Picking up half a million penguins - from space

SMALL PRINT:COUNTING PENGUINS can be a tricky business, but a study out this week shows how it can be done from space.

The paper, published online at plosone.com, describes the difficulties in estimating the number of emperor penguins in Antarctica. The last global population estimate of 135,000 to 175,000 breeding pairs was compiled nearly 20 years ago and its accuracy has been questioned.

“The paucity of data regarding population status of emperor penguins is largely due to the logistical difficulties of accessing potential breeding habitat in areas of Antarctica that are not in close proximity to research stations,” write the authors.

To get around the problem, the UK, US and Australian researchers used satellite data to take a census of the birds. Using a combination of satellite imagery, they looked at the Antarctic coastline to find out where the colonies were. Then they got remotely-sensed images of the colonies in the 2009 breeding season and analysed them to separate adult penguins from snow, shadow and guano. Their tally comes to around 238,000 breeding pairs, which suggests about 595,000 birds.

The authors point out there are some limitations to the approach – the count only includes adult birds at the breeding site – but they describe it as “the first global, synoptic survey of a species from space”.