Animals

“Forever chemicals” are pervasive, and researchers have in recent years been ringing the alarms about the negative impacts on human health. But humans aren’t the only animals to be concerned about.

Freshwater turtles in Australia exposed to per- and polyfluoroalkyl substances, or PFAS, experienced changes to their metabolic functions, environmental biochemist David Beale and colleagues report in the Dec. 15 Science of the Total Environment. “We found a whole range of biomarkers that are indicative of cancer and other health problems within reptiles,” says Beale, of the Commonwealth Scientific and Industrial Research Organisation in Dutton Park, Australia. More

Courtship dazzle in spiders can lose some zing in uncertain climates. Males in places with hard-to-predict rain and temperatures devolve into suitors who woo mostly with cheap, useless gifts.

Researchers have described gift giving in courtship in only 15 or 20 of the world’s more than 50,000 known species of spiders, says evolutionary biologist Maria José Albo of Universidad La República in Montevideo, Uruguay (SN: 7/26/16). Since 2015, she and her lab have focused on spiders that flirt mostly in evenings and nights among the rocks and pebbles of rivers of Uruguay and southern Brazil. More

Pooping whales changed the course of Asha de Vos’ career.

The Sri Lankan marine biologist was aboard a research vessel near her home island in 2003 when she spotted six blue whales congregating. A bright red plume of whale waste was spreading across the water’s surface.

Seeing whale poop, colored red thanks to the whale’s diet, was the first clue that Sri Lanka’s blue whales don’t migrate between feeding and breeding areas.A. de Vos

De Vos, then a master’s student, recalls being “super excited.” What she witnessed went against prevailing dogma: Her textbooks and professors had taught that blue whales, like other large whales, embark on long-distance migrations between colder feeding areas and warmer breeding and calving areas. But seeing whales pooping in tropical waters meant the behemoths must be feasting locally.

Intrigued, de Vos spent the next few years documenting how blue whales near Sri Lanka differ from those elsewhere in the world. For one, the population feeds on shrimp rather than krill. The whales also have unique songs. But the key difference, she realized, is that they remain year-round in the waters between Sri Lanka, Oman and the Maldives — making them the only nonmigratory blue whales in the world. Abundant upwellings of nutrient-rich water from the ocean depths support a steady food supply for the whales.

Eventually, the International Whaling Commission, the intergovernmental body dedicated to protecting whales, recognized Sri Lanka’s blue whales as a distinct subspecies called Balaenoptera musculus indica.

By studying the blue whales around Sri Lanka, marine biologist Asha de Vos discovered they are the only nonmigratory blue whales in the world.Franco Banfi/Nature Picture Library/Alamy Stock Photo

This distinction is crucial for conservation management, explains retired whale biologist Phillip Clapham, formerly of the U.S. National Oceanic and Atmospheric Administration’s National Marine Fisheries Service. Small, localized populations — like the one in Sri Lanka — face higher risks of being wiped out in the face of environmental or human threats, such as deep-sea mining.

More than two decades on, de Vos is now one of Sri Lanka’s most renowned scientists — famed for nurturing the country’s nascent marine biology scene. She is also an ardent champion for greater diversity among researchers in ocean conservation. More

Some tadpoles don’t poop for the first weeks of their lives. At least, that’s the case for Eiffinger’s tree frogs (Kurixalus eiffingeri), scientists report September 22 in Ecology.

Eiffinger’s tree frogs are tiny frogs that live in Taiwan and on two Japanese islands: Ishigaki and Iriomote. The tree-dwelling amphibians lay their eggs in puny puddles, which are often nestled in plant stems, tree hollows and bamboo stumps.

Once the tadpoles hatch, they spend their early lives in these puddles. However, in pools as small as these, there’s not a lot of water to dilute ammonia — a toxic chemical animals release when they pee or poop.

Bun Ito and Yasukazu Okada, biologists from Nagoya University in Japan, now have uncovered the tadpoles’ secret sanitation strategy — self-induced constipation. The tadpoles store their poop in an intestinal pouch until they start to metamorphize into full-fledged frogs.

The tadpoles of Eiffinger’s tree frogs (Kurixalus eiffingeri) spend their first few weeks of life in tiny puddles of water nestled within tree hollows and bamboo stumps.Bun Ito

Ito and Okada raised tadpoles from four different frog species in makeshift nurseries. Once the experiment began, they moved the tadpoles to smaller cribs, plastic cases with a little more than a tablespoon of water. The team measured and compared how much ammonia each species released. They also measured the amount of ammonia each species stored in their guts.

Eiffinger’s tree frog tadpoles released less than half as much ammonia on average than the species that released the most. And compared with two of the other species, the tadpoles kept more ammonia in their guts. The researchers note that unlike Eiffinger’s tree frogs, the other species typically lay their eggs in open ponds where ammonia is easily diluted. More

In 1998, at the age of 22, conservation biologist Ximena Velez-Liendo came face-to-face with South America’s largest carnivore on her first day of field research in Bolivia. Her life changed forever when she turned around to see “this beautiful, amazing bear coming out of the forest,” Velez-Liendo says. “It was like love at first sight.” She thought in that moment: “If I can do anything for you, I’ll do it.”

Also known as spectacled bears, Andean bears are easily recognized by the ring of pale fur that often encircles one or both eyes. Bolivia is home to about 3,000 adult bears, or roughly one-third of the world’s total Andean bears, whose range arcs through five countries along the western edge of South America. Listed as vulnerable by the International Union for Conservation of Nature, or IUCN, the species (Tremarctos ornatus) suffers mainly from habitat loss and conflicts with humans, who sometimes kill the bears in retaliation when bears raid crops or hunt livestock. More

McKenzie Prillaman was the Spring 2023 science writing intern at Science News. She holds a bachelor’s degree in neuroscience with a minor in bioethics from the University of Virginia and a master’s degree in science communication from the University of California, Santa Cruz. More

Despite the sensationalized portrayal of sharks in movies like Jaws, the ocean’s apex predators have far more to fear from people than vice versa.

