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|White Rhinoceros - Ceratotherium simum|
|Tweet Topic Started: Jan 7 2012, 02:08 PM (2,866 Views)|
|Taipan||Jan 7 2012, 02:08 PM Post #1|
White Rhinoceros - Ceratotherium simum
Body Length (head/body): 142-165 in.
Tail Length: 25-39 in.
Shoulder Height: 67-81 in.
Longest recorded anterior horn – 62 ¼ in.
Base of horn – 22 ¼ in.
Obtained in South Africa around 1845 by Roualeyn Gordon Cumming of Altyre, Scotland.
Second longest anterior horn – 54 ½ in.
Base of horn – 21 ½ in.
Females 1,800 kg (3968 lbs); Males 2,700 kg (5952 lbs)
Body part weight of a 4,413lb. rhino:
Head 410 lbs
Pelvis 256 lbs
penis 62 lbs
Nuchal hump and neck 425 lbs
Stomach 107 lbs
Intestine, small 64 lbs
Intestine, large 708 lbs
Lungs and heart 90 lbs
Liver 64 lbs
Kidneys 20 lbs
Spleen 11 lbs
Body 818 lbs
Left foreleg and shoulder 332 lbs
Right foreleg and shoulder 310 lbs
Left hind leg 265 lbs
Right hind leg 283 lbs
Liquid (including estimated loss in evaporation) 188 lbs
•Very thick, gray skin with deep folds; heavy, stocky body; short neck, large head; almost hairless (except for fringes of ears and tip of tail); Two horns on the rostrum, one in front of the other.
oHigh point (=crests of dorsal vertebrae) on the back is saddle area.
oBroad, flat upper lip
oFlexible neck; large bulge (nuchal hump) visible on dorsal side of the neck.
oTend to hold the head low during rest
oFront edge base of anterior horn tends to be straight edged
oTracks longer; outer toes more separated from center; prominent notch along back edge
•Little sexual dimorphism; males tend to be larger and may have shorter, thicker horns.
•Some females have forward pointing horns.
•Male with backward facing genitalia (as in hippo)
•Males w/o scrotum (testes abdominal)
•Female with two teats
•Scent glands: possible preputial gland in white rhino.
•Poor eyesight; easier to discern a moving object than a stationary one; there is very little overlap in field of vision of the two eyes, limiting the forward, 3 dimensional view. The rhinoceros has weak vision and is able to see a moving person from 90 to 150 ft (30 – 50m) but is unable to detect a person standing still at 100 feet.
•Good sense of smell and hearing. Rhinos have an excellent sense of smell. The nasal cavity takes up more space in the skull than that of the brain.
"Whenever one sees a white rhino in the wild, one cannot escape the impression of size, of incredible benign strength and of a strange inner passiveness. The creature looks peaceful, amiable and secure. If a creature can be said to have discovered transcendental meditation, then it must be the white rhino. They have about themselves a distinct aura of calm and I have to admit to finding them quite pacifully beautiful. Yet I have seen them in another light: not charging malevolently or stomping and pawing the ground with bull-like suppresses anger, but rather cavorting like lambs in a field, chasing each other like puppies. I have to add, however, that the ground shook."
Quote by Martin Booth taken from the book Rhino Road
The southern white rhino is the most numerous of all the world’s rhino taxa and its main stronghold is in South Africa. The approximately 11,600 southern white rhinos have a discontinuous range that has been reduced to national parks, private conservancies and other protected areas. Historically they have had a much more restricted distribution that the black rhino. 94% of the wild white rhinos live in South Africa, 4% live in Botswana (reintroduced), Namibia (reintroduced), Swaziland (reintroduced), Zambia (introduced), Zimbabwe (reintroduced) and the remaining 2% are located in Kenya (introduced), Tanzania (introduced) and the Ivory Coast (introduced). Altogether, there are 248 discrete populations, 10 of which are considered key to the species survival. The largest single population of over 1,600 animals is in Hluhluwe/Umfolozi Game Reserve in South Africa; a location that proved to be critical to their survival as a species.
