COTTAAR F KOFFIJBERG K, BERREVOETS C & CLAUSEN P (1999) Light-bellied Brent Geese Branta bernicla hrota in The Netherlands in 1995/96 and 1996/97. LIMOSA 72 (3): 89-98.

Light-bellied Brent Geese from the breeding population of Spitsbergen are scarce but regular winter visitors in The Netherlands. In the past, several influxes have been recorded from their regular wintering areas in Denmark and England during prolonged cold-spells. This paper describes two influxes which occurred in 1995/96 and 1996/97 respectively, and is based on the results of the national goose and swan census scheme and an extensive enquiry among goose observers and others. In both winters, arrival of Light-bellied Brents coincided with severe cold and heavy snowfall in Denmark in the second half of December (Fig. 4). In 1995/96, numbers in The Netherlands rapidly built up to 600 individuals in the first weeks of January (Fig. I). By half February, numbers had dropped already by 25%, but new arrivals in the second half of February resulted in an hitherto unknown number for The Netherlands of 800 geese, which stayed in the country until the beginning of March. The seasonal pattern at Lindisfarne, England (their main wintering area), as well as reports from individually marked individuals in England and The Netherlands and observations of northbound passage along the Dutch North Sea coast off Noord-Holland suggest that these birds originated from northern and eastern England (Figs. 2,4; Tab. 1). In the second half of March most birds returned to their spring staging areas in Denmark and only small numbers stayed well into May. In 1996/97, the general picture was different. Again, most arrivals were recorded in January and numbers peaked at 345 individuals in the first days of February, but many birds had already left by mid-February. Contrary to the previous winter, sightings of marked individuals suggest that the 1996/97 influx mainly consisted of birds which had left Denmark and returned there from the end of February onwards. Both in 1995/96 and 1996/97, most birds occurred at sites in the western part of the country, mainly the same which also supported Light-bellied Brents during previous influxes (Fig. 3). In spring, the remaining birds mainly concentrated in the Wadden Sea area, together which large numbers of Black-bellied Brent Geese. Observations of marked individuals suggest that in these flocks at least some birds were present which had stayed along the western coast in January and February. Especially in 1995/96, several small flocks were also found far inland, often at sites near rivers and other large water bodies. This phenomenon is not known for Black-bellied Brent Geese, which only occur in the Delta area in the SW-Netherlands and in the Wadden Sea.
      Both the 1995/96 and the 1996/97 influx are the largest which have been recorded in The Netherlands so far. During previous influxes, in 1978/79, 1981/82, 1984/85 and 1986/87, 100-190 birds were recorded (Tab. 2), about 5% of the Spitsbergen population. The higher numbers in the two recent winters are due to a population increase and to a larger share of the overall population, in 1995/96 even 18%. This indicates that under harsh conditions, The Netherlands may serve as an important winter refuge.

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