The effects of reseeding, fertilizer application and disturbance on the use of grasslands by barnacle geese, and the implications for refuge management.

Published online
03 Sep 1993
Content type
Journal article
Journal title
Journal of Applied Ecology
DOI
10.2307/2404184

Author(s)
Percival, S. M.

Publication language
English
Location
UK

Abstract

Because of increasing numbers of barnacle geese (Branta leucopsis) wintering on the island of Islay, Scotland, UK, a network of refuges has been established to provide attractive feeding areas in an attempt to reduce damage to agricultural pastures. The effects of different management practices on goose grazing were evaluated by trials at Loch Gruinart on Islay in 1984-87. Reseeding pastures with a Lolium perenne-dominated seed mixture increased the goose grazing density by 60-135%. It gave a proportionately smaller increase over older pastures as the total area of rotational grassland available to the geese on the reserve increased. The preference for reseeded pastures was greatest in the autumn but also peaked in the spring immediately prior to the birds' departure north. Fertilizer application in early Oct. and Mar. increased the amount of time that the geese spent grazing a pasture, but the increase (17-42%) was less than for reseeding and was not apparent in all fields in all years. The seasonal use of fertilized plots was similar to those which were reseeded, with selection in autumn and, to a lesser extent, in spring. Disturbance by traffic was not an important factor affecting the birds' choice of feeding site over the winter as a whole. The combination of proximity to a road and overhead electric wires did reduce grazing intensity in adjacent (<25 m) plots. These disturbed plots were avoided in autumn and spring, but were used more than control undisturbed ones in mid-winter. Although reseeding and fertilizer application increased the numbers of geese using experimental fields, they did not affect the numbers using the reserve as a whole. The latter declined slightly over the 3 winters of the study whilst the area of rotational grass increased by a factor of three. Grassland management appeared to concentrate the local birds in the improved fields rather than attracting large numbers from elsewhere on the island.

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