Host specificity and niche partitioning in flea-small mammal networks in Bornean rainforests

The diversity of ectoparasites in Southeast Asia and flea-host associations remain largely understudied. We explore specialization and interaction patterns of fleas infesting non-volant small mammals in Bornean rainforests, using material from a field survey carried out in two montane localities in northwestern Borneo (Sabah, Malaysia) and from a literature database of all available interactions in both lowland and montane forests. A total of 234 flea individuals collected during our field survey resulted in an interaction network of eight flea species on seven live-captured small mammal species. The interaction network from all compiled studies currently includes 15 flea species and 16 small mammal species. Host specificity and niche partitioning of fleas infesting diurnal treeshrews and squirrels were low, with little difference in specialization among taxa, but host specificity in lowland forests was found to be higher than in montane forests. By contrast, Sigmactenus alticola (Siphonaptera: Leptopsyllidae) exhibited low host specificity by infesting various montane and lowland nocturnal rats. However, this species exhibited low niche partitioning as it was the only commonly recorded flea from rats on Borneo. Overall complementary specialization was of intermediate intensity for both networks and differed significantly from random association; this has important implications for specific interactions that are also relevant to the potential spread of vector-borne diseases.     

Speciation in an avian complex endemic to the mountains of Middle America (Ergaticus, Aves: Parulidae)

The implementation of the phylogeographic approach for the study of biodiversity is critical in poorly sampled regions like the montane systems of Middle America, as complex evolutionary histories often result in the presence of independent lineages not properly considered by traditional taxonomy. Herein we sequenced 2370 bp of mtDNA (ND2, cyt b and ATPase) from 81 individuals of Ergaticus, a complex of birds endemic to the montane forests of Middle America. Although current taxonomy recognizes two species, the results reveal considerable genetic structure with the presence of four mtDNA lineages. Two of these lineages within Ergaticus ruber evidence the need of a revaluation of the species limits for this taxon. The general phylogeographic pattern can be explained as a consequence of relative isolation of the populations in different mountain ranges separated by low elevation barriers. Most population groups did not show signals of demographic expansion with the exception of the one corresponding to clade 1. The divergence time estimates point to the Pleistocene as an important time period for the diversification of this complex.     

Extensive color polymorphism in the southeast Asian oriental dwarf kingfisher Ceyx erithaca: a result of gene flow during population divergence?

Extensive plumage color polymorphism in the oriental dwarf kingfisher Ceyx erithaca has long intrigued ornithologists of the Indo–Malayan region. A large proportion of birds in Sumatra, Peninsular Malaysia and Borneo have plumages intermediate between the northerly black form and the southerly rufous form. We used molecular genetic techniques to investigate whether the pattern is likely caused by selection, contemporary hybridization or past introgression of genes. These data consist of DNA sequences of a mitochondrial gene (ND2) and five nuclear intronic loci. Phylogenetic analyses indicated that birds from continental southeast Asia (excluding the Thai–Malay Peninsula) are well differentiated from those from insular southeast Asia. This genetic distinction correlates well with a fixed difference in mantle coloration. Northern birds have black mantles and are consistently dark; southern birds, though highly variable in parts of the plumage, consistently possess a rusty brown mantle. Multivariate analyses of morphometric data also support clustering birds in the two groups defined by mantle coloration. Coalescent analyses suggest that gene flow occurred after initial population splitting. We hypothesized that the dynamic geography of the Indo–Malayan Archipelago, as driven by eustatic sea‐level changes related to glacial cycles, is responsible for extensive secondary contact, and gene flow, between the two color forms. Such periodic contacts, after initial separation of the populations, may be equally common in other geographically dynamic regions of the world.     

Avian population trends in the vulnerable montane forests of the Northern Appalachians,USA

Declines in bird populations are an important issue facing conservationists. Although studies have documented bird declines in a variety of lowland habitats, montane habitats are generally under represented in these investigations. Nevertheless, montane habitats are vulnerable because of their restricted geographic distribution as well as their exposure to environmental stressors such as atmospheric deposition and climate change. We surveyed birds at 768 points on 42 transects in montane spruce-fir forests the White Mountains of New Hampshire from 1993–2003. We detected 17,479 individuals of 73 species during this period, of which 10 were abundant enough for analyses. Of these 10 species, three exhibited significant population declines during the survey period: Yellow-bellied Flycatcher (Empidonax flaviventris), Bicknell’s Thrush (Catharus bicknelli) and Magnolia Warbler (Dendroica magnolia). Two of these species (Yellow-bellied Flycatcher and Bicknell’s Thrush) are considered ecological indicator species for montane spruce-fir forest. Declines in these species are an indication that recent concern on the part of conservationists about montane spruce-fir forest and the birds that inhabit them are justified. Our observation that these trends were not reflected in the National Breeding Bird Survey (BBS) analyses, and that one high priority species, the Bicknell’s Thrush, did not occur on BBS routes in New Hampshire during the survey period, argues for the importance of continued efforts to monitor these habitats.     

