SHARED WATER RESOURCES: REVIEW OF CO-OPERATIVE ACTION IN LATIN AMERICA

Present disputes between Bangladesh and India, Iraq and Syria, and Argentina and Brazil, to give only a few examples, have made headlines and brought world-wide attention to the difficult problem of management of fresh water resources shared by two or more countries. Through an in-depth analysis of the Latin American experience from the earliest bilateral treaties and continental conventions to existing multilateral agreements and up to the 1977 United Nations Water Conference in Argentina, Mr. Souto-Maior provides some insight into the factors which have led to successful negotiations and guidance to improve the management of international rivers and lakes.     

An Adaptive‐Management Framework for Optimal Control of Hiking Near Golden Eagle Nests in Denali National Park

Abstract: Unintended effects of recreational activities in protected areas are of growing concern. We used an adaptive‐management framework to develop guidelines for optimally managing hiking activities to maintain desired levels of territory occupancy and reproductive success of Golden Eagles (Aquila chrysaetos) in Denali National Park (Alaska, U.S.A.). The management decision was to restrict human access (hikers) to particular nesting territories to reduce disturbance. The management objective was to minimize restrictions on hikers while maintaining reproductive performance of eagles above some specified level. We based our decision analysis on predictive models of site occupancy of eagles developed using a combination of expert opinion and data collected from 93 eagle territories over 20 years. The best predictive model showed that restricting human access to eagle territories had little effect on occupancy dynamics. However, when considering important sources of uncertainty in the models, including environmental stochasticity, imperfect detection of hares on which eagles prey, and model uncertainty, restricting access of territories to hikers improved eagle reproduction substantially. An adaptive management framework such as ours may help reduce uncertainty of the effects of hiking activities on Golden Eagles.     

Founding Lineages and Genic Variability in Plains Bison (Bison bison) from Badlands National Park, South Dakota

Abstract: Starch-gel electrophoresis was used to screen 101 bison from Badlands National Park, South Dakota, for variation at 24 genetic loci. The population was descended from founder groups of about 6 and 3 individuals, separated geographically for a minimum of 64 years. The purpose of this study was (1) to estimate levels of genic variability in this bison population, (2) to assess the extent to which descendents of the two founder groups differ genetically, and (3) to compare the genetic characteristics of the Badlands population with other bison populations. The Badlands herd was found to be polymorphic for only a single locus (MDH–1). Descendents of the founder groups were homogeneous with respect to allelic and genotypic frequencies at this locus. The MDH–1 polymorphism has not been observed in other bison populations, while several polymorphism reported in other bison populations were not detected in the Badlands herd. A mean heterozygosity of 0.012 was observed in the Badlands herd; this value is lower than that typically reported for mammals, though not as low as heterozygosities seen in other populations that have passed through severe bottlenecks in size. These results underscore the need for genetic data in planning breeding programs for species in captivity or managed in isolate reserves.     

Effects of Agricultural, Industrial, and Recreational Expansion on Frequency of Wildlife Law Violations in the Central Rocky Mountains, USA

Abstract: As human populations expand into previously unoccupied habitats, conflicts with wild vertebrate species are inevitable. On the basis of literature concerning human attitudes toward nature, we hypothesized that the intensity of conflicts and impacts would vary with the type of land use expansion. We tested our hypothesis by examining data on socioeconomic profiles of discrete expanding human populations in relation to the frequency of wildlife law violations in the central Rocky Mountains of the United States. We estimated possible human-related effects by comparing rates of wildlife law violations among populations varying in growth rates and socioeconomic status over an eleven-year period 1969–1980. We found that agrarian-based population centers had fewer violations per capita than areas with industrial-based (petroleum development) boom towns. Recreation-oriented (ski) boom towns had the lowest number of violations during periods of the most rapid growth. While the relationship between wildlife law violations and actual impact on animal population sizes remains unknown, our findings underscore the necessity of a priori recognition and planning by government and private agencies to combat potential harmful effects when expanding human population centers are likely to be characterized by immigrants with a low regard for wild species.     

Persistence of Different-sized Populations: An Empirical Assessment of Rapid Extinctions in Bighorn Sheep

Abstract: Theory and simulation models suggest that small populations are more susceptible to extinction than large populations, yet assessment of this idea has been hampered by lack of an empirical base. I address the problem by asking how long different-sized populations persist and present demographic and weather data spanning up to 70 years for 122 bighorn sheep ( Ovis canadensis ) populations in southwestern North America Analyses reveal that: (1) 100 percent of the populations with fewer than 50 individuals went extinct within 50 years; (2) populations with greater than 100 individuals persisted for up to 70 years; and (3) the rapid loss of populations was not likely to be caused by food shortages, severe weather, predation, or interspecific competition These data suggest that population size is a marker of persistence trajectories and they indicate that local extinction cannot be overcome because 50 individuals, even in the short term, are not a minimum viable population size for bighorn sheep.     

Estimation of Body‐Size Traits by Photogrammetry in Large Mammals to Inform Conservation

Abstract: Photography, including remote imagery and camera traps, has contributed substantially to conservation. However, the potential to use photography to understand demography and inform policy is limited. To have practical value, remote assessments must be reasonably accurate and widely deployable. Prior efforts to develop noninvasive methods of estimating trait size have been motivated by a desire to answer evolutionary questions, measure physiological growth, or, in the case of illegal trade, assess economics of horn sizes; but rarely have such methods been directed at conservation. Here I demonstrate a simple, noninvasive photographic technique and address how knowledge of values of individual‐specific metrics bears on conservation policy. I used 10 years of data on juvenile moose (Alces alces) to examine whether body size and probability of survival are positively correlated in cold climates. I investigated whether the presence of mothers improved juvenile survival. The posited latter relation is relevant to policy because harvest of adult females has been permitted in some Canadian and American jurisdictions under the assumption that probability of survival of young is independent of maternal presence. The accuracy of estimates of head sizes made from photographs exceeded 98%. The estimates revealed that overwinter juvenile survival had no relation to the juvenile's estimated mass (p < 0.64) and was more strongly associated with maternal presence (p < 0.02) than winter snow depth (p < 0.18). These findings highlight the effects on survival of a social dynamic (the mother‐young association) rather than body size and suggest a change in harvest policy will increase survival. Furthermore, photographic imaging of growth of individual juvenile muskoxen (Ovibos moschatus) over 3 Arctic winters revealed annual variability in size, which supports the idea that noninvasive monitoring may allow one to detect how some environmental conditions ultimately affect body growth.