Animal communities have changed

Animal communities have changed.

Many wild animals in Boulder have come to depend on irrigation ditches and reservoirs supplied by ditches.

  • Coyotes, fox and owls eat rodents which live along ditches.
  • Owls prefer to nest in large cottonwoods which are found along ditches.
  • Brown bats prefer hunting insects above reservoirs and ponds.
  • Rare leopard frogs are found in stock ponds.
  • Native and introduced fish populate reservoirs, gravel ponds and creeks. So does the calix mosquito, the main host to the West Nile virus.

Riparian animals such as the muskrat, mink, beaver, heron, and other water birds depend on bodies of water for food, homes and safety. Irrigation ditches and reservoirs have become prime habitat for many of these species in Boulder.

By depending on man-made structures so much, are these creatures less wild or less native? Do we now have a responsibility to maintain the structures upon which these animals depend?

The 1127 acres of man-made ponds and lakes near City of Boulder Open Space lands are now part of the Central Flyway, which migratory birds use, traveling from the Arctic to South America.

Historically white pelicans, osprey and bald eagles were almost never spotted over the Front Range. With the development of reservoirs, that has changed. Today, osprey and bald eagles are nesting around Boulder Reservoir and Valmont Lakes. White pelicans are commonly seen feeding in Boulder County.

Are these birds "invasive" if they didn't used to live here?

Right, clockwise from the top: White pelican feeding; Owl in cottonwood; Coyote hunting; Mink swimming; White pelicans flocking; Heron feeding; Duck diving.  Photos courtesy of Boulder Open Space and Mountain Parks.

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