South Africa. Player & Feely (1960) listed four basic habitat requirements: - areas of short grass, for which they have a marked preference; - stands of medium tall Panicum maximum which they find under trees (Emslie, pers. comm.); - the availability of water for drinking and in which to wallow; - adequate bush cover, and relatively flat terrain. These requirements are met in the wooded grasslands, common in many parts of the Subregion, where they formerly occurred. This woodland carries the palatable grasses which form their principal food. Reintroduced to areas where these conditions prevail, the species is flourishing. The type of woodland is a secondary consideration, for its function is to provide shade from the sun during the hotter parts of the day. Steep slopes within the habitat are avoided, although they will traverse them freely to feeding grounds or to water. Melton (1987) found that white rhinoceros showed a reduction in broad scale habitat selectivity during winter, changing from favoring the Acacia nigrescens open woodland in west Umfolozi in summer to using habitats at random during winter.
TERRITORY AND HOME RANGES
Territorial white rhino bulls occupied non-overlapping home ranges and left these territories only to proceed to and from water. In some instances one or two adult bulls shared the home range of a territorial bull but behaved in a subordinate manner. Territorial bulls ejected their urine in powerful sprays, while subordinate bulls and cows urinated in a conventional stream. Territorial males scattered their dung after defecating, while subordinate males, females and subadults did not scatter their dung or only made a few ineffectual kicking movements. The annual range size of territorial white rhino males in the south-western KNP ranged from 6,2 to 13,8 km² with a mean of 9,9 ± 3,4 km². Associated core area sizes ranged from 1,7 to 4,2 km² with a mean of 2,7 ± 0,8 km² . The boundaries of annual ranges for males did not overlap although short forays into neighboring ranges were occasionally observed. The annual range size of white rhino females ranged from 7,2 to 45,2 km² with a mean of 22,8 ± 11,9 km² . The sizes of the associated core areas ranged from 2,9 to 8,9 km² with a mean of 4,7 ± 2,1 km². Annual ranges of females showed extensive overlap. The mean annual range size of male white rhino differed significantly from that of females (P= 0,005, n = 15). There was also a significant difference in core area size for male and female white rhinos (P=0,011, n=15). Two male territory takeovers were observed during the study period. In one case the defeated male moved to a neighboring territory where he assumed a subordinate position. In the second case, the defeated male stayed on in the same territory but restricted his movements to a small area and assumed a subordinate position. In both cases the defeated territorial males ceased to spray-urinate or scatter their dung. No seasonal movements, such as those mentioned by Heppes for the northern white rhinoceros Ceratotherium simum cottoni, were found in the present study although white rhinoceros females did show a seasonal variation in range size. In the summer wet season, the mean range size of white rhino females in the KNP was 21,44 ± 11,98 km² compared with 11,64 ± 6,2 km² in the winter dry season (P= 0,03, n = 8). The wet season range size was comparable to the annual range size, whereas a reduction in range size was observed during the dry season. The ranges of territorial males did not show seasonally induced shifts in size. One white rhino female, however, had a dry season range that was larger than the wet season range. Table 1. Comparison of white rhinoceros densities (animals per km²), male territory and female range sizes ( km²) in four game reserves; The Kruger National Park, Umfolozi Game Reserve and Ndumu Game Reserve in South Africa and Kyle National Park in Zimbabwe Area Density Male Female territory range Kruger 0,5 – 1,4 6,2 – 13,8* 7,2 – 45,2 Kyle 0,7 5 – 11 * 3 – 20 Ndumu 0,6 – 1,8 2,5 – 13,9 4,7 – 22,9 Umfolozi 3,2 – 5,7 0,75 – 2,6* 8,9 – 20,5 * Male territory sizes are significantly smaller than female ranges.
•Most active (feeding) during early morning and late afternoon; least active (rest period) during midday; also active (alternating between eating and resting) at night.
•Periods of rest and sleep both last an average of 1.5 to 3 hours, but vary with season, temperature, and cloud cover. Sleep periods can last as long as 10 hours.
•Usually rest lying down, as opposed to standing
•Resting occurs at night, hottest part of the day, and during prolonged periods of feeding.
•Daytime resting spots (bare ground, in the shade) are used communally by individuals who are grazing in the same area.
•Not observed to lie downwind, as seen in black rhinos.
