Critically Endangered Species of the Week: the Black Rhinoceros!

    Today is our last Critically Endangered Species of the Week; sad, I know! All I hope is that this segment has helped highlight a few of the many endangered species in different evolutionary groups, and that some of you may think more than you did about what a large impact human society is having on other species. Thanks for reading these, and today I thought we would look at a larger, more well-known species: the Black Rhinoceros.

The Black Rhinoceros, native to Africa and critically endangered.
Photo from the IUCN.

About:
    The Black Rhinoceros, Diceros bicornis, is one of the most well-known critically endangered species on Earth; being a somewhat 'poster-species' against poaching. They have two horns, the anterior longer than the posterior, and sometimes a third horn further back [2, 3]. Individuals may weigh 800-1,400 kg [3].
    Black Rhino occur in a variety of habitats, from desert in Namibia to wetter forested areas. They are found in highest densities on savanna. The rhinos are browsers, feeding mainly on small Acacias and other woody species of plant, herbs and succulents [1, 2, 3].
   Like White Rhino, Black Rhino are actually grey but have an identifiable pointed upper lip due to plucking off leaves and fruit for their browsing diet [2, 3]. Aside from females and their offspring, individual Black Rhino are solitary [2, 3]. Females reproduce every two and a half to five years, with calves becoming independent only after three years [2]. Black Rhino can reach 40-50 years of age [3]. 

The Black Rhinoceros, Diceros bicornis, has been hunted almost
to extinction for it's horn. Photo from National Geographic.

Geographical Range in the wild:
    There are actually three remaining subspecies of the Black Rhino, due to their occupation of different African countries. The D. b. michaeli subspecies is found in primarily Kenya, South Africa and Tanzania [1, 3]. D. b. bicornis occur likely in only Namibia and South Africa [1, 3], and D. b. minor can be found in South Africa, Zimbabwe and southern Tanzania [1, 3]. All subspecies have much wider historical ranges, but are extinct in many of their native African countries - a fourth subspecies is also considered extinct.

Geographical range of the Black Rhinocerous.
Red = extinct, Orange = extant, Purple = Reintroduced,
Blue = Introduced. Map from IUCN.

   I find it particularly sad that the IUCN cannot even release more detailed information than the country on the whereabouts of rhino populations for fear of poaching.

Number left in existence:
    Throughout much of the 20th century the Black Rhino was the most numerous of the world's Rhino species, with a population of around 850,000 [1].
    The population of Black Rhino has declined by around 97.6% since 1960 [1, 3]. Numbers were at an all-time-low in 1995 with 2,410 (Emslie and Brooks, 1999), but have steadily increased to 4,880 by the end of 2010 (Emslie, 2006; AfRSG data 2008, 2011) [1, 3]. However current numbers are still 90% lower than they were three generations ago [1].

Why they are endangered:

• The main, historical, threat to the Black Rhino is poaching for the international trade in rhino horn [1, 2, 3]. A recent surge in black market prices for rhino horn has lead to an increase in poaching in some ranges; this has also coincided with its new use to supposedly treat cancer (unsubstantiated).
• They are hunted for traditional rhino horn use in Chinese medicine, and secondly for ornamental use; i.e. it is highly prized to form handles of ceremonial daggers used in some Middle East countries [1, 2].
• Black Rhino populations have also suffered due to African civil unrest and free flow of weapons since the 1960s; this has hampered conservation efforts (Emslie and Brooks, 1999; 1, 3). Due to this, funds have also been diverted away from wildlife conservation, and further harmed the species.
• Like other species, the Black Rhino is also under threat of habitat changes and alien species [3].

What can we do to help?
    Many measures to protect the Black Rhino are already in place (thanks to it being a large, well-known species): all international commercial trade in Black Rhinos and their products has been prohibited; many remaining individuals are present in fenced sanctuaries with more concentrated law enforcement; populations are constantly monitored and managed; and animals have been translocated to set up new populations [1, 3].
   Additionally, the rhinos are now managed by a range of different stakeholders to increase their long-term security, and several regional Africa rhino conservation initiatives operate [1, 3].
   Thankfully all that needs to be done to hopefully improve population numbers is continued enforcement of the above measures, and increased effort to improve biological management so we can aid rising populations more. However, the Black Rhino is very much in the minority of endangered species that are actually receiving sufficient aid, and so it needs to be remembered how much other species need similar help.

Watch this video to see Black Rhino closer up!

From the National Geographic on the move of a Black Rhino

to an American conservation centre.

References:
1. http://www.iucnredlist.org/details/6557/0 
2. http://animals.nationalgeographic.co.uk/animals/mammals/black-rhinoceros/
3. http://wwf.panda.org/what_we_do/endangered_species/rhinoceros/african_rhinos/black_rhinoceros/
4. http://www.bbc.co.uk/nature/life/Black_Rhinoceros