Diet of a muriqui group (<Emphasis Type="Italic">Brachyteles arachnoides</Emphasis>) in continuous primary forest

The feeding behaviour of a group of free-ranging muriquis (Brachyteles arachnoides) was monitored in the 380 km² Carlos Botelho State Park (PECB), between February 1992 and November 1993. Scan sample data indicated that 59.1% of feeding time was devoted to fruit, 33.2% to leaves, 4.1% to flowers, and 3.6% to other items (twigs, stem and bark). Little seasonal variation was recorded. These results contrast with those of all previous studies of Brachyteles, in which the consumption of leaves was generally double that of fruit. One key difference in comparison with previous studies is that the PECB is part of the largest remaining continuous area of primary Atlantic forest, in the Serra do Mar coastal range. Such intraspecific differences in ecology may have important implications for the conservation of the species.     

Diet of Southern Muriquis in Continuous Brazilian Atlantic Forest

We systematically collected data on feeding behavior for one group of 33–39 southern muriquis (Brachyteles arachnoides) in Parque Estadual Carlos Botelho (PECB), São Paulo State, Brazil (37,432.45 ha of continuous Atlantic Forest), between January and December 1995. We determined food item consumption from instantaneous scans of behavior. Fruits were the most eaten food items in all 12 mo (40–80% of scan in every mo, average = 71.3%). Muriquis ate young leaves more than mature leaves or flowers. Our results are consistent with previous findings at the same and neighboring forest sites that southern muriquis have a consistently frugivorous diet when inhabiting less disturbed habitats, but contrast with previous observations on oppportunistic frugivory in muriqui populations inhabiting fragmented forests. Sustained high levels of frugivory probably result from year-round availability of fruit within large continuous forests.     

Effects of Group Size on Ranging Patterns in Brachyteles arachnoides hypoxanthus

We collected systematic data on the home range and day ranges of one group of 57–63 muriquis (Brachyteles arachnoides hypoxanthus) at the Estação Biológica de Caratinga, Minas Gerais, Brazil from September 1998–July 1999, and compared them with similar data collected 15 years ago when the 23–27 individuals in the group traveled together as a cohesive unit. Home range size increased from 168 ha to 309 ha, reflecting an expansion into areas of the forest that were previously unutilized and consistent with the positive relationship predicted between group size and home range size. By contrast, muriquis exhibited remarkable seasonal and interannual stability in their day ranges. Day ranges, which were calculated from 144 days with 8 h of observation, averaged 1,313 ± 573 m (median = 1,206 m). Day ranges did not vary with the size of subgroups, defined as independent individuals that traveled with one another out of contact with other group members. Subgroups were significantly larger during the rainy season (mean = 41.8 ± 12.7, median = 46.0 individuals, n = 72) than the dry season (mean = 36.6 ± 13.25, median = 39.5 individuals, n = 72). Subgroups were also larger than the size of the entire group during the previous study, yet their day ranges are indistinguishable. The stability in muriqui day ranges is consistent with predictions for folivorous primates in which other indicators of intragroup feeding competition, such as female dominance relationships, are also absent. We attribute the transition from cohesive to fluid grouping patterns to limits on the number of individuals that can coordinate their movements when they spread out while foraging and suggest that seasonal differences in subgroup sizes without corresponding adjustments in day ranges reflect seasonal differences in the distribution of preferred foods coupled with the effects of reproductive seasonality on muriqui grouping patterns.     

Vegetation composition,structure, and biomass of two unpolluted watersheds in the Cordillera de Piuchué, Chiloé Island,Chile

