Understorey Birds Research Articles

Understorey-nesting bird community responses to land use in the Korup National Park, an Afrotropical rainforest in South-Western Cameroon

Tropical forest biodiversity is under immense pressure due to a combination of global and local factors, including climate change and intensive land use. Birds play an important role in tropical forest ecosystems, contributing significantly to various ecosystem services. This study examined the impact of deforestation on the richness and abundance of understorey-nesting bird communities along a land-use intensification gradient in the peripheral zone of Korup National Park, Southwest Cameroon. We selected 30 sampling plots, each covering 4 ha, across five habitat types: near-primary forest, secondary forest, disturbed forest, cocoa/coffee plantations, and annual food crop fields. A total of 236 understorey bird nests were identified, representing 16 species. Our findings revealed that land use intensity significantly influenced bird species richness and abundance. Primary and secondary forests provided 75% of the nesting species and 71% of the nests. However, 19% of the species either appeared or increased in cocoa/coffee plantations and annual crop fields. Among the feeding groups, frugivores were the most sensitive group to deforestation. This study corroborates the adverse effects of forest destruction on birds communities and highlights the urgent need to address the rapid and extensive forest conversion occurring within Korup National Park. Allowing secondary forests to regenerate and preserving large patches of primary forest are essential strategies to help understorey-nesting bird communities mitigate the impacts of global changes.

Preliminary checklist on species composition of small mammals and birds in Marine Research Excellence Centre (MAREC), Pulau Tuba.

Located in Langkawi archipelago, Andaman Sea, Pulau Tuba is one of the islands that is densely protected as a forest reserve. We investigated and documented the species composition of small mammals and birds at two different sites in the forest of UiTM Marine Research Excellence Centre (MAREC). Wire cage traps were used to capture non-volant small mammals while mist nets were used to capture bats and understorey birds. A total of 35 individuals were captured consisting of four species of small mammals and four species of birds. Among the most abundant species captured were Rattus tiomanicus, Leopoldamys sabanus and Cynopterus brachyotis. The calculated Shannon diversity index was 1.58 indicating a low diversity of small mammals and birds within the area. Our current study stipulated that few individuals were caught due to the rainy season affecting Pulau Tuba during the study period. Further surveys and studies should be conducted for a longer period in different seasons so that more species of fauna can be documented.

Elevational patterns of species richness and community structure of understorey birds in an East African montane forest

AbstractMt. Kasigau is the northeastern most of the Eastern Arc Mountains global hotspot and harbours some endemic and threatened species, but little is known about bird community changes along its elevational gradient. We assessed the relationship between bird biodiversity metrics, season, human disturbance, elevation and temperature using mist‐netting data collected bi‐annually over a 10‐year period. Birds were sampled along the mountain's elevational gradient at four elevation levels (858, 1104, 1321 and 1547 m). Bird richness, diversity and evenness decreased with increasing altitude in both dry and wet seasons. Bird abundance declined with increasing elevation for the lower three elevation levels but peaked at the highest elevation. All diversity metrics were higher in the wet season compared to the dry season across all the years. Elevation had a greater effect on species assemblages than season, disturbance and temperature. Temperature had significant effects on abundance, diversity and richness, while disturbance had significant effects on diversity, evenness and richness. We conclude that bird assemblages in Mt. Kasigau are strongly shaped by elevational changes, while temperature and disturbance constitute important factors influencing bird conservation in the face of global warming. Our study highlights that elevation, disturbance and temperature influence bird assemblages along tropical elevational gradients.

