Species Reintroduction: Impacts and Problems

We have heard many times that the government is trying to reintroduce or relocate several species. Why do we need such reintroduction initiatives? Will it solve the present ecological problems? Read the article to know about this.

Top predators are becoming extinct due to loss of prey, habitat loss, hunting, climate change, or extreme events.

They are important in maintaining the ecological balance and a balanced food web. They are being introduced again in a particular area through species reintroduction initiatives.

The reintroduction of species is the release of a particular species into an area in which they are capable of survival.

An ecosystem is a place where plants, animals, and other organisms interact among themselves and with their environment. Every species are connected and transfers energy through the food web. This interaction is obvious, and top predators play a vital role in maintaining a food web balance. Therefore they are important for the overall health of an ecosystem.

Examples of top predators include lions, cheetahs, wolves, sharks, polar bears, jaguars, tigers, etc.

Impact  of Top Predators on an Ecosystem

Top predators affect and control prey species populations by:

1. They remove vulnerable prey populations such as the old, sick, or injured, leaving more food available for the survival of healthy prey populations.
2. They help in controlling the spread of diseases among prey populations by controlling their size.
3. Its presence can reduce the effect of trophic cascades. A trophic cascade occurs when the number of top predators is reduced. It enhances the survival of the following trophic level species whereby they have relative changes in the prey population on which they are dependent.

For example, the Sea otter (Top predator) depends on Sea urchins and other invertebrates for their food needs. These sea urchins in turn prey on kelp forests (algal seaweeds). These kelp forests were in turn dependent on the fish population present in that community.

When the number of sea otters gets reduced, the population of sea urchins and other invertebrates gets increases and their food needs also increase. This led to the over-exploitation of kelp forests which again affects the fish population in that community.

In identifying the importance of top predators in a community, scientists were trying to introduce them and thereby balance the food web.

Related topic: Climate change

Let us see some of the successful species reintroductions done in several countries:

1. Reintroduction of wolves to Yellowstone national park, US. This had been done to control the rising elk population which was overgrazing much of the park. It caused unanticipated results in the national park. The end to overgrazing stabilized riverbanks. Rivers were recovered and flowed in new directions. Several species such as songbirds, beavers, Eagles, and foxes were returned. As the size of the elk population gets curbed, new trees also take root in areas.
2. The introduction of Sea Otters in the Northern Pacific ocean near Alaska also shows great results.
3. Chinese water deer were reintroduced to Shangai which were its native species.
4. The reintroduction of the world’s smallest and rarest wild pigs, Pygmy hogs into Sonai Rupai Wildlife Sanctuary in Assam was also a successful one.
5. American Bison population came down to as few as 750 animals in the 1890s due to the excessive hunting and slaughter for the fur trade. After reintroduction and various other conservation initiatives, its population has rebounded to around 350,000.

However, it is not that always the reintroduction programs were successful. Sometimes it failed too, that is it had negative consequences.

An example of such reintroduction of species was that of a wild dog introduced in Africa. It failed either to reduce the effect of a trophic cascade or to improve ecosystem stability. It led to increased competition and negative consequences as it started attacking other unintended animals.

Problems associated with the introduction of species:

1. Administrative problems – permission is required from different groups. Expertise advice and equipment are needed. Stress, injury, and fatalities are associated with capturing and transporting animals.
2. Susceptible to disease – small groups are more prone to disease. They are exposed to the disease in captivity. Due to a lack of immunity among the newly introduced species, they are more susceptible to endemic diseases.
3. More expensive – expenses are there in planning, monitoring, and captive breeding. Whereas it is difficult to value reintroduction benefits.
4. Site availability – there are changes in the environmental setting since the removal of a species. It causes food chain disruption.
5. Adaptability issues – Reintroduced species experience increased vulnerability to the gene flow evolutionary processes and climate and ecological differences between source and native habitats.

Recently, the Union Minister for Environment, Forest and Climate Change launched the ‘Action plan for the introduction of Cheetah in India’ under which 50 of these cats will be introduced in the next five years.

“In India, we have traditionally been more concerned about species than ecosystems. So we’d reintroduce tigers in Sariska and Panna, where they were locally extinct, or move rhinoceros to Dudhwa, or captive breed gharials and release them in rivers in North India.

Soon, eight big cats are to be relocated from South Africa to the Kuno National Park in Madhya Pradesh. If all goes as planned, the region could become the country’s first-ever cheetah sanctuary.

Read: Invasive species

Article written by: Krishnapriya jr