Hidden Nightlife
May 15, 2015
Wintering shorebirds rest in flooded rice fields
Ever wonder where all those shorebirds in flooded rice fields go at night? Finding a safe place to rest each night may be harder than it sounds if you are a small migratory shorebird in the Sacramento Valley during winter.
Hundreds of thousands of shorebirds that nest in the Arctic migrate to the flooded rice fields and wetlands in the Sacramento Valley each winter and darkness comprises more than half of each day during most of their stay.
Researchers at Point Blue Conservation Science discovered that flooded rice fields are preferred by wintering shorebirds over man-made wetlands at night. To make this discovery, we attached small radio-tags to wintering Dunlin and tracked their locations within Colusa National Wildlife Refuge and nearby rice fields during the day and at night.
We found Dunlin used flooded rice fields at night exclusively from February until early March. By late March when most rice fields had dried, Dunlin were only found in refuge wetlands at night. Overall, the use of rice fields declined during both day and night from February to April and only a few radio-tagged Dunlin remained in the study area by early April.
This new information allows land managers to better understand the importance of flooded rice fields and wetlands, as well as how that changes from winter to spring when water is removed from rice fields in preparation for planting.
With increasing human demands for water and more extreme drought projected due to climate change, this research demonstrates the importance of maintaining both flooded rice fields and wetlands for migratory birds in the Sacramento Valley.
Innovative ways to maintain habitat for Dunlin are needed during March and April in the Sacramento Valley, as this is a critical time period in the annual cycle of migratory shorebirds when they must gain fat in preparation for migration and nesting.
Blake Barbaree is an avian habitat ecologist with Point Blue Conservation Science.
Main photo: Blake Barbaree
This story also appeared on the California Rice Commission‘s blog.