Even though millions of people around the world swim in the ocean each year, just 91 people were bitten by sharks in 2023 and only 10 of those bites were fatal, according to a new report from the Florida Museum of Natural History in Gainesville. Out of all bites, 69 were unprovoked while 22 were provoked, defined as a human-initiated interaction such as trying to touch or feed a shark. These numbers — reported by beach safety officers, hospital staff and other emergency responders — are consistent with the five-year global average. More

How do you look for an animal you don’t even know exists anymore?

The last sighting of the purple-winged ground dove (Paraclaravis geoffroyi) — a small, bamboo-loving dove native to the South American Atlantic Forest in Brazil, Argentina and Paraguay — was in 1985. But, researchers wondered, was it possible to capture the elusive bird’s sound in the wild to find out if any individuals are left?

It’s not an unheard-of idea. Scientists have used bioacoustics — a subfield of ecology that relies on sound to make environmental analyses — for everything from recording dolphins’ communication patterns to studying bats from afar to avoid virus spillover from humans (SN: 12/7/17; SN: 10/23/22). With artificial intelligence, it is now possible to use large audio datasets to train algorithms to spot different animal sounds within the cacophony of a natural background.

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But the problem is that recordings of the purple-winged ground dove singing are as rare as the bird itself.

“I came across [the bird’s song] watching a 1985 interview with Carlos Keller, a former bird breeder in São Paulo state, who had a few individuals of the dove,” says Carlos Araújo, an ecologist at the Instituto de Biología Subtropical at the Universidad Nacional de Misiones in Argentina. “And they sang while he spoke.”

With Keller’s help, Araujo and colleagues accessed the decades-old recording and isolated the bird’s song.

The next challenge was to see if it was even possible to identify individual bird songs amidst the sounds of other birds chirping, leaves rustling, rain falling, insects whirring and gnawing and larger animals moving through the forest.

“We took a step back and did some analyses with other birds that are critically endangered but there are known individuals,” Araújo says. The team focused on three species found in Foz do Iguaçu, a national park that straddles the border of Brazil and Argentina: the cherry-throated tanager (Nemosia rourei), the Alagoas antwren (Myrmotherula snowi) and the blue-eyed ground-dove (Columbina cyanopis). These birds live in the same environments as the purple-winged ground dove. And the blue-eyed ground dove’s story inspires hope: The species went missing in 1941 and was rediscovered in 2016.

To test their setup, the researchers looked for the cherry-throated tanager (shown) and two other rare birds.Ben Phalan/Parque das Aves

The researchers installed 30 recorders in strategic spots along green areas in the Brazilian part of Foz do Iguaçu and recorded from July 2021 to April 2022. They also used data from another 100 recorders on the Argentinian side of Foz.

“We went looking for the Guadua trinii bamboo to place the recorders,” says Benjamin Phalan, Head of Conservation at Parque das Aves, a private institution in Foz do Iguaçu focused on the conservation of Atlantic Forest birds. Like the purple-winged ground dove, the three bird species follow the flowering season of the G. trinii bamboo, which happens about once every 30 years.

The team pushed through thickets of bamboo, braved ticks and biting flies, and watched out for venomous snakes such as jacaracas pit vipers. Bumping into these snakes is “rare but can happen. So we use galoshes or gaiters to protect us in case anyone steps on a snake or near it,” Phalan says.

Carlos de Araujo installs a recording device in a South American forest. He and colleagues hope to pluck the song of rare birds out of the forest sounds the device picks up. Ben Phalan/Parque das Aves

The recorders captured one minute of landscape sound every 10 minutes and generated about 3,000 days’ worth of recordings. “A lot of data to sift through,” says Araújo.

Readily available analysis software wouldn’t work. These software, Araújo says, “need a lot of data input. With such rare species, we just don’t have that much data to train the identification algorithm.”

So the team started from scratch, working with the little data they had for the three endangered birds. First, Araújo created a signal template — exactly like the birds’ singing — based on just a few recordings. The algorithm then compares that template with the soundscape recordings, separating signal from noise. If it spots a sound that is similar to the template, chances are that it is the bird that the researchers are looking for.

The method relies on a statistical model “that is not new, but was used in a very clever and unusual way,” says David Donoso, an ecosystem ecology researcher at the Technische Universität Darmstadt in Germany. Donoso and colleagues recently used bioacoustics to investigate the recovery of Choco, a biodiversity hot spot in Ecuador that had been transformed in an agricultural area.

There are different approaches to bioacoustics depending on what you’re looking for, Donoso says. “You can either use fewer recordings to map a whole animal soundscape to tell what species are there, like we did, or you can use lots of recordings to look for a single sound pattern,” he says. The study at Foz do Iguaçu “shows that you can use a relatively simple model to answer a complex question — and it works.”

The tool worked reasonably well to identify the cherry-throated tanager and blue-eyed ground-dove singing, but not so much for the Alagoas antwren, Araújo’s team reports October 23 in Bioacoustics. “We’re trying to understand what happened, but we know that the algorithm works,” he says.

The next step, Araújo says, is to refine the algorithm’s precision to find the Alagoas antwren and train it to look for the purple-winged ground dove. And they will do so at the same time. “We’re aiming at both goals at once because we’re running against the clock to find these birds,” Araújo says. “In the end, we are looking for a ghost.” But not a silent one, he hopes.  More