DOI: 10.5061/dryad.6q5k86q
title: Data from: Waterbird response to variable-timing of drawdown in rice fields after winter-flooding

description: Wetland loss and degradation have been extensive across the world,
 especially in California's Central Valley where over 90% of the
 natural wetlands have been converted to agricultural and urban uses. In
 the Central Valley today, a much smaller network of managed wetlands and
 flooded agricultural fields supports almost five million waterfowl and
 half a million shorebirds. Over 50% of waterbird habitat in the Central
 Valley is provided by flooded agricultural land, primarily rice (Oryza
 sativa). Each year non-breeding waterbird habitat decreases in the late
 winter as flooded agricultural fields are drained after waterfowl hunting
 season in late-January to prepare for the next crop. This study evaluated
 a practice called 'variable drawdown' that involves delaying the
 removal of water from rice fields by 1, 2, and 3 weeks to extend the
 availability of flooded habitat later into February and March. We studied
 waterbird response to variable drawdown in 2012 and 2013 at twenty rice
 farms throughout the northern half of the Central Valley. The staggered
 drawdown created a mosaic of water depths throughout the six-week study
 period. The 3-week delay in drawdown supported more dabbling ducks than
 earlier drawdowns in the first half of the study and more shorebirds and
 long-legged wading birds during the second half of the study. The timing
 of highest use of each drawdown treatment differed for each waterbird
 guild; dabbling ducks, geese and swans benefited at the beginning, then
 long-legged wading birds, followed by shorebirds. Despite the presence of
 appropriate water depths for shorebirds across the treatments during the
 entire study period, shorebird densities were highest near the end of the
 study when the 3-week-delayed drawdown was providing the majority of the
 habitat on the landscape. This suggests that shorebirds may have
 concentrated in our study fields due to decreasing availability of shallow
 water habitat elsewhere. The practice of variable drawdown successfully
 extended the availability of waterbird habitat provided by post-harvest
 flooded rice fields later into winter.
description: Raw bird count data from
 waterbird surveys conducted in rice fields of the Sacramento Valley,
 California.These data were
 collected from waterbird surveys conducted in rice fields in the
 Sacramento Valley in February-March 2012 and 2013 to evaluate the
 effectiveness of a practice called variable drawdown. Columns A-J relate
 to information about the waterbird survey itself such as date, time,
 observer, and unique id for survey areas (sitecode-yr). Columns K-U relate
 to information about the site conditions present during each survey such
 as proportion dry/moist/or flooded, height of stubble/vegetation, and
 general survey notes. Columns V-AA relate to information about the survey
 area such as area (hectare), treatment, and farm. Column AB relates to
 whether the survey area was removed from the analysis as described in the
 paper (1=Yes). Columns AC-AG are the waterbirds counted during each survey
 and the group (guild) they were analyzed with.Sesser_etal_variable_drawdown_full_dataset.csv