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Rare captive-bred crocodiles develop new, ‘odd’ habits in Philippine wild

  • Crocodile experts in the Philippines have discovered new habits among the critically endangered Philippine crocodile (Crocodylus mindorensis) that could help them better understand how to protect and repopulate the species in the wild.
  • Since 2013, the Philippines has taken steps to reintroduce captive-bred juvenile crocs into the wild.
  • Eight years on, experts have discovered that the crocodiles can climb steep hilly slopes and that they’re nesting several months out from the previously understood breeding period.
  • Conservationists have also welcomed two juvenile Philippine crocodiles bred at Cologne Zoo in Germany, the first of a batch of 12 from an international captive-breeding program.

MISAMIS ORIENTAL, Philippines — The southern Philippines is home to the world’s rarest and most endangered crocodile species: the freshwater Philippine crocodile (Crocodylus mindorensis). After decades of sliding toward extinction, things may be turning around for the species, as experts make new discoveries about its behavior that could impact its conservation and repopulation in the wild.

In 2013, three dozen captive-bred Philippine crocodiles were reintroduced to a new habitat on the island of Siargao in the southwestern Philippines. Eight years on, conservationists have discovered a behavior never before observed among this shy species: These rare crocs can climb steep hills.

“These crocodiles can climb to as high as 16 meters [52 feet] or about more than two-story house equivalent and with 50 degrees steep slope limestone wall,” said Rainier I. Manalo, marine biologist and program head for crocodile research at the conservation outfit Crocodylus Porosus Philippines Incorporated (CPPI). “This is the first time that anyone has recorded and observed this behavior which is very unusual.”

The discovery could help experts better understand how the species can be better protected and repopulated in the wild, Manalo said. It comes at a crucial time, as efforts are intensifying to breed the species in captivity and rewild zoo-born juveniles.

A Philippine Crocodile (Crocodylus mindorensis) photographed along the banks of Paghungawan Marsh, Pilar town, Siargao Island in the province of Surigao del Norte.
A Philippine Crocodile (Crocodylus mindorensis) photographed along the banks of Paghungawan Marsh, Pilar town, Siargao Island in the province of Surigao del Norte. Image by Erwin M. Mascariñas.

Past studies into crocodile behavior suggest the species bury themselves deeper into the mud or crevices near the water line to stay cool during the dry season in the Philippines. This recent observation expands this notion, where the temperature is much cooler.

“We cannot imagine how those crocodiles got up those crevices and small caves when we had a hard time climbing those slopes ourselves,” Manalo told Mongabay. “We might have been looking at the wrong places, and maybe that’s why we’ve only documented so few in the wild.”

The wild population of the Philippine crocodile is estimated at fewer than 100, making the species critically endangered on both the national red list and the IUCN Red List. Under the country’s Wildlife Act, killing a Philippine crocodile carries a minimum penalty of six years’ imprisonment and/or a fine of 100,000 pesos ($2,100).

The Philippines is home to two species of crocodiles: the saltwater crocodile (Crocodylus porosus), which can grow up to 6 meters (20 feet) long and is common across much of Southeast Asia and Australia; and the freshwater Philippine crocodile, about half the size and significantly rarer.

“These crocodiles play a very big role in our ecosystem,” said Jurgenne Honculada Primavera, chief mangrove scientific adviser for the Zoological Society of London and a Time magazine “hero of the environment” in 2008. “The waste from these creatures provide much-needed nitrogen and phosphorus to our plants and microorganisms. This in turn provides food to other forms of animals in the area, from small insects, birds, crustaceans and of course fish, as one big web of feeding chains.”

Rainier I. Manalo (right) of the Crocodylus Porosus Philippines Incorporated together with his assistant attached a radio transmitter on the back of a Philippine Crocodile (Crocodylus mindorensis) in Barangay Jaboy, Pilar town, Siargao Island, Surigao del Norte. Image by Erwin M. Mascariñas.

For years, scientists and conservationists have pushed for more research and studies to better understand the behavior of the Philippine crocodile, in an effort to better protect what’s left in the wild amid rising threats from hunting and habitat loss.

With the new observation of the crocodile’s rock-climbing skills, Manalo said, conservationists can get a glimpse into the animal’s life cycle and the areas it utilizes. While it suggests reassessing the population survey techniques for the species by expanding the search area, Manalo said more work is needed to understand the species’ behavior patterns.

New breeding habits?

