasture can fulfill major quantity of water requirement from plant and may require drinking in a few days interval but sheep foraging dry pasture should drink water more frequently . Vegetation near to water points often tend to be overgrazed .
In grasslands of Australian sheep rangelands, daily water consumption varies from 0.6 l per day to 6.2 l per day per adult and average daily distance walked for drinking ranges from 4.7 km to 6.2 km depending upon drinking frequency . But in saltbush area of sheep rangeland, volume of water consumed per day ranges from 2.3 l to 9.3 l according to season and sheep walk 8 km to 14 km per day according to drinking frequency . Drinking frequency is once daily in early summer and twice daily in late summer . They start to graze within one hour of sunrise  and seven percent of daylight hour is generally consumed to travel to and from water point . This duration may extend up to forty percent of daylight our (Burnside et al. 1990; as cited in O'Reagain and McMeniman 2002). Squires (1981; cited in O'Reagain and McMeniman 2002) has recommended to keep water points in 5 to 7 km apart.
Major part of kangaroo diet in sheep rangelands of Australia contains grasses and chenopods with small but regular amount of composites . Large and small kangaroos eat 21 g and 35 g DM per kg body weight daily . Grasses are first choice in lush season  and forbs are in second rank [20, 32] but chenopods are preferred only when grasses are scarce during dry period [30, 32]. They don't select particular parts of plants except avoiding woody stem and root .
Kangaroos are nocturnal in habit, therefore most of the grazing takes place at night . Grazing generally starts shortly before sunset  and continue till 10 PM then starts again in the morning till 10 AM .
They are very adaptable to dry condition and able to maintain only in dry forage for a few months . Mating generally takes place when there is enough green pasture and majority of females show anoestrus during drought . Forbs of genus Bassia are important feed source during drought which remains green and fleshy even in dry times .
Although some of the scientist [30, 34] have reported about exceptionally long distance travelled by some kangaroos, they are sedentary animals and like to remain in certain territory [31, 32, 34, 35] and tend to utilize feed within this range . When feed resources are scarce in home range the kangaroos become weak and some even may die in extreme cases . Male are more mobile than female and size of home range for adult female is 18 km and that for male is 36 km . They generally prefer to live in small group .