Barnacle Geese on Kolguev Island 69
©Wildfowl & Wetlands Trust
Wildfowl
(2013) 63: 56–71
when they tend to share the same lakes and
lake shores for feeding (A. Kondratyev
unpubl. data).
Taking into account all of the above
changes in Barnacle Goose numbers and
distribution across the island, there are
several future possibilities for the future of
Barnacle Goose nesting on Kolguev Island.
These include, firstly, stabilisation of the
growth of the delta colony and coastal
colonies in the near future, especially on the
edges, as overall density in the central part of
the colony no longer seems to be increasing.
All remaining gaps within low-lying nesting
habitats will probably soon be filled, and as
the geese are not occupying the slopes of
the delta, the remarkable growth of the
main delta colony is expected to plateau.
Secondly, a continued increase in nest
numbers around raptor colonies can be
expected elsewhere, with the extent of each
colony limited to a 250–300 m protected
radius around a raptor nest. Currently, based
on the colony size and distances between
the furthest nests, the nesting density does
not exceed 1,500 nests/km
2
, but this still
permits a potential fourfold increase in
nesting density to reach the maximum of
6,000 nests/km
2
sometimes observed in the
delta colony (Anisimov 2007). Colonies
around raptor nests therefore could reach
500–600 nests; 6,000–10,000 more nests in
total, given the current raptor distribution.
Thirdly, the new “sedge-moss bog” colony
types that have appeared in the centre of the
island seem to be limited by available
suitable habitats. Colony size in these cases
is limited by the availability of dry places
protruding from the flooded lake bottom,
so the potential for these specific colonies
appear to be physically restricted to not
more than 1,000 more nests over the entire
island, due to low number of suitable dry
lakes with peat hummocks protruding from
spring-flooded wet boggy bottoms. Lastly,
solitary nests that successfully fledge young
in the areas between several closely placed
and constantly growing colonies of the
upper Peschanka River have the potential to
attract other breeders, thus filling the gaps
between these colonies and making the
process of joining several colonies into one
larger-sized colony even more rapid. As
broods are free to move after hatching to
any part of the island, the potential for this
colony to grow might be limited only by the
overall carrying capacity of the entire island
ecosystem during the brood-rearing period.
To conclude it is suggested that the
carrying capacity of the brood-rearing and
moulting habitats need to be studied more
thoroughly to assess the possible future
impact of increased Barnacle Goose
numbers on the breeding
Anser
species, and
possibly also with regard to the vegetation
types present on the island.
Acknowledgements
We would like to thank the many students
and volunteers who supported us in our
work on Kolguev Island during the five-year
study. We are also grateful to the German
Committee for Bird Protection (VsK,
Hamburg) and the ECORA GEF Project
for financial support of the expeditions
made in 2006–2008. In 2011 and 2012 this
study was part of a project of the Institute
of Avian Research, the Department of
Biology and Environmental Science,
University of Oldenburg, the Institute for