Kruger NP. White rhino are selective grazers; no browsing was observed in the KNP or in the Umfolozi Game Reserve. Forbs were also avoided and white rhino even avoided favored grass patches that contained plenty of forbs. In the Umfolozi Game Reserve Owen-Smith noticed that during the wet months white rhino concentrated their grazing on short grass grasslands. As the dry season advanced and the short grass grasslands were depleted, they shifted their grazing to areas of medium-tall Themeda grassland. By the end of the dry season white rhinos moved up into hill slopes to graze remaining reserves of taller grassland. In the KNP white rhino also sought out short grass species such as Sporobolus nitens, Dectyloctenium segyptium, Panicum coloratum, Urochlos mosembicensis and Digiteris spp. White rhinos were very partial to shade grasses, in particular Panicum maximum and actively sought out these grasses along the riverbanks. Themeda triandre was only grazed after a burn when it was freshly sprouting. White rhino were very partial to freshly burnt areas and on a number of occasions they were observed to feed on the burnt stubble the day after a block had burnt. As the dry season advanced the white rhino continued to select the more palatable grasses and did not shift their diet towards the taller stands of Theinede. In the late dry season white rhino would extend their feeding activities into the midslope areas where they would walk from tree to tree and feed on Panicum maximum growing in the shade. In the granitic Pretoriuskop area of the KNP rainfall is high, the soils are deep and sandy and the foot slopes are not well developed. In these areas termite mounds are important feeding sites for white rhino.
White rhinoceroses are also very partial to wallowing in the mud-holes that form on the clayey soil on the bottom-lands. It seems thus that the Combretum woodland landscapes fulfill most of the white rhinoceros’s needs. Wallowing also took place at waterholes. White rhino either rolled in muddy hollows to secure a thick coating of mud or they lay down in pools of water for periods of up to several hours. Following a mud wallow, white rhino rubbed themselves against stumps or rocks in the vicinity. Ticks that had been rubbed off with the mud could be seen.
•Fairly sedentary; do not disperse rapidly.
•Walking speed (i.e., towards a water-hole): 3.0 – 3.8 kg/hr (1.9-2.4 mi/hr)
•Trotting speed (i.e., to escape a threat; maintained for several km): 29 km/hr (18 mi/hr)
•Galloping speed (charging by adult males when provoked; short distances): up to 40 km/hr (24.8 mi/hr)
Owen-Smith distinguished five social categories differing in their patterns of interaction, spatial dispersion and roles in reproduction: i. juveniles; ii. Subadults; iii. Cows; iv. Territorial adult males; v. subordinate adult males. White rhino cows were usually accompanied only by a single calf, while white rhino bulls were most often solitary. Subadults tended to be associated in pairs, either of the same or opposite sex. Groups of three generally consisted of either a subadult attached to a cow-calf pair, or an adult male accompanying a cow plus calf. A few groups comprised three or more subadults and in one instance a group of seven subadults was seen. The average group size in the KNP was 2.1-2.3 animals.
COURTSHIP AND MATING
The mating of the white rhino is non-seasonal, but the rain seasons tend to promote estrus and more mating (H. ZOO, 2006; Pienaar Social 1994). The female estrus cycle is approximately 30 days long while gestation lasts 16 months (S. D. ZOO, 2003; Pienaar Social 1994). The males’ testes are in the abdomen and have genitals that face the posterior like the hippo (S. D. ZOO, 2003). The litter will only consist of one calf that is weaned after a month, but will continue to nurse up to a year after birth and will stay with the mother for 2-3 years until she kicks the older offspring out in preparation for a new offspring’s arrival. The inter-birth interval is usually 2-4 years, but can occur as early as 22 months after birth (H. ZOO, 2006).
For 2-3 weeks, when a female is in estrus, the male that occupies the territory she is presently using will try to be near the female or constantly in her presence. While the female is still rejecting the male’s attempts and acting aggressive towards him, the male will give a hic-throb call that signals he is approaching the female (S. D. ZOO, 2003; Estes, 1999). The male is extremely patient during courtship. If the female tries to leave the male’s territory, the male will stand directly in her path and chase her while squealing to prevent her form leaving. The male will not follow the female into another male’s territory if she successfully crosses the boundary. When a female accepts the male her tail curls and allows for the half hour copulation (S. D. ZOO, 2003).
