Region, Nature, Science

Lagoons for the dry season: This is how the ACG plans to combat animal deaths due to heat

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Translator: Arianna Hernandez

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For a few weeks now, photos and videos of howler monkeys sprawled on the ground, victims of a heat wave in Mexico, have gone viral on social networks. As of May 31, according to official numbers, 204 dead monkeys have been counted. They all died in less than a month.

Something similar happened in Guanacaste eight years ago, during the megadrought between 2014 and 2015. It didn’t happen on a large scale and suddenly, but howler monkeys did turn up on the side of the road from Sámara in Nicoya to Playa Negra, in Veintisiete de Abril of Santa Cruz, with signs of dehydration such as hair loss and weight loss.

At that time, Brenda Bombard, director of what was then the Nosara Animal Shelter Foundation, now International Animal Rescue (IAR), explained, “This has been the worst year ever. The monkeys are so hungry, so weak and dehydrated that they don’t know what to do with themselves.” 

Changes in rainfall patterns and increased temperatures as a result of climate change could force us to face similar situations more and more often.

The Guanacaste Conservation Area (Spanish acronym: ACG) knows it, because in that protected wildlife area, too, they have seen monkeys die in the same way. That’s why they developed a plan to try to ensure that mammals such as monkeys, deer and felines, and even pollinators such as insects, have water during the harshest months of the dry season.

In August of 2019, a group of baby monkeys electrocuted in Nosara recovers at the International Animal Rescue (IAR) center. This same center treated dehydrated howler monkeys in April of 2016.Photo: César Arroyo Castro

An oasis in the dry forest

The ACG is the last large patch of dry forest in Mesoamerica. From the sky, the 163,000 hectares (402,782 acres) of green and yellow tones look like a dense carpet, covered in trees from the top of the volcanoes to the coast. But it wasn’t always that way. In fact, conservation there has just 50 years of history.

For centuries, these lands were cattle ranches. And they were a strategic point for those who transported livestock and goods through Central America, because their animals could get water there. This is documented in the book Viajeros por Guanacaste (Travelers Through Guanacaste) by historian Carlos Meléndez.

On the cattle ranches, such as Santa Rosa, there were natural or semi-artificial reservoirs to gather water in the rainy season to provide them with water during the dry season.

These water reservoirs had different characteristics. They could be permanent freshwater lagoons or meadows that flooded seasonally. Or stone dams built to accumulate water in the natural depression through which a stream runs. The 2018 National Wetlands Inventory described these small systems as being mostly covered by vegetation.

“In the 80s, it was said that ‘no, there’s no need to clean the lagoons here because we need this national park to be restored to its natural condition,’” recalls ACG research coordinator Roger Blanco, who has worked in the protected area since 39 years ago.

He didn’t imagine that four decades later, due to the climate crisis, they would be thinking of removing all that vegetation and sediment to recover those water sources, this time not for livestock but for wildlife.

A group of officials does cleaning work at Piñuelita lagoon in Santa Rosa National Park in the month of February.Photo: Melissa Espinoza

Since last year, the ACG started its 2023 – 2033 Biodiversity Resource Management Plan, and one of the actions proposed in this plan is the recovery of the lagoons to now convert them into water reservoirs for fauna.

They identified 17 reservoirs in the Guanacaste National Park and Santa Rosa Park and made a profile of each of them, describing their current state and what actions to take to restore or maintain them.

From that group, they chose seven to start with and, of them, they will give priority to work on two located in Santa Rosa Park: Escondida Lagoon and Piñuelita Lagoon.

The Santa Rosa sector is the part of the protected area that doesn’t have permanent rivers. So during the dry season, water as a resource almost disappears throughout a large region,” explains Blanco.

They are currently working to waterproof Piñuelita’s wall and repair the cracks so that during the rainy season, they form the reflecting pool. In the next stage, they’ll have to remove the sediments that have accumulated in the reservoir for years.

All of these water reservoirs form naturally when the rainy season begins. Once the rains fall, the topography of the land fills the streams, lakes or reservoirs with water. Reservoirs such as Puñuelita and Escondida, have a wall as a dam and a water outlet that ensures that there’s a natural water flow downstream.

In addition to helping the fauna, both reservoirs have historical and architectural value since they were built more than 100 years ago.

The Piñuelita and Escondida dams indicate that their construction involved advanced engineering work due to the site’s conditions, its distance from the country’s capital and the time period in which they were built.Photo: ACG

“We might be talking that perhaps by the summer of 2028 they’ll already be rehabilitated and will be able to efficiently contain rainwater if we have good [rainy seasons],” adds Blanco.

Less monkeys

Something similar to what happened between Sámara and Playa Negra was experienced within the ACG with a troop of howler monkeys that they were studying.

“That troop of monkeys had 15 females that were pregnant. The 15 babies died. Some females had a premature miscarriage and others did have the baby, but since there wasn’t much food, they didn’t have milk, and the new generation died,” recalls Blanco.

This problem goes further back. A joint research project by the universities of Tulane (United States) and Calgary (Canada) took 15 censuses collected by the same study houses during a period of 43 years from the entire Santa Rosa National Park. And they determined that the population of howler monkeys decreased by 40% between 2007 and 2014 and maintained the downward trend in 2015.

Although there are no clear reasons to explain the decline of these populations, several climate trends occurred during this period: prolonged phases dominated by La Niña to phases dominated by El Niño, a severe drought and a clear sign of climate warming.

“We know that the most vulnerable always, practically in any species, are the juveniles. So one makes those waterholes more for juveniles than for the old, to maintain the population,” says ACG biologist and researcher María Martha Chavarría.

Water retention wall at Piñuelita reservoir, more than 100 years old.Photo: Juan Bravo

The biologist emphasizes the urgent need to take measures to try to deal with the impacts of global warming that are increasingly more evident within the protected area.

We’ve reached a point where everything is so so impacted that if we don’t try to manage a little, I believe that we will lose everything,” adds Chavarría.

Regarding these types of interventions, Blanco explains that there is no standard or protocol for how they should be carried out since these measures are in response to very recent circumstances.

“The sad reality in this story is that the effects that are being generated every day are intensifying. All of this that was predicted by meteorological scientists that was going to happen in the year 2040, 2050 – we’re 20 years ahead of that and it’s already happening,” Blanco highlights.

The coordinator is confident that, just as the ACG was a pioneer in managing forest fires in the 1980s, they can now be the spearhead in creating reservoirs for fauna within protected areas.

“The reality that is not going to change is that this ecosystem is going to become more difficult for life. So helping to contain water and being able to have it available to use in the dry season are solutions that will possibly become popular and will be taken into account more in the coming years,” she believes.