From the smallest hummingbird to the largest raptor, birds occupy many different trophic levels in food webs worldwide.
Birds play many roles — they are a keystone species and are crucial to the functioning of particular ecosystems.
How are birds good for the environment?
Birds pollinate flowering plants and are seed dispersal agents. Scavenging birds, like vultures, remove decomposing carcasses; birds of prey keep rodents and other pest populations at sustainable levels; and insectivorous birds control insect populations, thus avoiding plagues.
Birds Occupy Many Different Niches and Ecological Roles
Within ecosystems, there are trophic webs – energy flows from producers to consumers and eventually to top predators.
Organisms within these trophic webs regulate one another, keeping the whole ecosystem in balance.
For example, seeding grasses are primary producers, finches are primary consumers that feed on the grass seed, and hawks are mid-level consumers because they prey on finches.
They, in turn, are preyed on by eagles, owls, and crows. Birds and their eggs are also prey to other animals, like snakes, raccoons, and foxes.
Birds occupy a wide variety of ecological niches – as consumers and predators. By preying on other species, birds keep prey populations at sustainable levels.
Even smaller birds that are the prey species play a role by maintaining their predators’ population levels. These are examples of direct effects.
Birds’ behavior can also have indirect effects on other species. For example, the holes that woodpeckers bore into trees create habitats for other animals.
Parasitic invertebrates like lice, mites, and flies rely on birds as host species. Many of these insects are host-specific, relying on certain species of birds to survive.
The Value of Birds in Ecosystems
Insectivorous birds, like bluebirds, swifts, grosbeaks, and warblers, control pests by eating large numbers of insects, thereby keeping their populations under control.
Research has shown that birds consume between 400 and 500 million tons of insects annually.
Not only insects, like butterflies and bees, pollinate flowers. Sunbirds, hummingbirds, and honeyeaters are important pollinating agents for a variety of flowering plants.
Birds have a much stronger sense of sight than smell. Thus bird-pollinated flowers are brightly colored, have sweet nectar and do not have a scent.
Scavenging birds, like vultures and crows, are nature’s morticians. They play a crucial role in efficiently removing dead carcasses.
This prevents rotting flesh from becoming a food source for rats and feral dogs, which spread pathogens like tuberculosis and rabies.
Some birds play a role in nutrient cycles, particularly seabirds. They travel great distances, feeding far out over the ocean.
Upon returning to their colonies, they excrete their nutrient-rich guano. Their droppings fertilize nearby coral reefs, enabling fish living on the reef to grow faster and larger.
Some species of bird have symbiotic relationships with plants in their environment.
When a bird eats a berry or fruit, it benefits by getting a nutritious snack and the plant benefits by having its seeds dispersed great distances in the bird’s digestive tract.
When the bird poops, the hard outer layer of the seed is scarified, and it can germinate.
In this way, birds promote forest growth and increase plant populations’ genetic diversity by spreading their seeds far and wide.
Birds can have massive ecological impacts. They can transform whole landscapes, like wetlands and marshes.
For example, the lush cordgrass that grows on the coastal mudflats in the south-eastern USA protects the coast from erosion.
The grass is only able to exist in such abundance and serve such a vital role in the landscape because American Oystercatchers feed on Littoraria irrorate, periwinkle snails that would otherwise decimate the cordgrass.
How Birds Benefit Humans
Birds are significant to humans due to the ecosystem services they provide. Without birds, the world would be a very different place.
Birds and their many ecological functions benefit humans in a variety of ways. We call these ecosystem services.
Birds directly impact the world’s economy, the production of food, and human health.
In agriculture, birds are important for regulating pest populations.
Having more birds around crops leads to less crop damage by insects and small mammals, which can significantly increase the profit a farmer can make from their crops.
Birds are also hugely beneficial in livestock agriculture. Many birds have developed mutualistic relationships with domestic animals, like cattle egrets.
They perch on cattle, picking off ticks and other harmful parasites. Healthy cows can produce more milk; therefore, the egrets have a direct impact on dairy farmers’ profits.
We do not often realize the important role scavengers, like vultures, play in preventing outbreaks of disease and other threats to human health.
Studies on vultures in the African Serengeti have shown that these birds can consume hundreds of pounds of bones and meat annually.
In Yemen and India, vultures are important for removing organic waste from human settlements. Vultures are amazingly efficient at cleaning up the environment.
In places where vulture populations are in decline, like India, the accumulation of animal carcasses has led to an explosion of feral dog populations.
Dogs are less efficient scavengers than vultures. This has led to outbreaks of rabies and dog attacks.
Altogether the health cost of declining vulture populations between 1993 and 2006 was a staggering $34 billion.
Birds Benefit the Entire Planet
In many parts of the world, habitat loss and pollution have pushed some species to the brink of extinction. The absence of these birds is becoming more noticeable.
Many plants rely on birds for seed dispersal and germination. Certain hard-shelled seeds can only start growing once they have been through a bird’s digestive system.
In this way, birds contribute significantly to promoting forest growth.
In Sweden, where Eurasian jays once dispersed oak seeds, the cost of replacing the birds’ ecosystem service is valued at $4900 per hectare.
Forests sequester carbon, reducing the amount of carbon dioxide in the atmosphere, preventing it from contributing to climate change.
Reforesting vast areas with the help of birds is one way that we can mitigate climate change.
Birds play important roles in ecosystems at many different trophic levels:
- Birds prey on insects and small mammals, controlling pest populations. This is important for agriculture and food production.
- They pollinate flowering plants, disperse seeds from berries and fruits, and contribute to forest growth.
- Birds affect the flow of nutrients through ecosystems, fertilizing coral reefs and marshes.
- Scavengers play an important role in keeping the environment clean and free of decomposing carcasses and preventing the outbreak of diseases like rabies.
Humans need to protect bird populations because the global economy, food production, and human health depend on the ecosystem services that birds provide.