A Gannet tracking first?!

By on Tuesday, April 25th, 2017

My first field work blog of the year is a little earlier than usual. This is because, excitingly, we are attempting to gather some slightly different data this year.

As I explained in Gannet Grabbing, the GPS tagging of adult gannets has traditionally taken place during the period of the breeding season when the birds are feeding chicks. At this stage the gannets are almost guaranteed to return to the nest, allowing them to be re-caught to retrieve the loggers. This has given us a really fabulous insight into where the gannets are going during the summer months when they are feeding chicks but we know very little about their behaviour during the remaining 10 months of the year.

This year we are going to attempt to change that and see if we can get GPS data from adult gannets making foraging trips in April before they lay their eggs and begin incubation.

So why are we interested in doing this? If successful, it will be very exciting as no-one has managed to gather data on gannet foraging trips during this stage of the breeding season before. During the chick-rearing period we know adults are repeatable in their foraging behaviour with individuals consistently returning to the same areas presumably because they know they will find prey there – see last summer’s post about B037. Their time away from the colony is constrained by the need to return with food for the chick so their foraging trips need to be as efficient as possible in terms of time and energy expenditure. When there is no chick to feed we don’t know whether they are repeatable in their foraging trip destinations or whether they are able to be more flexible in the amount of time they spend away from the colony.

I use the words ‘attempt’ and ‘if successful’ as we are as yet unsure whether it will be possible to catch the gannets in April. When gannets have chicks they will remain with the chick and avoid straying into the territories of neighbours who will give them a hard time. With no chick to protect and potentially less aggressive neighbours (as they also have no chicks) the gannets may simply run or fly off! If we do catch them and attach the loggers the second question mark lies over whether we’ll be able to re-catch them again for much the same reasons plus the fact they will be wiser to being caught when they see the pole approach for a second time!

So keep your fingers crossed for us and hopefully my next post will be able to bring news of a successful April tagging trip!