Tuesday, December 24, 2013

Greenland White-fronted Goose census.

Last week ( 17th-18th ) saw the completion of the International Census of Greenland White-fronted Geese in which Islay plays a prominent part given its significant wintering population.  Such counts are completed at three distinct points over each winter, supplemented, on Islay, by the counts arising from within the formal counts regularly undertaken as part of the monitoring of geese associated with the subsidy system for farmers.

As has been said before the Greenland White-fronted Goose is actually a sub-species, but because of its distinct breeding distribution and wintering areas is treated as if it were a full species. Recent years has seen  growing concerns about its numbers which have reduced dramatically. For this reason its numbers are monitored over the whole of its regular wintering areas to gain an insight into its current status as clearly attempting to monitor the population in Greenland itself is nigh on impossible.

To achieve this on Islay the island is split into six distinct sectors and counted over each of two consecutive days recognizing that birds may be missed due to a variety of circumstances. The average figure is then used in the various summaries drawn together, although with keen attention being paid to the constituent totals for each individual day.  Last week that figure was 5869, which was remarkably "close" to the figure derived from the November counts, 5888.  Comparison of the figures associated with the individual days for each sector can show some changes as birds move around a little of their own volition or are disturbed and move onto ground in another of the designated sectors. Whilst it would be easy to conclude the totals are derived from a few large flocks within each sector such is certainly not the case and the totals very often arise from the accumulation of sightings of endless smaller groups. It makes for a long couple of days involving the exploration of all known favoured sites and other sheltered nooks and crannies, particularly if the weather is a bit iffy and the birds seek shelter which they're very adept at identifying.

At the same time all numbers of Barnacle Geese encountered are also logged on the recording sheets. Last week saw 36,244 birds "in residence", contrasted against the 46,931 birds logged in November suggesting perhaps that some birds had moved on.  One pleasing aspect this winter has been to note that there is a significant presence of young birds within the Greenland White-front flocks which is a very welcome sight. Previously the general rule was to note that, whilst Barnacle Goose numbers were increasing, those of Greenland White-fronts were moving in the other direction!! In that sense it seems, temporarily or otherwise, a corner may have been turned, which justifies the basis upon which the census work rests. Good news!

No comments:

Post a Comment