REPRODUCTION AND MOTHER/OFFSPRING BEHAVIOR
Behavioral observations of captive white rhino indicated estrous cycle lengths ranging from 30-90 days, whereas Owen Smith reported an estrous cycle length of about 30 days for animals in South Africa. Wagner (1986) said 42 days. Another study using urinary steroid analysis indicated the estrous cycle was 25 and 32 in lengths for northern and southern subspecies respectively. Finally, Radcliffe et al. 1997 using combined ultrasonography and faecal progesterone metabolite monitoring in one white rhino showed an initial period of ca. 3 months in which there was some ovarian activity, but no ovulation, followed by 2 non-conceptive cycles (31-35 days in length) and 2 conceptive cycles which ended in early embryonic death after day 28. The conceptive periods were 73-78 days in length, and the luteal structures persisted 42-48 days.
The estrous cycle length is approximately 28 days (n=5) based on the inter-estrus intervals and hormonal profiles of captive C. s. cottoni.
The calf is weaned at about 12 months of age but stays with the mother for the first 2-3 years of its life.
•Snort: Keep away. Used by all except territorial males.
•Snarl: (“gruff vocal roar”): Keep away. Stronger message than the snort.
•Pant: A message to restore contact; between mother and young, or male and female adults.
•Hic (“repetitive wheezy exhalations, with a throb produced at the initiation of each inhalation”): Male announcing his approach to a receptive female.
•Squeal: To stop a female from leaving a male’s territory; courtship context; produced at a territorial boundary.
•Shriek: Fear. From one territorial male towards another to keep him from attacking.
•Whine (“a thin mewing tone”): Distress call used by calves.
•Gasp-Puff: Sudden fright
At the end of the dry season when water is scarce some mates have to cross other territories on their way to water. This leads to an increase in conflict and more fighting ensues. In the Kruger National Park this contributes to an increase of adult male mortalities at end of dry season. On a game farm more than one waterpoint would lessen the friction between territorial males. Typical fighting wounds seen on male white rhino other than obvious lacerations on the head include broken jaw bones, wounds between hind legs, punctured abdomens, broken front legs and dislocated hind legs. These wounds are usually fatal. A game farmer should also be able to distinguish territorial adult males from subordinate adult males.
Male collected in Umfolozi in 1961. Death ensued from a fight with an adult male, a broken left rib being one of the injuries sustained. The right ramus of the mandible had previously been broken. The blow responsible for the injury could have been delivered at a gallop of 40 kph. In this instance, pugnaciousness from pain of the injury (perhaps incurred from the same antagonist) may have led indirectly to death by combat.
ANTIPREDATOR BEHAVIOR AND
A bull Ceratotherium simum charged a pride of lions and sent one male lion clean through the strong boundary fence.
Meanwhile 2 white rhinos have been lost. One was a calf killed by an adult bull white rhino, the other a female who died after breaking her leg in a waterhole.
Ceratotherium simum – Kruger NP, reintroduced. An adult bull fell down a steep embankment in search of water in the Numbi area. It found the steep bank of the ravine impossible to negotiate and died here before it was found. A cow drowned when she attempted to cross the Sabi River at a deep point.
Fighting between territorial bulls accounts for 50% of mortalities. If young animals are introduced onto properties where rhinos occur, territorial bulls may injure or kill the new animals. A natural mortality rate of 6% can be expected for young rhinos.
Parasites found on white rhinos: nematodes, trypanosomes, piroplasms, gyrostigmid fly larvae (bot flies), blood sucking flies (Rhinomusca dutoiti), and ticks.
Lion Predation on White Rhinos
Ceratotherium simum – Kruger NP, reintroduced. A very large bull was so badly mauled by lions at Mlakeni that it had to be destroyed. Pienaar, U. de V., 1970.
In 1987, 4 dead rhino were found and the horns retrieved. One was killed as an immature at Chinga by lions.