Elevational and geographic variation in army ant swarm raid rates

Geographic and elevational variation in the local abundance of swarm-raiding army ants has implications for the population dynamics of their prey, as well as affecting the profitability of army-ant-following behavior for birds. Here, we analyze systematically collected data on E. burchellii and L. praedator raid rates from geographically and elevationally wide-ranging sites, from lowland to montane forests. We show that raids of each species, and of both species pooled, reach peak densities at intermediate (premontane) elevations. These patterns suggest that army ant swarm raids are relatively abundant in Neotropical montane forests. Therefore, a paucity of ant raids does not explain the absence of obligate ant-following bird species, particularly true antbirds (Thamnophilidae), from montane forests. As army ant raids are relatively common at middle elevations, opportunities exist for other montane bird taxa to exploit army ant raids as a food source.     

Elevational plumage divergence in the Rufous-capped Babbler (Cyanoderma ruficeps) on a mountainous island

Environment plays an important role in the evolution of plumage coloration in birds and may also lead to sexual dichromatism if males and females face different selection pressures. Mountains exhibit varying ecological conditions along their elevation gradient that may impose divergent selection on elevationally widespread species, causing intraspecific plumage divergence. For example, UV light environments often vary between montane and lowland habitats, which could potentially cause differences in plumage UV reflection between birds occurring in the two types of habitats. However, few studies have examined the effects of elevation on plumage evolution. In this study, we quantified the plumage coloration of the Rufous-capped Babbler Cyanoderma ruficeps from montane and lowland habitats on a mountainous island, Taiwan. We aimed to examine whether their plumage showed differences associated with changing ecological environments across the elevational gradient. The results supported that the plumage of babblers occupying montane habitats had higher UV-reflectance and brightness than that of lowland birds, corresponding to the higher UV intensity in montane than lowland background light environments. The elevational differences were mainly found across the ventral parts of babblers that had relatively higher levels of UV reflectance compared with their dorsal parts. Alternatively, the brighter plumage, with higher UV-reflectance in montane than lowland birds, might be mediated by physiological adaptation to other ecological factors, such as parasite pressures. The elevational differences in plumage UV-reflectance and brightness were more dramatic in males than in females. However, we found significant sexual dichromatism in different body parts between montane and lowland babblers in which females had brighter or stronger UV-associated coloration than males, suggesting that sexual selection has little impact on babbler plumage. Our study suggests the importance of elevational divergent selection associated with UV light or other ecological environments on avian plumage evolution.     

Intraspecific differences in behaviour and physiology: effects of captive breeding on patterns of torpor in feathertail gliders

Studies on the physiology of mammals and birds are often conducted using captive-bred individuals and it is commonly assumed that the resulting data are representative of individuals living in the field. To investigate whether these assumptions are justified, we quantified morphological, behavioural, and physiological variables of the small marsupial feathertail glider (Acrobates pygmaeus). We compared three populations: (i) individuals from a cool-temperate, montane area, (ii) individuals form a subtropical, coastal area, and (iii) captive-bred individuals. Captive-bred gliders differed from the montane field gliders in morphology (longer tails and snouts), behaviour (longer activity periods) and physiology (less frequent torpor, shorter torpor, shallower torpor, higher metabolic rates during rest and torpor, and slower rates of rewarming). Most of these differences were also apparent between the captive-bred and the coastal field gliders. Unlike both field populations, captive-bred gliders often became hypothermic and were unable to rewarm. In contrast to the other physiological variables, the minimum body temperatures defended during torpor and the corresponding air temperatures differed between the montane and coastal field gliders, but were similar in coastal field and captive-bred gliders. Our study shows that morphology, behaviour and physiology can be strongly affected by breeding in or acclimation to captivity. The poor expression of torpor and thermal performance of the captive-bred gliders raises the question of whether they possess the physiological capability for survival in the wild. Even though captive breeding appears to have only minor effects on some physiological variables, data from captive-bred individuals should only be extrapolated to the field with caution.     

