Satellite-mapping technology that detects stains on the ice from penguin droppings has revealed there are nearly 20% more Emperor colonies than previously identified in fast-warming Antarctica.

Eleven new colonies of the species were found, taking the census to 61 across the polar continent, according to a study by scientists at the British Antarctic Survey published Wednesday. The scientists used images from Europe’s Copernicus Sentinel-2 mission to locate the flightless birds.

“This is an exciting discovery,” said lead author and geographer Peter Fretwell in a statement. “Whilst this is good news, the colonies are small and so only take the overall population count up by 5-10%, to just over half a million penguins.”

Emperors are the largest of the species, and they live and breed in Antarctica, a continent that’s warming at a faster rate than the rest of the world. The discovery will be used by scientists who are monitoring the birds and raising concerns because they’re particularly vulnerable to sea ice melting from climate change.

Observing far-flung colonies has been extremely difficult in the past because they are found in remote locations where temperatures can drop to -59 Fahrenheit (-50 degrees Celsius). For the past decade, scientists at the British Antarctic Survey have scouring images of ice fields for new colonies by searching for penguin guano markings on the ice.

Scientists warned that most of the newly found colonies are in locations likely to be lost as the climate warms and large sections of seasonal ice — where penguins mate — risk disappearing.

“Birds in these sites are therefore probably the ‘canaries in the coal mine’,” said Phil Trathan, head of conservation biology at BAS. “We need to watch these sites carefully as climate change will affect this region.”