Giant eland

The giant eland, also known as Lord Derby's eland or greater eland, is an open-forest and savanna antelope. A species of the family Bovidae and genus Taurotragus, it was described in 1847 by John Edward Gray. The giant eland is the largest species of antelope, with a body length ranging from. There are two subspecies: T. d. derbianus and T. d. gigas.
The giant eland is a herbivore, eating grasses, foliage and branches. They usually form small herds consisting of 15–25 members, both males and females. Giant elands are not territorial, and have large home ranges. They are naturally alert and wary, which makes them difficult to approach and observe. They can run at up to and use this speed as a defence against predators. Mating occurs throughout the year but peaks in the wet season. They mostly inhabit broad-leafed savannas, woodlands and glades.
The giant eland is native to Cameroon, Central African Republic, Chad, Democratic Republic of the Congo, Guinea, Mali, Senegal, and South Sudan. It is no longer present in The Gambia, Ghana, Ivory Coast, and Togo. It can also be found in the Jos wildlife park in Nigeria, Guinea-Bissau, and Uganda. The subspecies have been listed with different conservation statuses by the International Union for Conservation of Nature.

Etymology

The scientific name of the giant eland is Taurotragus derbianus, derived from three words: tauros, tragos, and derbianus. Tauros is Greek for a bull or bullock. Tragos is Greek for a male goat, and refers to the tuft of hair that grows in the eland's ear which resembles a goat's beard.
The giant eland is also called "Lord Derby's eland" in honour of Edward Smith-Stanley, 13th Earl of Derby. It was due to his efforts that the giant eland was first introduced to England between 1835 and 1851. Lord Derby sent botanist Joseph Burke to collect animals, either alive or dead, from South Africa for his museum and menagerie. The first elands introduced in England were a pair of common elands, and what would later be identified as a giant eland bull. The details were recorded in Smith-Stanley's privately printed work, Gleanings from the Menagerie at Knowsley Hall. The Latin name indicates that it "belonged to" Derby, hence derbianus.
Although the giant eland is somewhat larger than the common eland, the epithet 'giant' actually refers to its large horns. The name 'eland' is Dutch for "elk" or "moose". It has a Baltic source similar to the Lithuanian élnis, which means "deer". It was borrowed earlier as ellan in the 1610s or elend.

Taxonomy

The giant eland was first described in 1847 by John Edward Gray, a British zoologist, who called it Boselaphus derbianus. At that time, it was also called the 'black-necked eland' and Gingi-ganga.
Giant eland is placed in the genus Taurotragus of family Bovidae. Giant elands are sometimes considered part of the genus Tragelaphus on the basis of molecular phylogenetics, but are usually categorized as Taurotragus, along with the common eland. Together with the bongo, Giant eland and common eland are the only antelopes in the tribe Tragelaphini to be given a generic name other than Tragelaphus. Although some authors, like Theodor Haltenorth, regarded the giant eland as conspecific with the common eland, they are usually considered two distinct species.
Two subspecies of giant eland have been recognized:

Image	Name	Distribution
	T. d. derbianus J. E. Gray, 1847 – western giant eland	found in western Africa, particularly Senegal to Mali
	T. d. gigas Heuglin, 1863 – eastern giant eland	found in central to eastern Africa, particularly Cameroon to South Sudan

Description

The giant elands are spiral-horned antelopes. Despite its common name, this species broadly overlaps in size with the common eland. However, the giant eland is somewhat larger on average than the common eland and is thus the largest species of antelope in the world. They are typically between in head-and-body length and stand approximately at the shoulder. Giant elands exhibit sexual dimorphism, as males are larger than females. The males weigh and females weigh. The tail is long, having a dark tuft of hair, and averages in length. The life expectancy of giant elands is up to 25 years.
The smooth coat is reddish-brown to chestnut, usually darker in males than females, with 8–12 well-defined vertical white stripes on the torso. The colour of the male's coat darkens with age. According to zoologist Jakob Bro-Jørgensen, the colour of the male's coat can reflect the levels of androgen, a male hormone, which is highest during rutting. Comparing the subspecies, T. d. derbianus is characterised by 15 body stripes, smaller size, and a rufous colour, while T. d. gigas is larger, a sandy colour, and has 12 body stripes.
A crest of short black hair extends down the neck to the middle of the back, and is particularly prominent on the shoulders. The slender legs are slightly lighter on their inner surfaces, with black and white markings just above the hooves. There are large black spots on the upper forelegs. The bridge of the nose is charcoal black, and there is a thin, indistinct tan-coloured line, which is the chevron, between the eyes. The lips are white, as are several dots along the jawline. A pendulous dewlap, larger in males than females, originates from between the jowls and hangs to the upper chest when they reach sexual maturity, with a fringe of hair on its edge. The large ears of the giant eland serve as signaling devices. Giant elands have comparatively longer legs than the common eland, as well as much brighter black and white markings on the legs and pasterns.
Both sexes have tightly spiraled, V-shaped horns. They can be up to long on males and on females. Males have horns that are thicker at the ends, longer, and more divergent than those of females. These features of the horns suggest that the giant eland evolved from an ancestor with true display horns.

