130925-studie-wildlife-comeback-in-europe

No. of individuals
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
1975
1977
1979
1981
Figure 1.
Number of Whiteheaded
Ducks in
Spain since 1975 [13, 14] .
1983
1985
1987
1989
1991
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
II of the Bern Convention, and Annex I and II of
the Convention on Migratory Species [5] . The West
Mediterranean population (Spain and Morocco)
is classified in Column A of AEWA (categories 1a, b
and c) [6] .
Abundance:
current status and changes
In the early 20 th century, the global population of
White-headed ducks was over 100,000 individuals,
but by 1996 it had declined to 20,000 [1, 10] and today
it is estimated at 8,000–13,000 individuals [11] . In
Spain, the number of birds declined from about
400 individuals in the 1950s [12] to a low point of 22
individuals in 1977 [13] . Since then, the population
has increased by two orders of magnitude, and in
2012 there were 2,080 individuals [14] (Figure 1).
Distribution:
current status and changes
Historically, the White-headed duck suffered
dramatic declines in distribution in Europe. It
became extinct as a breeding bird from Italy
(1977), France (late 1960s), Morocco, Hungary
(1961), Albania (1920), Serbia (1962), Croatia
(1965), Romania (1920), Greece (19 th century) and
Ukraine [1, 3, 10, 12] (Figure 2). In Spain, the majority of
the population has always been found in Andalucía,
and during the late 1970s and early 1980s, the
entire population was restricted to one wetland in
Córdoba [12] . Following the increase in population
size in the 1980s, there was considerable expansion
of the species’ distribution [1] (Figure 2).
Major threats
The greatest threat to the survival of the Whiteheaded
duck is hybridisation with the non-native
North American Ruddy duck (O. jamaicensis) originating
mainly from the feral population in the UK,
which was introduced from captive collections in
the 1950s [1, 16, 17] . Ruddy ducks have dispersed from
the UK, reaching Spain, France, the Netherlands,
Morocco, Scandinavia, the Czech Republic and
Iceland and the population greatly increased [10, 14, 17, 18] .
The introduction of Carp (Cyprinus carpio) in Spain
is also a major threat [19] , as habitat modification by
the fish amounts to habitat loss for White-headed
ducks [1] .
In Spain, fluctuations in climate have been
shown to influence the population dynamics
Figure 2. Current
distribution of
White-headed
duck in Europe and
historical distribution
in the early 20th
century [12] and in
1977 [15] .
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