Greenland White-fronted Goose trends

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Greenland White-fronted Geese migrate between their breeding grounds in Greenland and their winter homes in Ireland and Britain, stopping for several weeks in Autumn and Spring in Iceland to re-fuel. In the 1980’s when the population had been showing a steady decline a hunting ban was introduced in Britain and Ireland. This was followed by a similar ban in Iceland in 2006.  The hunting ban has saved 1,000’s of adults but the overall population  for the last 16 years has continued to decline.

 

gwf-pop-trendFigure 2. Total estimated global population size of Greenland White-fronted Geese spring 1983-2016 (filled squares), showing Wexford (filled circles) and Islay (open circles) annual contributions to these counts. The arrow marks 2006, when autumn hunting was banned in Iceland. (from the Report of the 2015/16 International Census of Greenland White-fronted Geese  October 2016)

The graph below shows the flock numbers at Sheskinmore during November-December for most winters since 2003.

sheskinmore-gwf-pop-trend

The flock size has almost halved here in the last ten years. Prior to that flock sizes were often around 100.  The average flock size between 1994-1998 was 103. So what is the cause of this continuous decline for a bird that is relatively long lived and why are the numbers not remaining stable or increasing in the years following the shooting ban ?

Reproduction fails to balance natural losses within the population, despite adult survival being between 75-85 % (Goose in trouble as Atlantic warms T. Fox & A. Walsh I-WeBS News August 2016).  These geese take up to 6 years to mature, have small broods, the parent-offspring relationship can last for up to 16 years and most geese don’t ever reproduce at all in their adult lives.  The average brood size in the Irish flock is 2.6 and only six percent of the Irish flock are juveniles. At Sheskinmore there is often no juveniles in the flock, this winter, there is one family with 3 juveniles, which out of a total flock of 26  is 11.5%. Most of the Irish flock are found in Wexford, with a significant flock at Loughs Foyle and Lough Swilly.

For the ones that do take the plunge, which is so vital to maintain the population, a recent obstacle to their success has been the increase in sea temperatures in the North Atlantic since the 1990’s which results in increased precipitation in west Greenland in April and May.  This falls as snow and covers the breeding grounds just when the geese have returned to breed. In Wexford the correlation has been identified between  the rate of precipitation at the breeding ground in Greenland and the number of juvenile birds in the winter flock.

If the climate is hindering reproductive success in Greenland, then while the geese are here we can take steps to ensure the adults are in good condition returning to their summer home. As anyone who has come across them knows they are really wary and will readily take flight when disturbed. Sheskinmore is a relatively undisturbed location for them but do be mindful not to disturb them during the winter. They leave from Sheskinmore in early April.

 

 

 

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