The distribution of Soemmerring's gazelle (Gazella soemmerillgi), which had a wide range inrnthe East Ali"ica, is currently dwindling with the increasing human population density in thernprevious range. In Ethiopia, it had a wide range in the Eastern and Northeastem part 0 f therncountry. However, the population is declining, because of the loss of important habitats as arnresult of overgrazing, indiscriminate killing and other human factors. Field study on thernpopulation status and some ecological aspects of the species was conducted every month fromrnJanuary to December 2000 for eleven months in I1ala Sala (Awash National Park) and forrnnine months (April to December) at Alledeghi Wildlife Reserve. The result indicated thatrnmean populations of 457.8 individuals were found in the selected study site in AlledeghirnWildlife Reserve, and 41.9 individuals were counted at IIala Sala - Awash National Park.rnGrouping pattem showed that cohesion was stronger. TelTitorial males detain females andrnother members of the group. The difference in mean group sizes of the gazelle between therntwo areas was significant. In comparing the two populations based on the main categories therndifference was not significant (p=0.795). Mean group size for ANP was 4.4 while for A WR itrnwas 16.8 individuals. A paired-sample t-test comparison of the total fi'equency of categoriesrnof the group sizes for the two areas showed a significant difference (p=0.026). Local variationrnin group size did exist in AWR (p=0.021). But this variable showed no significant differencern(p= 0.414) in ANP. Herds of 6 - 10 were most common at Ilala Sala and 20 - 50 at AWR.rnHowever, herd size ranges Ii-om 3 - 250 individuals at A WR. Compating seasonal variationsrnin group sizes showed no significant difference. The proPOliioni of time budgets apportionedrnto the five types of activities vatied among seasons and month~' Feeding activity comprisesrnmuch of the time budgets of Soemmerring's gazelle ranging fr, m 39.8 to 50.7% during therndry season from 38.4 to 45.7% in the wet season in male an from 51.0 to 59.6% in dryrnseason and from 59.8 to 64.6% in wet season in female. Df:.S:tribution of group sizes inrngrassland habitats of the two study sites showed a very high si ificant difference (p=O.OO).rnHigh proportion of groups of Soemmerring's gazelle was obsen ed in short-sized grass coverrnin Alledeghi Wildlife Reserve, where as in Awash National Ii frk most were observed inrnmedium-sized grass cover. Open grassland habitat was the best p; rferred habitat to other.rnV111rnungulate evolves behavioral and morphological adaptations that optimize the tradeoffsrnbetween these problems. Thus, within the constraints of effective strategies againstrnpredator and successful mating, one would expect strong selective pressures towardsrnefficient use of energy and nutrients for maintenance and reproduction. Ungulates showrnvariation in ecological behavior in response to environmental stress through time andrnspace. Some move to higher elevations in spring and summer in search of nutritious, newrngrowing forage (Festa-Bianchet, 1988), while others migrate to exploit temporalrndifferences in vegetation phenology (Berger, 1991).rnForage quality, quantity and predator avoidance influence the migratory behavior ofrncertain mammals (Festa-Bianchet, 1988). Habitat selection by an animal reflects a strategyrnthat enhances survivorship and successful reproduction (Bowyer et ai., 1998). Onernsolution offered to explain how animals deal with conflicting needs to forage efficientlyrnand avoid predation is selection of habitats that minimize the ratio of predation risk tornavailable forage (Pulliam and Danielson, 1991). Conversely, such animals would tend tornavoid other habitats in which predation risk is higher and value of food lower. In areasrnwhere there is an inverse linear relation between risk of predation and forage, animalsrnwould be distributed mostly in the habitat with low predation and high forage. If, however,rnanimals are displaced from this optimal habitat, because of inter-specific competition orrndominance interactions with superior individuals, sub-optimal habitats could be selectedrnuntil predation become too severe or forage too limiting for them to persist (FestaBianchet,rn1988).rnMany of the life history characteristics of ungulates are shaped by risk of predationrn(Berger, 1991; Festa-Bianchet, 1988; Hilih, 1977), and predators are capable of regulating populations of ungulates under celiain conditions (Van Ballenberghe, 1987; Van Ordsol,rn1984). Selection of habitat is likely to depend upon a dynamic set of conditions thatrninclude the 'state' of the individual, its environment, and perhaps its past and potentialrnfuture state (Mangle and Clark, 1986 cited in Festa-Bianchet, 1988).rnBehavioral information is essential to the full understanding of the ecology of a species.rnDifferent animals show different behavioral responses to the ecological changes that occurrnin their habitats, seasonal changes of the year, and presence or absence of predators, etc.rnVigilant behavior, as one of the behaviors observed in response to various changes in thernenvironment, may help an animal to locate food source and avoid capture by predatorrn(Bertram, 1980). Underwood (1982) investigated vigilance behavior in several Africanrnantelopes in relation to finding food as well as in avoiding predation. Large predatorsrnprefer tall grass for successful hunting. Van Ordsol (1984) noted that hunts by lions werernmore successful in tall grass than in short grass. On the other hand, prey species likernreedbucks of the family