Densities and dispersion of breeding Eurasian Hobbies Falco subbuteo in southeast England

Capsule Breeding Hobbies are more numerous in parts of southeast England than previously recognized, and in suitable habitat their breeding dispersion shows a regular pattern.

Aims To establish the density and breeding dispersion pattern of a population of Hobbies in southeast England.

Methods Surveys to locate every pair of Hobbies present were conducted in six study areas of between 48.0 and 201.2 km² in three counties in southeast England during 2005–10.

Results Each study area held between 7 and 21 pairs. Densities were higher than in previous studies conducted in Britain, at between 9.0 and 15.0 pairs per 100 km². Mean densities per unit area of non-developed habitat were also consistently higher than expected, at between 10.1 and 17.3 pairs per 100 km². The mean nearest known neighbour distances fell within the range 1.8–2.8 km. In all six study areas, pairs were regularly spaced. The majority (68.0%) of nesting and territorial pairs occupied sites in woodland.

Conclusions Breeding Hobbies are considerably more numerous in parts of southeast England than previously recognized, and numbers appear to be continuing to increase. Accurate population estimates for Hobbies require species-specific fieldwork.     

The breeding ecology and diet of the Hobby Falco subbuteo in southern England

Brecding densities, nest spacing, breeding habitat, productivity and diet are compared for Hobbies Falco subbuteo in the New Forest (heathland and largely coniferous woodland), river valley farmland and largely cultivated chalk downland. Regular spacing of nests was characteristic of the three areas. The New Forest had the highest density and lowest mean nearest neighbour distance for nests. Nest areas tended to be traditional. A high proportion of clutches were laid in disused nests of Carrion Crows Corvus corone which favoured the crowns of Scots pine Pinus sylvestris. Except on downland, the availability of such sites is unlikely to provide a constraint on Hobby distribution. In the New Forest, woodland clearings and valley mires were a feature of nest territories. There was no evidence of a habitat-related difference in fledging success.
Division of labour between sexes is marked. The male is responsible for provisioning the female throughout most of the breeding season as well as the young. During the incubation period many woodland passerines were taken but when feeding nestlings Hobbies tended to specialize on Swallows Hirundo rustica , House Martins Delichon urbica and, where they had access to more urban areas, Swifts Apus apus. By breeding relatively late, Hobbies take advantage of the availability of the juveniles of such prey on which to feed their young. Large insects supplemented the diet before egg-laying and when the Hedged young were learning to hunt.     

Breeding populations of the Hobby Falco subbuteo on farmland in the southern Midlands of England

Site occupancy, dispersion, density and nest sites of Hobbies Falco subbuteo were studied in two areas of farmland in the English southern Midlands between 1975 and 1983. Nesting ranges were identified within which Hobby nests were regularly found but which contained only one pair of birds in any one year. Breeding was not proved in all nesting ranges in every year. Within nesting ranges, birds sometimes used the same nest in consecutive years but nests were also commonly found more than 1 km apart in consecutive years. The mean nearest-known-neighbour distance between simultaneously occupied breeding sites was 4 6 km (range 20-9.6 km) and the minimum estimated densities of Hobbies in the two study areas were 3.8 and 4.8 nesting ranges/100 km. Small inter-nest distances, less than 30 km, were recorded only in the area with the lowest density. Hobbies nested in old Crow Corvus corone nests in a wide range of tree species but prior to the onset of Dutch elm disease, elms Ulmus spp. were probably used almost exclusively in one of the areas. It is concluded that substantial numbers of Hobbies nest on farmland north of the River Thames, outside what has been traditionally regarded as the main range of the species, and that previous published estimates of the size of the British population have been far too low.     

