Geoscience Reference
In-Depth Information
animal species. Along with muskrat, mink, otters
and seals, they were hunted throughout Eurasia
and North America for their high-value fur. Fur
farming and declining demand for natural furs
combined with conservation efforts have allowed
remaining populations to stabilize, and some
species are even expanding their ranges.
For all wetland animals, human encroach-
ment and continuing loss of viable habitats are
the greatest threats to their existence. Human
hunting for feathers, skin, fur, food, or sport has
severely impacted many wetland animals and
driven some species to extinction. Pollution
from human sources
-
pesticides, herbicides,
fertilizer and heavy metals
-
may weaken animal
immune systems, interfere with reproduction,
or cause death. Humans have directly or indi-
rectly allowed many wetland species to migrate
beyond their native habitats and, thus, to become
invasive in other areas. Once established, such
invasive animals may alter local habitats,
adversely impact native species, impair human
land use, and be extremely difi cult to control
or eradicate.
