Phenology of figs in Budongo Forest Uganda and its importance for the chimpanzee diet

This paper reports on the phenological patterns of figs in Budongo Forest, Uganda, and how it relates to chimpanzee food availability in different seasons. In addition, we analysed the dung of chimpanzees to understand the composition of fruits in their diet. The aim of our study was to assess Ficus phenology and how it affects chimpanzee diet. Fifteen species of figs were monitored for fruit (syconium) and leaf phenology between June 2000 and 2001. Ficus fruit production varied significantly between and within species, and also with tree trunk and crown diameters. Fig fruit production was asynchronous and individual fig trees produced crops from one to five times in a year. In addition to fruits, chimpanzees fed on young leaves of some Ficus species. Shedding of old Ficus leaves coincided with the dry season, followed by appearance of young leaves. The dry season in Budongo is a period of general fruit scarcity. The combination of fig fruits and young leaves make up the most important food in the diet of chimpanzees. From the chimpanzee dung, more than 78% of seeds comprised fig ‘seeds’ (nutlets) and the rest of the diaspores were from other tree species. Our findings suggest that chimpanzees disperse large number of diaspores in their dung, thereby serving as important agents of natural forest regeneration.     

Fruiting phenology of fig trees in Kalinzu Forest,Uganda

The study determined the abundance and species composition of fig trees that fruited in the different forest types of Kalinzu Forest Reserve (KFR), Uganda. It also assessed the seasonal variations in abundance and species composition of the fig trees, the relationships between the fruiting patterns and rainfall and the figs’ inter‐ and intraspecific patterns of fruiting episodes. Sixteen fig species represented by 515 individuals were monitored monthly from December 2007 to January 2010. Most individuals and species that fruited were in the secondary forest types (the Musanga‐ and Parinari‐dominated secondary forests) and abundances of individuals of the different species were significantly associated with particular forest types. One colonizing species (Ficus sur) was the most abundant species that fruited and was mostly recorded in the secondary forests. Species composition and abundances of trees that fruited varied seasonally, and only the abundances of two canopy species (Ficus lingua and Ficus sansibarica) were significantly related with monthly rainfall. Most species experienced at least four fruiting phases, and F. sur displayed the longest episode covering 22 months. The results suggest that the past intensive logging in KFR promoted the regeneration of a diversity of fig species, and most species generally experience community‐wide asynchronous fruiting.     

Ficus sp. and Musanga leo‐errerae: coexistent keystone fruits for chimpanzees in Kalinzu forest

The composition of Ficus sp. and Musanga leo‐errerae in Chimpanzees’ diet was investigated by faecal analysis and direct observation in the medium altitude forest of Kalinzu, along the albertine rift, south‐western Uganda. The fruit availability of Ficus species showed significant variations while that of Musanga leo‐errerae was consistent and significantly higher than that of Ficus (P = 0.053; t = ?2.034) all year round. Their consumption was not opportunistic as no correlation existed between their fruit abundance and their occurrence in chimpanzee faecal samples/diet (Musanga leo‐errerae: r = 0.153, P = 0.456; Ficus sp.: r = 0.039, P = 0.848). Results showed that Musanga leo‐errerae and Ficus species seeds occurred in 80.2% and 67.2% respectively of the total 2635 chimpanzee faecal samples analyzed. Although there was no significant difference between chimpanzees party size that fed on Musanga leo‐errerae and Ficus tree species, the rate of consumption was significantly different in the low (t = 3.835; P = 0.031) than the high fruiting season (t = 2.379; P = 0.063). Ficus sp. and Musanga leo‐errerae genera function as coexistent keystone fruits for chimpanzees because they perfectly complement each other in terms of chimpanzees’ sustenance. This information has significant implications in the management of tropical forests like Kibale, Budongo, Bwindi Impenetrable, Gombe and Mahale inhabited by primate populations especially the endangered ones like the chimpanzee.     

Tree fruiting phenology in Kalinzu Forest, Uganda

The spatial and temporal variations in species composition and abundance of trees that fruited in mechanically logged, intensively pit‐sawn and essentially undisturbed forest areas in Kalinzu Forest (0°17′S, 0°30′S and 30°00′, 30°07′E) were assessed. The duration and frequency of fruiting episodes of selected pioneer, understorey and canopy tree species were also determined. These phenology aspects were monitored for 18 months (between February 1997 and July 1998) in 99 plots, each 20 m × 20 m in size. Eighty species consisting of 1489 trees fruited during the study. Most of the species were recorded in the undisturbed forest area and least in the mechanically logged areas. Monthly number of individuals and species that fruited in each forest condition were significantly related to monthly rainfall. Two pioneer species (Musanga leo‐errerae and Trema orientalis), one sub‐canopy (Funtumia africana) and canopy (Parinari excelsa) species had extended fruiting phases (>5 months). Two understorey species (Oxyancius speciosus and Tabernaemontana spp.) had an extended phase while the third (Teclea nobilis) had a short (≤5 months) fruiting phase. Of the selected species, only Strombosia scheffleri (a sub‐canopy species) and P. excelsa had more than one fruiting episode.     

