Large Animals Need Riparian Zones

Riparian zones are utilized by wildlife as a sort of "natural highway".  As roads and highways are important to humans, forested riverbanks are important to mammals and birds as they journey up and down the river during daily movements and seasonal migrations.  These areas may be important corridors for more than just wildlife migration, however: as plant and animal habitats shrink or become fragmented, riparian zones may allow for the preservation of genetic variability by maintaining connections with other populations of their species, thus maintaining the gene pool within a species.

Whitetail deer
Whitetail deer along the Scioto River near Columbus, Ohio;
Jay DeLong photo

Animals need a degree of safety when visiting a site for drinking water. Riparian areas offer escape cover.



Throughout North America, riparian areas provide wildlife benefits far out of proportion to their extent on the landscape.  Riparian zones offer an all-in-one package of the three critical resources for wildlife: cover, food and water. These ecosystems provide year-round habitat for many species of mammals, amphibians, reptiles, and resident birds, as well as breeding sites, wintering areas, and stopover habitats for migratory birds.  The U.S. Forest Service found 359 out of 414 wildlife animals studied in upland forests in Oregon and Washington occupy riparian zones or wetlands during all or part of their lives.An Environmental Alternatives Analysis for a 4(d) Rule for the Northern Spotted Owl. USFWS Pacific region. http://www.r1.fws.gov/4deaa/welcome.html   Other researchers found that between 63 and 74% (depending on the area) of the 341 species of vertebrate animals in British Columbia's forested ecosystems are associated with riparian zones.Bunnell, F.L., and L.A. Dupuis. 1993. Riparian Habitats in British Columbia: Their Nature and Role. Proceedings, Riparian Habitat Management and Research, Kamloops, BC. Fraser River Action Plan

 Yellow-crowned night heron
Yellow-crowned night heron in Virginia wetland; Bruce Stallsmith photo

Riparian zones are elongated "edges" (narrow zones of overlap between two different ecosystems) that attract edge specialists as well as species that represent the surrounding ecosystems. 

The edge is valuable to a greater diversity of wildlife species than either habitat alone.  The importance of this "edge effect"  for many bird and mammal species is well documented.

If left undisturbed, stands of trees provide habitat for cavity nesting birds such as woodpeckers, owls, wood duck, common merganser, bufflehead, and common goldeneye. Other species such as some herons, osprey and bald eagle preferentially nest in large trees close to a water source. Osprey
Osprey in a dead tree in the Ocala National Forest, Florida; Jay DeLong photo


Riparian zones have a larger quantity of deciduous growth than upland forests, and these are generally faster-growing plants than those in adjacent upland habitats. There is also an increase in the variety of herbaceous species in wetter areas.  For these reasons, riparian zones are favored foraging habitats for many species including deer, elk, and moose.

 


Robert Carillio s_r_enterprises@hotmail.com and Jay DeLong thirdwind@att.net