Background:
The headwaters of Cienega creek begin and flow north through the Las Cienegas National Conservation Area (LCNCA).  The LCNCA is an approximate 46,000 acre preserve, managed by the Bureau of Land Management, that contains an isolated riparian gallery forest (cottonwood/willow/ash) which is absent of beavers (Castor canadensis).  Historically, beavers were present almost anywhere the appropriate habitat conditions existed (e.g., permanent water and deciduous treevegetation).  Beavers were extirpated from most of their range within Arizona in the late 1800’s. 

The purpose of this project was to evaluate the suitability of habitat along Cienega Creek for harboring a viable population of beavers.  Information from this project was used to aid managers from both the Arizona Game and Fish Department and the Bureau of Land Management in deciding if re-establishing beavers into Cienega Creek is warranted. 
 
Location:
The LCNCA is located approximately 50 miles southeast of Tucson, Arizona.

Approach:
Habitat characteristics were measured along seven miles of upper and lower Cienega Creek.  We used a combination of belt and line-intercept transects to measures various vegetation characteristics including woody species composition, tree canopy closure, tree diameter, shrub crown closure, and shrub height.  Stream gradient and water level fluctuations were also evaluated using topographic maps and stream flow data. A Habitat Suitability Index (HSI) model, developed by the United States Fish and Wildlife Service, was used to evaluate suitability of habitat along Cienega Creek for beavers using collected data. 

Results:
Vegetative data were collected along 125 transects on upper and lower Cienega Creek from mid-June through early August 2008.  Mean tree canopy closure was greater than 50% whereas shrub crown closure was much lower at 11%.  Mean percentage of trees in the 2.5 – 15.2cm DBH size class varied from 47% to 63% and mean shrub height ranged from 1.4m to 1.9m along the lower and upper portions of Cienega Creek.  Majority of transects were dominated by Fremont cottonwood (Populus fremontii) and Goodding willow (Salix gooddingii).  Based on the HSI model, a total of seven stream reaches (800m in length) were identified along Cienega Creek as suitable for potential beaver reintroduction.  Final HSI values for the identified reaches ranged from 0.7 – 0.8 (maximum value = 1.0).  The Arizona Game and Fish Department and Bureau of Land Management anticipate working on a plan for trapping and releasing beaver along Cienega Creek soon. 

Benefits:
Re-establishing beavers into Cienega creek will benefit the riparian area in several ways.  The landscape modifications they perform, such as damming and pooling of water, will decrease bank erosion and down cutting of the stream channel.  Constructed dams will slow flood waters producing more stable stream flows beneficial to invertebrate and fish production.  Flooding, as a result of damming activities, will create additional habitat for the federally endangered Gila topmminow (Poeciliopsis occidentalis) and candidate species, Gila chub (Gila intermedia), which are present in Cienega creek.  Other wildlife (e.g., waterfowl, amphibians, reptiles) favoring ponds and marshes will also benefit.

For more information contact:

Angela Stingelin, Arizona Game and Fish Department
5000 W. Carefree Highway Phoenix, AZ 85086-5000.
Phone: (520) 742-1911            Email: astingelin@azgfd.gov

Michael Ingraldi, Ph.D., Arizona Game and Fish Department
5000 W. Carefree Highway Phoenix, AZ 85086-5000.
Phone: (928) 532-5625            E-mail: mingraldi@frontiernet.net