Botanical and Topographical Factors Influencing Nesting-Site Selection by Chimpanzees in Kalinzu Forest,Uganda

We examined the relative importance of various botanical and topographical factors that influence nesting-site selection by chimpanzees ( Pan troglodytes schweinfurthii) in the Kalinzu Forest of Uganda. All of them—vegetation type; topographical features; frequency of preferred tree species; frequency of preferred tree size; fruit abundance—significantly influenced nesting-site selection. Fruit abundance and vegetation type had much stronger influences on site selection than the other factors did. In a dense forest environment like the Kalinzu Forest, the local and seasonal distributions of chimpanzee nests seem to reflect the pattern of home range use for feeding.     

Fruit Availability and Habitat Use by Chimpanzees in the Kalinzu Forest,Uganda: Examination of Fallback Foods

We studied seasonal change in habitat use by chimpanzees in the Kalinzu Forest, Uganda. The forest comprises various types of vegetation. For each vegetation type, we compared number of chimpanzees (per km²) that used the vegetation with fruit availability in different census periods. We estimated the number of chimpanzees by nest count and fruit availability via density of fallen fruit. The mixed mature forest contained a large amount of fruit during the high-fruiting season, but it decreased rapidly in the low-fruiting season. The number of chimpanzees also decreased in mixed mature forest in approximate proportion with fruit availability. In the Parinari-dominated mature and secondary forests, both fruit availability and number of chimpanzees were very low throughout the study. In the Musanga-dominated secondary forest, the number of chimpanzees increased toward the low-fruiting season, though the fruit availability decreased slightly. A multiple regression analysis showed that various fruits had significant effects on the number of chimpanzees during the high-fruiting season, while only Musanga leo-errerae had a significant effect during the low-fruiting season. The results suggest that the fruit of Musanga leo-errerae functions as a fallback food, and a combination of different vegetation types supports the chimpanzees in the Kalinzu Forest.     

Dietary selection of L'Hoest monkeys in Kalinzu forest reserve, southwestern Uganda

Reports on patterns of dietary selection of forest guenons tend to be general and often classify Cercopithecus l’hoesti as a frugivores–folivores species just like the other guenons, and to date there has been no systematic investigation into the inventory of the species’ food items in the remaining forest fragments to guide major conservation and management decisions. Here we report on the L’Hoest monkeys’ main food species and how the selection of these foods varies among different age groups of the troop in Kalinzu Forest, Uganda for a period of 12 months. Behavioural observations were determined using scan samples [Behaviour, 49 (1974) 227]. Two hypotheses were evaluated in this study. Results indicate that individuals of different age groups have the ability to select a variety of both plant and invertebrate food items in the vicinity to supplement their diets. There was no significant difference in dietary selection between different age groups of L’Hoest monkey for a particular food type (ANOVA: Column analysis, F_3,84 = 1.541337, P = 0.209827). However, significant difference was realized in dietary selection of the different food types by a particular age group (ANOVA: F_22,46 = 40.86429, P = 3.69 × 10^?23). Selective predation pressure against the infants and juveniles by Stephanoaetus coronatus was believed to be one of the likely reasons why infants and juveniles least exposed themselves in the trees feeding on fruits of Musanga leo‐errerae and Ficus spp. Invertebrate feeding was found to constitute high percentage (47.2%) of the species diet and plant materials comprised (52.8%) than previously reported in other study sites. These data provide potentially useful insight on the feeding ecology of the little studied C. l’hoesti and can provide baseline information on conservation of its food items in the remaining forests.     

Population census of the chimpanzees in the Kalinzu Forest,Uganda: Comparison between methods with nest counts

The population of chimpanzees in the Kalinzu Forest, Uganda was censused with nest counts using the line-transect method. Four methods were examined to estimate density. The estimated densities, ranging from 2.0 to 4.7 chimpanzees per km², all indicated a high population density, in comparison with other chimpanzee habitats. Moreover, the density in the logged area of the Kalinzu Forest was higher than that in the unlogged area. Several factors are thought to contribute to the high density in the Kalinzu Forest. Notable are the mosaic forest structure dominated by mature forest with patches of logged areas, selective logging of non-food tree species of chimpanzees, and low hunting pressure. These results suggest that selective logging may be a practical means of primate conservation in places where timbers are exploited.     

