Science News on Mammal Life Spans, Song Recognition Among Baby Birds

The latest science news: Mammals may live longer together than solo; some baby birds recognize their clan’s singing; New York surprises in carbon capture

Mark Wexler
Scope
Jul 04, 2023

Living Longer, Together

How long a mammal lives may depend on the company it keeps. In an analysis of scientific papers on the body masses, life spans and lifestyles of 974 species, Chinese zoologists found that mammals living in groups generally outlive solitary mammals. The finding, published in Nature Communications, held true for a wide array of species, from group-dwelling and long-lived golden snub-nosed monkeys (above), naked mole rats and horseshoe bats to solitary and shorter-lived giant armadillos and short-tailed shrews. The latter survive only about two years. The scientists suggest that group living may reduce mortality rates by limiting the risks of predation and starvation. But “the strong and stable social bonds formed among group members also have the power to enhance longevity,” writes lead author Xuming Zhou, an evolutionary biologist at the Chinese Academy of Sciences. By analyzing brain tissue from 94 species—including solitary, pair-living and group-living mammals—the researchers also identified 31 genes linked both to longevity and a species’ social system. They say those results suggest that mammalian life spans and social systems may have evolved together.

An image of Pied flycatcher chicks in nest box.

Nestlings Tuned To Local Dialects

When they are as young as 12 days old, nestling pied flycatchers (above) will respond—by begging for food—to songs from adult males that live in their own population, scientists have found. They do not respond, however, to songs from other bird species or even from other populations of their own species. To make this discovery, Swedish zoologists broadcast a variety of songs to some 2,000 wild flycatcher nestlings from seven populations—each with its own distinct dialect—then observed the baby birds’ responses. The results, published in Current Biology, “establish that songbirds are tuned from a young age to recognize their own populations’ songs,” says Stockholm University zoologist and lead author David Wheatcroft. That recognition is important, as singing the local dialect helps male birds attract appropriate mates. Because flycatcher hatchlings hear surprisingly few songs, Wheatcroft says the results also raise the intriguing possibility that the birds innately recognize their own dialects. “If differences in early song responses among populations are innate, it would suggest a remarkable coevolution between a cultural trait and the genes underlying it,” he says.

An image of a bird’s eye view of urban greenery in NYC.

Urban Greenery Surprises

During summer, trees, grasses and other vegetation in New York City (above) and nearby communities may play a larger than expected role counteracting human-caused carbon emissions. Scientists at Columbia University used high-resolution imagery to map urban vegetation and calculate the daily and seasonal changes, or “flux,” in carbon the plants capture during photosynthesis. They found that on some summer afternoons, carbon absorbed by vegetation may temporarily equal up to 40 percent of the area’s carbon emissions from all sources, or almost all carbon dioxide generated at those times by motor vehicles. Aerial radar revealed many pockets of previously undocumented vegetation. “There is a lot more greenery than we thought,” says co-author and Columbia atmospheric chemist Dandan Wei. In Environmental Research Letters, she and her colleagues suggest that without the greenery, overall carbon levels would be greater in summer. “If it matters in New York City, it probably matters everywhere else,” says Wei.

An image of an American Bison bull.

Microscope

Bison Boost Biodiversity

Bison reintroduced into tallgrass prairies increase plant species diversity by 86 percent compared to areas where the animals don’t graze, Kansas State University biologists report in the Proceedings of the National Academy of Sciences.