Alien Birds in North America – Challenges for Wildlife Managers

In Executive Order 13112 “Invasive Species”, an alien species is defined as one “that is not native” to a particular ecosystem. In North America today, there are nearly 100 alien bird species with self-sustaining populations. These include numerous game birds (primarily gallinaceous birds) and escaped pet birds (primarily psittacine species). Others, such as house sparrows (Passer domesticus), European starlings (Sturnus vulgaris), and mute swan (Cygnus olor), were originally introduced for aesthetic reasons or to control agricultural insect pests. The establishment of alien bird populations through purposeful or accidental introductions has resulted in numerous problems including crop damage, transmission of disease, adverse impacts to native species, and aircraft safety concerns. The estimated cost associated with alien bird species in North America approaches $2 billion annually. Although many alien bird species apparently cause minimal or no harm, others are considered persistent and destructive pest species. The challenge for wildlife managers often is one of public opinion and education rather than identifying effective management and control strategies. For many bird damage situations, techniques currently exist for addressing the specific problem, and ongoing research is providing new tools. Many times, however, the will of the public overrides the scientific and economic need to manage aggressively to reduce detrimental alien bird populations. Specific examples of this dilemma for wildlife managers are provided by case studies featuring monk parakeets (Myiopsitta monachus), and mute swan