Angel Alcala, former secretary of environment and natural resources, said he agreed on the urgency of better understanding the Philippine crocodile as part of conservation efforts.

“There were just too few of them left in the wild,” he said. “Wild population should be protected and should be a priority as the numbers of the Philippine crocodile is fast declining.”

The rock-climbing habit is just the latest unique behavior exhibited by the Philippine crocodile. Compared to other crocodilian species, C. mindorensis is “shy, very secretive and does not form into groups,” Alcala said “The only time they are with another crocodile is when they mate.”

Radio transmitter attached to the back of the Philippine Crocodile. Image by Erwin M. Mascariñas.

While conservationists have been able to successfully breed the crocodiles in captivity, they say they’re concerned that too much time in captivity will cause the species to lose some of its natural behaviors, particularly learned habits that pass down from one generation to another.

“That is why it is essential that we release and introduce them into the wild at an early age and then let them develop their traits, then hopefully have them mate creating their own offspring in their natural habitat,” Alcala said.

As part of these efforts, the government in 2013 introduced 36 juvenile crocodiles into Paghungawan Marsh on Siargao Island, an area that also hosts the more aggressive saltwater crocodiles. By 2017, an additional 29 juvenile Philippine crocodiles were released.

In November 2020, despite the pandemic lockdown halting habitat and conservation initiatives, citizen scientists monitoring the area discovered two nests with eggs in the wetland. They estimated the eggs were laid in October.

This shows that the captive-bred crocodiles are not only surviving and thriving in the wild, but are also able to reproduce. “This is the first in the Philippines, a huge significant development in the conservation program, a decisive factor indicating that the introduction of the species into a new habitat is a success,” Manalo said.

He added it may be easier for juveniles to adapt to the wild — by developing their hunting instincts — compared to adult crocodiles, a factor that could help improve the success rate of the repopulation program. Older crocodiles are used to being fed in captivity and thus less likely to learn to hunt, he said.

The attached radio transmitter is visible from the back of the Philippine Crocodile as it swims along the waters of Paghungawan Marsh. Image by Erwin M. Mascariñas.

Scientists are also puzzling of the discovery of the eggs. C. mindorensis is known to lay eggs between March and July, but the eggs that were found were laid several months later.

“This is an odd mix, as we did not expect to find nested eggs around [November], but since this is the first time for them to lay eggs [in the wild], we still need to further observe and study this behavior,” Manalo said. “We are not expecting a high rate of survival for the hatchlings, but we are very optimistic that next breeding season in 2021, we will find more nests.”

Fresh from Germany

On Dec. 15, 2020, Manalo’s group also received two Philippine crocodiles, offspring of loaned Philippine crocodiles in 2012, from Cologne Zoo in Germany.

The two young crocs, named Hulky and Dodong, are the first of 12 juveniles headed to the Philippines from a successful breeding program in Germany. After acclimation, the juveniles will become part of a new colony in the Philippines for subsequent reintroduction into the wild.

“This is an excellent and positive example how ex-situ measures such as conservation breeding projects, coordinated by modern, scientifically led zoos, can help to actively support the in-situ conservation measures in the country of origin,” said Thomas Ziegler, regional chair for Europe of the IUCN Crocodile Specialist Group.

Cologne Zoo director Theo B. Pagel, who is also president of the World Association of Zoos and Aquariums (WAZA), called the program another successful example of the “One Plan Approach,” which is supported by the IUCN and aims to develop integrative strategies to combine in-situ and ex-situ measures with groups of experts for species conservation.

A Philippine Crocodile (Crocodylus mindorensis), with a radio transmitter, sprints into the waters of Paghungawan Marsh after it was released. Image by Erwin M. Mascariñas.

The Philippine Department of Environment and Natural Resources’ Biodiversity Management Bureau (DENR-BMB), in collaboration with CPPI, has plans for further repatriation of offspring from the European captive-breeding program to the Philippines.

Manalo, who also is regional vice chairman for East and Southeast Asia of the IUCN Crocodile Specialist Group, said there’s sufficient space and suitable habitat in the southern Philippines for restocking Philippine crocodiles.

“We have come a full circle, after years of hard work, this is the culmination of our efforts,” he said, adding that the “next generation” of crocodiles will thrive in the Philippine wild.

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Banner image of the Crocodylus Porosus Philippines Incorporated team prepares the area at the back of the crocodiles where the radio transmitter will be attached. Image by Erwin M. Mascariñas.

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