A field study of Geoffroy's tamarin (Saguinus geoffroyi) in Panama

A 3-month field study was conducted in Panama to determine presence and relative abundance of Saguinus geoffroyi, the Geoffroy's tamarin, and status of its habitat (see Acknowledgments for taxonomic note). This primate has a wide geographical distribution in eastern Panama; however, local distribution is highly variable. Tropical forest habitat is rapidly being converted for agriculture and timber. Areas where human access was strictly limited showed tamarin densities significantly greater than in less protected areas. Disturbance has a distinct impact on population densities. There may also be a relationship between tamarin abundance and specific types of vegetation. Future actions regarding the conservation of S. geoffroyi and its habitat are recommended.     

Demographic properties of an outlier population of Orchis militaris L. (Orchidaceae) in England

Orchis militaris L. underwent a catastrophic decline in range and plant numbers in the British Isles around the end of the nineteenth century, and was long thought to be nationally extinct. A small number of colonies have been discovered since then, including one in Buckinghamshire, which has been recorded annually almost every year since its discovery in 1947. This paper presents an analysis of the demography and behaviour of this population using census data which have been collected annually from 1977 to 1995. Yew trees which shaded the site occupied by the orchids were removed in 1984 and 1989, and the growth of the herb layer has been strongly constrained by active management since 1989. Since the start of this period of intensive management, the annual gains and losses of plants in the population have become more pronounced, but in most years there has been a net gain in the number of plants. The number and proportion of the emergent plants which flower each year has increased considerably since 1986, and the age structure, which was dominated by older plants prior to 1984, has since become dominated by younger plants, reflecting the increased rate of recruitment and lack of a corresponding increase in mortality. Analyses are presented to show changes in behaviour in consecutive years between the pre-1984 and post-1986 management eras.     

Estimation of density of gibbon groups by use of loud songs

The density of gibbon populations may be estimated by listening for the loud duetted songs of monogamous territorial groups. This method requires a correction factor which must be estimated from the frequency of singing of an adequate number of known study groups. The correction factor and its error were estimated for pileated gibbons (Hylobates pileatus) in Khao Soi Dao Wildlife Sanctuary in southeastern Thailand. Among 30 groups studied, 47% sang per day, on average, but the variation between days and the variation in singing frequency between groups were large. Weather conditions, especially windiness, explained some variation in singing. During an area-wide survey of groups in the sanctuary, unexplained variation in singing from day to day accounted for approximately half of the sample error of group density estimated from 1-day listening samples. Error due to day-to-day variability can be reduced by listening for more than one day at each site. Correction factors based on the cumulative proportion of groups heard during longer (2–5-day) sample periods of listening were closer to 1.0, therefore leaving less room for error and bias of the correction factor. © 1993 Wiley-Liss, Inc.     

An assessment of the breeding range,colony sizes and population of the Westland petrel (Procellaria westlandica)

Abstract

The Westland petrel (Procellaria westlandica) is an endemic New Zealand species and one of the very few burrowing seabird species still breeding on mainland New Zealand. It nests only on a series of coastal ridgelines near to Punakaiki on the West Coast of the South Island. Between 2002 and 2005, surveys were undertaken at 28 of the 29 known colonies. The area occupied by the colonies was 73 ha; most colonies had fewer than 50 burrows, but six colonies had 201–500 burrows and four colonies had more than 1000 burrows. We find that the current breeding range of Westland petrel and the location of individual colonies are similar to those reported in both the 1950s and 1970s. Based on total burrow counts at 28 colonies and burrow occupancy rates determined by annual monitoring, the annual breeding population is estimated to be between 2954 and 5137 breeding pairs.     

Ultrastruttura della cellula apicale di Halopteris scoparia (L.) Sauvageau (Phaeophyceae,Sphacelariales)

Abstract

Ultrastructure of the apical cell of Halopteris scoparia (L.) Sauvageau (Phaeophyceae, Sphacelariales). - The ultrastructure of resting apical cells of Halopteris scoparia (L.) Sauvageau from material collected in December is described. The cytoplasm is higly vacuolated with lipids, poliphenolic substances and polisaccharides occurring inside the vacuoles (the classic « physodes »).

Two cell organelles are prominently active at this stage: conspicuosly hypertrophic dictyosomes and the budding endoplasmic reticulum. Both light and electron microscope observations show that the cell wall has an outer stratification and inner discontinuous thickenings, the constituent material of which is uniformerly dispersed.

The above observations point out that the apical cell of Halopteris scoparia at this stage of its life cycle is engaged in an elaboration of vacuolar and parietal substances which will be therefore readly available at the outset of the growing season.     

Topographic complexity and the power to detect structural and functional changes in temperate reef fish assemblages: The need for habitat-independent sample sizes

Functional approaches have shown promising results to detect degradation in marine fish assemblages. However, background variability significantly affects the amplitude of change that is detectable by a monitoring plan, and failing to detect such changes can have devastating consequences and carry aggravated recovery costs due to unnoticed degradation. The present study aimed to understand the relationship between topographic complexity in temperate reefs and the power to detect variations in fish-based metrics. Underwater visual census of fish assemblages was performed using strip transects and a Monte Carlo simulation approach was used to generate a large number of replicates and simulate three alternative hypotheses representing different magnitudes of change. Statistical power to detect differences between null and alternative hypotheses was estimated through 10,000 Mann–Whitney tests for numbers of replicates ranging from 2 to 15. Power tended to vary with topographic complexity particularly with small and medium changes in metric values and when using small sample sizes. While power increased with complexity for most metrics, some showed decreasing trends. With a large effect, 5–15 transects were needed, depending on the metric, to stabilise power above 0.80 independently of habitat features. A power of 0.95, however, could not be achieved for most metrics in all sites, even when using 15 transects. The observation that the power to detect degradation and recovery in temperate reef fish seems to vary with habitat features means that a monitoring programme that is correctly planned for a particular area may not be directly applicable in a nearby reef. Adding to the need to maximise power in monitoring, this study highlights the need to take into account habitat variability in these calculations and estimate habitat-independent sample sizes that are appropriate for the scale and location of interest.     

Comparisons among survey methodologies to test for abundance and size of a highly targeted fish species

Three sampling methods for estimating abundance and size of blue cod Parapercis colias were compared inside and outside Kapiti Marine Reserve, New Zealand (40° 49′ 31·77^′′ S; 174° 55′ 02·87^′′ E). Two baited methods, baited underwater video (BUV) and experimental angling (EA), were more efficient and had lower levels of estimate variation than diver‐based underwater visual census (UVC). The BUV and EA recorded more fish and of greater size ranges than UVC, and also had fewer zero count replicates. The BUV and EA methodologies revealed highly significant differences in abundance and size of fish between sites (reserve v. non‐reserve), whereas UVC revealed no such differences. These results indicate that BUV is likely to be the most accurate, cost‐effective and easy to use methodology for the surveying of carnivorous temperate reef fishes for future monitoring. It is noted, however, that new data acquired using the BUV methodology may need to be compared over a calibration period to data acquired using the UVC methodology to ensure that historical data sets derived from UVC still have validity and application for future monitoring activity.