The role of termites in an equatorial rain forest ecosystem of West Malaysia

Summary To estimate the rate of consumption of leaf litter by termites on the forest floor of Pasoh Forest Reserve, Negeri Sembilan, West Malaysia, newly fallen leaves were marked and distributed on the ground. The loss of leaf area due to termites was determined either photometrically or visually. An average of 1.70% of the total surface area of the leaf litter disappeared per week in experiment 1 and 1.25% in experiment 2 in Plot 1, and 2.9% per day in other plots located near the mounds of Macrotermes carbonarius. The amount of leaf litter accumulation in the Ao layer was estimated at about 2.3 t/ha at Plot 1, so it was likely that an amount equivalent to about 32% of the daily leaf-litter fall was transported by M. carbonarius to their mounds in experiment 1 and 22% in experiment 2. It was considered that the termites had an important role in the detritus food chain of the ecosystem.Japanese Contribution No. 13, IBP Pasoh Project     

Evidence of Late Palaeocene-Early Eocene equatorial rain forest refugia in southern Western Ghats,India

Equatorial rain forests that maintain a balance between speciation and extinction are hot-spots for studies of biodiversity. Western Ghats in southern India have gained attention due to high tropical biodiversity and endemism in their southern most area. We attempted to track the affinities of the pollen flora of the endemic plants of Western Ghat area within the fossil palynoflora of late Palaeocene-early Eocene (∼55–50 Ma) sedimentary deposits of western and northeastern Indian region. The study shows striking similarity of extant pollen with twenty eight most common fossil pollen taxa of the early Palaeogene. Widespread occurrences of coal and lignite deposits during early Palaeogene provide evidence of existence of well diversified rain forest community and swampy vegetation in the coastal low lying areas all along the western and northeastern margins of the Indian subcontinent. Prevalence of excessive humid climate during this period has been seen as a result of equatorial positioning of Indian subcontinent, superimposed by a long term global warming phase (PETM and EECO) during the early Palaeogene. The study presents clear evidence that highly diversified equatorial rain forest vegetation once widespread in the Indian subcontinent during early Palaeogene times, are now restricted in a small area as a refugia in the southernmost part of the Western Ghat area. High precipitation and shorter periods of dry months seem to have provided suitable environment to sustain lineages of ancient tropical vegetation in this area of Western Ghats in spite of dramatic climatic changes subsequent to the post India-Asia collision and during the Quaternary and Recent times.     

Molecular phylogenetics reveal multiple tertiary vicariance origins of the African rain forest trees

Background  

Tropical rain forests are the most diverse terrestrial ecosystems on the planet. How this diversity evolved remains largely unexplained. In Africa, rain forests are situated in two geographically isolated regions: the West-Central Guineo-Congolian region and the coastal and montane regions of East Africa. These regions have strong floristic affinities with each other, suggesting a former connection via an Eocene pan-African rain forest. High levels of endemism observed in both regions have been hypothesized to be the result of either 1) a single break-up followed by a long isolation or 2) multiple fragmentation and reconnection since the Oligocene. To test these hypotheses the evolutionary history of endemic taxa within a rain forest restricted African lineage of the plant family Annonaceae was studied. Molecular phylogenies and divergence dates were estimated using a Bayesian relaxed uncorrelated molecular clock assumption accounting for both calibration and phylogenetic uncertainties.     

The ecology of tree reproduction in an African medium altitude rain forest

The occurrence of flowering and fruiting in tropical trees will be affected by a variety of factors, linked to availability of resources and suitable climatic triggers, that may be affected by increasing global temperatures. Community‐wide flowering and fruiting of 2526 trees in 206 plots were monitored over 24 years in the Budongo Forest Reserve (BFR), Uganda. Factors that were assessed included the size of the tree, access to light, the impacts of liana load, effects of tree growth, and variation between guilds of trees. Most flowering occurs at the end of the long dry season from February to April. Trees that had access to more light flowered and fruited more frequently. Pioneer and non‐pioneer light‐demanding species tended to reproduce more frequently than shade‐bearing species. Trees that grew faster between 1993 and 2011 also fruited more frequently. When examining all factors, growth rate, tree size, and crown position were all important for fruiting, while liana load but not growth rate was important in reducing flowering. Trees in BFR show a large decline in fruiting over 24 years, particularly in non‐pioneer light demanders, shade‐bearers, and species that produce fleshy fruits eaten by primates. The decline in fruit production is of concern and is having impacts on primate diets and potential recruitment of mahogany trees. Whether climate change is responsible is unclear, but flowering of the guilds/dispersal types which show declines is correlated with months with the coolest maximum temperatures and we show temperature has been increasing in BFR since the early 1990s.     

