Most of you must have watched the movie Jurassic Park, and may have models or toys of those huge animals called dinosaurs, that roamed the earth millions of years ago. Well, there are so many theories behind their going extinct from the face of the earth, and one of the generally accepted theories is that a large asteroid struck earth around 66 million years ago. The impact caused massive fires and tsunamis, which led to the extinction of dinosaurs.

Another theory is that a series of volcanic eruptions caused the extinction of the dinosaurs. Anyway, it’s not just dinosaurs that swept away, there are other species too, such as the Dodo, that disappeared from the face of the earth, or, to use the proper term, became extinct.

Currently there are millions of animal species on planet Earth but, unfortunately, a number of them are on the verge of extinction, therefore, it is speculated that in a few years, many of these animals will not be alive. The species which are at risk of becoming extinct because of a decrease in their population are referred to as endangered species.

Why do species become endangered?

There are many different reasons that put these animals at risk of extinction or to be classified as endangered. These include human activity, loss of habitat, food scarcity, changing weather, etc. Unfortunately, human beings that are the greatest threat to biodiversity, whether it is to use animals for fur, the oil they produce or to consume them as a food source.

Human actions, driven by economic and cultural activities such as the large-scale conversion of land for agriculture, logging and infrastructure development, also result in the loss of natural habitat for many animals, which in turn threatens their very existence. Species also become endangered due to loss of genetic variation.

Loss of habitat

Loss of habitat is considered a major factor that causes species to become extinct. There are natural causes of loss of habitat, such as global warming and climate change, and those caused by human activity.

The best example of loss of habitat due to climate change and its effect is the extinction of dinosaurs. Dinosaurs lost their habitat about 65 million years ago, when during the Cretaceous period (a geological period that began 145 million years ago and ended 66 million years ago) the hot dry climate changed very quickly. It is believed that it was likely caused when an asteroid struck the Earth, the impact of which forced debris into the atmosphere, reducing the amount of heat and light that reached Earth’s surface. The dinosaurs were unable to adapt to this new, cooler habitat and soon became extinct.

Human activity

Species also lose their habitat because of human activity. This can happen in a number of ways. Forests are often cleared to make space for housing or cultivation to meet the needs of the growing population. For instance, in the Amazon Rainforest (the world’s largest rainforest) that is famed for its biodiversity, hundreds of thousands of acres of land have been cleared (i.e. all trees and vegetation has been removed from it) for cattle ranches, logging and urban use.

Large trees provide habitat for other species; birds make their nests in these trees while some plants/vines, fungi and insects thrive in the vicinity. When trees are cut, many species that depend on that particular type of trees lose their natural habitat leaving them with less room to live and reproduce, while species that thrive on their fruit/nuts or vegetation lose their source of food supply. This, in turn, makes the species endangered.

As urban areas are expanding, they encroach over the living space of many species or what is known as species range. Many animals have a range of hundreds of square kilometres, which they use for living and reproduction. As development takes place, animal habitats become smaller. Thus the habitats can now support fewer numbers of the given species, which ultimately results in a fight for space and food between the species.

When habitat is lost, it increases the chances of encounters between wild animals and humans. Oftentimes, we read and listen to news about wild animals, such as monkeys, tigers, bears, elephants, snakes etc., spotted in pools, backyards and on the roads. These animals are simply patrolling their range and humans have occupied the land which was once their home.

Birds are equally affected

It’s not just land animals, but certain species of birds, such as some parrots, cranes, houbara bustard, pheasants, snowy owls, yellow-eyed pigeons, Saker falcon, Asian white-backed vultures, etc. are also affected by habitat loss and are considered endangered.

Do you know how dodo, the flightless bird that solely lived on the island of Mauritius, became extinct? There was abundant food on the island and no predators, so they grew heavier and bigger. In the seventeenth century, sailors visiting the island began to hunt it in large numbers for food and since they could not fly, they became easy targets, which resulted in the rapid extinction of the species.

Along with overhunting and habitat loss, birds living on small islands or in desert or mountainous regions can be vulnerable to climate change and global warming. Other factors include bird trafficking, egg collecting and pollution. Fertilisers and pesticides and herbicides used for cultivation also affect the food that birds eat; these chemicals are used to kill the pests that are a food source of many bird species.

The effects on marine life

Many species of fish and other forms of aquatic and marine life are also threatened. While fish is a favourite seafood around the world, excessive fishing is harmful to the survival of many species, if caught in early life as they do not get the chance to reproduce. The meat and fins of many sharks, rays, chimaeras and whales fetch high prices in many parts of the world, as a result, several of those species are caught in greater numbers, which exacerbate population decline.

Moreover, freshwater habitats worldwide are progressively threatened by pollution from industry, agriculture, and human settlements. Additional threats to freshwater ecosystems include invasive species (species that is not native or indigenous but is introduced to the ecosystem, intentionally or accidentally) that compete with native organisms for limited resources and can destroy biodiversity and permanently alter habitats; canalisation of rivers and overharvesting of freshwater species.

The Indus River dolphin or the Blind Dolphin is one of the rarest mammals and the second most endangered freshwater dolphin. It is only found in Pakistan and is an indicator of the biological health of the aquatic and terrestrial environment adjoining the Indus River. The species is endangered because of various factors such as water pollution, poaching, fragmentation of habitat due to the construction of barrages and dolphin stranding in the irrigation canals. All these factors have reduced its population to approximately 2,000 specimens that exist in the lower reaches of the Indus River, which is just a small part of their former range.

Genetic variation

Loss of genetic variation also puts a species at the risk of extinction. Genetic variation is the difference in the DNA among individuals or the differences between populations. It is the cause of diversity seen within a species and allows species to adapt to changes in the environment. The greater the population of a species, the greater its genetic variation.

Groups of species that inbreed (reproduce) with close family members have little genetic variation because no new genetic information is introduced to the group. Among the inbred groups, diseases are more common and more deadly, as they do not have the genetic variation to develop resistance to the disease. For this reason, fewer offspring of inbred groups survive to maturity.

Loss of genetic variation can occur naturally. For example, the cheetah — a threatened species native to Africa and Asia — has very little genetic variation because, during the last ice age, the species went through a long period of inbreeding as a result of which there are very few genetic differences between cheetahs.

Along with natural causes, human activity also causes loss of genetic variation. The population of many animals has reduced due to overhunting and overfishing, leaving fewer breeding pairs that are not closely related. With fewer breeding pairs, genetic variation shrinks.

Saving endangered species

When a species is categorised as endangered, governments and international organisations make efforts to protect it. Laws are made that may limit hunting and destruction of the species’ habitat, and anyone breaking these laws has to face huge fines. In many countries, including Pakistan, sanctuaries are established to protect endangered species. Because of such actions, many species have recovered from their endangered status.

The IUCN Red List

The International Union for Conservation of Nature (IUCN) is an international organisation that works for the conservation of nature. In 1964, it established the Red List of Threatened Species, which is considered to be the world’s most comprehensive information source on the global conservation status of animal, fungi and plant species.

Currently, more than 41,000 species have been assessed to be under threat of extinction. The Red List is not just a list of species and their status, but a powerful tool to inform and initiate action for the conservation of biodiversity and changes in policy that are important for protecting natural resources. It provides information about the range, population size, habitat and ecology, use and/or trade, threats and conservation actions that will help inform necessary conservation decisions.

So, how about spending some time in the library or, since you are modern people with access to the internet, searching online for various species that are endangered around the world.

Published in Dawn, Young World, September 2nd, 2023