Little bird helps scientists understand climate change – 12/14/2023 – Science

Every month, for four or five days, a group of Brazilian scientists live the life of a bird.

They wake up early, before the sun rises, and delve for hours in swamps full of tall grasses and lots of insects.

The objective of the mission is one: to observe the marsh weevil (Formicivora acutirostris), a rare bird found only in specific regions of Guaratuba Bay, almost on the border between Paraná and Santa Catarina.

Among the more than 60 individuals of the species that are closely monitored, 1 became the favorite of the team of biologists: Rosaldo, a 16-year-old male, who is monitored by researchers even before he was born, when he was still developing in the egg.

This decade and a half of observing the same bird allowed experts to gather a series of data about its life history.

This information can help understand the strategies that the species adopts to adapt and respond to climate change — such as rising sea levels or the greater frequency of extreme events.

The time has come, then, to discover Rosaldo’s romantic and obstinate life.

An ‘unbelievable’ discovery

The marsh weevil was completely unknown to science until the early 1990s.

“In 1995, Bianca and I were doing field research in the swamp when I saw a female of a new species, which we didn’t know. Bianca didn’t want to believe in this possibility, as it was something beyond our reality”, reports ornithologist Marcos R. Bornschein, professor at the São Paulo State University (Unesp).

The Bianca mentioned by the scientist is the Brazilian biologist, journalist and conservationist Bianca Luiza Reinert, who dedicated her career to getting to know the marsh weevil. She died in 2018.

“Shortly later, on that same day in 1995, we saw two other individuals of the new species. From then on, we began emergency research to confirm the finding and describe the main characteristics of this bird”, adds Bornschein.

In just over ten years of work, experts were able to confirm that the boll weevil inhabits a very restricted region — the south of Paraná and the northeast of Santa Catarina.

Its habitat is limited to swampy areas, with tall grasses, which are close to the coastal coast.

“The weevil has the weight of a candy bar”, explains biologist Giovana Sandretti-Silva, who coordinates a conservation project for the species and is part of Bornschein’s research group.

“The male is a little darker and has a brown belly. The female has a carijó belly, with white and black feathers,” she says.

The first decade of research with the marsh weevil also revealed that these birds are territorial and maintain relationships for long periods.

“The couple lives in the same place for several years, feeds on small insects or crabs and uses marsh grass to build their nests”, adds Sandretti-Silva.

According to the biologist, weevils generate two eggs per reproductive cycle — and, if successful, they will have two babies to take care of for a few weeks.

“An interesting thing is that the male and female share all the tasks. Together, they build the nests, hatch the eggs, take care of the chicks…”, she explains.

When the child grows up and is able to fend for himself, he is kicked out by his own parents and needs to find his own territory.

“They don’t have much flight autonomy, so they jump from one grass to another and wander around until they find a new place”, points out Sandretti-Silva.

A star is born

Rosaldo entered this story in 2007, when researchers found the egg in which he was developing inside a nest in the swamp.

After being born, growing up and being expelled by its parents, the little bird found its territory on the same Jundiaquara Island where it came into the world — according to researchers, it was born on one end of the island and settled on the opposite end.

Asked about the origin of the name Rosaldo, Bornschein says that the group places rings of different colors on the legs of the birds observed.

The combination of colors and positions of these small rings allows scientists to identify each animal, so that all birds can be tracked individually over several years.

As soon as he hatched from the egg, Rosaldo received pink rings — hence the idea for the name he has carried ever since.

“Rosaldo has always been very precocious. He established his own territory when he was seven months old and soon met an older weevil, with whom he began breeding the following year, in 2008”, says Sandretti-Silva.

From this first marriage, which lasted four years, three marsh weevil chicks were produced.

The female disappeared — probably died — in early 2012. Shortly afterwards, Rosaldo had found a new partner.

“His second wife was the great love of Rosaldo’s life. They spent nine years together, always in the same place, always faithful to each other, and had eight puppies”, says the biologist.

“This gives almost one calf per year, which represents very high reproductive success for the territories we monitor.”

With the death of his second wife, Rosaldo is now in his third “marriage”, which began in 2021.

“They form a very lively couple, who build many nests. But, unfortunately, despite several attempts, they have not been able to produce offspring so far”, observes Sandretti-Silva.

Experts say that Rosaldo is used to the presence of human beings — although they try to interfere as little as possible while carrying out field research. The bird is classified as photogenic, as it poses naturally for the cameras.

Resilience, adaptation and persistence

With the main questions about the boll weevil’s biology answered, Brazilian scientists now want to understand how the species is affected by climate change — and Rosaldo can play a key role in these efforts.

Bornschein notes that the area in which these little birds live appears to be shrinking. They currently monitor around 32 territories and 64 different individuals.

“In the past, it was common for us to monitor up to 40 territories. Life is not very easy for the weevils”, he notes.

Researchers want to understand how these little birds are adapting to new realities, such as rising temperatures, rising sea levels, the occurrence of extreme events (such as cyclones) and the introduction of invasive species, such as African grasses.

A practical example: if the swamp has more water, this will require the weevils to build their nests in taller grass. This may save the chicks from flooding, but leaves the family more exposed to predators.

Bornschein states that, to understand these new realities, it will be necessary to carry out long-term monitoring, which exceeds 20 years of accumulated data.

This would help to consider cyclical adjustments in nature — the ornithologist remembers that tides, for example, have moments of highs and lows, which alternate in periods of around 16 years.

This is precisely where Rosaldo comes in: the fact that he has been followed for so long allows us to better understand how these birds react to changes in the environment.

“We want to compare the strategies that the boll weevil has at the beginning of life and how it changes as it becomes more experienced”, projects Sandretti-Silva.

“Rosaldo is contributing a lot to this, as we have data from his entire life that will help us understand this adaptation to changes.”

To understand these issues in detail, the researchers recently signed a partnership with the São Paulo Zoo. The idea is to research and learn the best ways to conserve the species – after all, the boll weevil is threatened with extinction.

Experts intend to increase the areas suitable for bird habitation and reproduction, so that more chicks are born and survive.

“Our dream is to be able to contribute in some way to preserving the species and at least reducing the risk of extinction of the weevils”, says biologist Marina Somenzari, from the SP Zoo.

For Bornschein, the almost three decades of contact with the boll weevil can be summed up in one word: persistence.

“As a researcher, it is difficult to humanize the behavior of other beings. But I will give myself the right to do this with the weevil: it is one of the most persistent species I have ever seen.”

“Our team was positively contaminated by the persistence of the weevil, which deals with a series of adversities and does not give up easily”, observes the specialist.

“And this symbol inspires us to continue our work every day,” he concludes.