Spatial variability in the vegetation structure and composition of an East African rain forest

We conducted a study of spatial variation in tree community structure and composition in the Kakamega Forest of western Kenya. We compared the tree communities at two sites, Buyangu and Isecheno, separated by approximately 11 km of contiguous forest. All trees ≥15 cm d.b.h. were censused along transects covering 4.95 ha at Buyangu and 4.15 ha at Isecheno. The structure of the forest at the two sites was similar as mean d.b.h. was comparable and stem size class distribution did not differ significantly. However, species richness and stem density were both much higher at Buyangu. The disparity in stem density may be because of the greater abundance at Isecheno of a semi‐woody undergrowth species, Brillantaisia nitens Lindau, believed to inhibit the establishment of tree seedlings. Floristic composition varied strikingly between sites, with 52% of the species occurring only at one site. Densities of those species present at both sites often differed markedly between sites. Potential sources of these intersite differences in floristic composition include small disparities in rainfall, soil composition, elevation, and temperature as well as past differences in anthropogenic disturbance and in large mammal distribution and abundance. Floristic differences between Buyangu and Isecheno appear to be at least partly responsible for the substantial dietary differences between redtail monkeys (Cercopithecus ascanius Audebert) at these sites.     

Testing alternative mechanisms of evolutionary divergence in an African rain forest passerine bird

Abstract Models of speciation in African rain forests have stressed either the role of isolation or ecological gradients. Here we contrast patterns of morphological and genetic divergence in parapatric and allopatric populations of the Little Greenbul, Andropadus virens, within different and similar habitats. We sampled 263 individuals from 18 sites and four different habitat types in Upper and Lower Guinea. We show that despite relatively high rates of gene flow among populations, A. virens has undergone significant morphological divergence across the savanna-forest ecotone and mountain-forest boundaries. These data support a central component of the divergence-with-gene-flow model of speciation by suggesting that despite large amounts of gene flow, selection is sufficiently intense to cause morphological divergence. Despite evidence of isolation based on neutral genetic markers, we find little evidence of morphological divergence in fitness-related traits between hypothesized refugial areas. Although genetic evidence suggests populations in Upper and Lower Guinea have been isolated for over 2 million years, morphological divergence appears to be driven more by habitat differences than geographic isolation and suggests that selection in parapatry may be more important than geographic isolation in causing adaptive divergence in morphology.     

Nest Defence Behaviour of the Eurasian Kestrel (Falco tinnunculus) Against Human Predators

Man has become the main predator of many animal species. Because the characteristics of humans are quite distinct with respect to other terrestrial predators, the cost and benefits of defence behaviour may also differ. In this paper, we study the factors affecting nest defence behaviour of the Eurasian Kestrel ( Falco tinnunculus canariensis ) against a potential human predator throughout the reproductive cycle, as well as the balance of cost and benefits of this behaviour. The study population inhabits the island of Tenerife, and the nests are located on cliffs. The intensity of the defensive behaviour was unrelated to the frequency of human visits, prey abundance (Orthoptera, Coleoptera, lizards, birds and rodents), laying date, or number of offspring in the nest. Both males and females increased their defensive behaviour as the nesting period advanced, particularly when the chicks were older than 15 days. Moreover, the intensity of the defensive behaviour, especially of males, decreased when nests were more inaccessible. Although nest defence behaviour against humans appeared to be similar to those against other predators, the benefits are not clear because the probability of nest robbing was greater for these more aggressive pairs.     

