There is an iconic African mammal unlike any other. They blend in perfectly with the African savanna, randomly revealing themselves as they emerge from acacia thickets. They are the giraffes.
Giraffes are the tallest animals alive today. Males can reach an average height of between 4.9 – 5.2 metres (measured from the hoof to the top of the head upright) and 4.3 – 4.6 metres for females. Males weigh in at between 970 – 1 400 kg and females between 700 – 950 kg.
The bizarre anatomy of a giraffe has necessitated a range of unique physiological adaptations. The heart is extraordinarily large making up 2.3% of overall body mass compared to just 0.5% in most other mammals. Blood pressure is also higher than in other mammals and this is to facilitate blood flow through the long neck to the head against the forces of gravity. They have a sophisticated heat-exchange system including a large nasal surface area to assist with the cooling of blood. The patches on the giraffe’s body also contain sweat glands to assist with cooling. Giraffes are unable to pant to cool themselves down.
Giraffes are distributed in acacia-savanna and generally avoid open grasslands, deserts and forests. In tropical forests they are replaced by a close relative, the okapi Okapia johnstoni, a bizarre animal that looks like a hybrid between an antelope and a giraffe. In arid regions they are always found in the vicinity of water and along watercourses that have adequate acacia trees. Their dietary composition is made up principally of acacia leaves but they will also eat the leaves, flowers and seed pods of other trees including Combretum, Ziziphus and Terminalia. Many of these trees are adorned with spikes and thorns which present little trouble to a browsing giraffe. Acacia (or now Senegalia and Vachellia species in Africa) tend to have a higher protein content than other tree species, especially in the rainy season. They shift dietary preferences as the seasons change.
Giraffe regularly search for salts and minerals in sand and soil and may chew and ingest soil minerals. They are also known to chew on bones and animal skins to supplement their mineral intake. Calcium and phosphate are important minerals.
Giraffe breed throughout the year and have a long gestation period of just over 15 months. The calf weighs around 100kg at birth and has a shoulder height of 1.5 metres. The average lifespan for wild giraffes appears to be between 20 and 30 years.
The horns of giraffe are called ossicones and are covered in coarse hair. In males these horns are more pronounced and some individuals will develop a third horn on the centre of the head. Males engage in combat by necking each other, or in other words, using their long necks as battering rams. The males have a dense bony skull which they batter each other with and can sometimes lead to serious injury on the opponent.
A giraffe can obtain a top speed of around 56km/hour and they gallop in an ungainly manner. Speed is not their virtue when running from predators, but adults can deliver a lethal kick or stamp with their powerful legs. Due to their large size few predators will attack giraffe. In previous studies, giraffe have made up less than 2% of lion kills. They can move over surprising distances with some giraffes travelling over 20km in one day.
How many species?
The giraffe was for a long time considered one wide-ranging species distributed in sub-Saharan, with the various patterns conforming to at least seven or nine different subspecies. However, a recent revised taxonomy using multi-locus genetic sampling has identified four clades corresponding to four unique species (Winter, Fennessy & Janke, 2018).
These are as follows:
• Southern Giraffe (Giraffa giraffa) – with two recognised subspecies: giraffa giraffa (South African Giraffe) and giraffa angolensis (Angolan Giraffe).
• Northern Giraffe (Giraffa camelopardalis) – with three subspecies: camelopardalis camelopardalis (Nubian Giraffe); camelopardalis antiquorum (Kordofan Giraffe); and camelopardalis peralta (West African Giraffe). Note: Rothschild’s Giraffe is considered to be the same subspecies as the Nubian Giraffe.
• Reticulated Giraffe (Giraffa reticulata) – Kenya north into Somalia and Ethiopia.
• Masai Giraffe (Giraffa tippelskirchi) – throughout Tanzania and southern Kenya.
There is some consensus that Thornicroft’s Giraffe from the Luangwa Valley in Zambia (which is genetically subsumed within the Masai Giraffe) should still be recognised as a distinct subspecies due to its isolation and for conservation efforts. This race would effectively be Giraffa tippelskirchi thornicrofti.
In terms of population numbers, there is estimated to be less than 600 West African Giraffe, around 5000 Northern Giraffe, 15 000 Reticulated Giraffe, 34 0000 Masai Giraffe (data from the Giraffe Conservation Foundation). Estimates of decline over three decades show a 95% decline in Northern Giraffe populations, 60% decline in Reticulated Giraffe and around 52% decline in the Masai Giraffe.
Giraffes are important ecosystem engineers in the savanna biome. They shape tree structure and density, stimulate new growth, distribute seeds, and have been shown to aid pollination in several tree species. Therefore, their role in ecosystems are important.
The conservation status of giraffes has received much attention of late, especially with the realisation that this animal is not one widely distributed species, as previously believed. In the past decade, numerous populations have declined drastically.
The Kordofan and Nubian Giraffe is listed as Critically Endangered, while the West African, Reticulated, and Masai giraffes are Endangered. It is only the Southern Giraffe that seems stable and largely protected in numerous national parks, nature and game reserves and private game farms, although there is some indication that these populations are also in decline.
The main drivers leading to population declines include poaching and loss of habitat. The Kordofan and Nubian Giraffes occur in areas of regular human conflict and therefore their protection is difficult to enforce. The Masai and Reticulated Giraffes are better protected, but have also experienced strong declines in recent decades.
- O’Conner, et al. 2019. Updated geographic range maps for giraffe, Giraffa spp., throughout sub-Saharan Africa, and implications of changing distributions for conservation. Mammal Review 49: 285-299.
- Winter, S., Fennessy, J. & Janke, A. 2018. Limited introgression supports division of giraffe into four species. Ecology & Evolution 2018; 8: 10156-10165. DOI:10.1002/ece3.4490
Article and photos by: Warren Schmidt
Warren holds a Master of Science degree in Ecological Sciences awarded by the University of KwaZulu-Natal, South Africa. He has three decades of experience in ecology, conservation science, invasion biology and herpetology. He has worked as a journalist, magazine editor, and lecturer, and has presented talks, seminars, and lectures.