Play Behaviour Reported in Crocodilians

Ask someone to name an animal that plays and they are very unlikely to suggest an alligator, however, in a new study conducted by a psychology professor at the University of Tennessee, its seems that crocodiles indulge in play behaviours and they quite enjoy it too. In the first study of its kind, Vladimir Dinets, a research assistant professor at the University’s Department of Psychology, has published a paper in the quarterly academic journal “Animal Behavior and Cognition”, the paper examines the evidence for play behaviour that has been observed in crocodilians (alligators, crocodiles, caimans and the gharials), not creatures that most people would associate with the word “fun”.

Crocodiles and Play

According to the Vladimir, over the ten years or so he has spent studying these reptiles, he has observed lots of play behaviour, including playing in water jets, toying with objects, surfing waves and riding on the backs of other crocodilians.  This type of research is important as it helps to shed light on how animals develop and provides an insight into the evolution of intelligence, after all, play and social interactions as a result of play behaviours are more commonly associated with mammals such as primates.  To generate more data, Vladimir conducted an informal survey of crocodile and alligator-themed groups on social media and raised the case for fun loving crocodiles at various conferences.

His results show that play behaviour in crocodilians is not uncommon, but it remains very poorly understood and there has been virtually no formal research conducted in this field.  Behaviour specialists have identified three basic types of play related to animals and all three types have been observed in various species of these toothy creatures with fearsome reputations.  Ironically, the amount of play indulged in by crocodilians may be under reported, reasons for this are that many crocodiles are most active at night when observation is difficult, some observers doubt their own observations, thinking that what they have seen may have a more credible explanation, whilst some witnesses may believe that their claims will not be taken seriously.

Main Types of Play Behaviour

• Locomotor play – defined as intense or sustained movements, often without any apparent reason or stimulus.  For example captive, young American alligators repeatedly sliding down chutes into water, a hatchling caiman deliberately propelling itself across a pool using a jet of water flowing from the bottom of its concrete enclosure, or a 2.5 metre long Estuarine crocodile “surfing” waves off a beach in Australia.
• Social play – defined as a pair of crocodiles (or more), indulging in play together, examples given included a pair of Cuban crocodiles in captivity with the male giving “piggyback rides” around the pool, the female being carried on the back of the male as he swam around.  Two young Black caimans chasing each other around in circles and reference to a “short sequence of film of two sibling Nile crocodiles tussling with each other in what looked like play behaviour” – a reference to personal communications between Vladimir Dinets and Dr Darren Naish (Honorary Research Fellow at the School of Earth & Environmental Sciences, University of Portsmouth).
• Play with objects – defined as playing with toys, interacting with various objects.  This is the most common form of play observed by zookeepers and staff responsible for looking after these reptiles in captivity.  Indeed, many zoos now toss in various objects such as robust floats and balls to provide a stimulus.

There has even been cases of interspecific play behaviour reported.  Vladimir cites the example of an American alligator interacting with a river otter (Big Cypress National Preserve, Florida).

It seems there may be a softer more playful side to these creatures, after all, as far as we at Everything Dinosaur are aware only about eight species are proven man-eaters.

A Strong Bond with Humans

There is also some evidence to suggest that crocodilians can form a strong bond with humans.  Back in 2011, Everything Dinosaur wrote a brief article about two Dwarf caimans from the Blue Planet Aquarium in Cheshire that seemed to respond to their pet names, coming when called.

To read more about this: Crocodilians Respond to Their Own Names.

However, there are a number of documented cases of crocodiles and people becoming playmates.  In the published paper, the story of an American crocodile called Pocho and its relationship with Gilberto “Chito” Shedden is recounted.  “Chito” rescued the crocodile and became its keeper, the crocodile was soon tamed and so strong was the bond between them that “Chito” would often swim with the crocodile.

Various play behaviours were observed, including the crocodile indulging in mock charges, it sneaking up behind “Chito” as if to try to startle him and in return the reptile accepted being caressed, hugged, rotated in the water and kissed on the snout.  This unique relationship continued for twenty years, until Pocho apparently died of old age.  The two became celebrities in their native Costa Rica and were even the subject of a documentary made by Roger Horix “The Man Who Swims With Crocodiles”.

