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Variation in Parental Food Provisioning of Arctic Tern Chicks in the High Arctic

Noort, H. I. van (2017) Variation in Parental Food Provisioning of Arctic Tern Chicks in the High Arctic. Master's Thesis / Essay, Marine Biology.

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Abstract

The Arctic tern is the only tern species nesting on Svalbard. A breeding area to which they return each year after an incredible annual return migration distance of up to 90.000 km measured from their overwintering grounds in the Antarctic. Once arrived in the Arctic, they have to cope with harsh and unpredictable conditions comparable to those in the Antarctic and affecting both their chick survival as their own. These conditions are expected to become increasingly unpredictable due to the adverse effects of climate change which has a heavier impact in the Arctic than anywhere else. In addition, the Arctic tern might be more sensitive to these changes in their breeding grounds due to a foraging strategy which is relatively vulnerable to these changes compared to other marine birds in this region. Despite these concerns, practically no research has been carried out involving the diet of Arctic terns in the high Arctic. Most of the studies involving Arctic terns in this region are population and migratory studies, only in the more temperate regions has their diet and feeding behavior been studied more intensively. Additional information about their Arctic diet is invaluable however, not only because of climate change and the lack of information about their diet as of yet, but also because several species that are known to be key prey species of the Arctic tern in areas where their diet has been studied, are currently in decline in the high north. Therefore, this study aims to gain a better insight into the diet of Arctic tern chicks in the high Arctic, with specific emphasis on variation in parental food provisioning in relation to changes in a number of environmental factors. Data on the diet of Arctic tern chicks were collected in Ny-Ålesund in July and August 2014 through daily nest observations with a telescope. A number of 11 nests were frequently observed for which information about delivered prey items was obtained. In concurrence with these dietary data, environmental variation in precipitation, wind speed, and tidal stages were monitored. Furthermore, nest specifics and parenting behavior were taken into account for the purpose of making a distinction between the individual nests observed for this project. The results of this study show significant correlations of predominantly the weather circumstances in Ny-Ålesund with the diet composition, feeding rate and caloric supply of Arctic tern chicks. The tidal stages had only a minor impact on food provisioning and on diet composition. Amongst the most evident results of this study are the diet composition of the Arctic tern chicks which was mostly made up out of crustaceans (51.6 % of known prey) with a proportion that is much higher than that of Arctic terns or congeners in other regions. Furthermore, this proportion of crustaceans as well as the feeding frequency were significantly positively affected by increasing wind speeds. Overall, these results stress the importance of small crustacean prey items as the main food source for Arctic tern chicks in the high Arctic. Also, they indicate the negative impact that rain and wind have on foraging conditions and therewith likely on foraging and breeding success of Arctic terns in this region.

Item Type: Thesis (Master's Thesis / Essay)
Degree programme: Marine Biology
Thesis type: Master's Thesis / Essay
Language: English
Date Deposited: 15 Feb 2018 08:32
Last Modified: 15 Feb 2018 08:32
URI: http://fse.studenttheses.ub.rug.nl/id/eprint/15865

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