Wildlife: Fish in Mexico team up to produce waves to protect them from birds of prey

Strikingly, by working with hundreds of thousands, fish living in sulfidic springs in Mexico can produce a Mexican wave that provides protection from birds.

This is the conclusion of researchers from the Leibniz Institute for Freshwater Ecology and Inland Fisheries in Germany, who studied sulfur mollies in the municipality of Teapa.

What remains unclear, however, is exactly why the waves seem to both deter birds from attacking and make launched offensives less likely to succeed.

While further studies are needed to investigate, the team has suggested the waves could confuse the birds — or tell them they’ve been spotted.

Birds that prey on sulfur mollies include kingfishers and kiskadees.

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Working in tandem with hundreds of thousands, fish living in sulfidic springs in Mexico are producing - aptly enough - a Mexican wave that protects against birds.  Pictured: sulfur mollies

Working in tandem with hundreds of thousands, fish living in sulfidic springs in Mexico are producing – aptly enough – a Mexican wave that protects against birds. Pictured: sulfur mollies

SULFUR MOLLIES

species name: Poecilia sulphuraria

Also known as: Molly del Teapa

Venue: Banos del Azufre, Teapas

Status: Critically Endangered

notable features: tolerance to high concentrations of toxic hydrogen sulfide in sulfidic sources

The study was conducted by biologist David Bierbach of the Leibniz-Institute of Freshwater Ecology and Inland Fisheries and his colleagues.

The mollies — whose sulfurous springtime habitat is too toxic for most fish — make waves not only in response to birds, but when they come into view of humans.

“At first we didn’t quite understand what the fish were actually doing,” said Dr. Bierbach of Mexican wave behavior.

“Once we realized that these are waves, we wondered what their function might be,” he added.

The team suspects the move could be some form of defensive measure after noting how many fish-eating birds could be found around the fish’s river.

When examining the mollies’ behavior, the researchers found that the waves could be characterized as striking, repetitive and rhythmic.

In addition, experimentally induced waves generally doubled the time birds waited by the river for their next attack on the mollies — with some even switching perches, suggesting they’d decided to focus elsewhere.

For kiskadees, but not kingfishers, the odds of successfully catching a fish decreased with increasing numbers of waves.

“The diving response in sulfur mollies probably evolved first as an individual escape behavior towards attacking birds,” the researchers explained in their paper.

“We hypothesize that fish that used close neighbor diving responses as a signal indicating the presence of predators (and prompting them to dive as well) had a fitness benefit.”

‘They could even react without having discovered the predator themselves. This in turn led to the evolution of synchronized diving behaviour.’

The mollies (D) — whose sulfurous spring habitat (pictured) is too toxic for most fish — not only make waves (E) in response to birds such as kingfishers (B) and kiskadees (C), but also when they approach humans in the water. eye also discovered the researchers

The mollies (D) — whose sulfurous spring habitat (pictured) is too toxic for most fish — not only make waves (E) in response to birds such as kingfishers (B) and kiskadees (C), but also when they approach humans in the water. eye also discovered the researchers

The mollies (D) — whose sulfurous spring habitat (pictured) is too toxic for most fish — not only make waves (E) in response to birds such as kingfishers (B) and kiskadees (C), but also when they approach humans in the water. eye also discovered the researchers

“The surprises came when we realized how many fish can interact in such repetitive waves,” added co-author and ecologist Jens Krause, also of the Leibniz Institute.

‘There are up to 4,000 fish per square meter and sometimes hundreds of thousands of fish participate in a single wave of fish.

“Fish can repeat these waves for up to two minutes, with a wave about every three to four seconds.”

For kiskadees, but not kingfishers, the odds of successfully catching a fish decreased with increasing numbers of waves.  Pictured: a kingfisher with a molly in its beak

For kiskadees, but not kingfishers, the odds of successfully catching a fish decreased with increasing numbers of waves.  Pictured: a kingfisher with a molly in its beak

For kiskadees, but not kingfishers, the odds of successfully catching a fish decreased with increasing numbers of waves. Pictured: a kingfisher with a molly in its beak

“At first we didn’t quite understand what the fish were actually doing,” said Dr. Bierbach of Mexican wave behavior. “Once we realized that these are waves, we wondered what their function might be,” he added. Pictured: A human Mexican wave at a sporting event

“Until now, scientists have mainly explained how collective patterns arise from the interactions of individuals, but it was unclear why animals produce these patterns at all,” explains Professor Krause.

“Our research shows that some collective patterns of behavior can be very effective in providing protection against predators.”

The study’s full findings were published in the journal current biology.

THE ORIGIN OF MEXICAN WAVES

The “Mexican” or “stadium” wave is thought to have first appeared in the United States during sporting events in the late 1970s and early 1980s.

It became widely popular, not to mention its common name in the English speaking world, after its appearance at the 1986 FIFA World Cup, which was held in Mexico.

However, unlike the waves created by the sulfur mollies, people do not change location when they create a wave.

Instead, people tend to get up and sit down and return to their original position at the end of the maneuver.

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