The theory of life and death is as simple as a mysterious dream. Nature shivers between survival and extinction. The world shows several obvious signs in its favor but the very breaths are bound to serve the divine omnipotence. There could be more than billions of species breathing at the same moment but who knows what species would not, in the very next unpredictable moment. Scientists believe that billions of species are on record but we know for sure that there are probably just has many that have yet to be described or articulated with precision. Thousands of species have already been declared extinct. Thousands and even more are going to be extinct soon due to several factors, which include human interventions, climate change, diseases and pollution.

The 19^th century was the worst century for wildlife. Poaching, climate variation, poisonous DTT and several other factors affected thousands of species and pushed them on the verge of extinction. The Endangered Species Act (1973) changed the behavior and perception of humans about animals and since then conservational plans were designed. ESA and some private organizations are working on this particular subject. Race extinctions are being studied and immediate actions are being taken to safeguard the wildlife. According to research, the precious animals that survived extinction include several known species.

15. Gray wolf

Gray wolves belong to the Mammalia class and the Canidae family. Apart from their wildness and ruthlessness, their grace is always appreciable. Wolf behavior is usually very difficult to predict and to study as well. They live in packs and they do not like it when you threaten their territory. Once there were more than 2 million gray wolves in the United States but then this species was close to extinction. In the early 20th century, wolves were forced to leave their homes as they were pushed away from various towns and cities. Heavy construction in that era was also the major cause of their extinction as it was the development phase for the whole world and such dangerous species were considered as a threat to human life.

Gray wolves faced a very tough time during that period but later on, due to conservational efforts, they were given a chance to survive and spread in numbers again. It is on record that this nearly extinct creature now has a population of 2500 pairs.

14. Night lizard

The night lizard is a small reptile but it has very distinctive characteristics compared to other small reptiles (lizards). They lack the capacity to sustain even the slightest climate change. It was not always their weakness but now with the passage of time, they have evolved in such a way. Night lizards have gradually developed some changes in their habitats according to their own comfort and security. They feed on plants and small insects while preferring to live in dark and covered areas.

When the population went dramatically down, a few steps by ESA with the cooperation of other private organizations were taken for their conservation. When their habitats restored and their population was recovered, they hit the 21 million mark and now they are neither endangered nor even at the risk of extinction.

13. American Alligators

The American alligator is a crocodilian reptile. It is considered an extremely dangerous species. This is the reason that it was wildly hunted to the point of extinction back in early 1950s. Climate change and other world developmental issues affected its reproduction rate. American alligators were listed among the endangered species.

American alligators prefer to live in freshwater, so it enhances the chance of interaction with other living things, which also includes human beings. It is a carnivore but not an alpha predator so it feeds on small mammals and reptiles. The ESA removed American alligators from the list of endangered species but still, its population has not recovered properly. American alligators are still rare and they now hold the status of threatened species.

12. Northern Sea Lion

Northern sea lions are massive carnivorous mammals. The average life span of females is approximately 30 years and males live around 18-20 years. They appear to be lazy and dull which is technically a fact but they have a very complex nature. During mating season, they are aggressive and competitive. They have certain requirements for mating unless they refuse to reproduce. When these intrinsic complications were added with external threats, their population fell down and even led them on the verge of extinction.

The ESA recorded that back in late 1970s, their total estimated population was less than 18,000 and when they were given proper care and protection, their population was increased to 70,000. Their huge size and their clusters help them to push back their enemies. It also causes unfortunate deaths of young pups, as they easily get crushed under the aggressively desperate male sea lions.

11. Virginia Northern Flying Squirrel

The Virginia northern flying squirrel is a beautiful and delicate creature. The largest of them can be 230-250 grams in weight. They feed on small plants, mushrooms, insects and even fungi. They have a tendency to expand their food sources when conditions are unfavorable. This helps them to sustain and survive a season. They have a patagium under their arms which can help them to glide. This is very rare in ground animals as it gives them an additional escape route other than their agility. With such unusual characteristics and blessings, these species were found on the verge of extinction.

In 1985 only 5 pairs were found. Deforestation took their home from them and they ran short of living space, expanding their habitat was not a possible option for them at that time. On the other hand, owls got an advantage, as flying squirrels were pathetically short of escape courses. Forest conservation was necessary to save their species and to grow as naturally as they can. After this act, more than 500 pairs were recorded in the same location in 2013.

10. Brown Pelican

The brown pelican belongs to the Aves class. A pelican is a bird of prey which is mostly found in coastal areas. They are the only plunge divers of their kind. Male and females cooperate with each other to build their nest, but before that, the male is supposed to attract the female. As a pair both work together to protect the nest and their eggs. Large predators are the biggest threat to their nest, eggs, and even the adult pelicans.

Back in the mid-20^th century, around 1,200 pelican were alive. Researchers found out that pesticides disturbed their reproduction. This affected their food chain and their eggshells became thinner. Numerous eggs got crushed under their own mothers, as they lack the capacity to resist even moderate physical pressures. It was a delicate matter and all the credit goes to the researchers for saving such a precious species. In 2007 11,000 pairs were recorded to be nesting.

9. Aleutian Canada Goose

The Aleutian Canada goose belongs to the Aves class and the Anatidae family. This species feed in grassland, bushes, stubble fields and swamps. They prefer to live around fresh water but it was not easily possible for the past 30 to 50 years. They kept moving from place to place for their survival and in search of their perfect habitat.