Microhabitat requirements and occupancy of understorey bird forest specialists in Southern Mistbelt Forests of KwaZulu-Natal, South Africa

Monitoring species’ habitat selection and microhabitat requirements is vital for conservation and management, though studies on bird species’ habitat selection at relatively fine scales are often limited. Camera traps are useful techniques for studying bird communities, particularly elusive species that are challenging to document using traditional survey techniques. Here, we installed 184 camera traps during the non-breeding and breeding seasons to study understorey forest-specialist birds’ habitat requirements in 14 selected Southern Mistbelt Forest patches of KwaZulu-Natal, South Africa. We conducted foliage profile and forest structure surveys and an inventory of tree species richness to characterise forest microhabitat. Over 7182 trap days, we had 615 detections of ten understorey forest-specialists, most of which were insectivores. We modelled the occupancy of Lemon Doves (Aplopelia larvata), Chorister Robin-chats (Cossypha dichroa), Crested Guineafowls (Guttera pucherani), and Red-necked Spurfowls (Pternistis afer) to determine microhabitat characteristics that influenced detection probability and occupancy. The main microhabitat characteristics influencing forest-specialist understorey birds were tree species richness, leaf litter, and water cover. Forest structural characteristics that influenced the occupancy of the selected understorey forest-specialists were those within 5 m of the forest floor. Microhabitat requirements for the birds were species-specific, with seasonal variation for Lemon Doves. Conservation strategies should maintain undisturbed forest understorey to allow for the persistence of understorey forest-specialist bird species.

Bird communities in a selectively logged tropical montane forest are dominated by small, low-elevation species

Tropical montane forests are critical centres of terrestrial biodiversity and endemism, and face a range of threats, including selective logging and climate change. However, few studies have explored the joint influence of these threats, particularly in tropical mountains, despite how crucial it is to understand the cumulative impact of forest loss and climate change on biodiversity. We used mist-netting and bird ringing data from a long-term (10-year) community and population monitoring program to examine how the composition of the mid-elevation Eastern Himalayan understorey bird community changed in the mid-elevation primary and logged forest. Because logged forest is warmer than primary forest, we hypothesised that the bird community would shift towards lower elevation species, with a faster transition in logged forest. Further, because logged forest has lower arthropod abundance, we hypothesised that the primary forest community would have larger species than the logged forest community. Our study shows that the bird community in the logged forest shifted towards lower-elevation species than in the primary forest (although this was not statistically significant). Moreover, we found that smaller species were better able to colonise warmer logged forest, whereas larger species reached higher densities in primary forest. These trends are likely to be driven by climate change causing upslope range shifts and logged forest selecting for species that are likely to tolerate the consequently altered abiotic (higher temperatures) and biotic (lower resources) environment. These findings have significant implications for understanding the impacts of forest loss and climate change on biodiversity, particularly in tropical montane forests.

Taxonomic and functional structure of understorey bird assemblages on Amazonian seasonally flooded river islands

Abstract The seasonal inundation of the floodplains of the Amazonian rivers is a natural and strong environmental filter for biota. Its effects on the taxonomic and functional attributes of assemblages, however, remain poorly understood. We investigated the taxonomic and trait diversity of understorey bird assemblages on fluvial islands subject to dramatic seasonal flooding in the Amazon. Birds were captured using mist-nets on ten fluvial islands and at 17 sites in unflooded terra firme forests. We captured 1552 individuals of 116 bird species in 4144 net-hours. Average capture rates were similar between the forest types, but species diversity was higher in terra firme forests. The bird assemblages of the islands showed higher species dominance, with only three species accounting for 47% of the individuals captured. Functional space was occupied similarly in both bird assemblages, as indicated by functional dispersion indices (Fdis). In contrast, functional evenness (Feve) was lower in the river island assemblages indicating that the dominant species share similar traits. Functional divergence indices (Fdiv) showed substantial niche differentiation between the bird assemblages of the two forest types. Low inter-annual variability in avian taxonomic and trait diversity was observed in river islands, probably associated with the predictability of the flooding regime.

Understorey bird assemblages in selected environmentally sensitive areas (ESA) of Selangor, Peninsular Malaysia.

