Comparative floorplan-analysis as a means to develop design guidelines

This study explores the usefulness of comparative floorplan-analysis for the development of spatio-organizational concepts in architectural design processes.Each floorplan can be considered as a reflection of the goals and activities of the users as interpreted by the architect. By comparing a wide range of building layouts for similar organizations one may achieve a good understanding of the way organizational characteristics are (can be) expressed in spatial solutions. In the study reported here, in which 50 Dutch health centres were analysed comparatively, definite relationships between organizational and spatial concepts were found. This information is used both as a means to make organizational principles more explicit as well as data for briefwriting and design guidelines.     

Applying the Declining Population Paradigm: Diagnosing Causes of Poor Reproduction in the Marbled Murrelet

Abstract:  We identified six approaches to diagnosing causes of population declines and illustrate the use of the most general one ("multiple competing hypotheses") to determine which of three candidate limiting factors—food availability, nesting site availability, and nest predation—were responsible for the exceptionally poor reproduction of Marbled Murrelets (  Brachyramphus marmoratus ) in central California. We predicted how six attributes of murrelet demography, behavior, and physiology should be affected by the candidate limiting factors and tested predictions with field data collected over 2 years. The average proportion of breeders, as estimated with radiotelemetry, was low (0.31) and varied significantly between years: 0.11 in 2000 and 0.50 in 2001. Murrelets spent significantly more time foraging in 2000 than in 2001, suggesting that low food availability limited breeding in 2000. In 2001, 50% of radio-marked murrelets nested and 67% of females were in breeding condition, suggesting that enough nest sites existed for much of the population to breed. However, rates of nest failure and nest predation were high (0.84 and 0.67–0.81, respectively) and few young were produced, even when a relatively high proportion of murrelets bred. Thus, we suggest that reproduction of Marbled Murrelets in central California is limited by food availability in some years and by nest predation in others, but apparently is not limited by availability of nesting sites. The multiple-competing-hypotheses approach provides a rigorous framework for identifying causes of population declines because it integrates multiple types of data sets and can incorporate elements of other commonly used approaches.     

Nestmate recognition in three species of stenogastrine wasps (Hymenoptera,Vespidae)

The capacity to recognise a conspecific intruder was investigated in Parischnogaster jacobsoni, Liostenogaster flavolineata and L. vechti, three species of primitively social wasps of the subfamily Stenogastrinae. Results of behavioural experiments carried out in the field showed that females of all three species react pacifically if presented with female nestmates, but aggressively reject an intruder from a conspecific colony. As L. flavolineata and L. vechti both build large clusters of nests, often very close to each other, the recognition capacity among females from different nests, but in the same conspecific cluster, was also investigated. Females of both species were more aggressive towards females from a different colony in the same cluster than towards their female nestmates. Additional experiments on L. flavolineata showed that there was no difference in reaction towards females from colonies nearer or further from the tested colony but within the same cluster, nor towards females from a different cluster. The capacity to recognise an alien conspecific nest containing immature brood was investigated in P. jacobsoni. Adult females of this species, invited to land on an alien nest which had experimentally been exchanged for their own, accepted the new nest and partially destroyed the immature brood. The behaviour of the females when they land on an alien nest, however, suggests that they do recognise the nest as foreign. Acceptance of foreign nests coupled with low immature brood destruction is probably due to the high energetic costs of egg-deposition and larval rearing in stenogastrine wasps. These results suggest that nestmate recognition in these wasps is very efficient, even though they belong to the most primitive subfamily of social wasps. Received: 16 April 1996/Accepted after revision: 9 August 1996     

Evaluating Causes of Population Change in North American Insectivorous Songbirds

Although the North American Breeding Bird Survey (BBS) is a principal source of information regarding populations of most North American bird species, many features of the survey complicate analysis of population change. Correlation studies based on BBS data cannot be used to define cause and effect relationships unambiguously. Recently, Böhning-Gaese et al. (1993) presented an analysis of population trends in insectivorous songbirds using data from the BBS. They concluded that predation has played an important role in influencing population trends. We review aspects of the analysis methods for estimating population trends (e.g., observer effects, data subset) and for associating mean trends with species attributes (e.g., confounding of attributes). Using alternative analyses of the same BBS data, we demonstrate that the evidence that predation is associated with population declines is weaker than they suggested. Based on our analyses the only factor among those tested that was consistently associated with population trends was migration status (short-distance migrant/resident versus long-distance migrant) during the period 1978–1987. Also, we present evidence that the harsh winters of the mid-1970s severely depressed populations of short-distance migrant species and may have been responsible for the observed associations between migration status and population trends.     

Reestablishment of the Perdido Key Beach Mouse (Peromyscus polionotus trissyllepsis) on Gulf Islands National Seashore

Abstract: In April 1986, the endangered Perdido Key beach mouse (Peromyscus polionotus trissyllepsis) existed only as a small population of less than 30 animals on the western end of Perdido Key at Gulf State Park, Alabama This population was vulnerable to extinction from a variety of causes. Fifteen pairs of mice from Alabama were moved approximately 20 km on the same island to Gulf Islands National Seashore Florida between November 1986 and April 1988. The Alabama population was surveyed by live-trapping before each removal and showed a large increase during this study. Eleven pairs of mice were released into enclosures to stimulate burrowing and reduce dispersal at the release site. The last four pairs w e released unrestricted into the dune habitat Trapping in July 1988 revealed that virtually all available dune habitat (11,000 linear m; approximately 160 ha) had been occupied by the mice. Fifty-five individuals were captured including four of the released mice. Exchanges between the populations are recommended to prevent loss of genetic diversity. Future research should investigate demographics, dispersal pattern, and the application of DNA fingerprinting techniques to determine rates of gene flow in the population. The Perdido Key beach mouse provides an excellent model for studying the effects of a population bottleneck on genetic diversity and testing the predictions of population viability analysis.