Pronghorn is a mammal of the genus pronghorn of pronghorn family.The body length is about 1.5m, and the shoulder height is about 1m.The male weighs about 50kg, and the female weighs about 40kg.Medium in shape, well proportioned and vigorous.The back and side are generally light or dark brown, the buttocks and abdomen are white, and the neck and abdomen have two white stripes.The male has two vertical horns on his head, while the female usually has no or very small horns.The structure of the horn is that the bone core is wrapped with a horny sheath, and the sheath has a branch at the proximal end.[8]There are 5 subspecies differentiation.[2][5]
The pronghorn lives in the semi-arid open grassland from northern Mexico to southern Canada at an altitude of 900-1800 meters.[8][9]In winter, males and females are clustered together, and in early spring, young males and females are separated, and adult males are alone.Pure herbivore, the food is various grasses and shrubs,[9]They even eat coarse or poisonous plants that livestock do not eat.Sexual alertness;Sharp vision, able to see objects thousands of meters away;Extremely good at running, the fastest speed can reach nearly 100km/h.The pronghorn mates in summer, from July to October. The female sheep's sexual maturity period is 16-17 months, and the pregnancy period is 252 days. There is one child every year, 1-2 offspring per child.The service life is about 10 years, rarely 15 years.[8]
The pronghorn was listed in the IUCN Red List of Endangered Species (ver 3.1 - LC) in 2016.[6]In 2019, pronghorn was listed in Appendix I, Appendix II and Appendix III of the Convention on International Trade in Endangered Species of Wild Fauna and Flora.[7]
The pronghorn is medium in size, 1.41 meters in length, 7.5-10 centimeters in tail length, 87 centimeters in shoulder height, and 47-70 kilograms in adult weight. The female is smaller than the male;Both male and female have permanent horns. The horns of female sheep are smaller than those of male sheep and do not bifurcate, while the horns of male sheep are more characteristic, with bifurcated ends, similar to members of the deer family.The horn is bone, without cavity or bifurcation.The outside is covered with hairsheathIt falls off after the annual breeding season, and before falling off, a new sheath grows under the old sheath.The angle is upright and flat on the side, and the tip is bent backward.The angle is about 25 cm long.The back is reddish brown, the neck has black mane, the abdomen and buttocks are white, and there are black patches on both sides of the cheek, face and neck;The fur is covered with coarse, brittle long hair under the coat. The pronghorn changes its hair in spring. The hair structure contains complex air chambers, which has excellent heat preservation function.When in danger, the white hair on the buttocks can stand up, which is a special signal to warn the companions.[3]
Prehistoric members of the pronghorn family have more complex horns.The horn base of pronghorn is bone (similar toBovidae）And will not fall off, but the hornsheaths formed by the mixture of cutin and some hairs fall off every year (similar to deer family).Pronghorn grows horns faster than bovidae.be situated betweenCave cornerAn angle between the antler and the antler.The bone heart does not bifurcate, but the horn sheath has a small fork, and the forked horn sheath has fusionhairThe hairy horn sheath is replaced after the reproductive period every year, and the bone core does not fall off.This horn is malePronghornThe female pronghorn has only a short horn heart and no horn sheath.
In proportion, pronghorn's eyes are North AmericaUngulatesMedium and largest, up to 50 mm in diameter;Compared with other herbivores, its growth position is more outward and upward.This allows it to have a broader vision and easier to find close natural enemies.Moreover, the vision is particularly developed, which is equivalent to the effect of people looking at the distance with 8 times binoculars.However, the ability of myopia is poor. If people 10 meters away do not move, pronghorn will be difficult to detect the existence of people.Pronghorn antelopes are naturally curious animals and like to approach new things without obvious threat characteristics.Hunters often use this to sit quietly and wave a white handkerchief to lure the hidden pronghorn to appear.