Gavor, I.K.N., 1988. Status report: Rhinos in Botswana. Report: pp. 1-10
Mala Mala Private Game Reserve
Late in the month, a rhino cow was killed on the eastern bank of the Sand River on northern Charleston. Nobody saw this animal being killed, but its distress calls were heard from a camp on Charleston late one night, and they went on for a couple of hours. The next day, a few lionesses were found at the carcass, and they had started feeding. It was only later that the six males of the Eyrefield Pride were seen at the kill, along with four lionesses of the same pride. These ten lions remained at the carcass for a week, eating at leisure, and passing rather large quantities of very dark, very liquid, very pungent dung! Nobody knows for certain which lions had killed the rhino, but one would certainly think that the six males would have been more likely to succeed in bringing down such a large beast, than a group of lionesses. Whatever the case, the males of the Eyrefield Pride certainly became pretty possessive of the carcass and the area around it, and there was evidence to suggest that other lions had dared approach the area, and had been chased away by the roaring Eyrefield Males.
The young male seen in poor condition near the New Airstrip last month eventually succumbed to the predators and was eaten by the Styx Pride and Split Rock Males.
(Same account as above)
Then midway through the month the whole pride was found on a sub adult rhino carcass close to Rattray’s Camp on the Western Bank of the Sand River . How the rhino died is still a mystery, but there is a strong feeling that the lions had in fact killed the young rhino, which had been seen limping and alone in the area for a few days prior to this.
The Southern Pride was seen attacking a fully mature White rhino this month as well! The pride only managed to wound the rhinoceros, but it was later established that it succumbed to the wounds, probably because of septicaemia. We have seen this rhino frequently and were noting that it had not been in top condition for a long time already. The lions must have picked this up and attempted the kill. A few days after the attempt by the pride, the rhino was found dead and the Southern Pride was observed feeding on the carcass for a few days.
(Same account as above)
An adult White Rhino bull was attacked by one of our lion prides this week. They only managed to wound the rhino, but a few days later it was found dead. It appeared as if a severe infection of the wounds, and thus septicemia, caused its death.
We were well aware of the bad condition the old bull was in before it was attacked by the lion pride and the infection from the wounds sustained by the attack must have been too much for him. After its death the carcass attracted hundreds of vultures and of course predators such a Spotted hyena, leopard and lion. At one instance, three leopards were seen feeding off the carcass simultaneously. A great spectacle that was certainly enjoyed by our guests!
In 13 years in the Mala Mala Private Game Reserve, 3 white rhinos were killed by lions. One subadult, one juvenile, and one sick bull.
Owen-Smith also gave the following annual mortality figures for white rhino: Adult males 3%; adult females 1.2%; subadults 3%, juvenile calves (0.5-2.5 years) 3.5% and infant calves (0-0,5 years) 8,3%. Predation does not have a big influence on a white rhino population. There have been a few cases in the KNP where white rhino calf’s were killed by lions. Animals with pieces of tail or ear missing that could indicate predation by hyena are also seldom seen. Other accidental white rhino deaths include drowning, getting stuck in mud, failing off cliffs, being killed by elephants and burning in runaway fires.
A summary of white rhino deaths attributed to lions.
1970 – Kruger NP- 1 death
Translocated bull – mauled by lions – had to be destroyed
1987 – 1 death – Botswana
In 13 years in the Mala Mala Private Game Reserve, from 1988 to 2000 – 3 deaths
1- sick bull
June 2005 – 1 death – Mala Mala Private Game Reserve
Adult cow – no witnesses to the kill, apparently healthy
May 2006 – 1 death – Mala Mala Private Game Reserve
Subadult Male – poor condition, limping
June 2006 – 1 death – Mala Mala Private Game Reserve
Adult bull – bad condition – lions wounded bull, he died from infections, septicaemia.
On small conservation areas, white rhinos and elephants may fight. Thirteen white rhinos were killed by young elephant bulls in Pilanesberg Game Reserve. A case has also been recorded of a hippo attacking and biting rhinos at a feeding site. The hippo was eventually killed by the territorial rhino bull. Fights may also break out between white and black rhinos – a case of a white rhino bull killing a black rhino bull is on record.