Diversity and faunistics of small moths (Microlepidoptera) in Bornean rainforest

Abstract.

• 1 Samples of Microlepidoptera (including Pyraloidea) collected at light in mangrove forest, lowland mixed dipterocarp forest, and montane oak-laurel forest in Borneo are compared.
• 2 Diversity (Williams' alpha) is very high in lowland forest, with a value of 414; it is lower, 226, in montane forest and very much lower, 47, at the edge of mangrove forest.
• 3 There is some evidence that apparent diversity increases with accumulation of samples.
• 4 Samples from the three forest types have very few species in common and come from separate assemblages.
• 5 Pyraloidea in samples taken 1km apart in lowland forest represent an assemblage common to the two sites but Microlepidoptera samples appear to represent slightly different assemblages.
• 6 There are no abundant species in lowland or montane forest: species with more than ten individuals comprised less than 4% of the samples. Four common species in mangrove forest accounted for 34% of the sample.
• 7 The proportion of Tineoidea, Gelechioidea and Pyraloidea is lower in montane forest than in lowland forest, while that of Yponomeutoidea and Tortricoidea is higher.
• 8 Just eight families of Microlepidoptera account for 90% of the species in samples from all three forest types.
• 9 The number of species of moths in Borneo is suggested to be in excess of 8500.

     

Comparative avian biodiversity of five mountains in northern Cameroon and Bioko

Larison, B., Smith, T.B., Fotso, R. & McNiven, D. 2000. Comparative avian biodiversity of five mountains in northem Cameroon and Bioko. Ostrich 71 (1 & 2): 269–276.

Endemism among birds is widespread in the montane forests of western Cameroon and the Gulf of Guinea. The region includes some of the rarest and most threatened species in Africa. We conducted avian surveys of four previously unsurveyed montane sites in northern Cameroon, including Mt. Ngang-Ha, Hoséré Vokré, Tchabal Gandaba, and Tchabal Mbabo, as well as the northern slope of Caldera de Luba on the island of Bioko, Equatorial Guinea. We report here on avian species richness and relative abundance, and evaluate the conservation potential of each site based on avifaunal richness. The montane forest on both Tchabal Mbabo and Caldera de Luba is extensive, while on the other mountains, the vegetation is not characteristic of montane forest, and consists primarily of small gallery forests embedded in savanna. Tchabal Mbabo and Caldera de Luba had the greatest species richness and abundance of montane birds, while Tchabal Gandaba had the greatest overall avian species richness and abundance. Few montane species were noted on Mt. Ngang-Ha and Hosere Vokre, and avian abundance was quite low on both mountains. Of the mountains surveyed, Tchabal Mbabo and Caldera de Luba exhibit the greatest potential for conservation based on extent of montane forest, and montane species richness and abundance.     

Short‐distance partial migration of Neotropical birds: a community‐level test of the foraging limitation hypothesis

Partial migration of tropical birds was long believed to be driven by variation in food abundance. Recent evidence from a partially‐migratory species suggests that in contrast, limited foraging opportunities at high elevations during severe wet season storms drives the most metabolically‐challenged individuals down to elevations where rainfall is lighter. Here, I test community‐level predictions of this hypothesis by examining the relationship between high‐elevation rainfall in the second half of the year and counts of migrant birds in lowland forest during late December each year from 1990–2009. I contrast results derived from analysis of all migrant species with both analyses of only the frugivorous migrants, and analyses of resident species. Counts of migrant species were on average positively associated with montane rainfall with differences of up to 72% in the numbers of birds counted in drier or wetter years. Frugivores and smaller birds responded more strongly to variation in rainfall compared to the broader migrant species pool. Interestingly, counts of resident species were also higher following wetter montane wet seasons. Results of analyses exploring the cause of resident responses were not consistent with climatic effects on breeding productivity or short‐term weather effects on detectability. Results were, however, consistent with cryptic down‐slope migration of individuals breeding at higher elevations augmenting lowland resident populations in wet years. These results suggest that changes in rainfall amount, storm intensity, and timing of severe weather events would lead to large increases in or losses of an important behaviour.     

