A new use for satellites: Counting elephants from orbit

Everyone knows that elephants are an endangered species, with only approximately 415,000 African elephants left on the continent according to the World Wildlife Fund. But it’s difficult for ecologists to accurately monitor elephant populations as it’s hard to count the animals directly.

Some elephants are shy, staying far away from human settlements. And groups may roam over large regions of land. All of this means that getting a count to estimate population numbers is difficult and time-consuming.

Now, a surprising new technique may be able to help: Using satellites to count elephants from orbit.

Researchers at the University of Oxford in the U.K. looked at the highest-resolution satellite data currently available, from Maxar Technologies’ Worldview-3 Earth observation satellite. They used deep learning methods from TensorFlow API and Google Brain, and were able to detect elephants with an accuracy comparable to the accuracy of human counting of populations.

Raw image in homogenous area compared with CNN detections (green boxes) and ground truth labels (red boxes). Worldview-3 Satellite images Maxar Technologies

To train computers to recognize elephants from satellite images, the researchers used a dataset of over 1,000 elephants in South Africa. After training, the computers were able to identify elephants with an accuracy (measured in a statistic called the F2 score) of between 0.78 and 0.73 depending on the environment, compared with an accuracy of between 0.77 and 0.80 for human detection. The model was originally trained on adult elephants only, but it was later able to identify young elephants as well.

The big advantage of the use of satellites over the traditional method of counting, which involves aerial surveys from aircraft or helicopters, is that it doesn’t disturb the animals at all. It also involves no risk to human life. Satellites can monitor areas that would be difficult or dangerous for humans to access, including easily being able to look between different countries which can be an administrative hassle for human counters.

In the future, surveys of elephant populations could be made more affordable by using this satellite detection method. Knowing how many elephants there are and where they are located could be an invaluable aid in preserving this fast-vanishing species.

The findings are published in the journal Remote Sensing in Ecology and Conservation.

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