Wading Bird Food Availability in Rice Fields and Crawfish Ponds of the Chenier Plain of Southwest Louisiana and Southeast Texas

Abstract

Wading birds in southwestern Louisiana and southeastern Texas rely heavily on rice fields and crawfish ponds as foraging areas; however, little information exists on food availability throughout the annual crop cycle. The objectives of this study are: 1) Develop a classification for rice and crawfish fields based upon tillage, forage crop (for crawfish fields), water depths, vegetation density, vegetation height, and other visible parameters; 2) Quantify the distribution of rice and crawfish fields in various stages across the landscape through time; 3) Determine the effects of rice and crawfish field types and landscape characteristics on wading bird use; and, 4) Evaluate the relationships among field classification, habitat characteristics, and invertebrate densities (including crawfish) in selected field types through time. To address these objectives, I used stratified-random sampling to select 50 1.6 km long road transects in 7 parishes and 3 counties of the major rice/crawfish producing parishes/counties in southwestern Louisiana and southeastern Texas. From April 2013 – April 2014 I conducted monthly surveys along the transects to assess rice/crawfish habitat conditions, as well as conduct waterbird surveys. From May 2013 until February 2014 I conducted quarterly macroinvertebrate and nekton sampling of selected fields in the region. The results of the study demonstrate the intra-annual variability in resources available to waterbirds and other wetland dependent wildlife throughout the coastal prairie region. Rice agriculture as a percentage of surveyed land use varied from 0-30%. Crawfish agriculture varied in a 12-month period from 0-15% of lands surveyed. Crop type, irrigation and tillage were the factors that contributed most to macroinvertebrate abundance and biomass. Waterbird use of fields was not randomly distributed. Irrigation, seeding method and tillage all seemed to contribute to waterbird use of fields surveyed in the region.