Red-tailed monkeys (Cercopithecus ascanius) hunt green pigeons (Treron calva) in the Kalinzu Forest in Uganda

Red-tailed monkeys (Cercopithecus ascanius) were observed hunting green pigeons (Treron calva) in the Kalinzu Forest in Uganda. During 2 h 39 min, I observed two cases of successful hunting and one case of unsuccessful hunting in a Ficus saussureana tree. Red-tailed monkeys stalked the pigeons until they were within 2–3 m, and then jumped and caught them. In both successful cases, blue monkeys (C. mitis) ran to the hunting site from adjacent trees in order to poach the prey, and the red-tailed monkeys fled. One of these red-tailed monkeys dropped the pigeon while fleeing, and the blue monkey climbed down from the tree to search for it. This is the first record of cercopithecoid monkeys hunting birds that are outside of the nest and moving freely, and also the first record of red-tailed monkeys hunting vertebrates. However rare it may be, the repeated hunting attempts using similar techniques and the immediate attempt of blue monkeys to poach the prey suggest that this type of hunting was not a one-time event that happened by chance. Blue monkeys and an adult chimpanzee (Pan troglodytes schweinfurthii) in and around the fig tree did not attempt to hunt. The hunting of volant birds may be enabled by the small body size and the quick movements of red-tailed monkeys.     

The diet of chimpanzees in the Budongo Forest Reserve, Uganda

Chimpanzee diets are highly variable, but in all cases dominated by ripe fruit. Previous work has suggested that in the Budongo Forest Reserve, Uganda, ripe fruit remains available throughout the year, but dietary data for chimpanzees at this site remain sparse. This paper details the diet of a recently habituated community of Budongo chimpanzees living in the Sonso region. Chimpanzees of this community spent 64.5% of their feeding time eating fruit, and 19.7% eating arboreal leaves. Terrestrial herbaceous vegetation formed only a minor component of the diet. In these general dietary characteristics, Budongo chimpanzees show greater similarity to those of the Gombe National Park than they do to those in the geographically closer and floristically more similar Kibale Forest National Park. The diet was dominated by the fruit of four species and leaves of two species, although the composition of the diet varied from month to month, remaining diverse. Figs were consumed throughout much of the year, and in consequence, should perhaps be regarded as a staple, rather than fallback, food. A period of food scarcity was not apparent in this study and future comparative nutritional investigation will be required to determine whether these chimpanzees face a time of dietary hardship.     

传粉方式和果实类型对木本植物繁殖物候的影响

该研究利用谱系独立比较法(Phylogenetically Independent Contrasts,PIC)和Wilcoxon秩和检验法,分析中国科学院植物研究所植物园(39°54'N,116°12'E)中的84个物种170株个体的传粉方式和果实类型对木本开花时间和结实时间的影响,其中Wilcoxon秩和检验法检验的结果作为PIC检验结果的参考。结果表明:(1)传粉方式显著影响植物开花和结实时间,风媒花植物比虫媒花植物开花和结实早;(2)果实类型对结实时间的影响在考虑和不考虑物种间系统发育关系时表现不同,当不考虑物种间系统发育关系时,肉质果实植物结实时间比非肉质果实植物早;(3)不同的传粉方式间以及不同的果实类型间植物的花果间隙期无显著差异,但本研究结果显示肉质果实植物结实时间比非肉质果实植物大约早20d。由此推论:(1)植物固有属性,如传粉方式和果实类型,会影响植物繁殖物候,且不同的属性影响强度不同;(2)与某一特定物候期或繁殖器官相关性大的属性对该物候期的影响可能更大,如传粉方式对开花时间的影响可能大于其对结实时间的影响,而果实类型对结实物候期的影响更大。     

How plant allometry influences bud phenology and fruit yield in two Vaccinium species