Multilocus analysis of the evolutionary dynamics of rainforest bird populations in Southeast Asia

Sundaland has a dynamic geographic history because its landmasses were periodically interconnected when sea levels fell during glacial periods. Superimposed on this geographic dynamism were environmental changes related to climatic oscillations. To investigate how tropical taxa responded to such changes, we studied the divergence and demographic history of two co-distributed rainforest passerine species, Arachnothera longirostra and Malacocincla malaccensis. We sampled birds primarily from Borneo and the Malay Peninsula, which straddle the now-submerged Sunda shelf, and analysed multilocus DNA data with a variety of coalescent and gene genealogy methods. Cross-shelf divergence in both species occurred well before the last glacial maximum, i.e., before the most recent land connection. However, post-divergence gene flow occurred, and it was more pronounced in A. longirostra (a highly vagile nectarivore/insectivore) than in M. malaccensis (an understory insectivore). Despite current habitat continuity on Borneo, the population of M. malaccensis in northeastern Borneo is substantially divergent from that on the rest of the island. The NE population experienced dramatic demographic fluctuations, probably because of competition with the other population, which expanded from western Borneo after the mid-Pleistocene. In contrast, the Borneo population of A. longirostra has little structure and appears to have experienced demographic expansion 16 kya, long after it had diverged from the Malay Peninsula population (630-690 kya). Malay Peninsula populations of both species have remained relatively stable. Overall, the most recent glacial period was not the chief determinant of the evolutionary dynamics of our study species, and in this respect, they are different from temperate species.     

Systematics of the Southeast Asian mongooses (Herpestidae,Carnivora): solving the mystery of the elusive collared mongoose and Palawan mongoose

Although recent molecular studies have clarified the phylogeny of mongooses, the systematics of the Southeast Asian species was incomplete as the collared mongoose Urva semitorquata and some debatable taxa (Hose's mongoose, Palawan mongoose) were missing in the analyses. We sequenced three mitochondrial (cytochrome b, ND2, control region) and one nuclear (beta‐fibrinogen intron 7) fragments of the Southeast Asian mongooses to clarify the systematic position of the different species and populations occurring in this region. Our results showed that the collared mongoose is closely related to the crab‐eating mongoose Urva urva, these two species forming a sister‐group to the short‐tailed mongoose Urva brachyura. Despite Sumatran collared mongooses having a peculiar orange phenotype, we showed that they exhibited very little genetic divergence to individuals from Borneo. In contrast, the populations of the short‐tailed mongoose from Borneo were strongly divergent to those from Peninsular Malaysia and Sumatra, and these might represent separate species. Within the crab‐eating mongoose, we observed little geographical genetic structure. Our study suggests that Hose's mongoose is not a valid species. The Palawan mongooses did not cluster with the other populations of the short‐tailed mongoose; they were closer to the collared mongoose and should be included in this species. © 2014 The Linnean Society of London     

Effects of habitat,season, and age on winter fat storage by migrant and resident birds in Jamaica

Most small birds wintering in the tropics should show little subcutaneous fat deposition (SFD), except in habitats where food availability may decline in late winter or, for some resident species, to prepare for incubation or brooding fasts. However, these predictions need re‐examination in light of a new, precise, cross‐validated method to compare SFD among habitats and species. We sampled 170 Nearctic‐Neotropical migrant and 279 resident birds during early and late winter in 1993 and 1994 in Jamaica, West Indies. Habitats, from greatest to least expected availability of insect prey, were (1) mangrove forest, (2) montane/foothills forest and cultivation, (3) dry limestone forest, and (4) acacia scrub. Percent lipid, estimated from multiple‐regression models using visual fat scoring (0–8 scale), total‐body electrical conductivity, and a variety of morphometrics, was categorized by percentile ranks to determine if SFD varied by habitat, season, or age for all species, resident species, migrant species, and several individual species. SFD averaged ~ 13% total mass for all birds, ranging from 8–24% for well‐sampled species. The few bird species in acacia scrub, primarily two facultative long‐distance migrants, averaged ~ 26% lipid content, significantly more than birds in other habitats. Most birds did not vary in SFD in the other three habitats, although Common Yellowthroats (Geothlypis trichas) had greater SFD in dry limestone habitat than in montane habitat. Bananaquits (Coereba flaveola) and Jamaican Euphonias (Euphonia jamaica) in montane habitat, especially in early winter, had higher SFD than other resident species. Contrary to our prediction, adults and juveniles had similar SFD, with the exception of juveniles having more SFD than adults in acacia scrub habitat. Winter fat deposition (or, in some cases, muscle‐protein catabolism) in the tropics may be an overlooked strategy, potentially important as a hedge against fasting for floaters, facultative migrants, some territorial migrants in habitats with seasonal declines in food resources, and some resident species prior to breeding.     

