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Temperate breeding in Barnacle Geese (Branta leucopsis): factors affecting growth and quality of food on Gotland, Sweden

Veen, I. T. van der (1994) Temperate breeding in Barnacle Geese (Branta leucopsis): factors affecting growth and quality of food on Gotland, Sweden. Master's Thesis / Essay, Biology.

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Abstract

In this report the phenology of food plants of Barnacle Geese breeding on Gotland (temperate zone) is investigated. Both study seasons (1992 and 1993) were very dry and grass growth was found to be inhibited by the lack of rain, Not all investigated species reacted in the same way to the lack of water. Agrostis stolonfera and Festuca rubra showed a comparable and strong reaction while Puccinellia maritina showed little reaction to the lack of rain. Puccinellia is growing closer to the sea and has probably better access to seawater. A watering experiment on the Festuca dominated vegetation showed that the decrease in production was slowed down when there was extra water. Not only production, but also nitrogen content of Festuca and Agrostis was decreasing during the season. The nitrogen content of Puccinellia increased during the season. At the end of the season, in the pre-migration period, the nitrogen content of Festuca and Agrostis increased again, after periods with rain. This seems to indicate that growth on this saltmarsh is primarily limited by water and not by nitrogen, as is the case in most arctic breeding areas. When there was sufficient water, nitrogen content was high, even late in the season. As the nitrogen content on the Festuca dominated vegetation decreased, the grazing pressure on this vegetation type also decreased. On Gotland, goose grazing had a stimulating effect on grass growth through the whole season. The increase in growth could not be accomplished by fertilization through goose droppings alone, as fertilization with droppings showed no effect. Nitrogen contents of food plants in the moulting period on Gotland were in the same order as those found by others on Spitsbergen (arctic zone). Also the observed total feeding time per day was in the same order as found on Spitsbergen. However, the Gotlandic geese seemed to have a lower digestion efficiency. In this respect the Gotlandic geese might be at a disadvantage on the breeding grounds compared to arctic breeding geese.

Item Type: Thesis (Master's Thesis / Essay)
Degree programme: Biology
Thesis type: Master's Thesis / Essay
Language: English
Date Deposited: 15 Feb 2018 07:47
Last Modified: 15 Feb 2018 07:47
URI: http://fse.studenttheses.ub.rug.nl/id/eprint/10012

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