Play Behaviour in Crocodilians

Dinets’ study builds on previous work undertaken by colleague  Professor Gordon Burghardt (Department of Psychology and the Department of Ecology and Evolutionary Biology).  It was Professor Burghardt who defined the concept of “play” in a way that allows it to be recognised in species not previously seen as playful or capable of play-like behaviours.  This new study supports the hypothesis that play behaviours are almost universal in “intelligent” animals, those capable of complex, flexible behaviour.  The research can help scientists to further explore the link between the evolution of more complex behaviour and even intelligence through playful activity.

Vladimir stated:

“Hundreds of thousands of crocodilians are now kept in captivity in zoos, commercial farms and breeding centres set up for endangered species.  Providing them with toys and other opportunities for play makes them happier and healthier.”

Did Dinosaurs Play Too?

This leads on to the question that if play is observed in animals such as crocodilians and we know that birds indulge in play too, then this has consequences for the Dinosauria.  It may be very difficult to prove given the limitations of the fossil record when it comes to preserving behaviour, but it can be speculated or even asserted that dinosaurs played as well.  Cavorting camarasaurs, or ticklish tyrannosaurs, now that’s a thought…

PNSO Yuyan the Sinosauropteryx dinosaur model. Did dinosaurs play too?

For dinosaur models, games and toys: Everything Dinosaur.

Latest Attack on Surfer Highlights Growing Crocodile Problem

The number of crocodiles inhabiting the mangrove swamps, rivers and estuaries of Costa Rica continue to give the local authorities cause for concern.  The problem of potential fatal attacks by American crocodiles (Crocodylus acutus) was highlighted again this month after a surfer narrowly escaped the jaws of a crocodile whist waiting to catch a wave near the mouth of the Tamarindo estuary on the county’s Pacific coast.  Apparently, the crocodile had swam down river out into the estuary and it grabbed the surfer’s leg.  The surfer, identified as Canadian Val Muscalu, was able to free his foot from the crocodile’s jaws and escape.  This is the second reported crocodile attack in the Tamarindo Bay area in the last two years.

Crocodile Problem

The American crocodile is widely distributed throughout the tropical areas of the New World. It ranges from Florida to the Caribbean, including Cuba. It is also found in southern Mexico,  Guatemala through to Nicaragua, Costa Rica, the Isthmus of Panama and the most northerly parts of South America.  Males can grow up to more than five metres in length and American crocodiles can be distinguished from Alligators and other large species of crocodylians as they tend to have a proportionately smaller, more narrow snout.  Attacks on people and livestock are rare, but Costa Rica has seen a dramatic rise in crocodile attacks over the last few years and this has been put down to the feeding of crocodiles as part river tours.

Tourism plays a significant role in the economy of Costa Rica and as American crocodiles are able to tolerate brackish water and even seem to prefer salt-water habitats.  As a result, attacks on people who come to explore the beaches and the surrounding coastlines are always a possibility.   The crocodile suspected of carrying out the attack, will remain in the estuary according to officials from Costa Rica’s National Park Service (SINAC).  There had been calls from hotel owners and locals to have the crocodile removed, but as the estuary is part of a national park, crocodiles cannot be relocated without scientific evidence of overpopulation.

Conflict Between Humans and Crocodiles

Commenting on the potential conflict between humans and crocodiles, Rotney Piedra, the administrator of Las Baulas National Marine Park, just up the coast from where the attack took place stated:

“The Tamarindo Estuary that leads into the mangrove forest is a protected area.  We can’t remove crocodiles, but we want to work with the community to manage the issue.”

Back in April last year, a fatality occurred at the Tárcoles River, located on the eastern side of the Gulf of Nicoya, some forty miles to the south-east of the latest surfer attack.  A man, who was apparently drunk, attempted to swim near the main river bridge.  A crocodile grabbed the swimmer and despite the efforts of onlookers, the victim, later identified as Omar de Jesús Jirón was killed.  His body has not been recovered.