Phylogeographic Pattern of the Striped Snakehead,Channa striata in Sundaland: Ancient River Connectivity,Geographical and Anthropogenic Singnatures

A phylogeographic study of an economically important freshwater fish, the striped snakehead, Channa striata in Sundaland was carried out using data from mtDNA ND5 gene target to elucidate genetic patterning. Templates obtained from a total of 280 individuals representing 24 sampling sites revealed 27 putative haplotypes. Three distinct genetic lineages were apparent; 1)northwest Peninsular Malaysia, 2)southern Peninsular, east Peninsular, Sumatra and SW (western Sarawak) and 3) central west Peninsular and Malaysian Borneo (except SW). Genetic structuring between lineages showed a significant signature of natural geographical barriers that have been acting as effective dividers between these populations. However, genetic propinquity between the SW and southern Peninsular and east Peninsular Malaysia populations was taken as evidence of ancient river connectivity between these regions during the Pleistocene epoch. Alternatively, close genetic relationship between central west Peninsular Malaysia and Malaysian Borneo populations implied anthropogenic activities. Further, haplotype sharing between the east Peninsular Malaysia and Sumatra populations revealed extraordinary migration ability of C. striata (>500 km) through ancient connectivity. These results provide interesting insights into the historical and contemporary landscape arrangement in shaping genetic patterns of freshwater species in Sundaland.     

REVISITING WALLACE'S HAUNT: COALESCENT SIMULATIONS AND COMPARATIVE NICHE MODELING REVEAL HISTORICAL MECHANISMS THAT PROMOTED AVIAN POPULATION DIVERGENCE IN THE MALAY ARCHIPELAGO

Sundaland, a biogeographic region of Southeast Asia, is a major biodiversity hotspot. However, little is known about the relative importance of Pleistocene habitat barriers and rivers in structuring populations and promoting diversification here. We sampled 16 lowland rainforest bird species primarily from peninsular Malaysia and Borneo to test the long‐standing hypothesis that animals on different Sundaic landmasses intermixed extensively when lower sea‐levels during the Last Glacial Maximum (LGM) exposed land‐bridges. This hypothesis was rejected in all but five species through coalescent simulations. Furthermore, we detected a range of phylogeographic patterns; Bornean populations are often genetically distinct from each other, despite their current habitat connectivity. Environmental niche modeling showed that the presence of unsuitable habitats between western and eastern Sundaland during the LGM coincided with deeper interpopulation genetic divergences. The location of this habitat barrier had been hypothesized previously based on other evidence. Paleo‐riverine barriers are unlikely to have produced such a pattern, but we cannot rule out that they acted with habitat changes to impede population exchanges across the Sunda shelf. The distinctiveness of northeastern Borneo populations may be underlied by a combination of factors such as rivers, LGM expansion of montane forests and other aspects of regional physiography.     

Current and historical factors influencing patterns of species richness and turnover of birds in the Gulf of Guinea highlands

Aim The aims of this paper are to: examine how current and historical ecological factors affect patterns of species richness, endemism and turnover in the Gulf of Guinea highlands, test theoretical biogeographical predictions and provide information for making informed conservation decisions. Location The Gulf of Guinea highlands in West Africa. Methods We used multivariate and matrix regression models, and cluster analyses to assess the influence of current climate and current and historical isolation on patterns of richness and turnover for montane birds across the highlands. We examined three groups of birds: montane species (including widespread species), montane endemics and endemic subspecies. We applied a complementarity‐based reserve selection algorithm using species richness with irreplaceability measures to identify areas of high conservation concern. Results Environmental factors influenced richness for all groups of birds (species, endemic species and subspecies). Areas with high and consistent annual rainfall showed the highest species and endemic richness. Species clusters for all groups of birds generally differentiated three major montane regions, which are topographically isolated. Multiple mantel tests identified these same regions for endemic species and subspecies. The influence of historical isolation varied by species group; distributions of endemic montane species and subspecies were more associated with historical breaks than were all montane species, which included widespread non‐endemic species. Main conclusions Our analyses indicated important geographical structure amongst the bird assemblages in the highlands and, therefore, conservation prioritization should include mountains from within the geographical subregions identified in these analyses because these regions may harbour evolutionarily distinct populations of birds.     

Neopsylla musseri n. sp. (Siphonaptera-Ctenophthalmidiae), a new flea from central Sulawesi (Indonesia)]

This flea is a montane flea, known from elevations of 1,700-2,300 m, that parasitizes endemic murid rodents. It represents a newly recorded genus and family of fleas for Sulawesi. Morphologically, the closest taxon to N. musseri n. sp. is N. sondaica Jordan, 1931 from Java; it is not closely related to N. luma Traub, 1954 from Borneo.     

