Ants are pushing montane birds into higher elevations

Did you know that mountains, covering only a quarter of the Earth’s surface, are home to 85% of the world’s species? These majestic landscapes support incredible biodiversity, including amphibians, birds, and mammals.

As some of the planet’s most diverse ecosystems, mountains are an essential focal point for conservationists.

Mountain biodiversity with altitude

The level of species diversity, or the range of different species in a specific area, often varies with altitude in mountainous regions. Factors such as changes in climate conditions contribute to this variance.

A recent study from the Centre for Ecological Sciences (CES) at the Indian Institute of Science (IISc) has unraveled another intriguing element that influences bird species diversity at mid-elevations. The element in question? Ants from the Oecophylla genus.

Kartik Shanker is a professor at CES and co-author of the research, which is published in the journal Ecology Letters.

“In mountains, you often see hump-shaped patterns of species diversity, and for a long time, people have been intrigued by why this happens. One of the mechanisms they did not ponder much about was biotic interactions like competition,” said Shanker.

How ants influence montane birds

The ants from the Oecophylla genus, notorious for their aggressive and dominant demeanor, are found at the base of mountains in the paleotropics, spanning continents from Africa and Asia to Oceania.

These ants are ferocious predators of insects. Researchers decided to test the effects of these ants on the diversity of insect-eating birds, particularly at lower elevations.

Study co-author Trevor D Price is a professor in the Department of Ecology and Evolution at the University of Chicago. A previous study led by Price had hinted at the presence of Oecophylla ants impacting montane birds.

The experts determined that these ants, present at the base of the eastern Himalayas, reduced the density of insects, which could potentially affect the presence of insect-eating birds. The current study was designed to see if this pattern extended to other insect-eating species.

Interesting patterns in mountain biodiversity

Under the leadership of Umesh Srinivasan, a professor at CES, the research team sifted through various datasets about bird species observed across different mountain ranges at multiple elevations.

The birds were categorized into dietary guilds – essentially groups having similar dietary needs, like insectivores and omnivores. The team discovered patterns which aligned with Oecophylla ants competing with montane birds for food at lower elevations.

Consequently, these birds might have migrated higher up the mountains, resulting in the most significant species diversity at an elevation level of about 960 meters.

Interestingly, bird categories like fruit and nectar eaters, which do not compete with Oecophylla ants, saw a decrease in their species diversity as the elevation increased.

The researchers concluded that the presence or absence of Oecophylla ants at the base of mountains could explain why the diversity of insect-eating birds peaked at mid-elevations.

Role of biotic interactions

Biotic interactions, such as those observed between Oecophylla ants and insect-eating birds, highlight the intricate ecological networks existing within mountain ecosystems.

These interactions are not limited to predation or competition; they extend to mutualisms and commensalism as well.

Such relationships can significantly influence species distribution and community structure. In mountain regions, where environmental conditions change swiftly with altitude, the importance of these interactions is further amplified.

Understanding the dynamics of mountain ecosystems can lead to more effective conservation management, ensuring the preservation of biodiversity amid environmental changes.

Species interactions and biodiversity patterns

The findings from the study emphasize the critical role of species interactions in shaping biodiversity patterns, which has far-reaching implications for conserving mountain ecosystems.

Conservationists need to factor in these interspecies relationships to maintain biodiversity.

Protecting key species like Oecophylla ants might be essential to sustain the complex food webs that support a multitude of species, including avian insectivores.

Protecting mountain biodiversity

Moreover, the mid-elevational peaks in species diversity reveal zones of high ecological value that merit focused conservation efforts.

Customized strategies that embrace the unique ecological processes at play could bolster efforts to protect these biodiversity-rich areas from the twin threats of habitat loss and climate change.

So, what does this mean for the future of mountains and their biodiversity with climate change knocking on our doors?

“With climate change, if the ants shift their ranges towards higher elevations, this might impact the bird species at higher elevations as well,” noted Srinivasan.

The study is published in the journal Ecology Letters.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–