16 May 2018

Scientists brave white-water rapids in search of Critically Endangered wren

How far would you go to study a Critically Endangered species? These four scientists went on a journey through Colombia’s deepest canyon.

The Niceforo's wren, which is Critically Endangered © Daniel Uribe
The Niceforo's wren, which is Critically Endangered © Daniel Uribe
By Margaret Sessa-Hawkins

With stark cliff walls over 1,600 meters high, the Chicamocha canyon is the deepest in Colombia. Unfortunately for biologists, its difficult terrain houses a number of endemic species.

It was in order to confirm the presence of one of these species – Nicéforo’s Wren Thryophilus niceforithat four biologists from Calidris (BirdLife in Colombia) set out on a two-day expedition in January travelling along the walls of the interior of the canyon the only way possible: by white-water rafting.

Rafting down the canyon would not be easy. The Chicamocha River has sections of rapids that range from Class I to Class V on the International Classification System. Although any rapid below Class III is not too hard to navigate, Class IV and V are far more challenging, and typically reserved for more experienced rafters. (For reference Class VI rapids, the hardest, are considered life-threatening and not commercially navigable.)

Prior to this trip, the team had minimal rafting experience. They would be relying on their guides, Christian Torres and Joao Gonzales of Rio Expediciones, to get them safely through the rapids. The first day they would be rafting for eight hours, the second for six. Determining if the wren was present in the canyon though, would be worth the journey.

The Niceforo’s Wren is Critically Endangered. From 2004-2008 conservationists conducted a series of population surveys to see how many of the birds remained in the wild. In this time, only 77 individuals were found, leading scientists to estimate that the total worldwide population is under 200.

“With a population as small as a couple of hundred individuals, a species is incredibly vulnerable,” said Stuart Butchart, Chief Scientist at BirdLife International. “Natural population fluctuations could easily tip the wren into extinction, while human-induced threats could rapidly wipe out the whole population. Discovering previously unknown individuals would make the outlook more positive than previously feared, and would be great news for the species.”

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Roughly 10 centimetres long from beak to tail, the Niceforo’s Wren is a tiny, dusky-brown bird with a white belly and black and white stripes on its cheek. It is endemic to Colombia, and inhabits a very limited range of sub-montane dry forests at the foot of the Andes Mountains where there is easy access to freshwater and dense undergrowth.

The wren is threatened by agricultural practices including clearing land for cattle to graze on, burning land to make space for farming, and logging for firewood. It has therefore retreated to exclusively remote habitats where these activities aren't present. Because this habitat is diminishing though, it is almost certain that the population of the wren is also in decline.

Despite this, the team held out hope that they would be able to spot some of the birds in the canyon. On January 17, they all loaded into a small blue raft. Wearing helmets, life jackets (and, naturally, helmet cameras) they set off down the Chicamocha.

Rafting down the river, especially with minimal experience, is tough. At extreme points the water is quite high, with tall waves curling over themselves among swirling eddies, and rocks jut out from the surface in random clusters. From the back of the boat, the guide was constantly yelling instructions to the team to help them navigate safely: ‘Forward! Forward hard! Left! Stop!’

Going through the rapids though, the team also discovered why so many tourists flock to the spot. Wending its way between tall mountains studded with deep green forest, the Chicamocha is beautiful. White-water rafting down the river is a popular sport among adrenaline seekers, and now, perhaps, scientists.

“It was maybe the best experience I have had in all my 25 years of being a biologist,” Expedition leader Felipe Estela said. “I did feel a lot of respect for the river, and I was conscious of the potential risks we were facing, but I knew that as long as we were following our guide’s directions, those risks were considerably diminished.”

On the very first day, the team heard three high whistles and one low. Even though they were not able to see it, it was unmistakably the call of a Niceforo’s Wren.

“We heard the wren and we were filled with emotion,” Estela said. “It was impossible to stop though. We had just hit a stretch of rapids, and it took us ten minutes to emerge from them.”

Fortunately, the team spotted four more wrens throughout the journey. Seeing five individuals not only confirmed that Niceforo’s Wren does in fact live along the canyon walls, thus establishing it as a new habitat for the bird, it also indicated that there are probably around 10 percent more individuals in existence than had previously been thought.

With the information gathered from the Chicamocha canyon expedition, conservationists can look into what should be done to protect this newly-discovered enclave of birds. Figuring out what that protection should look like though, may be difficult.

“What do we need to do to conserve these species? — that’s the big question”, Estela said. “We’re proposing everything from education efforts to ecological restoration of the region. But it’s not simple. It can be hard to carry projects out in terrain this inhospitable. It’s a big challenge working in this region.”  

One thing that would help the biologists though, is more research. The wrens are very territorial, and not much is known about their reproductive cycle. Going to the canyon at different times of year would give the biologists far more information about them, and also help to create better estimates of actual population numbers.

All of which means that the team could one day find themselves getting in their raft, and setting off down the river once again.

This project is part of the CEMEX-BirdLife Global Conservation Programme. Under the CEMEX-BirdLife global partnership, strategic partnerships between BirdLife Partners and CEMEX operations have been established at high priority locations around the world. Within this global business and nature partnership, priority is given to developing plans to protect and conserve wildlife at CEMEX quarries.