News / Science & Technology

Crocodiles, Alligators May Lure Prey with Sticks

A well-camouflaged mugger crocodile (Crocodylus palustris) in stick-displaying behavior. Madras Crocodile Bank, Tamil Nadu, India. (V. Dinets)
A well-camouflaged mugger crocodile (Crocodylus palustris) in stick-displaying behavior. Madras Crocodile Bank, Tamil Nadu, India. (V. Dinets)

Related Articles

Cyanide Kills Elephants, Ecosystem

Poachers kill hundreds of elephants in Zimbabwe

Lion Population Devastated by Illegal Snares

Snares set to catch antelope and other bush meat often catch lions, often crippling or killing them

Oil Rush in Africa's Parks Drives Hunt for Eco-friendly Methods

Oil companies explore new oil sources without damaging the environment
Egrets and other birds building nests near ponds that harbor crocodiles or alligators should be suspicious of sticks they see floating in the water. That twig or branch may be bait for a trap set by the reptiles, as new research suggests they may have joined the few species that use tools to lure prey.

According to Valdimir Dinets, a zoologist known for his studies of crocodilian (crocodiles and alligators) behavior, two species of the large reptiles have been observed using twigs and sticks as bird lures.

“At least one of them uses this method predominantly during the nest-building season of its prey,” he writes in a paper published in the journal Ethology Ecology & Evolution. “This is the first known case of a predator not just using objects as lures, but also taking into account the seasonality of prey behavior. It provides a surprising insight into previously unrecognized complexity of archosaurian behavior.”

According to the study, the use of objects as hunting lures is very rare among animals, only seen in captive capuchin monkeys, a few bird species and one insect.

Writing in the study, Dinets states that “it is common for some bird species to preferentially nest in trees growing in ponds with large numbers of crocodiles or alligators, apparently using the crocodilians as protection against tree-climbing nest predators such as snakes, monkeys and raccoons.”

But, he says, the birds have to “pay” for the protection because their chicks can sometimes fall into the water where they are usually devoured by crocodilians.

“But the protection seems to be worth the cost,” Dinets writes. “Almost any crocodile farm or alligator park with appropriate trees will sooner or later become the location of an egret rookery.”

An American alligator chomps a snowy egret at the St Augustine Alligator Farm Zoological Park, Florida. (Don Specht)An American alligator chomps a snowy egret at the St Augustine Alligator Farm Zoological Park, Florida. (Don Specht)
x
An American alligator chomps a snowy egret at the St Augustine Alligator Farm Zoological Park, Florida. (Don Specht)
An American alligator chomps a snowy egret at the St Augustine Alligator Farm Zoological Park, Florida. (Don Specht)
Dinets says he repeatedly saw crocodilians laying in shallow water with small sticks or twigs across their snouts around rookeries.

“The crocodiles remained perfectly still for hours, and if they did move to change position, they did it in such a way that the sticks remained balanced on their snouts,” he writes.

Dinets says the predators get the sticks onto their snouts by submerging under them.

“Then it takes some balancing act to keep the sticks in place,” he said in an email.

Observing alligators at two egret nesting sites for a year, Dinets saw stick displaying mostly during the bird’s breeding season, between March and June and more frequently during nest building, from late March and April.

Dinets noted that the increase in the behavior could be explained by higher amounts of sticks in the water, either because of nest building or trees shedding. He thinks, however that that explanation “seems unlikely.”

“Virtually no freely floating sticks or twigs were seen by the observer at that time, and none are visible in photographs of rookery ponds made at that time,” writes Dinets. “Any available sticks were probably quickly picked up by birds looking for nest material.”

Also, he notes that the most common trees around the waters don’t often shed branches.

Dinets says it’s “unknown” what factors lead to the stick-displaying behavior at particular locations and at certain times of the year.

“The predators might be reacting to the presence of large numbers of wading birds flying low over water, to the sounds made by courting birds, or to some other environmental clue,” he writes.

He also doesn’t know if the behavior is a learned behavior or an evolved instinct.

While Dinets says crocodilians have historically been viewed as “lethargic, stupid and boring,” the new research adds to the complex behavior already known such as signaling, advanced parental care and “highly coordinated group hunting tactics.”

“These discoveries are interesting not just because they show how easy it is to underestimate the intelligence of even relatively familiar animals, but also because crocodilians are a sister taxon of dinosaurs and flying reptiles,” he concludes.