Research in pristine forests provides a necessary reference of energy and nutrient cycling in absence of anthropogenic influence. Therefore two unpolluted watersheds in the Cordillera de Piuchué of southern Chile (42 °30 S) were chosen for detailed ecosystem analysis. The goals of this study were to quantify the distribution of the living biomass in the research watershed and to document topographic gradients in the vegetation. Across a small spatial gradient from ravine bottom to ridgetop (approximately 60 m in elevation and < 300 m in length) in the Cordillera de Piuchué watersheds, there were significant shifts in vegetation composition, structure, and biomass. Based on sampling in 18, 100 m² plots, we identified three distinct community associations: a Fitzroya forest at the bottom of the watershed, a mid-slope Pilgerodendron-Tepualia transition zone, and a ridgetop moorland community. The Fitzroya forest was dominated by a cohort of approximately 400 year-old Fitzroya cupressoides trees. Both tree basal area (138 m²/ha) and total live biomass (656 Mg ha^–1) reached a maximum in this vegetation type. The Pilgerodendron-Tepualia forest consisted of smaller, shorter, and younger trees with dominance shared by Pilgerodendron uviferum, Tepualia stipularis, and to a lesser extent, F. cupressoides. Basal area and biomass were half that of the Fitzroya forest (69.5 m² ha^–1; 350 Mg ha^–1) but tree density was 65% greater. The moorland can best be described as an open community of mosses and cushion plants that included low stature individuals of P. uviferum, F. cupressoides, and T. stipularis. The size and age structure of F. cupressoides in the bottomland forest suggest that the current cohort of adult trees was established following a catastrophic disturbance and that F. cupressoides is unable to regenerate under its own canopy. In contrast, the size structure of the tree populations in the Pilgerodendron-Tepualia zone indicates that all the constituent tree species, except F. cupressoides, are able to reproduce at least at some microsites in the understory. The watershed-level means for live biomass were 306 Mg ha^–1 of aboveground tree biomass, 25 Mg ha^–1 of large root biomass (diameter ge 1 cm), and 46 Mg ha^–1 of small root biomass (diameter < 1 cm).     

Suspension feeding in Bithynia tentaculata (Prosobranchia,Bithyniidae), as affected by body size,food and temperature

The suspension feeding of Bithynia tentaculata was tested in laboratory experiments. The animals were fed in 1-1 aerated glass beakers, and filtration rates were calculated from changes in cell concentrations during the 6-h experiment. Temperature influenced the filtering rate, with minimum values of 5ml · ind^–1 · h^–1 at 5° C and maxima of 17.2 ml · ind^–1 · h^–1 at 18° C. Three food species of different size, motility and cell surface characteristics (Chlamydomonas reinhardii, Chlorella vulgaris and Chlorogonium elongatum) did not affect filtration rates. Suspension feeding increased with increasing food concentrations up to 12 nl · ml^–1, above which feeding rate was kept constant by lowering the filtering rates. Even the smallest animals tested (<4 mm body length) were found to be feeding on suspended food at a rate of 2.7 ml · ind^–1 · h^–1, and increasing rates up to 8.4 ml were found in the 6–7 mm size class. All size classes of Bithynia showed a circannual fluctuation of their filtration rates. The ecological consequences of Bithynia's ability to switch between two feeding modes, grazing and suspension feeding, are discussed.     

Effects of patch size on feeding associations in muriquis (Brachyteles arachnoides)

Data were collected on one group of muriquis, or woolly spider monkeys (Brachyteles arachnoides) during a 14-month study at Fazenda Montes Claros, Minas Gerais, Brazil to examine the effects of food patch size on muriqui feeding associations. Muriqui food patches were larger than expected from the availability of patch sizes in the forest; fruit patches were significantly larger than leaf patches. Feeding aggregate size, the maximum number of simultaneous occupants, and patch occupancy time were positively related to the size of fruit patches. However, a greater number of individuals fed at leaf sources than expected from the size of these patches. Adult females tended to feed alone in patches more often than males, whereas males tended to feed in single-sexed groups more often than females. Yet in neither case were these differences statistically significant.     

Diet in one group of woolly spider monkeys,or muriquis (Brachyteles arachnoides)

Data on feeding behavior in one group of muriquis (Brachyteles arachnoides) were collected during a 14 month study at Fazenda Montes Claros, Minas Gerais, Brazil. Muriquis devoted an average of 51% of their annual feeding time to leaves, 32% to fruits, and 11% to flowers. The high proportion of leaves in their diet is consistent with predictions from the energetics of body size. However, they devoted a greater proportion of their feeding time to patchy fruit and flower resources than was expected from comparisons with smaller, sympatric howler monkeys. Muriqui diet varied with the availability of preferred food types across sample months. Fruit and flower consumption corresponded to the availability and abundance of these food resources in the forest. Leaves contributed substantially to muriqui diet throughout the year but appeared to be eaten primarily to provide necessary protein and/or necessary bulk. Male and female diets differed only in the greater proportion of feeding time females devoted to flowers.     

