Surveillance cameras are everywhere these days, capturing just about everything: the good, the bad, the unmentionable.

One has even soared above the Southern Ocean, attached to the back of black-browed albatrosses. It has captured a rare sight: albatrosses following a killer whale, probably to obtain food.

The camera weighs less than 3 ounces and includes depth and temperature sensors. It was installed on four albatrosses at Bird Island in the southern Atlantic.

Kentaro Q. Sakamoto of Hokkaido University in Japan, Philip N. Trathan of the British Antarctic Survey and colleagues pored through thousands of images. While most were of the featureless open ocean, they report in PLoS ONE that one bird encountered a killer whale. The bird appeared to have descended to the surface, perhaps to eat scraps left behind by the whale.

The photograph suggested albatrosses may sometimes forage in the open ocean the way other seabirds do closer to shore — by following other predators for clues or leftovers.

COUNTING COINS TO COUNT ROME’S POPULATION

In ancient Rome from about 250 B.C. to 130 B.C., census figures fluctuated between about 150,000 and 400,000 citizens. But subsequent censuses, after about 30 B.C., had totals of 4 million to nearly 6 million. So did the later surveys overcount, or the earlier ones undercount?

That’s been a longstanding question among historians. Now two researchers have tried to resolve it, using unusual data: Numbers of recovered coin hoards.

In times of unrest, someone who buries treasure to keep it safe might not survive to recover it. If these hoards are found later and can be accurately dated, they can serve as a proxy to help characterize certain periods of history.

“Coin hoards give you an objective way to measure the violence of any particular decade,” said Peter Turchin, a professor of ecology and evolutionary biology at the University of Connecticut. The more hoards, the more intense the upheaval.

Some whale facts

Blah, blah, blah, blubber, Moby Dick, heh-hey, you said Moby, blah, blah