Background and AimsUnderstanding how plant allometry, plant architecture and phenology contribute to fruit production can identify those plant traits that maximize fruit yield. In this study, we compared these variables and fruit yield for two shrub species, Vaccinium angustifolium and Vaccinium myrtilloides, to test the hypothesis that phenology is linked to the plants’ allometric traits, which are predictors of fruit production.MethodsWe measured leaf and flower phenology and the above-ground biomass of both Vaccinium species in a commercial wild lowbush blueberry field (Quebec, Canada) over a 2-year crop cycle; 1 year of pruning followed by 1 year of harvest. Leaf and flower phenology were measured, and the allometric traits of shoots and buds were monitored over the crop cycle. We hand-collected the fruits of each plant to determine fruit attributes and biomass.Key ResultsDuring the harvesting year, the leafing and flowering of V. angustifolium occurred earlier than that of V. myrtilloides. This difference was related to the allometric characteristics of the buds due to differences in carbon partitioning by the plants during the pruning year. Through structural equation modelling, we identified that the earlier leafing in V. angustifolium was related to a lower leaf bud number, while earlier flowering was linked to a lower number of flowers per bud. Despite differences in reproductive allometric traits, vegetative biomass still determined reproductive biomass in a log–log scale model.ConclusionsGrowing buds are competing sinks for non-structural carbohydrates. Their differences in both number and characteristics (e.g. number of flowers per bud) influence levels of fruit production and explain some of the phenological differences observed between the two Vaccinium species. For similar above-ground biomass, both Vaccinium species had similar reproductive outputs in terms of fruit biomass, despite differences in reproductive traits such as fruit size and number.     

The effect of human disturbance on tree species composition and demographic structure in Kalinzu Forest Reserve,Uganda

Tree abundance and species composition in the mechanically logged, intensively pitsawn and minimally disturbed areas of Kalinzu Forest Reserve were determined. The spatial and diameter size‐class distribution of ten selected tree species representing pioneer, secondary colonizer, understorey, canopy, dominant and endangered species were also assessed. The species were: Musanga leo‐errerae, Trema orientalis, Funtumia africana, Strombosia scheffleri, Oxyansus speciosus, Parinari excelsa, Tabernaemontana holstii, Newtonia buchananii, Lovoa swynnertonii and Entandrophragma angolense. The mean stem density of all trees ≥0.5 m in height was 2809.1 per hectare and 150 species were enumerated in the three forest areas. Most individuals (47.73%) and species (75.0%) were recorded in the minimally disturbed and least in the mechanically logged areas. Of the selected species, F. africana was the most abundant (n = 789) and widely distributed in each of the areas. Entandrophragma angolense was the least abundant (n = 63) and most of its individuals (74.6%) were recorded in the minimally disturbed area. Funtumia africana and S. scheffleri (subcanopy), O. speciosus and T. holstii (understorey), N. buchananii (canopy) and P. excelsa (an upper canopy and a climax species of this forest reserve) had an inverse J‐shaped diameter size‐class structure while pioneer species (M. leo‐errerae and T. orientalis) had a bell‐shaped size‐class structure.     

The smaller fruit tortrix, Grapholita lobarzewskii: predicting the phenology of adult emergence

The smaller fruit tortrix, Grapholita lobarzewskii Nowicki, has become a major pest in the recent past in apple orchards north of the Alps. Nevertheless little is known about the biology and the behaviour of this species. The effect of temperature on post-diapause development and survival was studied under controlled conditions in order to establish a basis for the forecasting of adult emergence. Survival was found to be highest at 17 °C and lowest at 11.8 °C. The sex ratio did not differ significantly from 1:1. Based on a linear relationship between temperature and developmental rates, thermal thresholds of 9.6 °C and 9.8 °C were determined for females and males respectively. The thermal constants, i.e., the mean developmental times in physiological time units, were found to be 342 day-degrees for females and 317 day-degrees for males, suggesting a slight protandry. Based on the mean and the variance of the developmental times, a simple temperature-driven phenology model was built using a time-varying distributed delay. The model was validated by visually comparing the predictions with independent observations on adult emergence, and by calculating the temporal deviations of the predictions. In 4 out of 5 years the mean error was less than 3 days. The model was therefore found to give reliable forecasts of the emergence of G. lobarzewskii and can be used to determine the optimal time for the exposure of pheromone traps, the application of pheromone dispensers for mating disruption, and for the timing of insecticide applications.     

