Fleeting¹ sightings of the world's rarest antelope², the hirola, in a new safe haven³ are cases of mistaken identity, a survey has found.

一项调查发现，飞速消失的世界上最珍贵的羚羊生活在安全的天堂里，这个想法是错误的。

A bit special: A lone⁴ adult male

That has dashed（猛掷，冲撞） hopes that some of the last hirola have managed to colonise（开拓） a new territory where they would be less vulnerable to（易受……攻击） flooding and hunting.

Fewer than 600 wild hirola remain, confined to a small area in Kenya.

It is sometimes called a 'living fossil（活化石）', being the sole survivor⁵ of a once diverse（不同的，相异的） group of antelope species.

Prior to 1970, an estimated 14,000 hirola existed in the wild.

But the antelope soon came under a host of pressures which led to a dramatic decline in its population over the next 30 years.

Hunting and predation（掠夺行为） killed many, while the animals' range became restricted by habitat loss and an increase in human settlements and farms rearing livestock⁶.

That left few animals surviving in a small area along the border between the River Tana in Kenya and the River Juba in Somalia.

The Somalia population is already thought to be extinct, while in Kenya the antelope survives in pockets within the Ijara, Garissa, Tana River and Lamu districts, while two small groups of animals translocated（移位改变位置） to the Tsavo East National park and are struggling to establish there.

An emancipated⁷ group of hirola in the Ijara district of Kenya

Under pressure

However, in the 1990s two new threats emerged.

The collapse⁸ of the Republic of Somalia in 1991 precipitated⁹（沉淀的） a massive influx¹⁰（流入，涌进） of refugees into Kenya.

"The majority of the Somali refugees were resettled in Garissa district which is part of the hirola's natural range," says Yakub Dahiye of the National Museums of Kenya in Nairobi. "The presence of large numbers of refugees increased poaching（偷猎，非法狩猎） activities and general insecurity of the area."

In 1997 significant flooding caused by the El Nino weather phenomenon covered the region.

In response to both, many large mammals including the hirola migrated either to higher or quieter areas.

Then conservationists started receiving exciting reports of hirola in northern Garissa, an area outside of the antelope's known historical range, suggesting that the antelope was migrating to safer territory. Previously¹¹, the antelope was confined to the southern part of the district.

So to check the authenticity¹²（确实性，真实性） of the reports, Dahiye performed an extensive survey of the region.

For six days, he travelled more than 1100km criss-crossing（纵横交错） the northern Garissa, observing and recording¹³ from the top of a moving vehicle the identity and locations of wildlife in the area. He also showed pictures of hirola to local people, asking if any had seen the elusive¹⁴（难懂的，易忘的） antelope in recent years.

None had, and despite spotting giraffe（长颈鹿）, Grant's gazelles（小羚羊）, gerenuk（非洲瞪羚）, lesser¹⁵ kudu（条纹羚） and oryx（羚羊）, Dahiye did not see a single hirola, he reports in the African Journal of Ecology.

"That confirms that the species is endemic（风土的，地方的） to a small area between the lower River Tana in Kenya and the lower River Juba in Somalia," he says.

"If this small natural habitat is destroyed, then we will not have an in situ（在原地） hirola population."

Effective management plans for the species are still lacking, says Dahiye.

Back in 1974, the Arawale National Reserve was set up mainly to conserve¹⁶ the hirola, but the reserve was later abandoned.

Local communities in Ijara district have now responded by establishing a Community Conservation Area to help protect those animals living there, but wider, strategic plans have yet to be put in place to conserve the species, Dahiye says.

Evolutionarily unique

The hirola is special because of both its rarity and evolutionary¹⁷ uniqueness.

Scientifically named (Beatragus hunteri), the hirola belongs to the family Bovidae, the group that includes all antelopes¹⁸, cattle, bison（野牛）, buffalo¹⁹, goats and sheep.

Within that group, it belong to the subfamily（亚科） Alcelaphinae, meaning it is most closely related to topi（转角牛羚）, wildebeests and hartbeest antelopes.

But what makes the hirola stand out is that it is the last living representative of the genus Beatragus.

The International Union for the Conservation of Nature considers it to be the most at risk antelope species, listing it as Critically Endangered, while the Zoological Society of London includes the hirola within its EDGE programme, which seeks to conserve the most evolutionary distinct（独特的，不同的） and globally endangered of all animals.

Dahiye thinks that the unconfirmed sightings of the hirola in northern Garrisa, which sparked much excitement among conservationists, were cases of mistaken identity.

Local people call both hirola and impala antelopes by the same name in Somali, while the two species also look similar, he says.