Important Bird Areas

Havasu National Wildlife Refuge

Arizona

The refuge protects 30 river miles - 300 miles of shoreline - from Needles, California, to Lake Havasu City, Arizona. One of the last remaining natural stretches of the lower Colorado River flows through the 20-mile-long Topock Gorge. The 4,000-acre Topock Marsh depends on water from the Colorado River. The passage of the Arizona Desert Wilderness Act in 1990 and the California Desert Protection Act in 1994, together designated 17,606 acres, or 32 percent of the refuge, as wilderness.

Ornithological Summary

The refuge shelters thousands of Canada and snow geese and ducks each winter.
Western and Clark?s grebes raise their young in both Topock Marsh and Topock Gorge. Herons and egrets nest in rookeries in the marsh. Banding operations were conducted for a total of 650.83 net hours during the winter of 2005-06. There were 139 individual birds captured (0.21 per net hour) and 45 recaptures (0.069 per net hour) for a total of 184 birds captured. Eighteen species were captured, with 4 species accounting for 68% of all captures: ruby-crowned kinglet 37%, orange-crowned warbler 15%, Audubon?s warbler 8%, and Bewick?s wren (Thryomanes bewickii) 8%

Riparian Species: In 2005, the Havasu banding site (HAVA) was monitored during the winter season for the first time. This site is located on the Havasu National Wildlife Refuge at the southern end of Topock Marsh approximately 1.2 miles (1.5 km) north of the town of Topock, AZ. Area searches are conducted at each site during each of the 6 banding periods to account for species that may not be captured during standard mist-net operations. A standard area search protocol was followed (Ralph et al. 1993). A large portion of the area is covered in Tamarix spp. and arrowweed (Pulchea sercea) with some large (greater than 45 ft (14 m) in height), mature cottonwoods forming an overstory over roughly 15% of the site. The cottonwoods are the remaining trees from a planting in 1988 where most of the trees planted did not survive. The south side of the dike consists of a monotypic stand of Tamarix spp., ranging in height from 20-26 ft (6-8 m), while the north side is comprised of Tamarix spp., with some areas having an overstory of cottonwoods. The northern edge of the site is bordered by marsh vegetation. This site is typical of the vegetation now found along the LCR.
Banding operations were conducted for a total of 650.83 net hours during the winter of 2005-06. There were 139 individual birds captured (0.21 per net hour) and 45 recaptures (0.069 per net hour) for a total of 184 birds captured. Eighteen species were captured, with 4 species accounting for 68% of all captures: ruby-crowned kinglet 37%, orange-crowned warbler 15%, Audubon?s warbler 8%, and Bewick?s wren (Thryomanes bewickii) 8%.

Area searches were performed for all 5 periods with a total 344 birds detected, an average of 68.8 birds detected per period. The first period only accounted for 7.8% of all detections, while the other four periods accounted for 18-27% of detections during each survey period. A comparison between area search data and mist-netting data can found in Figure 11. Area search detection rates were higher for the house finch (Carpodacus mexicanus), marsh wren (Cistothorus palustris), and yellow-rumped warbler. Yellow-rumped warblers cannot be reliably identified to subspecies during an area search, although all birds captured were the Audubon?s subspecies. The western sandpiper (Calidris mauri) was only detected using area searches.

Conservation Issues

Salt cedar, a tree originally from Asia, aggressively takes over disturbed areas along the Colorado River. Native cottonwood and willow trees cannot compete. The staff at Havasu NWR works to control salt cedar and reestablish our native forests, which are much more valuable for wildlife.
To protect floating nest birds, jet powered personal watercraft (PWC) such as Sea Doos, Wave Runners, etc. are not allowed in backwaters off the main Colorado River channel for the 15-mile stretch from the Island/Castle Rock location, north to the Interstate 40 bridge, buoy line.

Ownership

Ownership of this site is shared between the Bureau of Land Management, the Fort-Mohave Indian Reservation, Arizona Game and Fish, Lake Havasu National Wildlife Refuge, Private Land and State Trust Land, covering an area of 13,474.54 hectares in total. Please review the ownership map details for more accurate percentages of land ownership.

Habitat

One of the last remaining natural stretches of the lower Colorado River flows through the 20-mile-long Topock Gorge. The 4,000-acre Topock Marsh depends on water from the Colorado River