Aliens Newsletter - ISSG

The Eradication of Ruddy Ducks in the United Kingdom
Iain Henderson
The non-native Ruddy Duck Oxyura jamaicensis
became established in the wild in the United
Kingdom in the 1960s following escapes and
releases from waterfowl collections. During the
1970s and 1980s it spread into many areas of the
UK and was seen with increasing frequency in
mainland Europe. Hybridisation with the native
White-headed Duck O. leucocephala was first
recorded in Spain in 1991. Although the Whiteheaded
Duck is classed as “endangered”, the
population in Spain is heavily protected from
hunting and habitat loss, so hybridisation with
the Ruddy Duck is now regarded as the greatest
threat to its long-term survival. Following several
years of research, a programme aiming to
eradicate Ruddy Ducks from the UK began in
2005. Since then over 6,800 Ruddy Ducks have
been culled across England, Scotland and Wales,
and data suggest that by March 2010 the UK
population had been reduced by over 95%.
Introduction
Figure 1. Male White-headed Duck.
Photo: Joe Blossom
The White-headed Duck Oxyura leucocephala is
listed as Endangered on the IUCN Red List of
Threatened Animals (Hughes et al. 2006; IUCN
2009). This species was formerly found throughout
southern Europe, parts of North Africa and much of
Central Asia but its breeding areas are now highly
fragmented, principally due to habitat loss and overhunting.
The European breeding population is now
restricted to Spain (see Figure 1 and 2), which is the
only region where the White-headed Duck has expanded
its breeding range and population size in recent
years (Hughes et al. 2006). The Spanish population
had fallen to as few as 22 birds at just one
location by 1977 (Torres 2003), but recovered following
a hunting ban which came into force in 1980.
Habitat protection has safeguarded the key breeding
and wintering sites for the species (Carlos
Gutiérrez pers. comm.) and in recent years the postbreeding
population has stabilised at between 2,100
and 2,600 birds. In 2007 breeding occurred on 32
sites in southern and eastern Spain (Carlos Gutiérrez
pers. comm.).
Figure 2. Main breeding and wintering sites for Whiteheaded
Ducks in Spain
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