Londolozi Rangers, 2003. Rhino bull kills hippo bull. CCA Ecological Journal 5: 108
Fifty-eight white rhinos and five black rhinos were killed by elephants in Hluhluwe-Umfolozi Park between 1991 and 2001. The culprits were probably young male elephants that are entering musth younger in the absence of older males. Rhino deaths were more frequent from July to December and were distributed throughout the reserve. Deaths were associated with rivers, with 76% of carcasses being within 1 km of a river. Deaths were predominantly adult rhinos (86%), with a ratio of about 0.76 :1 . Given the success of the introduction of older male elephants to Pilanesberg National Park, which stopped young bulls entering musth and ended rhinos, being killed by elephants, introducing older male elephants is supported as a solution for Hluhluwe-Umfolozi Park, and for all reserves that have this problem.
POPULATION AND CONSERVATION STATUS
oC.s. cottoni (northern) CR = Critically Endangered
oC.s. simum (southern) NT = Near Threatened
oC. s. simum from South Africa, Appendix II
oall other populations of both subspecies, Appendix I
•Southern white rhino recovery is one of the most remarkable conservation achievements. Down to about 20 animals in South Africa, strict protections were put in place and the population grew. By 1961, individuals were being moved and reintroduced to other parts of southern Africa. Now it is the most numerous species of rhinoceros in the world.
Wild population – February 2005
Northern White Rhino: >10
Southern White Rhino: ~ 11,320
These are just brief excerpts from my personal white rhino report, I have much more information but I fear that I have posted too much already. I hope some of it will be of value to the few who are interested in this magnificent animal. I ended my rhino report with this quote from R.C. Dryer:
‘If there’s anything more to know about a rhino, it can only be of interest to another rhino’
|Taipan||Jan 9 2012, 09:37 PM Post #2|
Edited by Taipan, Jul 13 2015, 04:49 PM.
|Taipan||Jan 9 2012, 09:39 PM Post #3|
|221Extra||Sep 15 2012, 08:35 AM Post #4|
Old account of White Rhinoceros killing Lion in defense of calf:
"While we can always guarantee that you will see thousands of animals, it is more a matter of luck to witness interesting game incidents or even to see some of the rarer species. For instance, the lion-and-Rhino battle on August Seventh, which was reported in detail in the October issue of Ngorongoro's Bulletin. For the benefit of those who did not read the bulletin this is what happened: on August Seventh, an extremely interesting incident concerning a Rhino and a lion was observed in the crater by Licenced Guide Shehe. At 10.30 a.m. a lion tried to kill a Rhino, Felicia's eleven-month-old calf. Felicia who lives to the north of Lake Makat is rather hostile normally, and when her off-spring was in danger she was quite fierce. The lion managed to separate the calf from the mother. The calf ran away and the lion gave chase, with Felicia lumbering behind in hot pursuit, bellowing loudly. The calf circled back towards its mother, and Felicia immediately engaged the lion. The lion grabbed her by the hind leg and clawed and chewed her thigh viciously. Felicia wheeled round and gored the lion twice in the centre of the ribs. The lion rolled over paralysed by the tremendous blows. She then gored him in the neck, in the head and trampled him to death in a matter of minutes. Two other lions had sat by during the entire incident and kept a respectable distance. Within forty minutes of the killing the carcass was eaten clean by hyaenas. It is understood that a party of visitors from West Germany was lucky enough to film or to photograph the whole act."
Edited by 221Extra, Sep 15 2012, 08:35 AM.
|221Extra||Dec 23 2012, 06:40 PM Post #5|
Old article from old forum, for whatever reason didn't get transferred to this forum:
Science: Stocky rhinos confound the zoologists
04 July 1992
From New Scientist Print Edition.
Rhinoceros leg bones are much stronger than they need to be, say two zoologists who have tested the bones of a white rhinoceros that died recently at Whipsnade Zoo. The finding has important implications for studies of dinosaurs' bones: it may overturn the palaeontologists' assumption that the weight of a dinosaur was simply related to the maximum stress its leg bones could tolerate.
Robin McNeil Alexander of the University of Leeds and Caroline Pond of the Open University measured leg-bone sections of the white rhinoceros (Ceratotherium simum). From film of a rhino trotting and galloping they calculated the stresses which occur in the leg bones of a running rhinoceros. They concluded that the legs of these animals provide an unusually high margin of safety (Journal of Zoology, vol 227, p 63).
Rhinos, along with elephants and hippos, are the heaviest of all living land animals, weighing about 2200, 5000 and 1500 kilograms respectively. Such heavy bodies would seem to require very thick legs as supports, but McNeil Alexander and Pond question this assumption. They point out that the legs of giraffes are not especially thick, although their mass - about 1200 kilograms - is little different from a hippo's.
