Common Features of Mammals
Females have mammary glands which produce milk for young to suckle. The body is covered in hair at some stage in development. They are endothermic (warm-blooded). The inner ear has a system of 3 highly specialized bones for hearing. The heart is 4 chambered.
Major Groups of Mammals
Monotremes
These are the most primitive mammals. The young develop in an egg similar to birds and reptiles. Eggs are either carried or laid in a warm nest. No African representatives. The majority of these animals live in Australia. Example- Duck-billed Platypus
Marsupials
These are mammals with an abdominal pouch called a marsupium. The young develop in the marsupium where they feed from the mammary gland. They are born very poorly developed due to a poorly developed plancenta and all the remaining development takes place in the pouch. These animals live predominantly in Australia and New Zealand. Example- Kangaroo and Wombat.
Placental Mammals
Placental mammals have a prolonged gestation period with a well developed placenta. This allows the young to develop more fully inside the female. There is a very advanced nutrient and waste exchange between mother and fetus. Examples- Any African mammal.
Foot Structures
Plantigrade
This is the most primitive foot structure and the animal stands on the entire length of the foot. Used by the orders Primates and Eulipotyphla (was Insectivora).
Digitigrade
The heel and instep are slightly raised so primary motion is on the toes allowing the animals to move quietly and quickly. Typical of predators of the order Carivora.
Unguligrade
Most plantigrade and digitigrades animals have 4-5 digits. Unguligrade are usually 3,2 or as little as 1 toe. They are divided into odd-toed ungulates (those with 3 or 1 toe) and even-toed ungulates (2 toes).
White Rhino
Order- Perissodactyla, Family, Rhinocerotidae Genus Ceratotherium, Species-simum For identification see black rhino. They are water dependent and drink every day where water is available and every few days when it is scarce. Most drinking is between 17h00 and 21h00.
They are grazers and feed predominantly in the early morning and late afternoon. They are heavily poached by man and occasionally killed by lions. Unlike black rhino the calves are seldom preyed upon by hyaena because of the greater protection of a larger group of animals. When alert they will look in the direction of the disturbance with ears pricked forward. They will then either come closer to investigate but may also run into the down-wind position to use their best sense- smell. When they become agitated they may snort and paw the earth. They are less aggressive than black rhino but the safety precautions on foot are the same. White rhino are born after a gestation of 16 months and will live for about 40 years. Only 1 offspring born at a time. Calves wean at about a year and remain with the mother until 2-3 depending on the onset of her next pregnancy. Once the calf is seen off by the mother it will remain with other rhino until grown. At 8 they are fully grown but females may have their first calf as young as 6. Males are usually only competitive for territory and females after 10.
The social structure is that of a small group that consists of a territorial bull with several cows and their calves and often submissive bulls are also included in the group. Cows have home ranges and are not territorial. Bulls mark territory with dung middens and urine spraying.
Vocalizations are snorts, snarls and squeals.
Hippopotamus
Order Wippomorpha, Family Hippopotamidae Hippopotamus amphibius Hippo are water dependant. They are grazers and feed predominantly at night and will graze about 40kg of grass every night. As adults they are hunted only by humans and lions. Very rarely hyaena may attack the young on land and in the water large crocodiles may also attack young calves. When a hippo becomes alert it stops and listens. It will turn in the direction of the disturbance. Warning signs include staring, holding head high and bobbing head. Taking a few steps towards you and opening the mouth are serious warning signs and often followed with a serious charge. Hippo seldom mock-charge. For this reason if you encounter a hippo on foot with guests – get out of there quickly. If while extracting from the encounter the hippo charges there is no point standing your ground. Get to whatever cover you can as quickly as possible and do not block the animals path to the water. Getting between an alarmed hippo and the water is the surest way to get killed! Hippo calves are born after a very short gestation of only 8 months and the young weigh between 40-50kgs. Females will have their first calf at around 4 years old but young bulls only mature sexually at 7. Only 1 offspring born at a time. Young cows will stay within a herd their entire lives. Bulls will only begin to fight for territory at 12-15 under normal circumstances and only about 10% of bulls will ever hold territory. Many bulls will live as submissive bulls within the family groups and are tolerated by the territorial bull as long as they display the correct submissive gestures. Other bulls will exist as solitary bachelors and may from time to time challenge the territorial bull for dominance. Serious fights are common and often result in death. Territory is marked by vocalization and display in the water and on land by thrashing dung on bushes and tree stumps throughout the area. Average lifespan in the wild is 40 years. Vocalizations are usually a series of grunts and underwater they use clicks similar to that of whales. When fighting males utter bellowing screams and growls.