Environmentally Sensitive Areas (ESA) refer to areas that are of critical importance in terms of ecosystem services such as goods, services and life-support systems, such as water purification, pest control and erosion regulation. In addition, they also refer to areas that harbour the wealth of the nation's biodiversity. However, the classification of ESA in Malaysia is incomprehensible and lacks weightage on biological elements as the current classification is more centred on physical attributes. In order to enhance the existing classification of ESA by introducing biological elements, biological data are urgently required, especially for forest reserves and protected habitat. Hence, we conducted understorey birds surveys in three ESA rank II permanent forest reserves, located in northern Selangor as baseline information to strengthen the ESA classification. The surveys were carried out using mist-netting in three 400 m × 200 m plots. Alpha diversity indices were calculated and showed a significant difference in terms of diversity, composition and biomass of understorey birds between investigated sites. Analysis of similarity (ANOSIM) showed that bird assemblages from forest reserves designated as ESA rank II in Selangor, based on disturbances levels, have weakly diverged and SIMPER analysis has identified six species that contributed to 60% of the differences amongst the bird assemblages. The finding provides the first insight into understorey birds of the study sites and the importance of conserving and preserving ESA of permanent forest reserves, especially the small and fragmented forests.

Connecting Amazonian historical biogeography and local assemblages of understorey birds: Recurrent guild proportionality within areas of endemism

AbstractAimCurrent diversity patterns in local communities result from historical and contemporary events that operate at distinct spatial and temporal scales. However, the contribution of local and large‐scale processes in structuring species diversity remain a contentious topic in ecology. We investigated diversity patterns (species richness, composition and number of captures) of understorey bird assemblages in Amazonian unflooded (terra firme) forests. We sought to understand whether understorey bird assemblages in distinct areas of endemism show distinct patterns of diversity, and whether species replacements among areas of endemism occur while the proportion of species within guilds remains stable.LocationAmazonia.TaxonUnderstorey birds.MethodsTo investigate diversity patterns, we compiled studies that mist‐netted birds at 11 regions across seven Amazonian areas of endemism. We used coverage‐based rarefaction curves, non‐metric multidimensional scaling (NMDS) and created a heatmap based on the proportion of captures in each area of endemism to access patterns of richness, composition and captures of understorey birds, respectively. The relative variance (RVgp index) was calculated to investigate the existence of guild proportionality within each area of endemism.ResultsBird assemblages diverged across the seven areas of endemism, in terms of species richness, composition and captures. However, the proportion of species and individuals within guilds was similar among areas of endemism, indicating that species replacements across areas of endemism occur while maintaining the same ecological functions. Guild proportionality suggests that interspecific competition and resource availability are more important than environmental heterogeneity in structuring understorey bird assemblages.Main conclusionsThe similar proportion of species within guilds suggest that interspecific competition and resource availability are more important than environmental heterogeneity in structuring local assemblages, possibly via a process of limiting similarity in morphological and functional traits. The observed congruent structure in understorey bird assemblages across areas of endemism shows that coupled historical and ecological processes, operating at local to large scales, have led to current patterns of diversity and composition in Amazonian bird communities.

Impacts of selective logging on haemosporidian infection and physiological correlates in tropical birds

Tropical forest degradation affects host-parasite interactions, determining the probability of animals acquiring an infection. The activation of an immune response to fight off infections requires energy and other resources such as antioxidants which may be redirected from growth and reproduction. A key question is how selective logging—the most common form of tropical forest degradation—impacts the prevalence of avian haemosporidian infection and its correlated physiological responses (nutritional and oxidative status markers). We investigated the prevalence of Plasmodium, Haemoproteus, and Leucocytozoon parasites in 14 understorey bird species in lowland, logged and unlogged, old-growth forests of Borneo. Prevalences of infections were similar between selectively logged and unlogged forests. To explore nutritional and oxidative status effects of haemosporidian infections, we examined associations between infections and plasma proteins, plasma triglycerides, and multiple blood-based markers of oxidative status, testing for an impact of selective logging on those markers. Birds infected with Plasmodium showed higher levels of plasma proteins and non-enzymatic antioxidant capacity, and lower levels of plasma triglycerides and glutathione, compared with haemosporidian-free individuals. Conversely, birds infected with Haemoproteus showed no changes in nutritional or physiological markers compared with uninfected individuals. These results indicate higher metabolic and physiological costs of controlling Plasmodium infection, compared with Haemoproteus, possibly due to higher pathogenicity of Plasmodium. Selectively logged forests had no effect on the responses of birds to infection, suggesting that the environmental conditions of degraded forests do not appear to induce any appreciable physiological demands in parasitised birds.