Zooplankton feeding in the fish Trichogaster pectoralis Regan

The traditional culture method of Trichogaster pectoralis, using zooplankton produced from fermenting aquatic weeds as a source of food for the fry, leads to productions of ca 1 000 kg ha^–1 a^–1. If chicken manure is applied at a rate of ca 450 kg ha^–1 month^–1 instead, much more zooplankton is produced more rapidly, and fish production increases to ca 2 000 kg ha^–1 a^–1. This results from a higher survival rate of the fry, which feeds on rotifers, ciliates, copepods and cladocera until a size of ca 15.0 mm, when plant material also becomes important in the diet.     

Predation on Ceriodaphnia cornuta and Brachionus calyciflorus by two Mesocyclops species coexisting in Barra Bonita reservoir (SP,Brazil)

Feeding experiments with two species of carnivorous copepod, Mesocyclops longisetus (Thiebaud) and Mesocyclops kieferi Van de Velde from Barra Bonita, a eutrophic reservoir in São Paulo, Brasil, were performed using two common types of prey: Ceriodaphnia cornuta, a cladoceran, with a mean body length of 464 µm (including spines) or 393 µm (without spines), and Brachionus calyciflorus, a rotifer with a mean body length of 350 µm (including spines) or 279 µm (without spines).Both species showed higher consumption rates on Brachionus than on Ceriodaphnia. For Mesocyclops longisetus, the average rates were: 2.19 prey ind^–1 h^–1 (Brachionus), and 1.30 prey ind^–1 h^–1 (Ceriodaphnia). For Mesocyclops kieferi, the rates were 1.85 prey ind^–1 h^–1 (Brachionus) and 0.60 prey ind^–1 h^–1 (Ceriodaphnia). These experimental data are discussed with reference to the dynamics of the predator and prey populations in the reservoir.Laboratorio de Limnologia, Departamento de Ciencias Biologicas, Universidade Federal de São CarlosCentro de Recursos Hidricos e Ecologia Aplicada Lab. de Limnologia, Departamento de Hidraulica e Saneamento, Escola de Engenharia de São Carlos, Universidade de São Paulo     

Food Supply and Chimpanzee (Pan troglodytes schweinfurthii) Party Size in the Budongo Forest Reserve,Uganda

A central issue in socioecology is the nature of the relationship between an organism's environment and its social structure. In chimpanzees, the fission-fusion social system is thought to minimize feeding competition for primary dietary components: ephemeral, dispersed patches of ripe fruit. Intragroup feeding competition is thought to force individuals into small parties. Informal observations in the Sonso region of the Budongo forest had suggested that in this habitat, food supply was such that feeding competition was less important in determining grouping patterns than elsewhere. We used data collected on food supply and party sizes over a 4-year period to investigate this suggestion. In accord with theoretical expectation, sizes of foraging parties fluctuated with the size of food patches. However, party sizes showed either negative or no relationship with habitat-wide measures of food abundance. Likewise party sizes showed little relationship to overall measures of food dispersion. For important dietary items, both fruit and leaves had patchy distributions, though the degree of clumping was not strong, and fruit was not more clumped than leaves. Generally, abundant food appeared to be less patchy, and chimpanzees appeared to use more patches as food became more abundant rather than forming larger parties. We suggest that both dispersal and abundance need to be considered when investigating the impact of food supply on grouping patterns, and that the importance of food as a factor in determining chimpanzee grouping patterns declines with increasing levels of abundance.     

