Marsh bird research on Imperial NWR and the Lower Colorado River: adaptive management in practice Christopher P. Nadeau, University of Arizona Courtney J. Conway, USGS AZ Cooperative Fish and Wildlife Research Unit

A glimpse at our studies Restoring managed marsh units to benefit California black rails 1. Managing rail habitat with fire 2. Estimating the detection probability of Yuma clapper rails 3. Determining the patch size requirements of Yuma clapper rails 4.

Restoring managed marsh units for California black rails Determine the habitat requirements of California black rails (and other marsh birds). Provide detailed recommendations on the hydrologic and vegetative requirements of black rails to inform management and restoration.

Study Sites on Imperial NWR 18 16

Water and Vegetation Monitoring

Learning from the BLRA detections in field 16 6 total BLRA detections 0 detections on 66% of our surveys

Where Have All the Black Rails Gone???

What do we know about Black Rail habitat???

-2 – 2 inches 2 – 4 inches 4 inches Water Depth Building Spatial Models to Determine Optimal Water Depth

high moderate low Fine-stem Bulrush Stem Density

= Building Spatial Models to Determine Optimal Water Depth high moderate low Habitat Suitability water depth stem density

4 inches Field 16: 20 Apr 09 BLRA Detections

2 inches Field 16: 24 Apr 09 BLRA Detections

0.1 inches Field 16: 6 Jul 09 BLRA Detections

water depth (in)percent suitable habitat staff gaugeminmaxavgmoderatehigh moderate + high %0%3% %3%32% %11%62% %31%78% %65%82% %59%72% %39%46% %2% Field 16: Optimal Water Depth Optimal Staff Gauge Depth = 2 – 5 in

water depth (in)percent suitable habitat staff gaugeminmaxavgmoderatehigh moderate + high %11%31% %18%41% %27%47% %26%44% %23%37% %19%28% %15%22% %12%16% Field 18: Optimal Water Depth Optimal Staff Gauge Depth = 4 – 7 in

Upcoming Work Work with Imperial NWR to maintain optimal water depths Modify models as vegetation changes in Field 18 and to model water depth variation Build more statistically based models as BLRA detections increase in field 16

* * * * * * LCR and Gila River Salton Sea NWR 900 Survey Points

Managing Rails With Prescribed Fire

clapper rail black rail Virginia rail sora least bittern CLRA numbers increased post fire All other species not affected by fire Detection probability did not differ between pre- and post-burn surveys

Estimating the Detection Probability of Yuma Clapper Rails tracked 14 clapper rails: 3 at Imperial NWR 11 at Salton Sea NWR conducted 84 detection trials detected focal bird on only 27% (23) of the trials

Determining the Patch Size Requirements of Yuma Clapper Rails Mapping emergent marsh patches throughout the LCR basin What is the minimum patch size a CLRA will use?

Marsh Bird Training Workshop 16 – 18 March 2010 Yuma, AZ to register

Jun 2008 Field 18: a restoration comes to life Sep 2009

What do we know about Black Rail habitat??? fine-stemmed bulrush (e.g. Olney threesquare) high stem density to provide overhead cover

5 inches 2 inches

Field 18 Water Fluctuations and Black Rail Detections

Field 18 Vegetation Composition

Field 16 Vegetation Composition

7 inches

Field 16 Water Fluctuations and Black Rail Detections