Recovery of conservation values in Central African rain forest after logging and shifting cultivation

Secondary forests in Central Africa are increasing in importance for biodiversity conservation as old growth forests outside the few protected areas are disappearing rapidly. We examined vegetation recovery in a lowland rain forest area in Cameroon based on a detailed botanical survey of old growth forest and different-aged logging gaps (5–27 years) and shifting cultivation fields (10–60 years). Our analysis focuses on the long-term recovery of botanical conservation values by analysing trends in vegetation structure, species composition, species diversity and levels of endemism and rarity. In the total survey (4.25 ha), we recorded 834 species of which 23% were endemic to the Lower Guinea forest region. The proportion of endemic species was high in shrubs and low in herbs. Geographic range and (local) rarity were not significantly associated. The proportion of rare species (relative frequency <10%) was high in woody climbers and low in trees. In logging gaps, recovery of all vegetation characteristics was relatively quick (5–14 years). Recovery in shifting cultivation sites took longer (30–60 years). Endemic species were found to be highly sensitive to shifting cultivation practices and even after 50–60 years the level of endemism was still significantly lower compared to old growth forest. The proportion of rare species was not significantly different between disturbed sites and old growth forest. We conclude that secondary forests can contribute to biodiversity conservation, e.g. as buffer zones around protected areas. However, this contribution should be assessed differently between land use types and widespread versus endemic species.     

Population and genetic structure of the West African rain forest liana Ancistrocladus korupensis (Ancistrocladaceae)

Ancistrocladus korupensis D. W. Thomas & Gereau (Ancistrocladaceae) is a recently described liana from Cameroon. Its leaves yield the alkaloid michellamine B, which shows in vitro activity against HIV. The only known population is limited to ~15,000 ha within Korup National Park and its immediate surroundings. This study: (1) describes ecological patterns (geographic range, population density, stage and size class distributions, host tree characteristics, and seed dispersal patterns) of A. korupensis ; (2) quantifies patterns of genetic variation on species and subpopulation levels and fine-scale genetic structure; (3) describes variation in michellamine B content; and (4) makes conservation recommendations based on ecological and genetic data. Ecological data from 457 individuals from seven sites indicate that the A. korupensis population is dominated by canopy-climbing individuals. Population densities are low with values ranging from 2.5 to 12.9 individuals/ha. Reproduction data suggest limited seed dispersal, episodic fruiting, and no vegetative reproduction. Allozyme data indicate low genetic diversity with only 7.1% of the 14 loci polymorphic. Values for Hobs and He were 0.022 (_ 0.000 SE) and 0.041 (_ 0.000 SE), respectively. Wright's F statistics analysis suggests that A. korupensis is highly inbred (FIS = 0.455) with moderate levels of subpopulation differentiation (FST = 0.1153). Michellamine B content was best predicted by leaf type but also showed a significant relationship for stage class. The occurrence of rare, private alleles in most of the sites, low overall population size and density, and low availability of individuals for recruitment into the adult stage class are important considerations for the rational management of A. korupensis.     

Biometrics,possible breeding origins and migration routes of South African Grey Plovers,Pluvialis squatarola

Data on 355 Grey Plovers, Pluvialis squatarola, ringed in South Africa in 1971–1997 were analysed. Biometrics could not identify well-defined origins in the Siberian breeding grounds, but suggested the presence of birds from east of the Gydan Peninsula. Comparisons with populations spending the non-breeding period elsewhere did not allow a clear definition of the flyways used, although ringing recoveries indicated a migration route crossing the Mediterranean/Black Sea region during both southward and northward movements. First-year birds were on average smaller than adults. Bill length increased during the first year, reaching adult length by June. First-year wing length decreased by 4% before the outermost primary was shed, adult wing length did not change with season.