Water chemistry and nutrient budgets in an undisturbed evergreen rainforest of southern Chile

In a pristine evergreen rainforest of Nothofagus betuloides, located at the Cordillera de los Andes in southern Chile (41 °S), concentrations and fluxes of nutrients in bulk precipitation, cloud water, throughfall water, stemflow water, soil infiltration and percolation water and runoff water were measured. The main objectives of this study were to investigate canopy-soil-atmosphere interactions and to calculate input-output budgets. From May 1999 till April 2000, the experimental watershed received 8121 mm water (86% incident precipitation, 14% cloud water), of which the canopy intercepted 16%. Runoff water volume amounted 9527 mm. Bulk deposition of inorganic (DIN) and organic (DON) nitrogen amounted 3.6 kg ha^–1 year^–1 and 8.2 kg ha^–1 year^–1 respectively. Occult deposition (clouds + fog) contributes for 40% to the atmospheric nitrogen input (bulk + occult deposition) of the forest. An important part of the atmospheric ammonium deposition is retained within the canopy or converted to nitrate or organic nitrogen by epiphytic bacteria or lichens. Also the export of inorganic (0.9 kg ha^–1 year^–1) and organic (5.2 kg ha^–1 year^–1) nitrogen via runoff is lower than the input to the forest floor via throughfall and stemflow water (3.2 kg DIN ha–1 year^–1 and 5.6 kg DON ha^–1 year^–1). The low concentrations of NO ₃ ^– and NH ₄ ⁺ under the rooting depth suggest an effective biological immobilization by vegetation and soil microflora. Dry deposition and foliar leaching of base cations (K⁺, Ca²⁺, Mg²⁺) was estimated using a canopy budget model. Bulk deposition accounted for about 50% of the total atmospheric input. Calculated dry and occult deposition are both of equal value (about 25%). Foliar leaching of K⁺, Ca²⁺, and Mg²⁺ accounted for 45%, 38% and 6% of throughfall deposition respectively. On an annual basis, the experimental watershed was a net source for Na⁺, Ca²⁺ and Mg²⁺.     

Size and structure of crayfish (Astacus astacus) populations on different habitats in Finland

The many inland waters in Finland make crayfish production an important potential resource. The rational utilization and management of this resource requires knowledge of the size and structure of the crayfish populations. The difficulties often encountered in catching crayfish complicate population studies. Mark-recapture and electric fishing have been used in the studies. The number of adult crayfish measuring more than 70 mm in a 4-ha lake was estimated at 620, and the number in a 13-ha lake at 3 480. In the lakes, the density of adult crayfish was around 0.6–1.4 m^–2 and in one stream studied about 2.5 m^–2 rising to several individuals per m² in the best biotopes.     

Behavioral Correlates of Dispersal in Female Muriquis (Brachyteles arachnoides)

We documented four adolescent female transfers—two emigrations, two immigrations—during a 12-month study from August 1994 to July 1995 on one group of muriquis (Brachyteles arachnoides) at Estação Biológica de Caratinga in Minas Gerais, Brazil. Intergroup transfers occurred throughout the year independent of season. A total of 613 focal samples of 10-min duration conducted on six adolescent females (5–9 years of age) revealed significant differences in the behavior of migrant versus natal resident females. During the seasons encompassing their respective group transfers, both emigrants and immigrants devoted more of their time to resting than resident females belonging to the same age cohorts did. Time spent feeding on mature fruit was higher for one emigrant and lower for both immigrants compared to the two resident females. Emigrant females had fewer neighbors within a 1-m radius than resident females did, whereas immigrant females were within a 1-m radius of adult females and within a 5-m radius of adult males more often than resident adolescent females were. Adolescent females were displaced on 26 occasions. Displacements occurred mainly during the dry seasons (n = 21) and mainly at food sources (n = 21). Using the number of focal samples conducted on each female as an estimate of observation time, immigrant females were displaced at twice the rate of residents. However, like other behavioral differences detected between resident and migrant adolescent females, differences in individual displacement rates were evident only during the season in which each of the immigrants joined the group. Collectively, our findings imply that female intergroup transfer in this population involves relatively mild, short-term costs.     