Rudincinae prefer long grass to avoid predators (Irby, 1982;rnRoberts and Dunbar, 1991). Jamlan (1974) suggested that non-cryptic animals have tlll'eernmajor strategies available to avoid predation: (i) detecting the predator before it initiatesrnthe attack, (ii) outLUnning the predator during the attack, or (iii) attacking the predator.rnThis study will examine, in part, the response of the Soel11l11ert'ing's gazelle to predation inrndifferent heights of grass cover.rnSeasonal movements in water-dependent large communities show a wet season dispersalrnand dry season concentration which can be related to the seasonality of rainfall and waterrnavailability, but those similar pattems do not prevail in the water-independent speciesrn(Durant et al., 1986). It is suggested that seasonal migration of herbivores in the grassland ecosystems of Eastern Afi'ica is correlated to the availability of green vegetation and hencernin the proportion of important nutrients.rnDifferent species of animals make seasonal movements between habitats. In areas wherernfood resources change with seasons, populations of mammals are known to move fi'omrnone type of habitat to another depending upon the season (Began et al., 1986). Thernavailability of food resources affect the population dynamics and distribution of an animalrnspecies (Caughly and Sinclair, 1994). Knowledge of the relationship of an animal with itsrnhabitat is essential in understanding the ecological requirement of the species (Caughly,rn1977). In addition knowledge in the feeding habits of an animal are essential for makingrnand designing strategies for management.rnMany studies have dealt with the various ecological and behavioral aspects of the Wildlifernin AfiÂ·ica. Of the nearly dozens of gazelle species found in Africa, only few are wellrnstudied: Thomson's and Grant's gazelles are the most studied fi'om East Africa (Estes,rn1967; Walther, 1977), while the dorcas (Gazella dorcas) and dama (Gazella dama) (Salah,rn1987; Yoram Yom-tov, 1987; Grettenberg, 1986) gazelles fi'Om North Afi'ica and thernMiddle East have been studied to some extent. Excessive hunting by people, excessiverngrazing by domestic livestock, agricultural el(pansion, and other habitat modifications arernidentified as the main factors that adversely affected most population of the gazelle in thernMiddle East and Nm1h Africa (Salah, 1987). Little is known about the ecology andrnpopulation status of SoenmlelTing's gazelle.rnSoemmerring's Gazelle (Gazella soemlllerillgi) belongs to the family EOl'idae, subfamilyrnAntelopini. This Gazelle is large in size, with an elongated head and a relatively short neck (Dorest and Dandelot, 1970). It is adapted to bush and acacia scrub in hilly areas asrnwell as open grassy plain (Kingdon, 1997). This gazelle generally inhabits thorn bush,rnopen and grassy plain in hilly country and is considered to be both browser and grazerrn(Estes, 1991). It feeds on grass and herb, but may also browse on leaves of shrubs. Likernother African wildlife species, Soemmerring's Gazelle is affected by the rapid growth ofrnhuman population, which has an increasing demand of new land for agricultural expansionrnand grazing livestock (Hillman, 1988).rnIn most of its habitats, Soennnerring's gazelle has suffered from decades of uncontrolledrnhunting with firearms and severe habitat degradation caused by man and domesticrnlivestock, accentuated by recurrent droughts. These factors have reduced this formerlyrnabundant gazelle to scattered, remnant populations and its 10ng-teJID survival isrntluÂ·eatened. It occurs in few conservation areas such as Awash and Yangudi Rasa nationalrnparks, which have been considered as the important areas for the conservation of thisrngazelle.rnThe status of Soemmell'ing's Gazelle is classified as "Vulnerable" in the IUCN'srn(International Union for the Conservation of Nature and Natural Resources) Red DatarnBook (IUCN 1990). The species is under high pressure of threat to extinction within itsrnhighly restricted distribution. The distribution of Soemmerring's Gazelle in Ethiopia wasrndescribed as locally common in the N0l1heastell1, Eastell1 and Southeastell1 lowlandsrn(Hillman, 1988). However, recent reports indicate that the species is exterminated over therngreater part of their range, and occurs in numerous pockets (Kingdon, 1997).rnSchloeder et al. (1997) have repot1ed that large propot1ion of the population of the speciesrnin the Rift Valley of Ethiopia occurs in the Alledeghi Wildlife Reserve and the adjacentrnAfdem-Gewane Controlled Hunting Area. Thouless (1995) recorded 2,650 gazelles at thernAlledeghi plains on the grassland plain to the West of the A wash River and North of therncentral part of the Awash West Controlled Hunting area. Soemmerring's Gazelle has alsornwide geographical range in Eastem Ethiopia. Their status was assessed in Aysha-Jijigarnregion by Thouless (1995) and in the Ogaden Region by Wilhemi (1997). These repot1srnindicated that the population of the species is greatly on the decline.rnAlthough the status of Soemmerring's Gazelle is considered stable in the Awash Valleyrn(Schloeder et al., 1997), its size in the Awash National Park (ANP), which is legallyrnprotected, has declined as compared to other antelopes (Almaz Tadesse, PersonalrnCommunication). The population has declined by over 82% in 27 years and its importantrnhabitat shrunk by a similar margin (Schloeder et al., 1997).rnAssessment of the current status and ecology of So emmer ring's gazelle is impot1ant for thernpark management and will also provide some information on the existing knowledge gaprnon ecology of this gazelle.