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

At Khmer Rouge Court, Long-Awaited Verdict Approaches

First phase of trial, which is coming to an end, has focused on forced exodus of Phnom Penh in 1975 - and now many are hopeful justice will be served More

Video When Fighting Eases, Gazans Line Up at Bakeries

When there is a lull in the conflict, residents who have been hunkered down in their apartments rush out to stock up on food and other necessities More

Video Information War Rages Alongside Real One in Ukraine

Downing of Malaysian airliner, allegations of cross-border shelling move information war in war-torn country to a new level 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.
Information War Rages Alongside Real One in Ukrainei
X
Al Pessin
July 31, 2014 8:13 PM
The downing of the Malaysian airliner two weeks ago, and allegations that Russians are shelling Ukrainian troops across the border, have moved the information war swirling around the Ukrainian conflict to a new level. VOA's Al Pessin reports from Kyiv.
Video

Video Information War Rages Alongside Real One in Ukraine

The downing of the Malaysian airliner two weeks ago, and allegations that Russians are shelling Ukrainian troops across the border, have moved the information war swirling around the Ukrainian conflict to a new level. VOA's Al Pessin reports from Kyiv.
Video

Video When Fighting Eases, Gazans Line Up at Bakeries

When there is a lull in the conflict in Gaza, residents who have been hunkered down in their apartments rush out to stock up on food and other necessities. Probably the most important destination is the local bakery. VOA’s Scott Bobb reports from Gaza City.
Video

Video US-Funded Program Offers Honduran Children Alternative to Illegal Immigration

President Obama and Central American leaders recently agreed to come up with a plan to address poverty and crime in the region that is fueling the surge of young migrants trying to illegally enter the United States. VOA’s Brian Padden looks at one such program in Honduras - funded in part by the United States - which gives street kids not only food and safety but a chance for a better life without, crossing the border.
Video

Video 'Fab Lab' Igniting Revolution in Kenya

The University of Nairobi’s Science and Technology Park is banking on 3-D prototyping to spark a manufacturing revolution in the country. Lenny Ruvaga has more for from Nairobi's so-called “FabLab” for VOA.
Video

Video Gazans in Shelled School Sought Shelter

Israel's air and ground assault against Hamas-led fighters in Gaza has forced many Palestinians to flee their homes, seeking safety. But safe places are hard to find, as VOA’s Scott Bobb reports from Jabaliya.
Video

Video Rapid Spread of Ebola in West Africa Prompts Global Alert

Across West Africa, health officials are struggling to keep up with what the World Health Organization describes as the worst ebola outbreak on record. The virus has killed hundreds of people this year. U.S. President Barack Obama and other world leaders are watching the developments closely as they weigh what actions, if any, are needed to help contain the disease.
Video

Video Michelle Obama: Young Africans Need to Embrace Women's Rights

U.S. first lady Michelle Obama urged some of Africa's best and brightest to advocate for women's rights in their home countries. As VOA's Pam Dockins explains, Obama spoke to some 500 participants of the Young African Leaders Initiative, a six-week U.S.-based training and development program.
Video

Video Immigrant Influx on Texas Border Heats Up Political Debate

Immigrants from Central America continue to cross the U.S.-Mexico border in south Texas, seeking asylum in the United States, as officials grapple with ways to deal with the problem and provide shelter for thousands of minors among the illegal border crossers. As VOA's Greg Flakus reports from Houston, the issue is complicated by internal U.S. politics and U.S. relations with the troubled nations that immigrants are fleeing.
Video

Video Study: Latino Students Most Segregated in California

Even though legal school segregation ended in the United States 60 years ago, one study finds segregation still occurs in the U.S. based on income and race. The University of California Los Angeles Civil Rights Project finds that students in California are more segregated by race than ever before, especially Latinos. Elizabeth Lee reports for VOA from Los Angeles.

AppleAndroid