In the MARCIS project we want to understand how seabirds are affected by human stressors in marine areas. To do so, we need to know where they are and how they use their habitat. Since seabirds spend the majority of their life far out at sea, this is no easy task.
Breeding puffin from Runde instrumented with GPS-logger on its lower back. Photo: Ingar Støyle Bringsvor
Spring and summer is the peak season for seabird biologists who venture out to the seabird colonies to carry out fieldwork. This is a short and intense period not only for researchers but also for breeding seabirds.
During the breeding season, seabirds are central-place foragers, which means that their foraging ranges are constrained by the need to return to their colony at regular intervals to defend their nest and mate, incubate their eggs and provide for their chicks.
Adult seabirds must ensure that their chicks are sufficiently fed and protected until they leave the colony. This puts a limitation on the distance they can fly from the colony, and how long they can be away. The breeding season is therefore considered one of the periods where seabirds are most vulnerable to human development within their home range.
Kittiwake from Anda with GPS-logger mounted on the tail. This logger weighs six grams and can stay on during the whole chick rearing period. Photo: Signe Christensen-Dalsgaard.
To study the fine-scale movement and behaviour of breeding seabirds, researchers instrument them with GPS- and dive-loggers. Using the same tracking-technology as is used in mobile phones, for instance, we can now follow the seabirds to sea.
During recent decades GPS-loggers have become so small that they can be attached to most seabirds species, and many species are now being routinely tracked with high accuracy and resolution.
In Norway, seabirds are being instrumented with GPS- and dive-loggers through the monitoring and mapping programme for seabirds, SEAPOP, enabling MARCIS to include information on movement and behaviour of seabirds during the breeding season. The first SEAPOP study using GPS logging of seabirds was initiated in 2010, and by 2022 the tracking work includes 8 different species and 17 different colonies, spanning from Rogaland to Spitsbergen. This provides unique insight into how seabirds use the marine areas surrounding the colonies.
Different models of GPS-loggers are used, depending on study species and colony accessibility. The smallest GPS-loggers used by SEAPOP this summer weigh only about 4 grams, and are used on puffins. For other species, such as kittiwakes we can use GPS-loggers with remote download and solar panels, so the loggers can stay on the bird for longer periods of time.
GPS-loggers are usually fastened to the tail or back of the birds using tape, cable ties and/or glue, and are removed (or lost) after a given period of time, usually within a few days or weeks.
GPS-tracks from a breeding puffin on Runde.
The data from the GPS-logging of breeding seabirds enables us to map, in detail, which areas are the most important for key activities, such as foraging, resting and preening, when the birds are away from the nest. It also allows us to calculate the birds’ time budgets and energy expenditure. This is important information when modelling how different stressors might affect seabird populations.
Every field season is like a treasure hunt, searching for information and gathering data. Hopefully, the field season of 2022 will be successful, adding more pieces to the big puzzle of explaining how marine stressors can impact seabirds in Norwegian waters.