Invasive alien species in Switzerland - Schweizer ...

An inventory of alien species and their threat to biodiversity and economy in Switzerland FOEN 2006 50
groups is based on the support they receive from the human population, since some are
released and most are fed in the wild (or receive some other human support).
The environmental and economic impact of established alien birds in Switzerland is
probably fairly negligible and limited to some local effects. The exception on a European
scale is the ruddy duck, which is the critical issue for a native globally endangered
species. The possible and certain impacts are summarized in Table 2.3.
Birds seem to cause less concern and actual impact on biodiversity, as outlined above,
than mammals, but their impressive capability for spread underlines the concern about
both potential future spread and the unsatisfactory level of knowledge for predicting
spread and impact. The rapid increase in the number of newly introduced bird species
recorded in recent times and the spread of some older introductions underline the
urgency of implementing effective strategies to address the issue.
The pathway analysis indicates where prevention of future introductions will be most
efficient. The three major pathways identified are listed below, together with measures
to help close them.
Escaped birds from captivity (Psittacidae and Anatidae). Measures to prevent escapes
of alien bird species from captive collections can include strict standards of security for
aviaries, a register and documented bird monitoring, and penal and administrative
sanctions in the event of violation.
Released birds for aesthetic reasons and to enrich the native fauna (Anatidae). Legislation
to prevent deliberate introductions should be established, or improved and implemented.
As can be easily seen from the cases of species spreading through Europe
towards Switzerland, this issue needs to be tackled on a European scale. The international
conventions are in place and need to be implemented, e.g. Convention on Biological
Diversity (CBD), Bern Convention, Bonn Convention, Ramsar Convention. It
should be noted here that the domestic duck can also pose a problem for the wild
mallard (Anas platyrhynchos (L.)) because of hybridization. These noticeable hybrids
are most often observed in urban areas, but they should be eliminated in the wild.
Species released as game birds (Phasianidae). An environmental risk assessment needs
to be undertaken for all species considered for release in Europe. In the past chukar
(Alectoris chukar (Gray)) were released in the Alps, including Switzerland. They can
hybridize with the native rock partridge (Alectoris graeca (Meisner)). The chukar is the
eastern equivalent of the rock partridge. These releases are unnecessary and pose a
potential danger to the indigenous rock partridge, which is one of the nine European
endemic bird species.
Management options for the species which can cause problems are detailed in the text
relating to the species and in the Fact Sheets, e.g. ruddy duck and ruddy shelduck
should be shot.