Bighorn sheep have captivated human interest since the earliest recorded time. Throughout the west, thousands of bighorn are depicted on cliff faces. More than any other North American mammal, the bighorn sheep symbolizes remote and wild places. They occupy the most inaccessible, rugged, and spectacular mountain ranges on the continent. Yet despite this allure, bighorn sheep management and research is relatively new when compared to other big game animals in North America, and many fundamental questions remain unanswered.
The State of Arizona first afforded legal protection for the bighorn sheep in 1913 with enactment of the Arizona State Game code. Despite this protection, bighorn sheep numbers continued to decline during the early part of the century. In partial response, the Kofa Game Range was established in 1939 by Executive Order 8039 “for the conservation and development of natural wildlife resources, and for the protection of public grazing lands and natural forage resource.” Bighorn sheep were a driving factor in the establishment of the refuge, and much of the refuge management focuses on maintaining the sheep population.
Administrative responsibility for the Kofa was shared by the U.S. Fish and Wildlife Service (FWS) and the U.S. Grazing Service until 1946. At that time the game range came under joint management of the FWS and the U.S. Bureau of Land Management (BLM). With Public Law 94-223 in 1976, the refuge came under sole control of the FWS. After passage of the Arizona Desert Wilderness Act of 1990, parts of the refuge became designated wilderness. That act and the Wilderness Act of 1964 provide general legal guidance for wilderness portions of the refuge. About 547,719 acres (856 square miles) of the refuge’s total 664,327 acres (1,038 square miles) are designated wilderness. The Service has 5 objectives for designated wilderness management:
- Manage so as to maintain the wilderness resource for future benefit and enjoyment;
- Preserve the wilderness character of the biological and physical features of the area;
- Provide opportunities for research, solitude, and primitive recreational uses;
- Retain the same level of pre-wilderness designation condition of the area; and
- Ensure that the work of man remain substantially unnoticeable
The FWS and the BLM jointly developed the Kofa Refuge and Wilderness and New Water Mountains Wilderness Interagency Management Plan in 1996 to provide long term management guidance for the two areas. The plan was cooperatively developed and reviewed by a number of diverse public entities and government agencies, including the Arizona Game and Fish Department, and is the primary guide for managing the lands (including wilderness) within the Kofa NWR.
The AGFD acting under authority of the Arizona Game and Fish Commission, and Arizona Revised Statutes Title 17, has trust responsibilities for the protection and management of all wildlife in the state. The FWS, under the National Wildlife Refuge Administration Act of 1966 (as amended) and the National Wildlife Refuge Improvement Act of 1997, administers lands and waters in the National Wildlife Refuge System for the conservation, management, and restoration of fish, wildlife and plant resources and their habitats. For wildlife resources on National Wildlife Refuges within the State of Arizona, the FWS and the AGFD have always considered themselves as cooperative wildlife managers. The AGFD began pioneering and improving techniques to survey, trap and transplant bighorn sheep, and improve water availability and distribution for desert bighorn sheep in the 1950s.
Public hunting was prohibited on Kofa NWR until 1956 when the refuge was opened to mule deer hunting. The first desert bighorn sheep hunt followed in 1960. Although no specific population goal has been set for the bighorn herd, the long-term population estimate since 1981 has been approximately 800, and this is considered the carrying capacity of the refuge. A minimum population size of 800 in the refuge has been one of the factors considered when planning sheep capture and transplant efforts.
The current method of systematically surveying the entire refuge (Game Management Units 45A, B, and C – not including the New Water Mountains, which are surveyed with their respective hunt unit, 44B) by helicopter triennially was initiated in 1992. The Kofa and Castle Dome mountains are divided into blocks using geographic features in order to standardize areas flown and level of effort in each area. Sheep populations are estimated using the “Kofa Group Size Estimator” developed by Hervert et al. (1998).
Kofa Annual Narratives from 1955-1978 seem to suggest that the bighorn population may have ranged between 200-375 animals during that time period. This data is considered suspect since it pre-dates the implementation of systematic aerial surveys and the application of a tested, standardized population estimate methodology for this subspecies in this habitat.