Conservation/Environment

Piscivorous birds are birds that eat fish.  These birds have an effect on the survival of small salmon and steelhead that are migrating downstream past our dams.  Fish-eating birds found along our reservoirs include mergansers, double-crested cormorants, herons, gulls, and terns. 

Chelan County PUD conducts surveys along both Rock Island and Rocky Reach reservoirs to determine distribution and abundance of these birds.  Chelan PUD funded a 3-year study by the University of Washington to determine the number and kinds of fish eaten by birds at our hydroelectric projects.  Data collected also included forage locations and seasonal timing of predation.  Information collected from piscivorous bird surveys help Chelan PUD biologists manage bird populations and behaviors in order to reduce predation on salmon stocks passing through our hydro projects and to minimize impacts on the birds. 

In the summer of 2005, piling caps were installed on dock pilings at parks along Rocky Reach and Rock Island reservoirs.  The piling caps prevent the ability of gulls and other birds from perching on the dock pilings.  This removes the availability of over-water perches from which gulls could plunge from to prey on fish.  The elimination of perch sites on pilings also forces gulls to use other areas at parks where they are more exposed to disturbances, making this portion of the river less attractive to gulls. 

Grids of bird wires are installed over the tailraces (immediately downstream) of both Rock Island and Rocky Reach dams.  The wires greatly discourage gulls and terns from fishing in the tailrace of the dams by obstructing their flight.  The wires force birds to utilize downstream areas for foraging.  Fish are less susceptible to being preyed upon by birds in downstream areas were the river is calmer and the fish are able to swim at greater depths.  Hazing of the birds by using pyrotechnics (noise makers) such as propane cannons, bird screamers, and bangers also help to keep piscivorous birds away from the tailrace of the dams where young salmon and steelhead are most vulnerable to predation.