FERAL HORSES IN COYOTE CANYON

• Sponsoring Institution: Cooperating Schools of Veterinary Medicine
• Project Status: TERMINATED
• Funding Source: STATE
• Reporting Frequency: Annual
• Accession No.: 0194654
• Project No.: CALV-CDPR01-C0143059
• Project Start Date: Feb 22, 2002
• Project End Date: Dec 31, 2003

Project Director
Boyce, W. M.

Recipient Organization
UNIV OF CALIFORNIA (VET-MED)
(N/A)
DAVIS,CA 95616

Performing Department
PATHOLOGY, MICROBIOLOGY & IMMUNOLOGY

Non Technical Summary
An unknown number of feral horses occupy portions of Coyote Canyon and frequent the riparian areas along Coyote Canyon Creek in Anza-Borrego Desert State Park in California. This project will provide information to assist the California State Parks in managing the feral hourses and their impact on endangered secies including bighorn sheep and least Bell's vireo, as well as water quality, riparian plant communities and an extensive complex of archeological sites.

Animal Health Component

100%

Research Effort Categories

Basic

(N/A)

Applied

100%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
135	0850	1070	10%
135	0860	1070	10%
135	0899	1070	10%
135	3810	1070	20%
315	0850	1070	10%
315	0860	1070	10%
315	0899	1070	10%
315	3810	1070	20%

Knowledge Area
135 - Aquatic and Terrestrial Wildlife; 315 - Animal Welfare/Well-Being and Protection;

Subject Of Investigation
0850 - Wildlife habitats; 0860 - Endangered species; 3810 - Horses, ponies, and mules; 0899 - Wildlife and natural fisheries, general/other;

Field Of Science
1070 - Ecology;

Keywords

bighorn sheep

water quality

horses

feral animals

amphibia

reproduction

state parks

wildlife

wildlife habitats

endangered species

wildlife ecology

well being

wildlife management

land management

environmental impact

spatial distribution

temporal distribution

global positioning system

water supply

summer

riparian sites

archeology

decision making

recommendations

wild birds

nesting

success

streams

plant communities

Goals / Objectives
This research project focuses on the collection and analysis of data regarding feral horses. This information will assist California State Parks in managing Coyote Canyon in Anza Borrego Desert State Park.

Project Methods
1. Compile and summarize existing information regarding feral horses and their potential impacts in the canyon, 2. Evaluate the spatial and temporal relationships of feral horses to bighorn sheep over a 2-year period using GPS radiocollars and actual field observations, 3. Document and characterize interactions that occur between feral horses and bighorn sheep during summer period at watering sites in the canyon, 4. Assess the ecological effects of excluding horses from selected riparian areas along the creek, 5. Evaluate the spatial relationships and impacts of feral horses on archeological sites in the canyon. 6. Formulate management recommendations regarding feral horses. 7. Summarize information gathered during the study period which may include research on the effects of feral horses on amphibian reproduction, water quality, least Bells's vireo nesting success, archeological site impacts and riparian vegetation in Coyote Creek at Upper Willows.

Progress 02/22/02 to 12/31/03

Outputs
There was clear overlap in habitats used by bighorn sheep and feral horses, particularly near water, but both species were rarely seen using the same areas at the same time. A controlled experiment which placed 2-3 domestic horses at a frequently used bighorn watering site revealed that bighorn would water elsewhere if horses were present. This indicated indirect interference competition. Genetic analysis of 13 microsatellite loci revealed moderate levels of genetic variability and there was no indication of inbreeding in the horses. Anecdotal accounts of historic numbers of feral horses in Coyote Canyon have put the population between 20 and 40 animals. In 2002, 34 feral horses were counted in Coyote Canyon. Only 29 were counted in 2003. The feral horses were observed in poor physical condition during summer 2002 due to reduced forage brought on by drought. In March 2003, after the condition of the feral horses was evaluated by 2 equine veterinarians and 2 lay horse experts, State Parks made the decision to remove the feral horses from the canyon and transfer them to horse sanctuaries. A final report for this study was submitted to State Parks in January 2004 and manuscripts are being prepared for submission to peer reviewed scientific journals.

Impacts
Exotic species, such as feral horses, invariably impact the native species of an ecosystem as well as the overall health of an ecosystem. This study clearly demonstrated that feral horses caused bighorn sheep to alter their behavior and avoid certain areas.

Publications

• No publications reported this period

Progress 01/01/02 to 12/31/02

Outputs
Progress for the first six months of this period included designing, ordering, and testing GPS collars for horses, preliminary horse immobilization trials performed on horses at UCDavis, and design of the summer 2002 field work. The second six months of this period included three months of intensive field work collecting observational data on the feral horses in Coyote Canyon (Anza Borrego Desert State Park), followed by computer data entry and data analyis. The 2003 spring and summer field work program was also being developed.

Impacts
The overall objective of the Feral Horse Study is to determine the impacts of feral horses on ecosystem health and native species in Coyote Canyon within Anza-Borrego Desert State Park. The California State Parks system is facing a controversial decision of whether or not to remove the feral horses (a non-native species) from the park. This study will provide critical information on whether the feral horses are negatively impacting the park's fragile ecosystem.

Publications

• No publications reported this period