We define the concept of a common-pool resource based on two attributes: the difficulty of excluding beneficiaries and the subtractability of use. We present similarities and differences among common-pool resources in regard to their ecological and institutional significance. The design principles that characterize long-surviving, delicately balanced resource systems governed by local rules systems are presented, as is a synthesis of the research on factors affecting institutional change. More complex biological resources are a greater challenge to the design of sustainable institutions, but the same general principles appear to carry over to more complex systems. We present initial findings from pilot studies in Uganda related to the effects of institutions on forest conditions.

ABSTRACT. Meeting the desires of individuals while sustaining ecological "public goods" is a central challenge in natural resources conservation. Indigenous communities routinely make common property decisions balancing benefits to individuals with benefits to their communities. Such traditional knowledge offers insight for conservation. Using surveys and field observations, this case study examines aspects of indigenous institutions and ecological knowledge used by rural Ecuadorians to manage a forest commons before and after interacting with two U.S.-based conservation NGOs: Earthwatch Institute and People Allied for Nature. The rural farming community of Loma Alta has legal property rights to a 6842-ha watershed in western Ecuador. This selfgoverning community curtailed destruction of their moist forest commons, but not without the influence of modern scientific ecological knowledge. When Earthwatch Institute scientists provided evidence that forest clearing would reduce water supply to the community, villagers quickly modified land allocation patterns and set rules of use in the forest establishing the first community-owned forest reserve in western Ecuador. This case demonstrates that synergy between traditional knowledge and western knowledge can result in sustaining both ecosystem services and biodiversity in a forest commons.

Concerns about forest fragmentation and its conservation implications have motivated numerousstudies that investigate the influence of forest patch area and forest edge on songbird distribution patterns. The generalized effects of forest patch size and forest edge on animal distributions is still debatable because forest patch size and forest edge are often confounded and because of an incomplete synthesis of available data. To fill a portion of this gap, we incorporated all available published data (33 papers) in meta-analyses of forest edge and area effects on site occupancy patterns for 26 Neotropical migrant forest-nesting songbirds in eastern North America. All reported area effects are confounded or potentially confounded by edge effects, and we refer to these as "confounded" studies. The converse, however, is not true and most reported edge effects are independent of patch area. When considering only nonconfounded studies of edge effects, only 1 of 17 species showed significant edge avoidance and 3 had significant affinity for edges. In confounded studies, 12 of 22 species showed significant avoidance of small patches and edges, and 1 had an affinity for small patches and edges. Furthermore, average effect sizes averaged across studies or species tended to be higher for confounded studies than for edge studies. We discuss three possible reasons for differences in results between these two groups of studies. First, studies of edge effects tended to be carried out in landscapes with greater forest cover than studies of confounded effects; among confounded effects studies, as forest cover increased, we observed a nonsignificant trend towards decreasing strength of small patch or edge avoidance effects. Thus, the weaker effects in edge studies may be due to the fact that these studies were conducted in forest-dominated landscapes. Second, we may have detected strong effects only in confounded studies because area effects are much stronger than edge effects on bird occurrence, and area effects drive the results in confounded studies. Third, edge and area effects may interact in such a way that edge effects become more important as forest patch size decreases; thus, both edge and area effects are responsible for results in confounded studies. These three explanations cannot be adequately separated with existing data. Regardless, it is clear that fragmentation of forests into small patches is detrimental to many migrant songbird species. Efectos de Borde y deÁrea Sobre la Ocurrencia de Aves Canoras Migratorias Resumen: La preocupación sobre la fragmentación de bosques y sus implicaciones en conservación ha motivado numerosos estudios que investigan la influencia delárea de parches de bosque sobre los patrones de 1158 Area and Edge Effects on Forest Birds Parker et al. distribución de aves canoras. Los efectos generalizados del tamaño del parche y del borde de bosque sobre la distribución de animales aun son debatibles porque el tamaño y borde a menudo son confundidos y porque la síntesis de los datos disponibles ...

Monitoring of fog capture and bird communities helped to build social capital for conservation at Loma Alta, Ecuador and encouraged the local community to protect 3000 hectares of tropical forest. Data collected during monitoring were used to facilitate action and cooperation at local, regional, national, and international levels for conservation of biodiversity in western Ecuador, including the designation of an Important Bird Area in the region. Through involvement with the monitoring efforts, local people became more aware of the value of ecosystem services, learned about local birds and their conservation status, became familiar with ecotourism, and began to include conservation of biodiversity with sustainable development planning in their community. The context of monitoring, the objectives and participants, field methods, impacts in terms of conservation action, and the costs and benefits of the two monitoring initiatives are described.