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 behavioural 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.

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.

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.

Accelerometer studies.

Investigating at-sea activity patterns of free ranging sea turtles remains difficult. Direct in-water observations and the use of animal-borne video have allowed the collection of information on activity patterns for only short periods of time (i.e. a maximum of 24 hours). The recent development of a tri-axial accelerometer however provides new means to assimilate detailed activity-budgets over relatively long periods of time for free-ranging individuals.

G6a were deployed on female loggerhead turtles to investigate their activity patterns during their nesting season in Greece. Depth, temperature and accelerometry data were collected for 6 weeks and revealed interesting activity patterns that were never described before.