Evolution in the understorey: The Sulawesi babbler Pellorneum celebense (Passeriformes: Pellorneidae) has diverged rapidly on land-bridge islands in the Wallacean biodiversity hotspot

Tropical islands hold great treasures of Earth's biodiversity, but these fragile ecosystems may be lost before their diversity is fully catalogued or the evolutionary processes that birthed it are understood. We ran comparative analyses on the ND2 and ND3 mitochondrial genes of the Sulawesi babbler Pellorneum celebense, an understorey bird endemic to Sulawesi and its continental islands, along with its morphology and song. Genetic, acoustic, and morphological data agree on multiple isolated populations, likely representing independently evolving lineages. The Sulawesi babbler shows signs of rapid speciation, with populations diverging between Central and Southeast Sulawesi, and even on land-bridge islands which were connected within the last few tens of thousands of years. The genetic divergence between Sulawesi babbler populations in this time has been around 33% of their divergence from sister species which have been isolated from Sulawesi for millions of years. This is likely facilitated by the Sulawesi babbler's understorey lifestyle, which inhibits gene flow and promotes speciation. Similar patterns of endemism are seen in Sulawesi's mammals and amphibians. This work highlights the undocumented biodiversity of a threatened hotspot, wrought by complex processes of speciation which interact with ecology and geology. Subspecific taxonomy has at times been controversial, but we argue that discrete populations such as these play a key role in evolution. Lying as they do at the heart of the biodiversity hotspot of Wallacea, these islands can reveal much about the evolution of biodiversity at all of its levels, from the gene to the ecosystem.

Effects of landscape context and vegetation attributes on understorey bird communities of cloud forest riparian belts

In recent decades land cover change resulting from different types of human activity has severely reduced the original area of tropical montane cloud forest (TMCF). Deforested landscapes in neotropical America commonly have a heterogeneous structure (i.e. landscape context) with increasingly small forest patches immersed in an agricultural matrix. Often, this matrix is not completely devoid of trees, but contain numerous and widely spread arboreal elements. Many of these elements are remnants of the original forest, such as arboreal riparian belts. In 14 riparian belts of TMCF in central Veracruz, Mexico, we assessed the relationship between the attributes of the bird community that uses these belts and their vegetation attributes, as well as with landscape structure in their vicinity at four different scales (within 250, 500, 750 and 1000 m). Bird richness and abundance in riparian belts were positively related with mean tree height. Regarding landscape context, the amount of urban area in the vicinity of each belt was positively related with bird abundance at the four scales studied, explaining between 14 and 31% of spatial variation. However, the abundance of forest interior birds was negatively related with urban area, explaining from 46 to 50% of variation. Both, local (tree height) and landscape characteristics (urban and forest cover) influence differentially bird abundance in riparian belts of cloud forest. Thus, both kinds of variables should be relevant for designing management plans aimed at enhancing the conservation of the native avifauna of the cloud forest and its ecosystem services within transformed landscapes.

Bird communities in African cocoa agroforestry are diverse but lack specialized insectivores

