A "calcified" swallow sings in stony silence along northern Tanzania's Lake Natron (map), which contains so much soda and salt that it would "strip the ink of my Kodak film boxes in a few seconds," according to photographer Nick Brandt.
Brandt unexpectedly found the dead animals that had washed up on the shore, preserved by the lake, and posed them as they had been in life. The photographs, taken between 2010 and 2012, appear in Brandt's new book Across the Ravaged Land. (Also see "Pictures: Best Wild Animal Photos of 2012 Announced.")
Lake Natron's unusually harsh composition comes from a unique neighboring volcano, Ol Doinyo, which spews alkali-rich natrocarbonatites that end up in Lake Natron via rainwater runoff.
Thure Cerling, professor of geology and geophysics at the University of Utah, said by email that the animals in Brandt's photographs likely died of natural causes. Since there are few predators in the area, their bodies remain and become salt-encrusted when the lake's water level drops.
However, Brandt said that many people in the region have seen birds crash-land into the water. So he believes the birds and bats were confused by the sky's reflection in the lake and killed when they hit the water.
The animals probably aren't truly calcified, but are coated with sodium carbonate or sodium bicarbonate, said Cerling, who has researched the chemistry of Africa's Rift Valley lakes.
"There is almost no calcium in the lake, although the inflowing fresh waters have calcium, which precipitates as it mixes with the high-pH alkaline waters of the lake."