Occupancy Model for Wintering Meadowlarks as a Proxy for Yellow Rails in Southeastern Oklahoma

Abstract

Yellow Rails (Coturnicops noveboracensis) are a secretive rail species that winter in marshes along the Eastern and Gulf Coasts of the United States. In 2008, a wintering population of Yellow Rails was discovered in the damp grasslands of Red Slough WMA in southeastern Oklahoma. Due to their reticent, nocturnal nature, Yellow Rails are difficult to survey. However, we have noticed that Eastern Meadowlarks (Sturnella magna) often co-occur in fields with Yellow Rails. We hypothesized that Eastern Meadowlarks may act as an indicator species for the presence of Yellow Rail. We conducted monthly surveys in fields at Red Slough WMA and Sequoyah NWR survey sites beginning in October. We surveyed the units by slowly dragging a rope with noise-making bottles across the field, flushing out species of interest. We recorded each Yellow Rail and meadowlark flushed, and then conducted an occupancy model with the survey data using Program R. We found that Eastern Meadowlarks were present in more fields than Yellow Rails, with Eastern Meadowlarks occupying 0.751 ± 0.217 of the fields surveyed, while Yellow Rails occupied 0.526 ± 0.268 of the fields surveyed. There was only a weak correlation (phi = 0.13) with observations of Eastern Meadowlarks and Yellow Rails. This indicates that Eastern Meadowlarks may not necessarily be the best choice as an indicator species for the presence of Yellow Rails.