With other ruminantCloven hoofed animalIn contrast, the pronghorn's hooves have no declaw structure, and all the lateral toes have disappeared (this shows that the pronghorn is a highly evolved cloven hoofed animal).[4]
Habitat environment
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The pronghorn feeds on grass, shrubs, reeds, etc.The pronghorn lives in a wide grassland and desert area, and the terrain elevation is 900-2400 meters.[3]
Life habits
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They like to live in groups. In summer, they form about 50-100 small groups, and in winter, they gather into thousands of large groups.When encountering enemies, they will use the method of erecting white hair on their buttocks and ringing their noses to warn their companions.Mark territory with urine and hoof prints.They feed on cactus, grass, shrub leaves, reeds, etc., but still have high teeth that are suitable for eating grass, and occasionally eat grass.Able to dig plants buried by snow with forefoot.If you can get enough grass, you can not drink water.Good at swimming.In search of food and water, migration is often carried out several times a year.She is alert and has sharp vision, and can see objects several kilometers away.When in danger, the white hair on the buttocks can stand up, which is a special signal to warn the companions.[3]
The pronghorn is the fastest running mammal in the American continent, the fastest running animal in the Western Hemisphere, and the second fastest running animal on the earth after the cheetah (its endurance is far stronger than the cheetah).The top speed is 86 kilometers per hour.And it has amazing endurance.It can run for 11 kilometers at 72 kilometers per hour, and can jump up to 6 meters at a time.The cheetah's adaptation to high-speed running is the evolution of a spine with good elasticity, while the pronghorn's stocky body is adapted to running by its slender limbs and enlarged heart.In high-speed running, slender limbs can jump farther, and pronghorn can jump 4.5-6 meters in one jump;The enlarged heart is conducive to oxygen metabolism and reduces the oxygen debt caused by exercise.Unlike deer, pronghorn has a particularly poor ability to jump high and cannot jump over the fence, so long-distance fences often hinder the migration of pronghorn.[3]
Distribution range
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The pronghorn is distributed in the open area of western North America, starting from southern Canada in the north to northern Mexico in the south. It is good at running and is the fastest running animal in the Americas.[3]
At the beginning of March every year, male pronghorn began to divide and compete for each other's territory.The male will smell out urine, feces and secretions from glands behind the ear.Usually, the division of territory will be solved by staring at the game, but sometimes it will also chase and fight.During this period, a group composed of females, generally up to 23 members, will move freely between the territories of different males, while young males who are eager to mate will move around the edge of the area controlled by the male territory in order to obtain opportunities.[3]
The pronghorn mates in summer from July to October.The sexual maturity period of female sheep is 16-17 months, and the pregnancy period is 252 days.One baby in the first birth, and two babies in the future if there is enough food.The pronghorn breed in a strange way.Female sheep will discharge 4-7 eggs during ovulation.After fertilization, the egg begins to develop and become slender.The slender fertilized eggs are twisted together in the uterus, intertwining and pushing each other.Finally, most of the eggs will die of malnutrition due to the reduction of the cell membrane area, and the remaining two eggs will eventually develop into embryos.This competition between intrauterine fertilized eggs is still unique so far.The gestation period is about 8 months. The first baby usually gives birth to 1 baby, and then 2 babies per baby.[3]
The tacit cooperation between ewes and lambs is also an interesting phenomenon.Generally, ewes will circle around the lamb hiding place and act as if nothing happened to avoid being found by coyotes.Because coyotes often observe nearby suspicious ewes patiently.The coyotes can use the ewe's frequent glances at the lamb's hiding place to find the lamb.The ewes return to the lambs for feeding every 4 hours on average.Then the lamb changes its hiding place.The ewe left quickly.The memory of ewes is amazing.Before leaving, the ewe will turn around and memorize the new hiding place of the lamb. This process only takes 3 seconds.Within a few hours, the ewe could find the lamb again accurately.Lambs that are four days old can run faster than people.
In order to avoid the discovery of enemies, the ability of lambs to adapt to long periods of rest is still amazing.In the wet and cold weather in March and April in western North America, the lamb can only maintain its body temperature by generating a lot of body heat.In addition, before the last moment, the sleeping lamb can still remain still when the danger is approaching.It was once found that the feet of some lambs were broken in two by the hooves of passing bison on the grassland where bison and pronghorn coexist.Obviously, when the buffalo's hoof stepped down, the lamb still kept still.[3-4]
Population status
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The natural enemies of pronghorn are mainly wolves, cougars and people.Coyotes, lynx and golden eagles pose a threat to lambs.In fact, pronghorn competed with cheetah in running speed for 4 million years through coevolution, reaching a speed of nearly 100 kilometers per hour.After the extinction of the North American cheetah at the end of the Pleistocene epoch 10000 years ago, the adult pronghorn basically had no natural enemies.Therefore, lambs become the main target of other animals to attack pronghorn.In the grassland without cover, the main way for the lamb to resist the enemy is to lie on the ground quietly with its protective color to avoid being found by the enemy.
Pumas occasionally use some hilly terrain to ambush pronghorn.Wolves sometimes attack pronghorn with extraordinary endurance and physical strength.But none of these can pose a real threat to pronghorn, except those with guns.
At the beginning of the 19th century, there were thousands of pronghorn in the United States.However, people used to hunt and kill a large number of people to take meat, skin and use their heads as decorations.In the past 100 years, the number has dropped sharply to less than 20000.Due to strong protection, the number has increased greatly.
It is estimated that when white people arrived in North America, there were about 35 million pronghorn (another 100 million), the population size was second only toBison。During the reclamation period in the western United States, the number dropped sharply to less than 30000 in 1924.Through protection measures, it has recovered to more than 2 million to 3 million (including the United States and Canada). It is one of the most common wild animals in the western United States and the main hunting object of the hunting industry in the United States. The annual hunting quota is 4000.[6]
Protection level
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Pronghorn Mexican subspecies（A.a.mexicana）The state of the animals is not good, with only about 1200 left, which belongs to endangered protected animals.Other less protected subspecies include Peninsular subspecies（A.a.peninsularis）Sonora（A.a.sonoriensis）
