Case studies: Electronic tag applications

A wider range of applications

The G5 is much smaller and lighter than previous generations of Data Storage Tag (DST), yet has a much higher memory. The tag is opening up new fields of research for a wider range of species.

Little penguins are the first diving bird to be tagged
using the G5. © Y. Ropert-Coudert

Diving birds

One of the first applications for the tags was studying little penguin behaviour in Australia. Large tags have the effect of introducing underwater drag, which can affect the behaviour of tagged diving birds. As the drag effect is cumulative, so the behavioural effects may be increased over time, and accuracy of results diminished. The small size of the G5 tag means reduced drag, and therefore genuine data are collected.

Data were collected during the day-long diving trips that the penguins undertook. Depth and temperature information was recorded every second during the penguins’ dives, and graphs of the results produced once the tags were retrieved. The G5 also recently demonstrated its reliability and robustness when it was used in studying little auk diving behaviour in the Arctic Ocean.

Plaice are just one fish species standing to benefit
from the introduction of the new tags.

Fish behaviour

Studies of North Sea plaice have largely been restricted to tagging mature female fish, which are larger than males and juveniles and can carry older generations of DST. However, the small size and low weight of the G5 enables it to be used successfully to tag male and immature female plaice. Previous studies demonstrated that North Sea plaice have a relatively elaborate population structure. Using the G5, population structures are already being seen that have not been predicted in spite of 100 years of conventional tagging data. Scientists are also using the tags to investigate the differences in female and male plaice behaviour.

G5 tags have revealed new insights into mink behaviour.
© Harrington Photography

Diving mammals

Scientists have used the G5 to investigate diving behaviour in free-living American mink in lowland rivers. The size and the weight of the G5 allows tags to be attached directly to radio-collars. Because mink are nocturnal, elusive and only active for a few hours per day, it is generally impossible to directly observe their behaviour, and radiotracking does not show exactly what an individual is doing.

Most previous studies of mink diving behaviour have been limited to laboratory studies. Several hundred dives have been recorded using the G5, already revealing new insights into mink behaviour.