A Four-part Plan

A four-part plan is being implemented by authorities to try and reduce such incidents.  It is hoped that SINAC will be able to educate the local community and tourists about crocodile behaviour.  More warning signs are being posted up at the mouth of the river, replacing those that were stolen, most probably by tourists looking for an unusual souvenir from their stay.   A helpline is being set up to help the authorities to be alerted when crocodiles stray out of the park, these animals can then be relocated.  In addition, a survey is being conducted to try to determine whether the estuary is over populated.

Perhaps most importantly of all, the officials from SINAC hope to educate river tour operators not to feed the crocodiles as part of their crocodile spotting river cruises.  These river trips are very popular with tourists and provide a significant boost to the economy, but by feeding the crocodiles, on some occasions, hand-feeding them, these reptiles begin to associate humans with food and this could lead to further attacks.

Not Regarded as an Aggressive Species

Although the American crocodile is not regarded as a very aggressive species, hand-feeding these animals could be modifying their natural behaviour and making them much less afraid of humans and more likely to approach.

A spokesperson from Everything Dinosaur explained:

“Although American crocodile attacks are statistically very rare and the American crocodile is not known for its aggressive behaviour, not when compared to the likes of the Nile crocodile or the Estuarine for example.  These animals can grow up to five metres in length and at a little over a metre long they would be capable of causing very serious injury should a person be grabbed by one.”

Visit Everything Dinosaur’s award-winning website: Visit Everything Dinosaur.

Many Native Mammal Species on the Brink of Extinction

A survey on Australia’s native mammal species due to be published this week will reveal that Australia is losing its mammal species at a faster rate than almost anywhere else in the world.  Much of the native fauna of Australia is unique and the introduction of cats and foxes is having an dramatic toll on small mammal species.  As most of these mammals are shy and nocturnal, people are simply not aware that many species are threatened.

In a scientific report prepared by Charles Darwin University (Northern Territory) the research team state that since 1788, the year of the founding of the first European colony on the continent, 11% of the 273 native, terrestrial mammals had become extinct.  The report suggests that 21% are threatened with a further 15% near threatened.

The Thylacine – A Famous Australian Extinction

A Thylacine (bottom right), is included in the Australian mammals part of the gallery (Senckenberg Museum).

Picture credit: Everything Dinosaur

Extinction Rate

Lead author of the study, conservation biologist John Woinarski declared:

“No other country has had such a high rate and number of mammal extinctions over this period, and the number we report for Australia is substantially higher than previous estimates.”

Cats are regarded as the number one problem.  Nobody knows for sure how many feral cats there are in Australia, but some estimates put it at around 23 million.  That’s one cat for every person in the country.  Foxes introduced for hunting, have also had an impact on native wildlife.  However, land management and agricultural practices may also be playing a role in the decline of many native species.

Fires either natural or deliberately started are also having a dramatic effect on the small mammal population.

Dr Woinarski explained:

“Now we are seeing much more extensive and hot fires and that’s having an impact as well.  It’s not as serious a factor as predation by feral cats, which we think is the number one factor.  But the two factors aren’t independent.  It seems the impact of feral cats is far worse in extensively burnt areas, simply because many of those native land mammals species don’t have enough refuge left.”

Native Mammals Under Threat

In time, some of Australia’s most famous inhabitants might become extinct, animals like the Koala and many types of Wallaby.

The Charles Darwin University has been prominent in recent years, undertaking a number of significant and highly influential environmental research projects to assess the health of the country’s native flora and fauna.  The Brush-Tailed-Rabbit-Rat (Conilurus penicillatus), is one such mammal that has declined in numbers over the years.  Its small size and secretive nature has meant that the reduction in population has gone unnoticed by most Australians.

A spokesperson from Everything Dinosaur commented:

“Hopefully, this new study will help to highlight the plight of many of Australia’s shy, nocturnal small mammals.  Tough choices may have to be made with regards to controlling feral cat populations and reducing the number of foxes if the decline in native species is to be halted.”

