Hydrology Studies for Avian Riparian Obligate Species

Research is being conducted to measure hydrologic conditions such as soil moisture, depth to ground water, and amount of standing water in the habitat for the southwestern willow flycatcher and the yellow-billed cuckoo in order to manage habitat creation sites.

Based on information gathered during surveys for southwestern willow flycatchers on the LCR since 1997, it has been noted that within the dense, moist riparian habitats where flycatchers are found, several other LCR MSCP covered species are also commonly encountered. These species include yellow-billed cuckoos, summer tanagers, vermilion flycatchers, Sonoran yellow warblers, gilded flickers, and Gila woodpeckers. Some soil moisture and/or standing water may be an important feature of optimal riparian habitat, but the exact role this water has in habitat use is unknown. It may increase vegetation health, which may relate to insect abundance, or it may increase humidity and lower temperatures. It is also unknown how long moisture needs to be present or how large an area needs to be kept in this state during the breeding season.

Although much has been determined regarding site conditions needed for breeding southwestern willow flycatchers (flycatchers) and yellow-billed cuckoos (cuckoos), quantification of how much moist soil or standing water within breeding locations, and how to maintain needed hydrological conditions is still undetermined. This study will review hydrological studies that have been completed already within other river systems that have nesting flycatchers and cuckoos. Monitoring will also begin on hydrologic conditions such as ground water, soil moisture and standing water under known breeding flycatcher and cuckoo sites along the Virgin and lower Colorado River systems.

For additional information on this project, please refer to Work Task C37: Hydrology Studies for Avian Riparian Obligate Species (PDF). Find Technical Reports for this Work Task here.

Updated October 14, 2011