Earthweek: a diary of the planet

For the week ending Friday, Sept. 25. By Steve Newman

Feeder contagion

Researchers have found that birds eating at feeders placed outside by concerned humans are more likely to get sick and spread a common eye disease. A team from Virginia Tech observed the behaviors of house finches, a common backyard songbird. They then compared the birds’ social networks with the spread of a naturally occurring disease. They found that it wasn’t the number of companions a bird had that put it at greater risk but, instead, its eating preferences.

Hawaiian rumblings

Geologists raised the alert level for the world’s largest active volcano as Mauna Loa showed increasing signs of unrest on Hawaii’s Big Island. The Hawaiian Volcano Observatory made the move after seismic activity, which began to increase in 2014, reached a level that was causing the landscape around the volcano to become deformed. Geologists say the reshaped ground is “consistent with recharge” of the volcano’s magma chamber. Mauna Loa last erupted in 1984 after about three years of mounting seismic activity. The change in status from “normal” to “advisory”

Tree of Life

The first draft of what’s being called the Tree of Life shows how all of the planet’s 2.3 million named species of animals, plants, fungi and microbes are related. Researchers from 11 separate institutions created the detailed family tree of all creatures great and small, which shows how life evolved. While tens of thousands of smaller “trees” have been published for specific branches of nature, this is the first time they’ve been combined to give an organized structure

Nocturnal humming

It seems that giraffes are not as voiceless as previously thought, and have been observed humming in the night as a possible form of communication when their vision is limited. Many wildlife experts have thought the animals’ necks are too long for them to be able to vocalize. But analysis of sound recordings of giraffe habitats at three European zoos revealed the stately animals occasionally emit a low-frequency sound at about 92 hertz — barely

Arctic feedback

The melting of the Arctic ice cap is encouraging more natural emissions of methane — one of the most potent greenhouse gases driving climate change. Researchers at Sweden’s Lund University worked with Dutch and American colleagues to find that the recent accelerated melt of sea ice around the North Pole is allowing the Arctic’s surface waters to absorb more heat and promote the growth of microorganisms in the adjacent tundra. Those microbes in turn give off natural methane emissions that accelerate climate change.