Contaminants such as pesticides, herbicides, heavy metals, and automobile and industrial emissions, as well as sedimentation and siltation in aquatic systems, continue to play a role in the decline of many species in Minnesota. Species can be affected directly by the toxicity of pollutants, or indirectly by the influence that pollutants have on their food resources.

Lead poisoning is one of the greatest threats to trumpeter swans in Minnesota and responsible for about 40% of the swan fatalities in the state. Trumpeter swans ingest lead fishing sinkers and lead shots when they eat grit and forage for tubers and roots from marsh and lake bottoms.

Trumpeter Swan (Cygnus buccinator)


Ten reasons why species become rare

Habitat loss and degradation Invasive species and competition Pollution Habitat specificity Persecution and exploitation

Peripheral populations Vunerable characteristics Relict populations Disease Global climate change

back to rare species guide