Influence of tidal height on detection of breeding marsh birds along the northern gulf of Mexico

We studied variation in detection probabilities of several marsh bird species during the breeding season in relation to tidal height (i.e., water level) within several tidal marshes of the northern Gulf of Mexico. Specifically, we examined the influence of tidal height on our ability to detect Clapper Rail (Rallus longirostris), Seaside Sparrow (Ammodramus maritimus), Marsh Wren (Cistothorus palustris), Purple Gallinule (Porphyrio martinica), and Common Moorhen (Gallinula chloropus). Detection of Clapper Rails and Seaside Sparrows increased relative to tidal height while detection of Marsh Wrens decreased. Our results suggest that tidal height influences detection of specific marsh bird species, although these effects may differ geographically. We advocate including collection of tidal height information as a part of the survey protocol for effective monitoring of marsh bird populations. Received 21 July 2008. Accepted 27 November 2008.