Nesting ground abandonment by the maleo (Macrocephalon maleo) in North Sulawesi: Identifying conservation priorities for Indonesia’s endemic megapode

The maleo (Macrocephalon maleo) is an endemic bird of Sulawesi that lays eggs in communal nesting grounds incubated by solar or geothermal sources. In recent years, maleo nesting grounds have become increasingly vulnerable to threats associated with the growing human population of the island. Consequently, the maleo has become one of the most imperiled bird species in Indonesia and is classified as Endangered on the IUCN Red List. We report on the 2004 status of maleo nesting grounds in North Sulawesi focusing on the Bogani Landscape, the region in and around Bogani Nani Wartabone National Park, where the nesting grounds are concentrated. We compare our results to those of a similar study in 1990-1991, examining changes in nesting ground status in relation to habitat and land use factors such as protection status, geographic position (coastal or inland), and distance to forest, human settlements, and roads. Nesting grounds were more likely to be abandoned if they were: (a) in coastal areas; (b) near settlements and roads; and (c) not in protected areas. Binary logistic regression identified connectivity between nesting grounds and forest in 1991 as the best predictor of whether or not sites were abandoned by maleo over the next 12 years; a loss of local continuity between nesting grounds and forest is associated with a sixfold increase in the probability of abandonment. Access to forest was itself highly correlated with other variables examined, and thus represented a composite index of threats to maleo. The application of this model to the 2004 data identified six active nesting grounds that are at high risk of abandonment in the near future, seven at intermediate risk, and five at low risk. These results offer conservationists priorities for future maleo conservation.     

A survey of the orangutan (Pongo pygmaeus wurmbii) population in and around Gunung Palung National Park, West Kalimantan, Indonesia based on nest counts

We conducted the first orangutan population census of Gunung Palung National Park, West Kalimantan, Indonesia, between April and September 2001. We used a refined line-transect nest-count methodology utilizing transect recounts to survey 69 km at 14 sites within the park and 14.2 km in the buffer zone. We present the first Bornean orangutan density estimate using complete site-specific parameters and long term monitoring of nest decay rates. Average orangutan density was 3.0 individuals/km², with densities ranging from 2.4 ind/km² in montane forest to 4.1 ind/km² in primary peat swamp. In addition, we tested alternative approaches to calculation of the nest-duration parameter. The second count of each transect resulted in 30% higher density estimates overall. We conclude that recounts should be incorporated into standard line-transect methodology. We estimate there to be ≈2500 individual orangutans in Gunung Palung, indicating the importance of this site in plans to conserve a network of viable orangutan populations. While logging may reduce densities, disturbed forest both inside and adjacent to the park has high conservation value as orangutan habitat. Further research into long-term orangutan population persistence in disturbed forest is needed.     

Effect of dietary essential fatty acids on level of oestradiol‐17β and vitellogenin,reproductive performance and larval quality of striped catfish (Pangasianodon hypophthalmus) in out‐of‐spawning season

A study was conducted to determine the effect of essential fatty acid in striped catfish (Pangasianodon hypophthalmus) broodstock diets on a level of oestradiol‐17β and vitellogenin, reproductive performance and larval quality in out‐of‐spawning season. Five female and five male broodstock were stocked into a net cage (3 × 5 × 1.5 m³) and fed with pelleted diets containing 1.5% fish oil and different amounts of corn oil (CO) in diet formulation, that is 0%, 1%, 2% and 3% respectively. Gonadal development, oestradiol‐17ß and vitellogenin concentrations were examined every 2 weeks. Oestradiol‐17ß and vitellogenin concentrations showed an increase during the maturation process. The significantly highest percentage of female mature, fecundity, hatching rate, larval production and larval survival rate were obtained from fish fed with 2% corn oil in the diet. This result revealed that the administration of 2% corn oil in the diet as a source of n‐6 (linoleic acid) and 1.5% fish oil as a source of n‐3 (linolenic acid) can improve the reproductive performance of striped catfish broodstock in out‐of‐spawning season.     

The blowgun is mightier than the chainsaw in determining population density of Bornean orangutans (Pongo pygmaeus morio) in the forests of East Kalimantan

Due to its practical relevance to conservation, considerable efforts have been devoted to understanding the effects of logging on orangutan (Pongo spp.) population densities. Despite these efforts, consistent patterns have yet to emerge. We conducted orangutan nest surveys and measured forest quality and disturbance level at 108 independent locations in 22 distinct sites in the forests of the Berau and East Kutai regencies of East Kalimantan, Indonesia. Survey locations varied substantially in orangutan density, forest structure, distance to villages, and logging intensity. We incorporated site-specific nest tree composition into our estimates of nest decay rates to reduce errors associated with inter-site differences in nest tree selection. Orangutan nest densities were uncorrelated with altitude, fig density, or any other ecological measure. Multivariate analyses demonstrated that densities were not significantly affected by logging intensity (at the relatively light levels we report here) or the distance to the nearest village, but were positively correlated with the distance from the nearest village known to hunt orangutans. These results indicate that provided hunting is absent, lightly to moderately degraded forests retain high conservation value for orangutans. Widespread incorporation of degraded areas into management plans for orangutan populations would substantially increase the size of populations that could be protected, and thereby improve their changes for long-term survival.     

Tree growth performance and estimation of wood quality in plantation trials for Maesopsis eminii and Shorea spp.

Plantations of tropical species are becoming an increasingly important source of wood.However, it is important that research trials focus not only on tree growth performance, but also on wood quality.The aims of this study were to assess the growth performance of six commercially and ecologically important tree species from separate plantation trials in Indonesia and to determine the relationships between tree growth and wood quality in terms of the dynamic modulus of elasticity(MOE) and wood density.Forty-eight 7-year Maesopsis eminii Engl.and thirty-five 9-year specimens(7 each of 5 Shorea spp.)were selected from two trials.The MOE, based on acoustic velocity, was indirectly measured to evaluate wood stiffness.Tree-growth performance was evaluated, and correlations between growth traits and acoustic velocity as well as density and wood stiffness properties were estimated.The growth performance of M.eminii in terms of tree volume was significantly different in three different categories of growth(i.e.fast, medium, slow).Of the five Shorea spp.studied, Shorea leprosula Miq.had the highest growth rate, as expected since it is known to be a fastgrowing Shorea species.Indirect measurement of wood quality by means of non-destructive ultrasonic methods showed a weak negative correlation between tree volume and acoustic velocity and dynamic MOE.Although each fast-growing tree could reach a merchantable size faster than other varieties or species, wood traits of various species tested were not significantly different based on tree growth rate performance.The findings from this study could be used to improve selection criteria in future breeding trials; indirect measurements of the dynamic modulus of elasticity can be used in mass pre-selection of genetic materials, to choose the most-promising material for in-depth evaluation.