Large Herbivorous Animals
Herbivore Digestive Systems
Ruminants have a 4 chambered stomach. The first 2 chambers are known as the rumen and reticulum (together called the reticulorumen) and in these chambers food (digesta) separates according to particle size. Larger, poorly chewed particles drift to the top and form the cud. This cud ball is then regurgitated back into the mouth where it is chewed again. While the food is in the reticulorumen the cellulose is broken down through fermentation by micro-organisms. The now finely chewed and fermented food particles are dissolved in saliva and re-swallowed. They more liquid contents with finer foods separate to the bottom of the reticulorumen and flows into the omasum. The function of the omasum is to recycle the saliva by absorbing water and inorganic minerals. Once most of the water has been absorbed the food particles pass into the abomasum. The abomasum is the acid stomach and breakdown here is no longer through fermentation but now uses acid. After acid breakdown absorption continues as the food moves into the small intestine and when it reaches the last stage, the large intestine, fermentation and absorption continues. All antelope are ruminants as are giraffe. Hind-gut fermenters – This refers to herbivores with a single stomach. Fermentation takes place in the large intestine and caecum after passing through the acid stomach. Because acid cannot break down cellulose and the digesta is exposed to the acid before fermentation (where the cellulose is broken down) the digestion is not as efficient as ruminant digestion. However hind-gut fermenters are able to survive on a lower quality food than ruminants. Hind-gut fermenters include elephant, both rhino, zebra and warthog Foregut fermeters- Hippo.
Most herbivores, including browsers, grazers, ruminants and hind gut fermenters practice geophagy where they intentionally eat clay soil. The soil contains trace elements which animals need for normal body function. Because of the nutrient poor Kalahari sands on which most of the plants grow, many of these trace elements are missing from the diet.
Grazers can be selective and these have narrow mouthparts for selecting specific graze (eg Springbok) or they may be bulk grazers (eg zebra). Bulk grazers have broader mouths and feed indiscriminately on all types of graze.
Mixed feeders are able to feed on browse and graze and include impala and eland. Omnivores feed on plant and animal matter. Fructivores feed primarily on fruit.
Caracal
Order Carnivora Family Felidae Felis caracal
Caracal are solitary and predominantly nocturnal predators with a stalk and pounce method of hunting. The prey is made up of mostly medium sized mammals and birds but exceptionally sprinbok and even adult impala are killed by males. When threatened they will flatten their ears and snarl and hiss with the body flattened to the ground. Caracal are home-range animals and females have smaller home-ranges than males. A dominant males home-range will overlap the home-range of 3-4 females and will constantly check the reproductive status of the resident females by testing where they have scent marked. When a female is receptive the male will locate her and they will mate After a gestation period of 80 days an average of 2 cubs are born. They will spend about 10-12 months with the female before dispersing and will live to about 17 years. No reliable records of weaning age are available.
Serval
Order Carnivora Family Felidae Felis serval
Serval are solitary and activity times depend largely on preferred prey. In most areas they are primarily nocturnal but in others they are primarily diurnal. They are stalk and pounce predators that feed predominantly on rodents and birds. The massive ears are adapted to hunting in long grass and swampy habitat where visibility is poor. The long legs allow the serval to move through this terrain easily and improve pouncing ability. Serval are home-range animals with significant overlap of home-ranges. A dominant males home-range will overlap the home-range of 3-4 females and will constantly check the reproductive status of the resident females by testing where they have scent marked. Mating takes place throughout the year but peak breeding times are in late summer where 2-3 kittens are born after a gestation of 70 days. They remain with the mother for over a year before dispersing. No reliable records of weaning age are available. Average lifespan in the wild is 17 years.
African Wildcat
Order Carnivora Family Felidae Felis lybica
African wildcat are solitary, nocturnal stalk and pounce predators feeding primarily on rodents and birds. May also take small antelope, arthropods and occasionally fruit. Wildcats are strongly territorial and both males and females mark and defend territory. Males are alerted to a females coming into oestrus by testing the urine they have used for scent marking. After a gestation period of 2 months an average of 3 kittens (1-5) are born, usually in a disused springhare or aardvark burrow. Average lifespan in the wild is 15 years.
Spotted-necked Otter Order Carnivora Family Mustelidae- Lutra maculicollis
Spotted-necked otter are primarily crepuscular in their activity. They are aquatic predators feeding mainly on small fish and crabs. Although spotted-necked otters are often solitary after breeding they may be in family groups of up to 5 but rarely aggregations of up to 10 may be seen together. The Okavango has good populations but elsewhere this otter is rare. It is protected under CITES Appendix 2. They are territorial and the female will leave the water to have her pups in secluded hollow or crevice where they are safe from all predators except python. An average of 2 cubs are born and there is no evidence of breeding seasonality. Observations from guides in Botswana would be appreciated.