On Friday 16 September Christine and I visited Pathtrack Ltd, the company that makes the GPS loggers (Nanofix GEO+) that we deploy on Sooty Terns (and that we also put on Brown Noddies with Camille Lebarbenchon, our friend based at Reunion Island). Following increased demand for their tracking equipment Pathtrack have relocated to a larger building in the Yorkshire town of Otley, and have employed more staff. They now produce a range of loggers suitable for smaller seabirds. In addition to our work in Seychelles, they have supplied loggers that have been used on Sooty Terns in the Caribbean (Louise Soanes) and on Sooty Terns, Brown Noddies and especially Lesser Noddies on the Houtman Abrolhos Islands, Western Australia (Chris Surman).
During our Sooty Tern studies on Bird Island in 2016 we had occasional difficulties downloading data from some loggers and we took them to Pathtrack to see if they
could access the data for us. They could and did; it seems that our difficulties had been due to inadequate cleaning of the terminals on the loggers, leading to poor connection with the computer. The formerly unobtainable data were duly downloaded, providing further amazing tracks of Sooty Terns during their searches for food in the ocean around Seychelles. This is enabling us to build up a picture of feeding areas used by the birds in both good and bad breeding seasons. This is revealing the commonly used regions, knowledge that could contribute to deliberations on the designation of Marine Protected Areas as part of Seychelles government environmental initiatives. Some of the tracks also show the lengths to which Bird Island’s Sooty Terns travel in bad years. In 2014, a very poor year, one incubating adult flew 900 kilometres west of Bird Island, half way to the African coast, in search of food, while another undertook a journey of 2700 kilometres searching for fish before returning to relieve its mate on the egg six days later.
Pathtrack have now developed a new small GPS logger suitable for Sooty Terns. This logger (Nanofix GEO+RF) will download location data automatically to a base station each time a bird returns to the colony, thereby
obviating the need to recapture the tagged birds. The tag is the same weight as the tags we have been using (c. 3 g) but the current design makes it about 1 centimetre longer (see photo). This could restrict a bird’s access to its preen gland and so the attachment method needs to be designed appropriately to avoid this.
We thank the British High Commission (Seychelles), Percy Sladen Memorial Fund, and James Cadbury for contributory funding to support our 2014 and 2016 studies, and Bird Island for their continuing support of our studies of the island’s Sooty Terns. We are also grateful to Gary Brodin and his colleagues at Pathtrack for their speedy attention to our queries, both when we are in Seychelles and also when questions arise in UK. The Pathtrack website is www.pathtrack.co.uk