Parasites

Fecal studies of the western giant eland revealed the presence of a newly found species Eimeria derbani, of genus Eimeria, which consists of Apicomplexan parasites. The sporulation lasted for two days at a temperature of. The species has been differentiated from E. canna and E. triffittae, which parasitize the common eland. The giant eland is also parasitised by Carmyerius spatiosus, Taenia crocutae and T. hyaennae.

Genetics and evolution

The giant eland has 31 male chromosomes and 32 female chromosomes. In a 2008 phylogenomic study of spiral-horned antelopes, chromosomal similarities were observed between cattle and eight species of spiral-horned antelopes, namely: nyala, lesser kudu, bongo, bushbuck, greater kudu, sitatunga, giant eland and common eland. It was found that chromosomes involved in centric fusions in these species used a complete set of cattle painting probes generated by laser microdissection. The study confirmed the presence of the chromosome translocation known as Robertsonian translocation, a widespread evolutionary marker common to all known tragelaphid species.
An accidental mating between a male giant eland and a female kudu produced a male offspring, but it was azoospermic. Analysis showed that it completely lacked germ cells, which produce gametes. Still, the hybrid had a strong male scent and exhibited male behaviour. Chromosomal examination showed that chromosomes 1, 3, 5, 9, and 11 differed from the parental karyotypes. Notable mixed inherited traits were pointed ears like the eland's, but a bit widened like kudu's. The tail was half the length of that of an eland with a tuft of hair at the end as in kudu.
Previous genetic studies of African savanna ungulates revealed the presence of a long-standing Pleistocene refugium in eastern and southern Africa, which also includes the giant eland. The common eland and giant eland have been estimated to have diverged about 1.6 million years ago.

Habitat and distribution

Giant elands live in the broad-leafed savanna, woodlands, and glades of central and western Africa, which correspond to the two subspecies. They also live in forests as well as on the fringes of deserts. The giant elands can also live in deserts, as they produce very dry dung. They are found in South Sudan and Central African Republic into northern Cameroon and southern Chad.
They inhabit places near hilly or rocky landscapes and those with water sources nearby. Science author Jonathan Kingdon had thought the giant elands lived only in woodlands of Isoberlinia doka, an African hardwood tree. The giant eland is adapted to these broad-leafed, deciduous Isoberlinia woodlands. Recent studies proved that they also inhabit woodlands with trees of the genera Terminalia, Combretum, and Afzelia.
In the past, giant elands occurred throughout the relatively narrow belt of savanna woodland that extends across West and Central Africa from Senegal to the Nile. Today they are conserved in national parks and reserves, and occur mostly in Senegal. The western giant eland is largely restricted to Niokolo-Koba National Park in Senegal. The eastern giant eland is found in several reserves, for example in Bénoué National Park, Faro National Park and Bouba Njida National Park in Cameroon and in Manovo-Gounda St. Floris National Park in the Central African Republic. They are also kept in captivity.

Ecology and behaviour

Primarily nocturnal, giant elands have large home ranges and seasonal migration patterns. They form separate groups of males and of females and juveniles. Adult males mainly remain alone, and often spend time with females for an hour to a week. A gregarious species, giant eland herds usually consist of 15–25 animals and do not disband during the wet season, suggesting that social rather than ecological factors are responsible for herding. During the day, herds often rest in sheltered areas. As many other animals do, giant elands scrape mineral lick sites with the help of horns to loosen soil.
Giant elands are alert and wary, making them difficult to approach and observe or to hunt. If a bull senses danger, he will give deep-throated barks while leaving the herd, repeating the process until the whole herd is aware of the danger. Giant elands can move quickly, running at over, and despite their size are exceptional jumpers, easily clearing heights of. Their primary predators are the lion, nile crocodile and spotted hyena, while young, sickly and a rare adult may be vulnerable to leopards, cheetahs and African wild dogs. Due to their large size, they prove a good meal for the predators. However, they are not easily taken by any predator, especially the heavier and larger horned bulls which can be a dangerous adversary even for a lion pride.