Important Bird Areas

Cutler Reservoir and Marsh UT08

Utah

This IBA includes the lands that PacifiCorp owns within the project boundaries of the Cutler Reservoir Project and Marsh, any sovereign lands (the submerged meander corridor) of the Bear River within the boundaries, the 150 acre Bud Phelps WMA owned by Utah Division of Wildlife Resources, and the 146 acres owned by Bridgerland Audubon Society.

Cutler Reservoir and Marsh was created by the construction of the Cutler Dam in 1927. PacifiCorp Energy, a subsidiary of PacifiCorp, operates the Cutler Dam Hydroelectric Project under authorization granted by the Federal Power Act, and under the jurisdiction of the Federal Energy Regulatory Commission (FERC). The primary obligation of the Cutler Dam Project is to provide water for agricultural use. Power generation is a secondary obligation and supplemental benefit. Cutler Dam impounds the waters of the Bear, Logan and Little Bear Rivers as well as Spring Creek and other small drainages. Backup from the dam produced the reservoir, which is approximately 9,700 acres of open water and associated wetlands and uplands, 5,500 acres of which lie below the high water level of the reservoir. The Cutler project is also managed for public recreation, wildlife and compatible agricultural uses.

Ornithological Summary

Bald Eagles use trees and perches for resting and hunting in the spring. Ferruginous Hawks hunt and Grasshopper Sparrows nest in grasslands around the reservoir. There are significant numbers of American White Pelicans that use the area for foraging and loafing. Numbers are under 4(b) below. Peregrine Falcons (migration and summer resident), Swainson's Hawks (nest/forage), Caspian Terns (forage), Short-eared owls (nest), Osprey (forage), Burrowing Owls (nest) and Long-billed Curlews (nest?) use the area, but transect survey data provides very limited numbers. Survey data is on file with the IBA nomination.

There are American Avocets and Black-necked Stilts that breed in the area as documented on the chart of Ornithological Importance. Willow Flycatchers breed along the tributaries near the Cutler Reservoir, including the Logan and Bear Rivers.

Over 20 species of ducks, geese, and swans nest or migrate through Cutler Marsh. The wetland maze website mentioned above provides additional information. Canada Geese also nest in the area. However, existing survey data do not demonstrate that waterfowl meet the criteria.

Wading bird survey numbers show counts of 200 American White Pelicans, and 30 Great Blue Heron. Survey data specific to the White-faced Ibis rookery for 2005-2006 provide counts between just under 4,000 and just over 8,000. Survey data showed that the rookery failed in 2007, but counts from 2008 through 2010 demonstrate that the rookery has had counts well over 1,500 for these three years, with a high count in this time period of 7,311 on May 12, 2009

Survey numbers show a count of 275 Franklin's Gulls. Other Gulls as well as Terns also use the area, but existing survey data do not demonstrate gulls or terns meet the criteria. Although formal counts have not been made, anecdotal evidence from census workers is that Franklin?s Gulls may number as high as ten times the number of White-faced Ibis returning to the rookery on June evenings.

There is shorebird use by American Avocets, Black-necked stilts and many other shorebirds. But existing survey data do not demonstrate that the shorebirds meet the criteria.

Bridgerland Audubon Society began transect surveys of grasslands adjacent to Cutler Marsh and Reservoir area beginning in Spring 2001. The surveys were conducted on a monthly to bi-monthly basis. Bridgerland Audubon also has conducted surveys of the Amalga Barrens area beginning in 2001 and continuing through 2006. Much of Cutler Marsh and all of the Bud Phelps and Barrens Sanctuary properties have been included in Bridgerland Audubon Society?s Christmas Bird Count since the 1980s (though counts have not been broken out for these lands).

Cutler Reservoir and marsh provide a diversity of lowland riparian, wetlands, wet meadow, open water, and agriculture in close proximity to the playas in an area called the Amalga Barrens. Essentially this area is a good microcosm of the Great Salt Lake and provides habitat for many of the same birds as the Great Salt Lake. In high water years, habitat lost around the Great Salt Lake may push birds elsewhere, and at least one rookery of White-faced Ibis was established in Cutler Marsh during the 1980s perhaps as a result. The marshes and mudflats therefore quite probably offer a buffer for habitat stressed nearby because water levels are kept very constant by PacifiCorp to comply with irrigation and power generation requirements. Some species (e.g., White-faced Ibis and Great Blue Heron) feed in agricultural fields and wetlands throughout the valley, but return to Cutler Marsh for nesting and roosting sites.

Local birders have provided anecdotal reports of greatly increased numbers of shorebirds in Cache Valley beginning when the Great Salt Lake was flooding in the 1980s. Sometime in the early 1990s reports began of annual rookeries of egrets, ibis, and Franklin?s Gulls on the east shore of Cutler Marsh approximately 0.9 miles north of Utah Highway 30 (UTM Zone 12T Easting: 0421780 Northing: 4623390, WGS84 datum).

As mentioned above, beginning in May 2005, local volunteers began systematic censuses of ibis using the rookery. A protocol was established and accepted by ornithologists at Utah State University (Dr, Kim Sullivan and Dr. Ron Ryel), and counts of birds flying above the rookery have been conducted primarily in May and June from 2005 through 2010. No counts were made of birds on the ground (on nests or otherwise) to avoid disturbing the site. It seems likely, therefore, that actual numbers of adult birds during the breeding period are significantly higher. With a total world population estimate of 120,000 birds, this rookery therefore regularly supports well over 1% of the world?s population of White-faced Ibis.

Ownership

The total acreage included in the IBA is approximately 9,996 acres. PacifiCorp owns most of the property. However, within the boundaries of the IBA, there are the sovereign lands (submerged meander corridor) of the Bear River that are managed by the Utah Division of Forestry, Fire and State Lands. The amount of sovereign lands is relatively small and the total acreage has not been determined. In the table these sovereign lands are included in the for profit category and the total acreage is 7,000 acres. The Bud Phelps WMA managed by the Utah Division of Wildlife Resources is 150 acres and the Barrens Sanctuary owned by Bridgerland Audubon Society is 146 acres.

Habitat

The approximate percentage of habitat types for the area are 48% open water, 5% lowland riparian, 15% wetland, 15% wet meadow, less than 2% playa, 11% grassland, and 4% agriculture.

Land Use

There are multiple uses of the area. The major land uses and the approximate percent of land that is used for the particular purpose are: Agriculture - 10%; Fisheries - 20%; hunting - 30%; Nature Conservation/Research - 17%; Tourism/recreation - 11%; Water management for irrigation - 93%; and Water storage for power - 93%. This equals 346% if the percentages above are added together. The table on land use recalibrates these percentages so that the total land use is equal to 100%. (For example 97% of the area is used for water storage for power, but adding up all the multiple uses results in 346% and 97 divided by 346 results in 27% of all the land uses added together being for water storage for power.)