You May Like

Nigeria Incumbent in Tight Spot as Poll Nears

Muhammadu Buhari is running a strong challenge to Goodluck Jonathan, amid a faltering economy and Boko Haram security worries More

Video Liberia's Almost Last Ebola Patient Grateful but Still Grieving

Beatrice Yardolo tells VOA that despite her fame, life is still a struggle as she waits for government's promise of support to arrive More

Video Cambodian Land Grabs Threaten Traditional Communities

At least seven different indigenous groups in Ratanakiri depend mainly on forest products for their survival, say they face loss of their land, traditional way of life More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Liberia's Almost Last Ebola Patient Grateful but Still Grievingi
X
Benno Muchler
March 26, 2015 3:41 PM
Beatrice Yardolo was to make history as Liberia’s last Ebola patient. Liberians recently started counting down 42 days, the period that has to go by without a single new infection until the World Health Organization can declare a country Ebola-free. That countdown stopped on March 20 when there was another new case of Ebola, making Yardolo’s story a reminder that Ebola is far from over. Benno Muchler reports from Monrovia.
Video

Video Liberia's Almost Last Ebola Patient Grateful but Still Grieving

Beatrice Yardolo was to make history as Liberia’s last Ebola patient. Liberians recently started counting down 42 days, the period that has to go by without a single new infection until the World Health Organization can declare a country Ebola-free. That countdown stopped on March 20 when there was another new case of Ebola, making Yardolo’s story a reminder that Ebola is far from over. Benno Muchler reports from Monrovia.
Video

Video Cambodian Land Grabs Threaten Traditional Communities

Indigenous communities in Cambodia's Ratanakiri province say the government’s economic land concession policy is taking away their land and traditional way of life, making many fear that their identity will soon be lost. Local authorities, though, have denied this is the case. VOA's Say Mony went to investigate and filed this report, narrated by Colin Lovett.
Video

Video US, South Korea Conduct Joint Military Exercises

The Eighth U.S. Army Division and the Eighth Republic of Korea Mechanized Infantry Division put on a well orchestrated show of force for the media this week during their joint military training exercises in South Korea. VOA’s Seoul correspondent Brian Padden was there and reports the soldiers were well disciplined both in conducting a complex live fire exercise and in staying on message with the press.
Video

Video Space Program Status Disappoints 'Last Man on the Moon'

One of the films that drew big crowds last week at the annual South by Southwest festival in Austin, Texas, tells the story of the last human being to stand on the moon, U.S. astronaut Eugene Cernan. It has been 42 years since Cernan returned from the moon and he laments that no one else has gone there since. VOA’s Greg Flakus reports.
Video

Video Young Filmmakers Shine Spotlight on Giving Back

A group of student filmmakers from across the United States joined President Barack Obama at the White House this month for the second annual White House Student Film Festival. Fifteen short films were officially selected from more than 1,500 entries by students aged 6 through 18. The filmmakers and their families then joined the president and a group of celebrities for a screening of their films. VOA’s Julie Taboh reports.
Video

Video VOA Exclusive: Interview with Afghan President Ashraf Ghani

Afghan President Ashraf Ghani, during his first visit as president to Washington, gave a one-on-one interview with VOA Afghan Service reporter Said Suleiman Ashna, about his request for a change in U.S. troop levels, the threat from the Islamic State, and repairing relations with the United States and Pakistan. The interview was held at Blair House, late Sunday, in Pashto.
Video

Video California Science Center Tells Story of Dead Sea Scrolls

The ancient manuscripts were uncovered in the mid-20th century, and they are still yielding clues about life and religious beliefs in ancient Israel. As VOA's Mike O'Sullivan reports, an exhibit in Los Angeles shows how modern science is bringing the history of these ancient documents to life.
Video

Video Angelina Jolie Takes Another Bold Step

Hollywood actress and filmmaker Angelina Jolie has revealed she had her ovaries and fallopian tubes removed to lower her odds of getting cancer. Doctors say the huge publicity over her decision will help raise awareness about the importance of cancer screening. VOA’s George Putic has more

All About America

Circumventing Censorship

An Internet Primer for Healthy Web Habits

As surveillance and censoring technologies advance, so, too, do new tools for your computer or mobile device that help protect your privacy and break through Internet censorship.
More