Community seed rain patterns and a comparison to adult community structure in a West African tropical forest

We examined the seed rain throughout a twelve month period in a lowlandtropical forest in Cameroon, West Africa, 1996–97. Traps (0.5m², n = 216) were erected throughout a 25km² area in 24 randomly placed clusters of nine trapseach. Fruits and seeds that landed in traps were collected every 7–10daysand classified by species and dispersal type. More than 32,000 seeds fromapproximately 200 species fell into the traps, an average of 297 seedsm^–2 yr^–1 Thirty species represent 82%of the total seed rain while an additional 175 species comprise the remaining18%. When we compared the adult community to the seed rain community within thesame plots, we found no apparent correlation between seed rain patterns andadult community structure for this year of study. Furthermore, only 49% of theadult tree community produced and dispersed seed into traps in this year. Morethan 100 species (52%) found in the seed rain represented long-distanceimmigrant seed rain. Seed rain was highly variable at several scales, bothspatially and seasonally, although seeds arrived in traps during eachcollectionperiod. Cluster analyses showed that traps within plots were seldom moresimilarto one another than traps between plots. While 82% of the tree species in thecommunity are thought to be animal dispersed, only 28% of all seeds that fellinto traps had been obviously handled (bitten, chewed, or passed)by animals. Tests for fruit and seed removal by predators or dispersers found5%or less removal rate from traps.     

Newly Discovered Gorilla Population in the Ebo Forest,Littoral Province,Cameroon

We report on a new population of gorillas discovered in November 2002 in the Ebo Forest, Littoral Province, Cameroon. We observed A group of q7 gorillas directly for 83 min, and they were in auditory range for 155 min. Further evidence of gorilla presence included 8 nest groups totaling 38 nests, distinctive feeding signs accompanied by footprints, and a gorilla cranium collected from the nearby village of Iboti. This newly discovered gorilla population is geographically intermediate between the 2 extant populations of western gorillas: Gorilla gorilla gorilla, the most populous gorilla subspecies living in Gabon, Equatorial Guinea, Congo-Brazzaville, Central African Republic and Cameroon to the south of the Sanaga River, and G. g. diehli or the Cross River gorilla, a small population of ca. 250 individuals on the Cameroon-Nigeria border. It is not possible to assign the new gorilla population to either subspecies on the basis of measurements of the single male cranium. Genetic analyses of freshly shed hairs, collected from gorilla nests, may help to resolve the taxonomic status of the Ebo gorillas.     

Insectivory by Gorilla gorilla gorilla in Southeast Cameroon

Our study extends quantitative analyses of insect-eating by gorillas (Gorilla gorilla gorilla) to Cameroon. During a 2-mo period (May–June 2001), we recorded and analyzed feeding traces on plants and insects and in gorilla feces. We found 180 feeding traces, 17% of which involved insectivory. Seventy-eight percent of the fecal samples (n = 36) contained insects. Ants were found in 61% of the samples, termites in 39%, while 56% of the samples contained remains of other insects. We added 14 new species to the known insect diet of western lowland gorillas. Overall, social insects are predominant. The choice of prey by the Ntonga gorillas gives new clues for the existence of cross-cultural differences among gorilla populations. A comparison of the overall frequency of insectivory with those at other sites in Central Africa indicate a possible effect of forest disturbance on the insectivorous behavior of gorillas. The study suggests the existence of temporal variation in ant- and termite-eating by gorillas.     

Invasion of West African cattle by the tick Amblyomma variegatum

Studies in Cameroon and Burkina Faso examined the invasion process of cattle by adult Amblyomma variegatum Fabricius (Acari: Ixodidae) ticks. Nearly all the ticks picked up in the pasture during grazing were found on the limb ends, near the hooves, where they temporarily attached. Then when the cattle lay down, the ticks moved from the feet towards the predilection sites, where they attached definitively. Many ticks disappeared during this displacement. All the female ticks and approximately 70% of the males were thus unable to attach to the predilection sites as long as the pioneer males had not attached and started to produce attraction-aggregation-attachment pheromones. Nevertheless, A. variegatum females and males attached to the feet in similar numbers during grazing, whether the cattle were already infested or not, indicating that stimuli originating from the hosts are powerful enough to attract both sexes. After attachment of the pioneer males, the number of ticks that successfully reached the predilection sites increased. However, even on infested animals, 40-50% of A. variegatum ticks found near the hooves after the grazing periods disappeared during the night following their capture. When moving from the temporary attachment sites towards the final ones, one-third of the ticks changed the individual host. Considering this two-stage infestation process, it is suggested that a targeted tick control, using a foot-bath, might greatly reduce cattle infestation. In particular, it could be effective in traditional herds, with animals grazing permanently during the day, lying down only once back in the night pen.     

Density and dispersal of the loaiasis vector Chrysops dimidiata in southern Cameroon

By mark-release-recapture experiments, we assessed the density of loaisis vectors, Chrysops dimidiata Wulp plus some Chrysops silacea Austen (Diptera: Tabanidae) and estimated their range of flight in the secondary forest of southern Cameroon. In 1993, the release point was at the centre of the study area and recapture points were at 1,100 m radius. In 1994, releases were on the periphery of the study area and recapture sites were 400-8,000 m from the release points. Results were concordant and showed Chrysops female densities of 785-3,682 flies/ km2. The theoretical flight range was < 6,000 m, with a maximum distance of 4,500 m observed. These results are considered promising for the use of vector control methods against loaiasis.     

American pika in a low‐elevation lava landscape: expanding the known distribution of a temperature‐sensitive species

In 2010, the American pika (Ochotona princeps fenisex) was denied federal protection based on limited evidence of persistence in low‐elevation environments. Studies in nonalpine areas have been limited to relatively few environments, and it is unclear whether patterns observed elsewhere (e.g., Bodie, CA) represent other nonalpine habitats. This study was designed to establish pika presence in a new location, determine distribution within the surveyed area, and evaluate influences of elevation, vegetation, lava complexity, and distance to habitat edge on pika site occupancy. In 2011 and 2012, we conducted surveys for American pika on four distinct subalpine lava flows of Newberry National Volcanic Monument, Oregon, USA. Field surveys were conducted at predetermined locations within lava flows via silent observation and active searching for pika sign. Site habitat characteristics were included as predictors of occupancy in multinomial regression models. Above and belowground temperatures were recorded at a subsample of pika detection sites. Pika were detected in 26% (2011) and 19% (2012) of survey plots. Seventy‐four pika were detected outside survey plot boundaries. Lava complexity was the strongest predictor of pika occurrence, where pika were up to seven times more likely to occur in the most complicated lava formations. Pika were two times more likely to occur with increasing elevation, although they were found at all elevations in the study area. This study expands the known distribution of the species and provides additional evidence for persistence in nonalpine habitats. Results partially support the predictive occupancy model developed for pika at Craters of the Moon National Monument, another lava environment. Characteristics of the lava environment clearly influence pika site occupancy, but habitat variables reported as important in other studies were inconclusive here. Further work is needed to gain a better understanding of the species’ current distribution and ability to persist under future climate conditions.     

海南蕨类植物自然分布及区系组成

海南岛现有蕨类植物种数约400种,分布基本上呈现西南部丰富,东北部贫乏的趋势,临高-琼中-万宁一线是其物种多寡的分界线,土壤、地形、地质多方面的共同作用形成这条分界线。海南岛蕨类区系组成复杂,且外来植物成分占据多数,马来西亚、印度、中南半岛和东亚植物区系成分在海南岛蕨类区系中占有较大比重。海南岛是现代蕨类发育的一个中心,多样的环境条件促成了蕨类植物的演化。