The Cane Toad

Intriguingly, Everything Dinosaur team members are not aware of any mention of the Cane Toad (Rhinella marina) and this amphibians impact on native mammal populations.  Introduced from Hawaii in the mid 1930s, the Cane Toad is poisonous and has no natural enemies in Australia.  The Cane Toads not only compete for food and resources with native species, but they also eat large numbers of insects, including pollinators, frogs, small lizards and occasionally small mammals.   As these animals are poisonous throughout their life cycle, many Australian species have declined as a result of being poisoned the Western Quoll (Dasyurus geoffroii) is particularly threatened.

Visit Everything Dinosaur’s award-winning website: Everything Dinosaur.

Past Mass Extinctions Linked to Changes in Global Climate

Planet Earth might be teetering on the brink of a sixth mass extinction event, climate change resulting in the huge loss of species associated with the Cretaceous mass extinction or the more devastating (in terms of species affected), Permian Great Dying.

Documentary

That is the conclusion reached in a documentary being aired on the Smithsonian channel in the United States tomorrow.  The documentary entitled “Mass Extinction: Life at the Brink” explains what scientists now know about the Permian and Cretaceous extinction events, two of the five great extinctions recorded in the fossil record (Phanerozoic extinctions).  The documentary also explores how our activities are altering the climate, which could lead to similar collapses within ecosystems.

Although global warming is still dismissed by some, most of the scientific community supports the theory that the Earth’s climate is changing and that the planet is getting warmer.  One of the key points in the film concerns the issue of if the Earth warms very suddenly, when climate change is examined against the backdrop of geological time, then what would be the consequences?

Mass Extinction

This documentary and a book written by University of California (Berkeley) palaeontologist and professor of integrative biology, Anthony Barnosky (Dodging Extinction) is just one of a series of increasingly alarming accounts of the impact of climate change on our planet, produced by the academic community.  Back in 2010, a United Nations report stated that about 30% of all the flora and fauna on Earth was in danger of dying out by the end of the 21st Century due to the rapid industrialisation of parts of the world and the West’s inability to curb greenhouse gases that were potentially leading to dramatic changes in climate.

To read more about the United Nations report: Are we Heading for a Sixth Mass Extinction Event?

Professor Barnosky

Professor Barnosky and his wife, Dr Elizabeth Hadley (a biologist/ecologist at Stanford University), appear in the documentary, helping to explain the evidence that has been amassed that suggests climate change is happening and such shifts in Earth’s climate led to mass extinctions in the past.

Professor Barnosky, now in his early sixties explains:

” I go back to places where I was doing coal exploration geology, beautiful places in western Colorado and now the trees are all dead, mostly from beetle kill because winters have warmed enough so that the beetles can reproduce twice in a season rather than once.  In my lifetime, I have seen it go from verdant forests to literally tens of thousands of acres of dead trees, and that’s just in Colorado.  There are literally millions of square miles of dead trees up and down the Rocky Mountain chain.  All because of greenhouse gases warming the atmosphere”.

A Table Listing the Five Major Extinction Events of the Phanerozoic

Table credit: Everything Dinosaur

Five Major Mass Extinction Events

The table above documents the five mass extinction events from the Phanerozoic Eon (the eon of visible life from approximately 545 million years ago to the present day).  The table also provides information about the major animal groups affected.

The documentary film’s executive producer is evolutionary biologist Sean B. Carroll, he states that scientists and academics have learned more about what caused the great extinction events of the past.  Dramatic events like asteroid impacts and massive volcanic eruptions led to climate change on a global scale wrecking the world’s ecosystems and devastating life on our planet.

Professor Carroll explained:

“We now know with high confidence from recent work that The Great Dying [Permian extinction event] was caused by massive volcanic eruptions underneath present-day Siberia and that just pumped out massive amounts of climate-changing gases, including massive amounts of carbon dioxide.”

