Maximizing detection probability of wetland-dependent birds during point-count surveys in northwestern Florida

Influence of season and time of day on marsh bird detections

“…We conducted surveys during consecutive survey periods (morning-evening or eveningmorning) to minimize any daily variation in detections of birds (Nadeau et al 2008), and the order in which we conducted morning and evening surveys was varied so that one survey was not always conducted prior to the other (Conway et al 2004 (Conway 2007(Conway , 2011 and the late season included the 1-month period after established survey windows during which we hypothesized birds were still vocal. This allowed us to compare the number of marsh bird detections between surveys conducted during the established survey windows and after the established survey windows.…”

“…A single study found that vocalization probabilities of marsh birds are greater during morning surveys (Nadeau et al 2008); other studies have shown that such probabilities are greater during evening surveys Dinsmore 1986, Conway et al 2004). Environmental factors such as temperature, wind speed, and cloud cover may vary with time of day, potentially affecting the vocalization frequency of marsh birds (Nadeau et al 2008).…”

“…A single study found that vocalization probabilities of marsh birds are greater during morning surveys (Nadeau et al 2008); other studies have shown that such probabilities are greater during evening surveys Dinsmore 1986, Conway et al 2004). Environmental factors such as temperature, wind speed, and cloud cover may vary with time of day, potentially affecting the vocalization frequency of marsh birds (Nadeau et al 2008). Vocalization frequencies may vary with time of day at both the individual or species level because of behavioral variation of individual birds, differences in species-specific preferences in timing of calling, and individual breeding status (Conway et al 1993, Palmeirim andRabaça 1994).…”

“…Call-broadcast surveys have been implemented in several studies to elicit responses from marsh birds (Johnson and Dinsmore 1986, Manci and Rusch 1988, Gibbs and Melvin 1993, Lor and Malecki 2002 and produce higher detection rates when compared to passive surveys (Gibbs and Melvin 1993, Erwin et al 2002, Allen et al 2004, Conway and Gibbs 2005, DesRochers et al 2008. However, the effectiveness of callbroadcast surveys can vary temporally (Conway and Gibbs 2001, Rehm and Baldassarre 2007, Nadeau et al 2008 and by species (Manci and Rusch 1988, Gibbs and Melvin 1993, Lor and Malecki 2002, Soehren et al 2009). There is a need for additional information on seasonal variation in detection rates and whether detections vary between morning and evening.…”

Virginia and Yellow Rail autumn migration ecology: synthesis using multiple data sets

“…An understanding of rails' habitat selection during migration, including when they use those habitats, is needed before conservation and management efforts can be successful. However, rails' secretive behavior, including cryptic coloration, time spent in dense vegetation, rare daytime flight and infrequent vocalizations, makes them challenging to survey [8][9]. As a result, combining multiple data sources could provide us with a better assessment of the migratory phenology of rails [10].…”