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Kittiwake Foraging and Productivity

posted 18 Jul 2015, 07:03 by Ruth Dunn   [ updated 18 Jul 2015, 14:01 ]

Today I am going to take some time to finally tell you about the research on kittiwakes that I have been doing as part of my Masters course.

I am interested in seabirds because of their vulnerability and status as an increasingly threatened group of birds. They are also spatially wide-ranging in their foraging and migratory behaviour, and consequently make ideal study species for someone like me, who enjoys conducting research using geographical information systems (GIS). This long distance travel also means that seabirds are susceptible to the effects of numerous anthropogenic impacts worldwide. These include plastic ingestion and entanglement, fisheries conflict, bycatch issues, oil spills and the impact of marine renewable energy developments.

It is because of this interest that in May I moved to Liverpool (a copy of The Kittiwake by J.C. Coulson under my arm) with the aim of gaining seabird fieldwork experience and investigating the foraging behaviour of Puffin Island’s kittiwakes!

Heading to work across the island with Sam Patrick and Jon Green

In the past week SEGUL (Seabird Ecology Group University of Liverpool) have undertaken 4 trips to the island. Kittiwake productivity checks at my control plot suggest a higher rate of breeding success this year than within the rather disheartening last two years: I have observed a productivity of approximately 0.8 chicks per nest. Kittiwakes usually lay two eggs per year and therefore this figure is still not particularly high, especially when compared with observations from a decade ago. 73 kittiwake chicks were ringed this week and 65 retraps/ resightings of adults were made. Many of these adults have only been resighted a couple of times over the last 5 years which suggests that many are not breeding every year.

Jon on the look out for kittiwakes

Kittiwakes are an Amber listed species within the UK which have shown breeding population declines over the last 30 years. These declines are thought to be linked to changes in the marine environment and prey abundance.

Within my project I am hoping to analyse how interactions between annual differences in oceanic conditions, possible prey abundance, kittiwake foraging behaviour and breeding success influence each other. In order to do this I will work with remotely sensed environmetal data alongside productivity data and GPS tracking data collected during each breeding season since 2010.

This year we caught 15 kittiwakes from the cliffs that drop into the Irish Sea from the north side of the island. We attached GPS loggers, using waterproof tape, to their back feathers (see center photo below). Smaller 100 mAh batteries were used this year in order to reduce the disturbance that the extra mass of the loggers has on the birds. 9 tags were recovered and no visible signs of plumage damage or distress were observed.

Installing remote cameras to monitor productivity and equipping the birds with their GPS logger backpacks

Given their small size, at first it is quite surprising that Puffin Island’s kittiwakes have been found to forage up to 75 km from the island, travelling total distances of up to 180 km on these trips. This year the birds tend to have engaged mostly on lots of shorter trip: on average they have foraged for less than an hour at a time, travelling an average of 11 km in total (up to an average range of 5 km from the colony) in order to find invertebrates and fish to feed themselves and their chicks. Some longer trips can also be clearly seen in the map below.

Map of kittiwake foraging trips throughout 2015 including some of up to 45 km from the colony. Puffin Island is represented by a white star.

Thursday marked my last day of Puffin Island fieldwork. If you were to ask me whether I will miss the early starts, the long drives and train journeys wedged between piles of field gear, the uphill climb through head-high vegetation, the clamminess of sweat and sun-cream on my skin, the barking of greater black-backed gulls, the splattering of sludgy poo falling from the skies, the smell of guano that seems to waft in waves and the random patches of sunburn that I discover the next day then I would answer yes! I would more than happily do it all again.