Over the past decade, McNeil Alexander has shown that an elephant's mass severely limits its running speed. In the same way, the mass of the even larger dinosaurs limited their maximum running speeds.
Elephants can manage only a slow run of about 5 metres per second if the stresses in their relatively long legs are to be kept within acceptable limits by a rather straight-legged gait. The maximum speed of the largest dinosaurs probably did not exceed that of a human's fast walk.
By comparison, the rhino has short thick legs with bones strong enough and muscles powerful enough to achieve speeds of up to 7.5 metres per second. This is slightly above the maximum recorded speed for a buffalo, 7 metres per second, but considerably less than the giraffe's 11 metres per second.
McNeil Alexander and Pond calculated that the stresses in a rhino's leg bones while it is trotting are significantly lower than those in the bones of buffalo, but similar to those in the bones of a cantering horse.
The two biologists concluded that low stresses in rhino leg bones may imply that their skeletons are built to unusually high margins of safety. However, the researchers do not know why.
Edited by 221Extra, Dec 23 2012, 06:41 PM.
|Taipan||Jun 9 2015, 05:36 PM Post #6|
Then There Were 5: Inside the Race to Save the Northern White Rhino
by Stephanie Pappas, Live Science Contributor | June 08, 2015 07:39am ET
Sudan is the last male northern white rhinoceros in the world.
For decades, humans have slaughtered Africa's rhinoceroses, driven by the Eastern medicine market's demand for their horns. On a reserve in Kenya, the end result of this decimation lives out his old age under armed guard, his horn docked to make him less valuable to poachers. Such is the life of Sudan, the last male northern white rhinoceros on Earth.
Now, researchers at the Ol Pejeta Conservancy, Sudan's home, and elsewhere are rushing to save this subspecies, of which only five individuals remain. A natural pregnancy is impossible at this point, according to experts, who have turned to assisted reproductive technology instead. And though Sudan is the only male northern white rhinoceros left alive, the real technical challenge will come in harvesting enough eggs from the four remaining females to achieve a viable baby rhino.
"It's kind of a race against time," said Richard Vigne, CEO of Ol Pejeta. "Those remaining females could all die tomorrow. Once they're gone, then the source of eggs disappears."
The northern white rhino (Ceratotherium simum cottoni) didn't disappear overnight. The subspecies had the misfortune of existing in areas torn apart by conflict, poverty and war: Uganda, Sudan, the Central African Republic, the Democratic Republic of the Congo, and Chad. Though there were at least 2,000 northern white rhinos roaming this habitat in the 1960s, according to the Ol Pejeta Conservancy, human poaching beat their numbers back to mere dozens in the Democratic Republic of the Congo's Garamba National Park by the 2000s.
In 2005, four northern whites still roamed Garamba, but they haven't been seen since 2007, and the subspecies is now assumed extinct in the wild.
Conservationists have been sounding the alarm about northern white rhinos for decades, but efforts to save the subspecies have become urgent, particularly as the elderly rhinos still in captivity begin to die off. In October 2014, Ol Pejeta lost 34-year-old Suni, a male. Mere months later, in December, the second-to-last male northern white rhino on Earth, Angalifu, died at the San Diego Zoo.
And then there were five
Now, only five northern white rhinos remain, and the chances of any of them breeding naturally are miniscule. Sudan will turn 42 this year, and he can hardly mount a female, Vigne said. His semen quality is also poor, likely because of his age.
Moreover, the two females at Ol Pejeta, Najin and Fatu, are incapable of carrying a pregnancy. Najin is old and has problems with her legs that make it impossible for her to sustain the weight of a male mounting her, and likely impossible for her to carry the extra weight of a 16-month-long rhinoceros pregnancy. Fatu has a uterine condition that makes breeding her unlikely, Vigne said.
Najin and Fatu are two of the four remaining female northern white rhinoceroses left.
Nola, the only remaining female northern white rhino at the San Diego Zoo, is at least as old as Sudan, far past reproductive age. The fifth and final northern white rhino left is Nabire, a 31-year-old female at the Dvur Kralove Zoo in the Czech Republic — and she has uterine cysts.