The Work of Walter Alvarez

Also appearing in the documentary programme is Walter Alvarez (University of California, Berkeley), who along with his late father, the physicist Luis Alvarez, first uncovered evidence that an extraterrestrial impact had struck the Earth at around the time of the demise of the dinosaurs.  Whilst there has always been extinctions (known as the background rate of extinction), the programme makers warn that as humans reduce the habitat available for other species and alter the composition of the atmosphere, animals and plants are being pushed towards extinction twelve times higher than the background level.

Global Temperatures Rising

For instance, temperatures may rise by perhaps as high as four degrees Celsius by the end of the 21st century, a rise almost as great as during the end Permian extinction event, which resulted in the loss of some 95% of all life on Earth.  It has been suggested that most of the coral reefs may vanish by the year 2070, as the oceans become more acidic due to increased levels of carbon dioxide in the atmosphere.  This could result in the loss of 25% of the fish species in the sea that depend on coral reefs resulting in the loss of 10% of the ocean’s fisheries with direct implications for the human population.

Still Time to Avert the Catastrophe

There may be still time to help avert this catastrophe, recent agreements on the restricted use of fossil fuels and greenhouse gas emission limits if implemented effectively, could help minimise the impact.  In the book, authored by Professor Barnosky, he proposes a series of steps that people can take to help prevent further global warming:

• Reduce the amount of intensively reared meat that you consume
• Avoid foods which contain palm oil (palm oil plantations replacing large amounts of natural forest)
• Only eat fish that has been sustainably harvested

In addition, the authors and the documentary makers urge people to lobby political and business leaders to help bring about fundamental changes in the way that we as a species perceive the natural world and its resources.

Visit Everything Dinosaur’s award-winning website: Everything Dinosaur.

More Crocodile Attacks Reported in Gujarat State

The number of crocodile attacks reported by the authorities in Gujarat State (western India), continues to rise with the latest victim a sixteen year old boy who was attacked by a crocodile as he swam in a lake close to Dena village (Gujarat).  A day earlier, a woman was dragged into the water by a crocodile near the town of Goraj.  The boy, Moin Qureshi managed to escape but suffered injuries to his legs.  Villagers report that the lake is home to at least two large crocodiles.

Crocodile Attacks

A spokes person for the villagers explained that locals had been requested to stay away from the water, Moin is in hospital recovering from his ordeal.  This attack follows a similar incident reported  from northern India last month when two girls were attacked by a crocodile, one of these attacks proved fatal.

There have been a number of such incidents reported from India this year, back in April, Everything Dinosaur team members reported on the series of crocodile attacks in Gujarat State.

To read more about these attacks: Third Fatality as a Result of Crocodile Attack Reported.

At certain times of the year, crocodiles are believed to be more aggressive and therefore more likely to attack people, when females are guarding nests or when males are competing for territory for example.  Loss of habitat and the increasing population pressure may also be a factor as people are coming into contact with large crocodiles more frequently.

More Crocodile Attack Fatalities

A Nile crocodile (Crocodylus niloticus) is reported to have attacked and killed a woman whilst she was collecting reeds in the Shire River (Mangochi district, southern Malawi).  Mangochi Police Station Public Relations Officer, Inspector Rodrick Maida stated that the deceased had been in the river gathering reeds with two female friends when the crocodile grabbed her.  The women were unable to free the victim from the crocodile’s grip and ran to nearby houses to fetch help.

Crocodile Attacks

A search conducted by a group of villagers from Mtalimanja also ended in tragedy when Walani Lawe (aged 51) was attacked and severely injured whilst attempting to retrieve the woman’s body.  The dead woman’s body has yet to be recovered.  Mr Lawe was taken to Mangochi District Hospital and it has been reported that he is responding well to treatment.

This attack comes just a few days after another fatal crocodile attack this time in Papua New Guinea and the species concerned was a Saltwater or Estuarine crocodile (C. porosus).  Several media sources have reported that a four-metre-long reptile attacked and killed an eleven year old boy whilst he fished with his parents.  The incident took place on the Siloura River in Gulf Province, in the southern part of Papua New Guinea. The attack occurred on Thursday afternoon.

