Definition of indicator species and examples

If you are interested in biology or ecology, you may have heard of the term Indicator species. This term is used to define certain species, no matter whether they are minerals, plants or animals; to determine the overall health of a particular ecosystem.

To give you an illustration: Do you remember how miners in the twentieth century used canaries to find out if there was poisonous gas in the vicinity before it actually affected people? In this example, walnuts will be referred to as indicator species.

However, this is a very general definition, which is why we want to explore this subject in depth, to study a few examples and get a perspective on the importance of indicator species. Continue reading if you are wondering: What are indicator species?

What are Indicator species?

Indicator species are carefully selected organisms to be a barometer for assessing how certain ecosystems perform and how human activities affect the area. Indicator species have a response to any stress or disturbance that can be measured; because it's not as hard as the indicator species disappearing too fast, or it doesn't affect it enough so that the disturbance is not noticed.

The disorders mentioned are mostly caused by humanity, although there are also natural stressors in some cases such as freezing and drought. Although there are other ways to measure human impacts on nature, defining indicator species has proven to be very effective in various studies.


But what makes indicator species good? As we have said, this species must be sensitive to foreign disturbances more than others and must be strong enough to survive. To measure changes in the response of indicator species (which should affect the whole community or population of species), scientists measure the following rates of change:

Energy resources: The amount of food and light possessed by indicator species will vary proportionally.

Biotic interactions: Their behavior will change, especially regarding predation and competition.
Physical changes: general speed, shape .

Chemical changes: Especially when it comes to mold and algae

Because of this, mosses are very effective as indicator species, because they can survive but are the first to see changes in the ecosystem, thanks to their constant connection to the land. But while here, we will focus on animals which are examples of indicator species and cases where they have been monitored.


Insects are highly valued in terms of indicator species. This is because of their high interactions with the environment, making them very useful in assessing the level of water pollution, air pollution, soil quality, and overall ecosystem health.

For example, many invertebrate insects such as dragonflies or stone flies are an indicator species that can assess the amount of oxygen in a river, which means they are useful indicators for controlling river pollution.

On the other hand, pollinating insects such as butterflies and bees can accurately determine the health of plants in certain environments.


Fish is another species that is very useful for detecting the health of aquatic ecosystems. They have previously been used, for example in Koh Tao, Thailand, to assess the impact of the tourism industry on marine coral reefs. Some of the fish that become indicator species are, Sweetlips, Surgeonfish, Rays, Rabbitfish, butterfly fish, etc. In the case of large barrier reefs, coral bleaching and coral are the most striking indicators, although other common fish are used as indicators such as Parrotfish and Surgeonfish.

Salmon as an indicator species

Salmon is generally an indicator species in many ecosystems in the world, especially in North America. For example, salmon have been designated as an indicator species by the Environmental Protection Agency to determine the health of the wider Pacific Rim, which has been influenced by human actions through deforestation, dam building and pollution among other reasons. It is also an indicator species for the Great Vancouver wetland ecosystem. In both cases, salmon is a good indicator that reminds scientists of the state of the water.


You might not think that mammals make good indicator species, but the reality is that in many ecosystems, they can be very useful for ensuring balance in an ecosystem. A study at Aarhus University shows how small mammals can be the best indicators for determining the health of plant diversity in Peru's Mediterranean climate ecosystem. In this case, the Pikas colony, Rabbit, is useful for learning how these interact with plants by digging, grazing, and trampling them to learn how the herbaceous community is affected by water retention and changes in soil nutrition.

Another small animal is the only mammal from 7 New Zealand indicator species: short-tailed bat. These endemic species are now endangered and threatened by incoming predators, therefore the Kiwi conservation department gives significant importance to the monitoring of their indicator species.
Another small animal is the only mammal from 7 New Zealand indicator species: short-tailed bat. These endemic species are now endangered and threatened by incoming predators, therefore the Kiwi conservation department gives significant importance to the monitoring of their indicator species.

But make no mistake, large mammals can also be considered indicator species as well. For example the Grizzly Bear is considered an indicator species to assess the health and diversity of species in Alaska. In addition, prairie dogs are also an indicator species of American prairie ecosystems.

On the other side of the world we can find examples of other large mammals as indicator species. Uttar Pradesh is one of the states that Indian conservation departments need to pay attention to, due to the many human disorders that have occurred during the last few years. Open grasslands and savanna and forests need chital (also known as spotted deer) nilgais (also known as blue bull) and livestock to preserve biodiversity in the region according to the scientific journal JRNL.

Birds as an indicator species

Although you might think that birds are only good indicator species for air pollution, their interactions with other ecosystems make it very good to monitor the overall quality of certain habitats. Let's look at various problems that birds can determine:


In North America, spotted owls and red woodpeckers are the two main indicator species for determining the quality and quantity of old forests, which are threatened by deforestation and pollution. Red woodpeckers are very picky about nesting, because they need bigger and older trees to make nests, which is why monitoring this species can tell many scientists about the health of the forest and its ecosystem.


Certain bird eggs can also provide clues about soil health, because they are generally analyzed to find pesticides on them. High levels of DDT will also make the eggs lose thickness, creating a lower survival rate that can determine the amount of mercury found in the soil.

In addition, we can also see good indicator species in vultures, for example in the case of pollution in China. The decrease in the number of those who reminded of the high level of diclofenac given to livestock in the country, so poisoning vultures that eat it alternately.

Ecosystem health

Fantails species and kiwis are two birds species from 7 New Zealand indicator species that determine the health of the country's species wildlife habitat. There are many reasons why kiwis species are threatened with extinction, and many can also apply to other ecosystems in Zealand, which are severely threatened by human action.
Another case where birds are a good index of species for the entire ecosystem is in the everglades. Endemic swamps that nest on the Everglades depend on the abilities of other predators. With their decline in capacity, the number of nesting birds that are nesting is the first warning in the 1950s that action to maintain the Everglades ecosystem needs to be taken.

Frogs as indicator species

There are many questions about whether frogs are indicator species at all, although many amphibians can be great indicator species because of their flexibility when dealing with ecosystems for obvious reasons.

The truth is that tadpoles can successfully demonstrate water quality and, as they grow, their moist skin allows pollutants to enter their systems, thus helping to detect problems with environmental health in most of the world. In addition, according to a study by Malcolm McCallum of Texas University, there are 30% of species that are almost extinct only in the US. This may be the reason why they are questioned as indicator species, because there are many factors that can affect the extinction of these species and hence the cause of their reduction cannot be demonstrated by a single factor, because they are too vulnerable.

Organisms are not animals

Now that you know about animal indicator species, we want to give you a little insight into other non-animal species that are also considered indicators.

Especially mosses, and liverworts that can monitor pollution and overall environmental health. For example, metal concentrations found in moss tissue can show that ground transportation changes the environment that surrounds the haul road.