This protocol (Conway 2009) is designed to be used in surveys of secretive marsh birds (rails, bitterns, coots, grebes, and moorhens). It employs playback of target species’ vocalizations to increase their detectability. The protocol makes recommendations as to time of day and season during which to survey, frequency of surveys, placement of survey points, and equipment to be used. Data collection includes distance to bird, which can improve density estimation, type of call detected, as well as period of detection, which can be used to calculate components of detection probability. The protocol also includes the collection of coarse vegetation data. Data are stored in a centralized online database managed by the USGS Patuxent Wildlife Research Center, in cooperation with the University of Idaho and the USFWS Office of Migratory Birds.
The protocol has been field-tested for its efficacy in increasing detection probability of target species using broadcasts of calls compared to passive surveys; its effect of broadcasting calls of multiple marsh birds on the vocalization probability of each target species; and the calculation of observer bias associated with passive and call-broadcast surveys. The protocol is flexible in allowing for customization of broadcast contents, such that vocalizations of target species can be added or subtracted based on local species assemblage. The use of an online database maintains data quality (reduces entry errors) and ensures that data collected through the protocol can be stored, managed and analyzed in a centralized location which ensures that the data collected is easily available to analysts and managers in perpetuity
Preliminary results indicate that the effectiveness of call-broadcasting on increasing detections of target species is less pronounced for Least Bittern and American Bittern than it is for other species (Conway and Nadeau 2010).
Examples of use
The protocol has enjoyed widespread use in recent years, including its adoption by various USFWS National Wildlife Refuges in their marsh bird monitoring projects. This protocol is also being piloted in several states throughout the US (e.g., New York, Wisconsin, Michigan, Ohio, Idaho, and Florida) to inform development of a National Marsh Bird Monitoring Program, to inform harvest regulations of hunted species and to determine status of and evaluate conservation effectiveness for secretive marsh birds.
For more information
Conway, C. J. 2009. Standardized North American Marsh Bird Monitoring Protocols, version 2009-2. Wildlife Research Report #2009-02. U.S. Geological Survey, Arizona Cooperative Fish and Wildlife Research Unit, Tucson, AZ.
Conway, C. J., and C. P. Nadeau. 2010. Effects
of broadcasting conspecific and heterospecific calls on detection of marsh
birds in North America. Wetlands 30(2):358-368.
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