A quantitative comparison of terrestrial herbaceous food consumption by Pan paniscus in the Lomako Forest,Zaire, and Pan troglodytes in the Kibale Forest,Uganda

Differences in the social organization and dental morphology of Pan paniscus (bonobos) and Pan troglodytes (chimpanzees) have been related to differences in the spatiotemporal availability of food and its exploitation. The presence of abundant terrestrial herbaceous vegetation (THV) in the bonobo's habitat and the apparent greater reliance on herbs for food has been used to explain differences in party size and, by extension, social organization. Using fecal analysis, we assess quantitatively the amount of herbaceous foods consumed by Pan paniscus in the Lomako Forest, Zaire, compared to similar data for Pan troglodytes in the Kibale Forest, Uganda. We examine this data in the context of spatiotemporal patterns of availability of herbaceous foods and fruit, as well as their nutritional content. The results support the suggestion that bonobos consume more herbaceous food than do the Kibale chimpanzees and that these foods are more prevalent in the bonobo's habitat than in the Kibale Forest. However, temporal changes in fruit availability and herb consumption, along with nutritional analyses, suggest that chimpanzees consume herbs as a fallback source of carbohydrates, whereas bonobos consume herbs as a source of protein regardless of season or fruit abundance. Available data suggest that party size while feeding on terrestrial herbs is restricted at both sites, but a determination of the relative strength of this constraint is not possible at this time. Difficulties in methods used for data collection are discussed and areas where more information is needed are highlighted. © 1994 Wiley-Liss, Inc.     

The role of fruit traits of bird-dispersed plants in invasiveness and weed risk assessment

Aim  Birds play a major role in the dispersal of seeds of many fleshy-fruited invasive plants. The fruits that birds choose to consume are influenced by fruit traits. However, little is known of how the traits of invasive plant fruits contribute to invasiveness or to their use by frugivores. We aim to gain a greater understanding of these relationships to improve invasive plant management.
Location  South-east Queensland, Australia.
Methods  We measure a variety of fruit morphology, pulp nutrient and phenology traits of a suite of bird-dispersed alien plants. Frugivore richness of these aliens was derived from the literature. Using regressions and multivariate methods, we investigate relationships between fruit traits, frugivore richness and invasiveness.
Results  Plant invasiveness was negatively correlated to fruit size, and all highly invasive species had quite similar fruit morphology [smaller fruits, seeds of intermediate size and few (< 10) seeds per fruit]. Lower pulp water was the only pulp nutrient trait associated with invasiveness. There were strong positive relationships between the diversity of bird frugivores and plant invasiveness, and in the diversity of bird frugivores in the study region and another part of the plants' alien range.
Main conclusions  Our results suggest that weed risk assessments (WRA) and predictions of invasive success for bird-dispersed plants can be improved. Scoring criteria for WRA regarding fruit size would need to be system-specific, depending on the fruit-processing capabilities of local frugivores. Frugivore richness could be quantified in the plant's natural range, its invasive range elsewhere, or predictions made based on functionally similar fruits.     

Ranging Patterns of Chimpanzees in a Montane Forest of Kahuzi,Democratic Republic of Congo

I studied ranging patterns of a semihabituated unit-group of chimpanzees for 60 mo at Kahuzi. They had a total home range of 12.81 km² and a mean annual home range of 7.55 km². Considering the low density of chimpanzees in the area vis-à-vis chimpanzees in arid areas, their home range is very small. Kahuzi chimpanzees used the home range in a clumped pattern, frequently visiting the core area and only rarely entering peripheral areas. The monthly range changes with fruit availability, increasing during periods of fruit scarcity. There was no consistent seasonal difference in the size of the home range. However, use of different habitat types may vary seasonally. While there was no seasonal effect in the use of primary forest, the chimpanzees showed a statistically consistent seasonal difference in their use of secondary forest, visiting it mainly during the dry season when fig trees were in fruit. Since the primary forest provides them with more food fruits, chimpanzees tended to use more frequently the small patches of primary forest in their home range. Thus, the size and distribution of small fragmented primary forests may be an important factor influencing the ranging pattern of chimpanzees at Kahuzi.     

Frequent insectivory by two guenons (Cercopithecus lhoesti and Cercopithecus mitis) in the Kalinzu Forest, Uganda

I investigated the feeding ecology of lHoests monkeys (Cercopithecus lhoesti) and blue monkeys (Cercopithecus mitis) in the Kalinzu Forest, Uganda. Although forest guenons are generally thought to be frugivores or folivores, these two guenons spent a large proportion of their time feeding on invertebrates. The lHoests monkey and the blue monkey spent as much as 66 and 50% of their time on insectivory, respectively. These proportions of time spent on invertebrate feeding are higher than those reported elsewhere for forest guenons. LHoests monkeys mainly utilized the area near the ground for invertebrate feeding, while blue monkeys utilized the area around 20 m above the ground. It seemed that guenons have an ability to change their diet according to the environment.