Leaching of nitrate and ammonium in heathland and forest ecosystems in Northwest Germany under the influence of enhanced nitrogen deposition

To study the impact of high atmospheric nitrogen deposition on the leaching of NO₃^– and NH₄⁺ beneath forest and heathland vegetation, investigations were carried out in adjacent forest and heathland ecosystems in Northwest Germany. The study area is subjected to high deposition of nitrogen ranging from 15.9 kg ha^–1 yr^–1 in bulk precipitation to 65.3 kg ha^–1 yr^–1 beneath a stand of Pinus sylvestris L. with NH₄–N accounting for 70–80% of the nitrogen deposited. Considerable leaching of nitrogen compounds from the upper horizons of the soil, mostly as nitrate, occurred at most of the forest sites and below a mixed stand of Calluna vulgaris (L.) Hull. and Erica tetralix, but was low in a Betula pubescens Ehrh. swamp forest as well as beneath Erica tetralix L. wet heath and heath dominated by Molinia caerulea(L.) Moench. Ground water concentrations of both NO₃–N and NH₄–N did not exceed 1 mg L^–1 at most of the sites investigated.     

Mineral cycling in a tropical palm forest

Nutrient cycling and biomass characteristics of a tropical palm forest dominated byOrbignya cohune were found to be different from thsoe of hardwood dominated forests. The cohune palm forest had a high proportion of biomass in leaves (5%), a reduced sapling layer, a large amount of standing forest litter and an exceptionally low decomposition rate factor (0.1 year^–1). Mineral concentrations in palm leaves were generally lower than in hardwood species with the exception of Na, which was exceptionally high inOrbignya cohune. Biomass was estimated at 226 tons ha^–1 containing 1173 kg ha^–1 N; 126 kg ha^–1 P; 437 kg ha^–1 K; 1869 kg ha^–1 Mg; 125 kg ha^–1 Ca, and 2177 kg ha^–1 Na. Soils of cohune association did not differ significantly from those of neighbouring hardwood dominated associations with the exception of Na which occurred in higher concentration because of bioaccumulation in the dominant. The results suggest that the growth habits and physiology of a dominant can strongly influence some of the ecological parameters used to describe aforest association.     

Feeding behaviour and morphology of filtering combs of Daphnia galeata

The population of Daphnia galeata Sars from the fish pond Velký Pálenec (Blatná, Czechoslovakia) living in high food conditions (7 mgC l^–1) was characterized by a small size of the filtering comb on the thoracic limb 3, measured as seta length, length of the base of the comb and number of setae (population 1). One month cultivation of this population in low food conditions (1.5 mgC l^–1) in the laboratory resulted in twofold increase in size of the filtering comb (population 2). Filtering and ingestion rates of both populations were measured at eight concentrations of food (approximately 0.025–3.2 mgC l^–1) using ¹⁴C labeled Scenedesmus acutus. The results show that size of the filtering combs influences considerably feeding behavior of Daphnia. The comparison of animals with the same body length suggests that the population with a large comb feeds at concentration of food below 0.4 mgC l^–1 more intensively and reaches the maximum of the filtering rate at a lower concentration than the population with a small comb. The situation is opposite at concentration above 0.4 mgC l^–1. The higher values of theoretical flow in population with a small projection of filtering area suggest that this population has to compensate disadvantage of a small comb with the higher appendages beat frequency.     

Effects of Fruit Patch Availability on Feeding Subgroup Size and Spacing Patterns in Four Primate Species at Tinigua National Park, Colombia

We examined the effects of fruit patch size, density, and distribution on feeding subgroup size and feeding bout duration in four Neotropical primates—Lagothrix lagotricha, Ateles belzebuth, Cebus apella, and Alouatta seniculus—based on 2494 hr of focal animal sampling in Tinigua National Park, Colombia. All four species show positive correlations between patch size (tree diameter at breast height; DBH) and subgroup size (maximum number of individuals from the focal group feeding at the same time), but the determination coefficients are very low and this relationship does not seem to influence strongly the actual size of the groups. Ateles showed the weakest correlation between patch size and feeding party size, and their fission–fusion sociality is best explained as a mechanism to reduce intragroup competition rather than to adjust the subgroup size to the availability of patches. Feeding associations as well as proximal spacing patterns, in general, are more alike in species with similar ecological requirements.     

