Type: report
Article abstract: Surveys for the endangered Southwestern Willow Flycatcher (Empidonax traillii extimus) were conducted at Marine Corps Base Camp Pendleton, California, between 1 May and 31 July 2018. Sixty-six transient Willow Flycatchers of unknown subspecies were observed during Base-wide surveys. Transients occurred on 7 of the 16 drainages surveyed in 2018. No Willow Flycatchers were detected at De Luz Creek, Fallbrook Creek, French Creek, Horno Canyon, Newton Canyon, Piedra de Lumbre Canyon, Roblar Creek, San Mateo Creek, or Windmill Canyon. Transients occurred in a range of habitat types including mixed willow (Salix spp.) riparian, riparian scrub, and willow-sycamore (Platanus racemosa) dominated riparian vegetation. Exotic vegetation including poison hemlock (Conium maculatum) and black mustard (Brassica nigra) was present in the majority of flycatcher locations.
Number of pages: 116
Authors: Howell, Scarlett L.; Lynn, Suellen; Kus, Barbara;
Year: 2018
Purpose: The purpose of this study was to document the status of Southwestern Willow Flycatchers at Marine Corps Base Camp Pendleton (MCBCP or “Base”) in San Diego County, California. Specifically, our goals were to (1) determine the size and composition of the Willow Flycatcher population at the Base, (2) document survivorship and movement of resident flycatchers, (3) document nesting activities, and (4) characterize habitat used by flycatchers. Two additional tasks were undertaken in 2018; (1) evaluate the use of conspecific playback to attract breeding Willow Flycatchers to historically occupied habitat to facilitate recolonization, and (2) collect vegetation data to determine if there were differences in the 2018 habitat structure and composition when compared with historically occupied habitats and to use as a baseline for determining the efficacy of habitat enhancement in the future. These data, when combined with data from other years, will inform natural resource managers about the status of this endangered species at Camp Pendleton, and guide modification of land use and management practices as appropriate to ensure the species’ continued existence.
Prepared for: Assistant Chief of Staff, Environmental Security U.S. Marine Corps Base Camp Pendleton;
Keywords: cowbird; cowbird parasitism; habitat loss;
Species: Southwestern willow flycatcher
Vegetation communities: riparian forest & scrub
Threats: Parasitism/disease