B. Spaans et P. Postma, Inland pastures are an appropriate alternative for salt-marshes as a feeding area for spring-fattening Dark-bellied Brent Geese Branta bernicla, ARDEA-T NED, 89(3), 2001, pp. 427-440
On the Dutch Wadden Sea island Texel, spring-fattening Dark-bellied Brent G
eese Branta bernicla fed almost exclusively inland on improved grasslands,
whereas the remainder of the flyway population utilised coastal saltmarshes
elsewhere in the Wadden Sea. There are indications that inland pastures ar
e 'second choice habitat' during this important period. During spring-fatte
ning, salt-marsh food plants just started to grow, offering the geese high
quality food, while the growth of grasses on the inland pastures started ea
rlier in the season, so that the nutritional value of inland grasses declin
ed in the course of the spring-fattening period. This paper describes the h
abitat use of spring-fattening Dark-bellied Brent Geese on Texel and compar
es the reproductive output of pasture feeding and salt-marsh feeding geese.
Dark-bellied Brent Geese on Texel overcame the problem of declining grass
quality on inland pastures by tuning their grazing pressure to the plant pr
oduction in such a manner that they kept the grass in the young, protein ri
ch phase. Observations of individually marked Dark-bellied Brent Geese reve
aled the site-fidelity of spring-fattening geese on Texel. The annual survi
val of a sample of Texel geese (89%) was slightly higher than published val
ues for the whole population (86%). Between 1982 and 1993, Dark-bellied Bre
nt Geese successfully bred in six years, while the reproductive success of
inland pasture feeders and salt-marsh feeders was similar. The calculated l
ifetime reproduction of Dark-bellied Brent Geese spring-fattening on Texel
amounted to 1.39 offspring per goose, which was in accordance with overall
population trends during the period concerned. The results show that an imp
roved grassland reserve can be an appropriate alternative for salt marshes
for spring-fattening Brent Geese.