Ranging behavior of woolly spider monkeys,or muriquis,Brachyteles arachnoides

During a 14-month study of one group of woolly spider monkeys, or muriquis (Brachyteles arachnoides),at Fazenda Montes Claros, M. G., Brazil, the group used a home range of 168 ha. Day-range lengths averaged 1283 m and were longer in the wet season than in the dry season. An analysis of travel rates indicated that the group traveled faster on those days when they traveled farther. The availability of large patches of preferred food sources appears to affect daily movement patterns. Intraspecific comparisons, in addition to an apparent expansion of the study group’s home range as their group size has increased, suggest the importance of group size to muriqui range size. Interspecific comparisons between muriquis and sympatric brown howler monkeys suggest that locomotor adaptations are important to understanding species differences in ranging behavior.     

Age at first reproduction in philopatric female muriquis (<Emphasis Type="Italic">Brachyteles arachnoides hypoxanthus</Emphasis>)

Female northern muriquis (Brachyteles arachnoides hypoxanthus or B. hypoxanthus) at the Estação Biológica de Caratinga/RPPN-FMA, Minas Gerais, Brazil typically disperse from their natal groups at an average age of 6.1±0.6 years (median =6.0 years, range =5.3–7.8 years, n =22), prior to the onset of puberty and sexual activity. Immigrants do not conceive until at least their second mating season, and the minimum interval from immigration to first reproduction has been 2.0 years. Age at first reproduction in dispersing females, previously estimated at 8.9 years, has now been documented at 9.0 and 9.25 years for two females whose birth dates are known. This is older than the 7.5 years at which the only female previously known to have reproduced in her natal group gave birth. Here, we present new data from a second female that reproduced in her natal group. This female (BA) was first observed to copulate at 5.5 years, and gave birth to her first infant at 7.25 years of age. Her 1.75-year cycling-to-first conception delay was only slightly shorter than the minimum recorded for immigrant females, and thus was not responsible for her young age at first reproduction compared to dispersing females. Although our sample size is small, our findings suggest that early puberty may permit females to reproduce in their natal group, implying a possible link between life history trade-offs and dispersal patterns. Because the only two females that have reproduced in their natal group were maternal sisters, it is also possible that maternal effects on age at puberty can impact dispersal patterns, particularly in small populations of primates.     

Nitrogen cycling in the seasonally dry forest zone of Belize,Central America

Two forest associations, cohune palm (Cohune Ridge) and mixed tropical hardwood (High Bush), were assessed on the basis of nutrient movement and storage for their suitability for agriculture. Continuous monitoring of soil nitrogen and leaf litterfall over a one-year period provided information on soil building processes in the forest fallow. Destructive cuts revealed the storage of 690 kg N ha^–1 in the standing biomass of the Cohune forest versus 203 kg N ha^–1 in the High Bush. Litter biomass was exceptionally high in the Cohune Ridge (497 kg ha^–1 dry matter) as compared to the High Bush (65 kg ha^–1 dry matter) and other tropical forests. This is probably because of a low rate of decomposition in the Cohune Ridge palm forest. A substantial reserve of nitrogen is present in both forests' fallows, and this can in part be harvested by the small farmer for crop production.

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Ciclo de nitrógeno en la zona de bosque seco estacional de Belize, América Central

Resumen Dos asociaciones boscosas (Palma Cohune y Matorral Alto) se estudiaron en relación a sus reservas y flujos de nutrimentos y sus posibilidades de aprovechamiento agricola. Se siguió la evolución del nitrógeno en el suelo y en la caida de hojarasca durante un año obteniéndose asi información sobre los procesos pedogenéticos en el barbecho del bosque.A través de muestreos destructivos se encontró que en la biomasa del bosque de Palma Cohune habían 690 kg N ha^–1 y en el Matorral Alto solo 203 kg N ha^–1. La biomasa de hojarasca era excepcionalmente alta en Palma Cohune alcanzando un valor de 497 kg materia seca ha^–1; en el bosque de Matorral Alto la hojarasca era de 65 kg materia seca ha^–1. Esto probablemente se deba a la baja velocidad de descomposición en el caso de la palma.Las reservas sustanciales encontradas en ambos barbechos para el nitrógeno podrían ser parcialmente utilizadas para la producción agrícola campesina.