CITY OF TUCSON

HABITAT CONSERVATION PLAN

Yellow-billed Cuckoo Subcommittee

Meeting Notes

Topic: Stressors and threats to Yellow-billed Cuckoo

Date: May 11, 2004, 1 p.m.

Location: U.S. Fish and Wildlife Service office

Participants: Troy Corman, Arizona Game and Fish Department; Brian Wooldridge, U. S. Fish and Wildlife Service; Ann Phillips, Tucson Audubon Society; Ken Kingsley and Leslie Liberti, SWCA

The following notes summarize a wide-ranging discussion that centered on the Threats and Stressors Matrix. That matrix (attached) is annotated for this species based on the discussion.

Habitat: The group consensus was that there is currently no suitable breeding habitat in the planning area. There is, however, suitable and documented breeding habitat upstream from the planning area along the Santa Cruz River in Santa Cruz County at Tumacacori, in the pecan orchards in Green Valley, along Cienega Creek in the Empire-Cienega National Conservation area, and on the Buenos Aires National Wildlife Refuge. There is also suitable and documented migratory stopover habitat along the Santa Cruz River downstream from the currently defined planning area, as well as from the Simpson Farm site and upstream in the Altar Valley. Known sites at which this bird has been observed include Sweetwater Wetlands and the Avra Valley Water Treatment Plant.

Breeding: This species is known to breed in areas of large, dense riparian vegetation, especially cottonwood-willow but also including mesquite bosques, Tamarix thickets, and pecan orchards. The defining characteristics of suitable breeding habitat are thought to be large trees with well-developed midstory vegetation beneath the canopy, and high humidity. Bigger trees and bigger blocks of habitat are better than smaller trees and smaller blocks, although smaller blocks are known to have been used. The small size limit is not known. Continuous blocks of riparian habitat are better than areas with open grassy areas between blocks of trees. High humidity is thought to be of key importance for development of the eggs, as well as to insure abundant prey. Blocks of trees near ponds and/or wetlands may be suitable. Nests are placed in the midstory vegetation, not high up in the trees. There is usually a dense canopy of vegetation immediately above nests. Protective cover to reduce predation by raptors and nest predators is important.

Foraging: This bird feeds primarily on large insects, especially caterpillars, cicadas, and grasshoppers, which it catches in mesquite and cottonwood-willow woodland habitat.

The size of foraging ranges is not known.

Migration: This bird migrates to South America, where it winters, and migrates through our area. It flies at night, and rests by day in areas with riparian vegetation. The distance it flies each day is unknown. Migration northward occurs in June and July, and southward migration occurs in August and September. Creation of suitable migration stopover sites may be a better use of resources than an attempt to create breeding sites, especially where the potential for creation of riparian habitat is constrained by physical features or funds. The size of a block of habitat that would be minimally suitable is unknown, but undoubtedly small, since birds have been found in areas of only a few trees.

It is possible that good migratory stopover habitat could be created in association with Avra Valley water projects. Troy recommended investigation of the Gilbert water ranch outside of Phoenix, where recharge basins have been developed to provide habitat for many species of birds.

Exotic Species: Tamarix may be used by this species as nesting or resting habitat.

Habitat restoration/creation: The best approach would be to keep different stages of trees in growth at all times. The natural flood regime would be best for ensuring continually available habitat with minimized management costs. There is some concern about the hydrological effects of woody debris.

Water: This bird does drink, but open water is not considered necessary for its survival. Water is important for maintaining humidity and for sustaining trees. Effluent is acceptable and pools are acceptable.

Disturbance: Cuckoos may abandon their nests early in the season if they are directly disturbed or if there is major disturbance (noise, machinery) in the immediate vicinity. Disturbance thresholds are not known.

Roadkill: This is not generally considered to be a major problem, since the birds usually stick close to trees and fly above traffic level. However, bridges may be a special problem, since they are usually elevated to the level at which the birds fly. There have been a few reports of cuckoos killed by vehicle strikes.