Wild and Free-Roaming Horses and Burros Current Knowledge and Recommended Research. (1980) / Chapter Skim
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EXECUTIVE SUMMARY
Pages 1-12
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Modern wild horses and asses were reintroduced into North America by the Spaniards in the late l5th century. Some observers believe that the vegetation in the West was vulnerable to the introduction of domestic herbivores because it had experienced little grazing pressure since the late Pleistocene period.
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Ossabaw Island animals exhibit the reverse of these patterns. The basic social organization among wild horses is that of a family group with a dominant male, subdominant males, and females and their young, but some variations on this pattern occur, as do exchanges between groups.
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In contrast, two authors have projected increase rates with population models that incorporate birth and death rates similar to those published for several herds, and concluded that annual herd increase rates well below l0 percent are probable. Similar calculations with life tables in this report indicate that l5 to 20 percent increase rates can only occur in populations with geometric age distributions with (a)
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From page 4... ...
This dietary preference coincides closely with that of cattle, and overlaps to some degree and in some seasons with those of elk, bighorn sheep, bison, and pronghorn antelope. Most dietary studies have not related animal data to vegetation composition, nor have they described spatial and habitat overlap with sympatric ungulates or lack thereof.
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Recommended Research Seven research projects on the biology of horses and burros are recommended: • Project l: Habitat Preference and Use • Project 2: Food Consumption Rates and Nutrition • Project 3: Nutritional Plane, Condition Measures, and Reproductive Performance • Project 4: Blood Assays • Project 5: Demography • Project 6: Social Structure, Feeding Ecology, and Population Dynamics
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A study in the Lake Mead National Recreation Area, however, revealed no major impacts. Little controlled research has been done on impacts of grazing horses; the extensive management of horse range apparently proceeds largely from management-level inventories, experience, and j udgment.
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Overgrazing reduces vegetation mulch, increases the proportion of bare ground and rock cover, increases soil bulk density, and reduces moisture infiltration rates. Heavy grazing increases the sediment load of watershed runoff, an effect caused mostly by vegetative reduction, but also partly by trampling.
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From page 8... ...
evaluation of the costs of existing legal regulations and restrictions. The legal-political literature on wild horse and burro matters is extensive, particularly in terms of providing a perspective on the public agencies' overall land-management responsibilities -- the context in which policies concerning wild horses and burros should be considered.
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From page 9... ...
They will provide a base of socioeconomic and political data that will facilitate decision making in equid management. The projects are organized into three groups in descending priority in terms of importance of information and urgency of funding: Group l includes: • Project llA: Taxonomy of Values and Benefits • Project l3: Management Costs of Alternatives • Project l4: Economic Considerations for Management Alternatives Drawn from Proposed Research Programs Group 2 includes: Project llB: Public Preferences for Alternative Management and Control Strategies • Project l2: Analysis and Evaluation of Demands for Excess Wild Equids • Project l5: Nonmarket Values Group 3 includes Groups l and 2 and adds the following investigations to provide socioeconomic data necessary to a systems-level understanding of wild-equid management: • Project llC: Public Attitudes, Preferences, and Knowledge • Project l6: Conceptual Development of Public Rangeland Management Models
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From page 10... ...
Indices do not appear to have much potential in equid census, because they do not provide the estimates of actual numbers needed for forage allocation unless calibrated to total numbers. Current agency census efforts attempt complete counts from the air.
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The technique needs to be researched, however, initially in captive animals. Chemical immobilization is not deemed an efficient primary capture technique for wild horses, but it can be used to quiet captured animals for purposes of research and handling.
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From page 12... ...
l2 Project l7 should investigate the validity of two or three alternative census techniques, including "complete" counts. The project should begin with a pilot effort on horses, later extended to burros.
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