Artificial Cavities and Nest Site Selection by Puerto Rican Parrots: a Multiscale Assessment

We examined nest site selection by Puerto Rican Parrots, a secondary cavity nester, at several spatial scales using the nest entrance as the central focal point relative to 20 habitat and spatial variables. The Puerto Rican Parrot is unique in that, since 2001, all known nesting in the wild has occurred in artificial cavities, which also provided us with an opportunity to evaluate nest site selection without confounding effects of the actual nest cavity characteristics. Because of the data limitations imposed by the small population size of this critically endangered endemic species, we employed a distribution-free statistical simulation approach to assess site selection relative to characteristics of used and unused nesting sites. Nest sites selected by Puerto Rican Parrots were characterized by greater horizontal and vertical visibility from the nest entrance, greater density of mature sierra palms, and a more westerly and leeward orientation of nest entrances than unused sites. Our results suggest that nest site selection in this species is an adaptive response to predation pressure, to which the parrots respond by selecting nest sites offering advantages in predator detection and avoidance at all stages of the nesting cycle. We conclude that identifying and replicating the “nest gestalt” of successful nesting sites may facilitate conservation efforts for this and other endangered avian species.

Database Engines for Geographical Information Systems

Our ability to identify, acquire, store, enquire on and analyse data is increasing as never before, especially in the GIS field. Technologies are becoming available to manage a wider variety of data and to make intelligent inferences on that data. The mainstream arrival of large-scale database engines is not far away. The experience of using the first such products tells us that they will radically change data management in the GIS field.

The European Declarative System, Database, and Languages

The EP2025 EDS project develops a highly parallel information server that supports established high-value interfaces. We describe the motivation for the project, the architecture of the system, and the design and application of its database and language subsystems. The Elipsys logic programming language, its advanced applications, EDS Lisp, and the Metal machine translation system are examined.

The magma budget of Volcan Arenal, Costa Rica from 1980 to 2004

Using topographic data collected by radar interferometry, stereo-photogrammetry, and field survey we have measured the changing surface of Volcan Arenal in Costa Rica over the period from 1980 to 2004. During this time this young volcano has mainly effused basaltic andesite lava, continuing the activity that began in 1968. Explosive products form only a few percent of the volumetric output. We have calculated digital elevation models for the years 1961, 1988 and 1997 and modified existing models for 2000 and 2004. From these we have estimated the volume of lava effused and coupled this with the data presented by an earlier study for 1968-1980. We find that a dense rock equivalent volume of 551 M m(3) was effused from 1968 to 2004. The dense rock equivalent effusion rate fell from about 2 m(3) s(-1) to about 0.1-0.2 m(3) s(-1) over the same period, with an average rate of about 0.5 m(3) s(-1). Between 1980 and 2004, the average effusion rate was 0.36 m(3) s(-1), a similar rate to that measured between 1974 and 1980. There have been two significant deviations from this long-term rate. The effusion rate increased from 1984 to 1991, at the same time as explosivity increased. After a period of moderate effusion rates in the 1990s, the rate fell to lower levels around 1999. (c) 2006 Elsevier B.V. All rights reserved.