The major damage was the introduction of foxes in their territory. Non-native foxes almost wiped out this species from the world but few somehow survived. In mid-1970s, the ESA starting to protect the species and U.S. aided them in the removal of foxes from their locations. This restored the species and their population gradually increased to 110,000 according to a 2001 ESA report.

8. Peregrine Falcon

Peregrine falcons are also known as the duck hawks. They have the largest global range for residing and visiting. They mostly feed on small and medium-size birds. They are one of the fastest birds while diving in order to catch their prey, achieving the velocity of 320km/h. This makes them difficult to be dodged. They nest at high altitudes. They are one of the rarest alpha predators.

In the first World War, due to many justified or unjustified reasons regarding the use of pesticides, their food chain got disturbed. They fed on animals who directly consumed the DTT from lands. DTT is heavily poisonous. The falcon population started to reduce enormously until the ESA and other organizations medicated and protected them. Now there more than 1,500 breeding pairs in the United States alone.

7. Grizzly Bear

Grizzly bears are strong and huge hypo-carnivores. They mostly eat plants but they are considered aggressive animals. They can kill and eat other mammals when they desire. They are found in Asia, North America, and Europe. Grizzlies hibernate when the temperature falls, as they have low resistance to the cold. They reproduce in their dens, feed their cubs (mother milk) and productively deal with the season. Grizzly bears where once free to go anywhere and they were not bound to live in some particular areas.

When humans explored the world and expanded their territories, grizzlies were one of the most affected specie. They got hunted continuously all over the world, especially in North America. Their population was falling abruptly. The ESA recovery plan in 1975 saved them but still, they could not give them back the life they had 200 years ago. They are no longer endangered but they are still being monitored carefully as they still hold the status of threatened species (around 1,800 in the whole world).

6. Whooping Crane

The whooping crane was a critically endangered species back in 1940s. They are the tallest birds but sensitive as well. They love to live in grassy wetlands, marshes and mudflats. When they migrate, they glide over fields and land on different places to rest and probe for food. They live their lives together as flocks. They are not easy to be caught by medium-size predators. Whooping cranes are omnivorous but they mostly prefer small animals and fish. This species was almost extinct, as there were only 23 whooping cranes were left in the world.

Due to special and continuous conservation efforts, their number increased to 750 individuals in 2015. This was never easy and still, this species needs special attention for its protection and survival.

5. Gray Whale

The gray whale is one of the largest mammals on Earth. In early to mid-20^th century, this species was hunted wildly without considering the risks of its extinction. They have said to be descended from filter-feeding whales millions of years ago. This makes them a valuable creature. Gray whales have a very complex reproduction behavior where the females usually mate with more than one male and the gestation period varies between 13-14 months. During the early 1900’s, gray whales were losing their strength in their 3 major habitats. The pacific gray whale region was still recoverable.

The international whaling commission provided them full protection. As a result, they started to regain their lost numbers. Positive results regarding these actions were observed, now there are more than 20,000 gray whales in North Pacific Ocean

4. Mountain Gorilla

Mountain gorillas are omnivores and closest to a human being. They are naturally strong and they have high resistance to cold weather due to their thick fur. They live in mountain forests and feed on plants but rarely on animals. A century ago, humans expanded over the lands and islands. They invaded the territories of gorillas and destroyed their habitats. This was the only reason why their species faced the challenge concerning their survival.

They are now considered a critically endangered species. In the 1990s, they were considered as extinct but after the cooperation of ESA, AWF, WWF, IGCP and FFI their population was recovered in captivity and now there are more than 800 mountain gorillas in the wild.

3. Saiga Antelope

Saiga Antelopes usually form large herds and they graze in grasslands. This antelope is a critically endangered species. Climactic variability, human settlements and excessive hunting for the sake of fur, horns, and meat caused them to rapidly reduce in numbers. In early 20^th century, their population fell from millions to thousands in few decades and it was still going down.

Favorable conditions were needed for their full recovery but unfortunately, saiga antelopes were unable to survive some abrupt changes. It took years, first to maintain the population and then decades with extra precautions to conserve their species. Their habitats and migration routes were protected and their herds were carefully observed. They now range from 40 thousand to 50 thousand individuals.

2. Golden Lion Tamarin

Golden Lion Tamarins or Golden Marmosets are from Mammalia class and the Callitrichidae family. This kind was found only in Brazil and it is also the country’s national symbol. They are like small monkeys with long silky hair almost all over their body. They are omnivores and they feed on almost all the small available plants, animals, and insects. They are very agile and active which allows them to escape easily from alpha predators. During the early 1900s, they lost 97% of their actual habitat. It could be difficult for any species to sustain such a devastating incident. Their population fell down to only 150 individuals.

In the early 1960s, observations and monitoring programs were conducted by wildlife conservation organizations and finally in 2001, exactly one thousand marmosets were recorded in wildlife.

1. Black Rhinoceros

Black Rhinoceroses were once variously found in northern and eastern Africa. They are naturally strong and they are often aggressive. Rhinos are very unpredictable when it comes to mating and territorial distribution. They are herbivorous and they don’t like to be disturbed when grazing. In late 1950s, there were around 70 thousand black rhinos in the whole world but then their population started decreasing. It fell to less than 4,000. Successive poaching incidents and habitat loss were the actual reason for this population decline.

When conservational plans were discussed, the most immediate problem was a very low reproduction rate of this particular species. This increased the duration of recovery and according to 2017 report, there are around 5440 individuals.