Immunological effect of Moringa Oleifera leaf extract on vaccinated and non-vaccinated Hubbard chickens experimentally infected with Newcastle virus

In veterinary medicine plant based medicine is achieving a huge importance worldwide. This research was subjected to rectify the hydrophilic Moringa Oleifera alcoholic leaves extract could improve the immune system in vaccinated and non-vaccinated broiler Hubbard chickens experimentally exposed to Newcastle disease (ND) virus. Seventy five chicks with age one day old were splitted randomly into five groups equally in distribution with fifteen chick in each group. Group I was untreated unvaccinated (control negative group) while group IV was infected group with NDV (control positive group). The experimental Groups II and V were given daily oral treatment of hydrophilic alcoholic leaves extract of M. oleifera at 200 mg/kg body weight until day 21 of age while groups III and V were ND vaccinated with La Sota strain of ND vaccines. The four groups (II, III, IV, V) were infected with ND virus velogenic strain (VNDV) on day 21. Following to infection, Monitoring of birds were done daily for clinical signs, postmortem examination, morbidity and mortality. Cellular, humeral immune response and phagocytic activity were evaluated and the data were statistically analyzed using (SPSS). Total and differential cell numbers as well as Haemagglutination inhibition (HI) titre increased in the extract treated and vaccinated group which give total protection against NDV much more than treated and unvaccinated group. As a result it could be recommended to use M. Olifera extract from the first day of rearing in Hubbard chicken with ND vaccination program as a prophylactic treatment in protection of birds against ND infection.     

Evidence for altitudinal migration of forest birds between montane Eastern Arc and lowland forests in East Africa

Burgess, N.D. & Mlingwa, C.O.F. 2000. Evidence for altitudinal migration of forest birds between montane Eastern Arc and lowland forests in East Africa. Ostrich 71 (1 & 2): 184–190.

In this paper we assess the evidence for altitudinal movements of forest birds from the montane forests of the Eastern Arc mountains of East Africa to nearby lowland forest patches. For 34 montane species, including all the Eastern Arc endemics except Banded Green Sunbird Anthreptes rubritorques there is no evidence that they undertake seasonal movements to lower altitudes. An additional 26 montane species, of somewhat wider distribution, have been recorded at low (<500 m) altitudes during the cold/dry season (June to September). Most records of these montane birds at lower altitudes are from sites adjoining montane forest areas, although a few records are from lowland coastal forests at 100–240 km distance from montane areas. Only five of the 26 species (White-chested Alethe Alethe fulleborni, White-starred Forest Robin Pogonocichla stellata, Orange Ground Thrush Zoothera gurneyi, Evergreen Forest Warbler Bradypterus mariae and Barred Long-tailed Cuckoo Cercococcyx montanus) are regularly and commonly reported in the lowlands. They are also found in the lowlands in small numbers during the warm/wet season (October to February), when they may breed. The abundance of at least four, and probably more, of the forest birds with a more widespread distribution in the lowland and montane forests of East Africa declines greatly at high altitudes from the onset of the cold/wet season (February) and only increases again at the start of the warm/wet season (September). It is not known how far these species move as they cannot be easily separated from resident populations in lowland forests, and there are no ringing recoveries in different forests. Altitudinal migration of a proportion of the Eastern Arc avifauna is the most likely explanation for available data, although source-sink metapopulation theories may be helpful to explain the distributions of some species. As the movement of forest birds from the Eastern Arc to the lowland forests does not involve the rare endemics, they are of lower conservation concern, but the presence of montane and lowland forest may be important for the long-term survival of some more widely distributed forest species.     

Reversal of breeding season by lowland birds at higher altitudes in western Cameroon

Evidence of breeding during the dry season is given for 31 species of lowland birds in montane and semi-montane areas in western Cameroon. At least 17 of these species are shown to breed in the wet season at lower altitudes in West Africa. This reversal of breeding season may be due to the unusually heavy rainfall and high humidities which cause temperatures to decrease more rapidly with altitude than on mountains with drier climates. Low temperatures and heavy rainfall during the wet season prevent almost all montane species from breeding then, and affect similarly the lowland birds whose ranges overlap with those of montane birds. Breeding seasons of some lowland species in Cameroon have previously been considered prolonged, but separation of breeding records by altitude reveals clear seasonality.