Kaibab - A Search for Answers to Important Questions

by Pete Cimellaro

In March of 2004, the Arizona Deer Association (ADA) retained the environmental consulting firm of Logan Simpson Design, Inc. (LSD) to assist in identifying management alternatives for the Kaibab mule deer herd in game management unit (GMU) 12A.  

The Arizona Game and Fish Department (AGFD) recommended that the Commission approve the issuance of 1,500 doe tags in GMU 12AW for the 2004 fall hunt. AGFD based this recommendation on a segment of the Alternative Management Strategy for the Kaibab mule deer herd, which called for herd reduction when utilization of a browse food item, cliffrose, exceeded 50 percent on the critical winter range. Data from the AGFD browse transects indicated that cliffrose utilization levels were 50 percent to 70 percent in parts of the critical winter range. 

Members of the ADA questioned whether the deer herd was large enough to warrant a population reduction of this magnitude and hired LSD to review the data. LSD reviewed harvest statistics and forage use data from GMU 12AW and interviewed big game biologists in states adjoining Arizona. The interviews revealed that all of the surveyed states base hunt recommendations on population surveys rather than on forage utilization. A review of the AGFD harvest statistics showed that the number of bucks harvested in 12AW had declined substantially over the past 10 years. The buck harvest during the 1993-94 hunt was 744 and the buck harvest in 2003-2004 was 175. This buck harvest figure represented a 66 percent reduction in the number of bucks shot during the fall hunting seasons, while AGFD population estimates showed only a 15 percent reduction in deer numbers. 

Further research found that the numbers of bucks harvested were real numbers gathered at hunter check stations or from hunter questionnaires. The population estimates, however, were generated by the computer model. LSD hypothesized that the reduction in bucks harvested was a result of a smaller population and that the computer model had overestimated the size of the deer herd. LSD found that the current ratio-based model is self correcting and does not use real population survey numbers. This raised the question of whether management recommendations were based on paper deer or real deer. 

Analysis of forage utilization data found that deer proof exclosures were not in use and that plant productivity was not being measured. Without this data, there was no way to estimate the amount of available forage going into the winter. The current browse transect data measures the condition of the plant at the end of the winter season, but does not provide information on how the plant recovers during the growing season. LSD also found that the data suggesting cliffrose constitutes 30 percent to 50 percent of the diet was more than 30 years old. 

Based on this analysis, LSD concluded that the clip twig data on cliffrose simply was not substantial to justify recommending 1,500 doe tags for the fall 2004 hunt. LSD prepared a presentation for the April meeting of the Arizona Game and Fish Commission and recommended a reduction in the number of doe tags on the Kaibab. This presentation was followed by testimony from nearly two dozen ADA members all of whom also recommended a reduction in doe tags. After much discussion during the commission meeting, Joe Melton moved to reduce the number of doe tags to zero. That motion would have reduced the number of deer tags available to junior hunters below the 2 percent quota established by the Commission, so the motion was withdrawn. Comissioners Gilstrap and Golightly introduced a motion to set the 2004 mule deer doe tag quota at 500 and the motion passed unanimously. The Commission also provided direction to AGFD to work with ADA to resolve the issues surrounding doe hunts on the Kaibab. 

After the April Commission Meeting, LSD entered into a second contract with ADA to identify the issues associated with mule deer management on the Kaibab and negotiate a compromise solution with the AGFD on issues of concern to ADA. The second contract had three objectives: 1) develop an aerial population survey technique;  2) develop a forage monitoring technique that provides data on the entire diet over the entire winter range;  3) develop a revegetation plan for the portion of winter ranger burned by the Bridger Fire.  

LSD biologists conducted a field trip to the Kaibab the first week of June and were accompanied by members of the ADA Buckskin Chapter from Page and Fredonia. Observations from the field trip revealed that the area below 6,500 feet elevation was suitable for aerial population surveys of the winter range. Above 6,500 feet, the area was too steep and the trees to thick for aerial observation. LSD recommends a helicopter survey of the area between 6,500 feet and 5,000 feet in elevation with dual observers. 

Cliffrose on the ends of points showed 50 percent to 70 percent usage during the past winter; however, all the plants contained a large amount of fresh green growth. Plants in the remaining parts of the winter range showed 10 percent or less utilization. Clearly, the mule deer were eating the terminal buds from the branches of the cliffrose. When the terminal buds were nipped off, the plant responded by producing new shoots from the base of the twig around the terminal bud. With the absence of livestock and elk on the winter range, the plants have the potential to fully recover from the 50 percent to 70 percent utilization by deer. All research studies have shown that plants browsed during the winter dormant season can recover and produce available forage during the following growing season. To test this theory, LSD recommends the construction of deer proof exclosures to measure the amount of available forage produced by plants that are not grazed by deer during the winter. This data can be compared to the amount of available forage produced by plants that are grazed by deer during the winter.

 
Winter range cliffrose.  Note the cliffrose plants in the
foreground showing all stages of growth and little deer usage.

In 1996, the Bridger Fire burned approximately 52,000 acres, or half of the winter range. Some burned areas show recovery of sagebrush and cliffrose, but most of the burn has not revegetated with good quality browse. Much of the burned area is now dominated by cheat grass and scrub oak saplings. These types of plants are not good winter food items for mule deer. If the remainder of the winter range should become dominated by these two plants, essentially half of the winter range could be lost for a long time. LSD recommends working with the U.S. Forest Service to develop a revegetation plan that will restore cliffrose and sagebrush for use by mule deer on the winter range.  

Area of the Bridger Fire dominated by cheat grass and scrub oak.

LSD will be coordinating a workshop with ADA, AGFD, and the U.S. Forest Service to find methods to survey the winter population, evaluate available forage going into winter, and ways to revegetate the burned area with high quality winter food items for mule deer.

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