Authorities Make Statement

Police Commander Lincoln Gerari, said in the statement that the boy had been identified as Melas Mero.  Following the fatal attack, a large crocodile was tracked by hunters and killed.   The boy’s limbs and part of the hips were found inside the crocodile’s stomach.  Other body parts have been recovered by the police team.

Describing the sudden attack, the Commander explained:

“The crocodile swept the boy with its tail and then attacked the defenceless child.”

This is the second fatal crocodile attack to be reported from Papua New Guinea in 2014.  On January 1st a man was killed by a Saltwater Crocodile at Rawa Bay in North Bougainville.   According to a Darwin based, crocodile data recording team, this is the seventy-fifth crocodile attack recorded in Papua New Guinea since 1958.  Of these seventy-five attacks, sixty-five have proved fatal.

Mugger Crocodiles Protecting Nests Blamed for Fatal Attacks

Indian media is reporting a third crocodile attack in as many weeks in and around the city of Vadodara in the state of Gujarat (north-western India).  A sixty year old man was attacked close to the Vishwamitri river on Friday afternoon, despite desperate attempts from local residents and members of the fire brigade, the man was pronounced dead at the scene.  The crocodile initially refused to relinquish the body, but persistent efforts finally succeeded in recovering the victim who has yet to be formally identified.

The Vishwamitri River

The Vishwamitri river runs through the city of Vadodara and recent surveys suggest that there is a healthy population of Mugger crocodiles (Crocodylus palustris) living in the river.  The Mugger or Marsh crocodile is the most common crocodile species found in India and although these reptiles predominately eat fish, snakes, turtles and small mammals, they have been known to attack people and livestock.   However, the spate of recent crocodile attacks has led city officials to issue notices and warnings with regards to the potential threat of an attack.

An elderly woman was killed by a crocodile three weeks ago, when she was seized close to a lock near the village of Savli.  A teenage boy was killed on April 20th when he fell into the Vishwamitri when trying to cross the river on a wooden plank.

Crocodile Attacks

The Mugger crocodile can grow up to around 4.5 metres in length, with adult males growing to larger sizes than females.  They are distributed throughout the Indian sub-continent and can be found in Sri Lanka, Bangladesh, Nepal, Pakistan with a small population reported from southern Iran.   The recent spate of attacks has been blamed on female crocodiles being extra aggressive at this time of year (spring).  Many female crocodiles might be guarding nests and as a result, they will instinctively attack any creature that wanders too near the eggs.  Animal activists and conservation groups have urged local people to avoid areas where crocodiles are known to nest, not to venture close to the riverbanks and not to go out at night near bodies of freshwater.

A recent study of Mugger crocodiles and American alligators (Alligator mississippiensis) by an international team of scientists proved the long held belief that these species use tools to help attract prey close enough for them to grab in their powerful jaws.  These two species of crocodylians are not closely related but both the American alligator and the Mugger find sticks and balance them on the top of their jaws in a bid to lure birds to perch on them and to steal the sticks during the nesting season when many wading birds are seeking sticks and other materials to help them build nests.

A paper on this observed behaviour was published in the academic journal “Ethology Ecology and Evolution”.

This is the only known incidence of tool use in the Reptilia.

Boy from Zimbabwe Attacked by Nile Crocodile

A twelve year old boy from Zimbabwe was killed by a Nile crocodile  (Crocodylus niloticus) on April 22nd and earlier this month a fisherman was mauled to death in Belize with an American crocodile (Crocodylus acutus) blamed for the assault.  A Nile crocodile which is believed to have been responsible for the deaths of at least six people was captured by Ugandan game wardens.  The crocodile measured nearly six metres in length and is estimated to have been at least eighty years old.

The Differene Between Crocodiles and Alligators

Crocodile (top) and Alligator (bottom).

We are grateful to Brandon who pointed out that the attack reported in Belize was not from an American Crocodile but from a Morelet’s crocodile (Mexican crocodile).  We thank him for the correction.