News in Science

Undercover penguin reduces wildlife stress

Penguin spy The use of remotely operated rovers to study penguins and seals in their natural habitats is less invasive and stressful for the animals, according to a new study.

The findings, published in Nature Methods, also suggest that the rover's lower impact on animal behavior results in the collection of more accurate scientific data.

"Approaching animals with a rover can reduce impact, as measured by heart rates and behaviour of king penguins, thus allowing such animals to be considered as undisturbed," the authors write.

"The relevance of this technology extends beyond terrestrial populations of seabirds or mammals, as rovers could be adapted for use in aquatic or aerial environments."

Existing techniques to minimise animal stress during studies often involve tagging animals with Passive Integrated Transponders or PIT-tags, which use Radio Frequency Identification (RFID) to monitor individual animals.

However, PIT-tags can only be read when the animal is within 60 centimetres of an antenna.

Researchers led by Dr Yvon Le Maho of the Centre National de la Recherche Scientifique in Strasbourg, looked at reducing animal stress levels during field research by using a remotely controlled rover as an antenna to read RFID tags.

Trials were conducted on 34 breeding king penguins (Aptenodytes patagonicus) which were fitted with external cardio-frequency meters and data recorders.

Researchers found that the birds' stress responses to approaching rovers, as measured by both heart rate and behaviour, was four times lower and lasted for shorter periods of time, compared to approaches by humans.

Once the rover or human came into close contact with the breeding penguins, the birds would begin attacking. However the penguins' maximum heart rate was significantly lower for the rover compared to the human, and more like the heart rate exprerienced by penguins when they defend their territory from other penguins.

The authors also found stress levels rapidly returned to normal soon after the rover stopped moving.

Undercover operatives

Le Maho and colleagues also studied the reaction of the less territorial but far shier emperor penguins (Aptenodytes forsteri) to the rover and found that almost half displayed no reaction at all. A quarter of the penguins were sufficiently curious to approach and investigate this strange new contraption.

The camouflaged rover was able to infiltrate a crèche without disturbance, and both chick and adult emperor penguins began vocalising at it.

The authors also tested the rover with a colony of southern elephant seals (Mirounga leonina).

The seals allowed the rover to approach within RFID distances of their heads, and also their tails, where they are usually tagged, with no visible signs of disturbance.

"This is notable, as elephant seals generally react strongly when humans approach their tails," the authors write.

As well as collecting data from animals fitted with tags, the researchers speculate that future rovers could be fitted with a range of scientific instruments and equipment to record the animals at very close range, providing high-quality data for studies in areas such as vocalisations.