Now that natural breeding attempts have failed, veterinarians and conservationists are turning to in vitro fertilization (IVF) to try to save the subspecies. In IVF, eggs are extracted from a female, and are fertilized by sperm extracted from a male in a laboratory culture. After a few days of development, the resulting embryo is re-implanted in the uterus to grow.
This might seem simple in a world where human babies are born via IVF every day, but no one has ever successfully conducted the procedure on a rhinoceros.
"Every species requires different culture conditions, and that's because the actual conditions in the uterus in the animal are different," said Barbara Durrant, director of reproductive physiology at the San Diego Zoo Institute for Conservation Research.
So first, researchers must develop a rhino IVF procedure. They're starting with a blueprint developed for horses, Durrant told Live Science, which are close relatives of rhinos. Unfortunately, Durrant said, IVF has proven difficult in horses.
And rhinos have their own challenges. Their reproductive tracts are large and difficult to access. Like humans, they ovulate only every 30 days or so, meaning there are few mature eggs to harvest. Researchers can collect immature eggs directly from the ovaries, but first, they have to learn how to get them to mature outside the body, Durrant said.
Next, these eggs must be fertilized. In order to save precious, limited northern white rhino sperm, Durrant and her colleagues in San Diego are working on a technique called intracytoplasmic sperm injection. With this method, the researchers pick a single sperm cell and inject it directly into an egg, instead of bathing an egg in sperm. Researchers at Ol Pejeta and the Dvur Kralove zoo are similarly working to harvest eggs from their northern whites and to develop IVF procedures. Keepers on all three continents where the rhinos reside work closely together on these efforts, said Jan Stejskal, director of communication and international projects at Zoo Dvur Kralove.
Because so few northern whites are left, all of the IVF experimentation is being done on a closely related subspecies, the southern white rhino. Ultimately, if researchers can create viable northern white rhinos, southern whites will act as surrogates to carry the embryos to term. The chances of a successful pregnancy, even an assisted pregnancy, in one of the remaining northern white females are just too small.
So far, Durrant said, big challenges remain for rhino IVF.
"It's been done once — actually, maybe twice — with no embryo development beyond the two-cell stage," she said.
So researchers are hedging their bets. At San Diego, Durrant and her team are exploring advanced genetic technologies: They've harvested regular rhino cells and turned them into stem cells, which are cells capable of becoming any sort of body cell — including sperm and egg.
Researchers have cells stored from 12 different northern whites, Durrant said. If they can get viable eggs and sperm out of these cells, they won't be dependent on living northern whites, or on the stored eggs and sperm from the few animals left.
"We could have a source of eggs that we could actually produce in the lab," Durrant said.
If all else fails, the race to save the northern white rhino may end in saving some of its genes. Researchers might be able to artificially inseminate southern white rhinos with frozen northern white rhino sperm, creating crossbred calves, Vigne said.
"Now, that's not ideal," he said. "But what it would do, assuming the calf is viable as an animal and reproductively viable, is save some of the genetic traits which are currently present in pure northern white rhinos, and which would be needed in the future to reintroduce white rhinos back into central Africa."
In other words, the species would be gone, but some of the adaptations that enabled it to survive in its habitat would live on. This genetic diversity might be crucial to rhinoceroses as a whole, as the northern white is hardly the only species on the brink. There are fewer than 5,000 black rhinoceroses (Diceros bicornis) left. In Indonesia, there are a mere 35 Javan rhinos (Rhinoceros sondaicus) left, and hardly more Sumatran rhinos (Dicerorhinus sumatrensis). [See Photos of All 5 Rhino Species]
"What's happened to the white rhino actually could happen just as easily to other species of rhino around the world," Vigne said. Any IVF techniques developed to save the northern white might be mustered to save other species, he added.
The question, of course, is whether any of these IVF techniques will be successful — and when. Under ideal circumstances, with no surprising roadblocks, it might be possible to get a viable pregnancy in five years, Durrant said. Some of today's surviving white rhinos may live long enough to see the next generation.
But five years is an optimistic estimate.
"I think we will be successful in saving the species," Vigne said. "But it might mean that the last remaining animals on the planet die off first."
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