Abstract Forests are being converted to agriculture throughout the Afrotropics, driving declines in sensitive rainforest taxa such as understorey birds. The ongoing expansion of cocoa agriculture, a common small‐scale farming commodity, has contributed to the loss of 80% rainforest cover in some African countries. African cocoa farms may provide habitat for biodiversity, yet little is known about their suitability for vertebrate fauna, or the effect of farm management on animal communities. Here, we report the first in‐depth investigation into avian diversity and community composition in African cocoa, by assembling a dataset of 9,566 individual birds caught across 83 sites over 30 years in Southern Cameroon. We compared bird diversity in mature forest and cocoa using measures of alpha, beta and gamma diversity, and we investigated the effect of cocoa farm shade and forest cover on bird communities. Gamma diversity was higher in cocoa than forest, though alpha diversity was similar, indicating a higher dissimilarity (beta diversity) between cocoa farms. Cocoa farms differed from forest in community composition, with a distinctive decrease in relative abundance of insectivores, forest specialists and ant‐followers and an increase in frugivores. Within cocoa farms, we found that farms with high shade cover in forested landscapes resulted in higher relative abundance and richness of sensitive forest species; shady farms contained up to five times the proportion of forest specialists than sunny farms. Synthesis and applications. Sunny African cocoa farms were less able to support sensitive bird guilds compared with shaded farms in forested landscapes. Our findings support the notion that certain ecological and dietary guilds, such as ant‐followers and forest specialists are disproportionately affected by land‐use change. In light of the current push to increase cocoa production in sub‐Saharan Africa, our results provide policymakers opportunities for more wildlife‐friendly cocoa schemes that maximize avian diversity.

Habitat fragmentation differentially shapes neutral and immune gene variation in a tropical bird species.

Habitat fragmentation is a major cause of biodiversity loss, responsible for an alteration of intraspecific patterns of neutral genetic diversity and structure. Although neutral genetic variation can be informative for demographic inferences, it may be a poor predictor of adaptive genetic diversity and thus of the consequences of habitat fragmentation on selective evolutionary processes. In this context, we contrasted patterns of genetic diversity and structure of neutral loci (microsatellites) and immune genes (i.e., toll-like receptors) in an understorey bird species, the wedge-billed woodcreeper Glyphorynchus spirurus. The objectives were (1) to investigate forest fragmentation effects on population genetic diversity, (2) to disentangle the relative role of demography (genetic drift and migration) and selection, and (3) to assess whether immunogenetic patterns could be associated with variation of ectoparasite (i.e., ticks) pressures. Our results revealed an erosion of neutral genetic diversity and a substantial genetic differentiation among fragmented populations, resulting from a decrease in landscape connectivity and leading to the divergence of distinct genetic pools at a small spatial scale. Patterns of genetic diversity observed for TLR4 and TLR5 were concordant with neutral genetic patterns, whereas those observed for TLR3 and TLR21 were discordant. This result underlines that the dominant evolutionary force shaping immunogenetic diversity (genetic drift vs. selection) may be different depending on loci considered. Finally, tick prevalence was higher in fragmented environments. We discussed the hypothesis that pathogen selective pressures may contribute to maintain adaptive genetic diversity despite the negative demographic effect of habitat fragmentation on neutral genetic diversity.

The elevated mist‐net frame: A robust and versatile manoeuvrable design for capturing upper strata birds

Abstract Classic standard mist‐netting limits sampling to understorey birds flying <3 m above‐ground level. Methodological innovations targeting higher strata birds (and bats) are important for ecological studies, particularly in tropical forests. I present and evaluate a method of applying elevated mist‐net frames (EMF) up to ~25–30 m. I designed detachable mobile alloy frames for standard‐sized 3 × 6 m mist‐nets, weighing ~11 kg including fittings, and suspended by three‐point cable‐wire mounting. State‐of‐the‐art archery and fishing gear are employed for securing anchor lines, with hoisting applied by pulley, ropes and guys. Elevated mist‐net frame is assembled and detached by two–three team members within 15–20 min, and up‐down hoisting lasts 1–3 min. EMF excludes tree‐climbing and arboreal platforms, through versatile manoeuvring in lightly cluttered naturally open corridors. EMF costs are source and quantity dependent, and feasible to institutions and grant beneficiaries. Elevated mist‐net frame is a workable alternative or supplement to existing elevated mist‐netting applying poles, ropes and pulleys, owing to strength and durability, replicable construction and versatile manoeuvrability in upper strata. The EMF design demonstrates favourable prospects for high‐tech development, thus further innovations are recommended.

Impacts of selective logging on the oxidative status of tropical understorey birds.

Selective logging is the dominant form of human disturbance in tropical forests, driving changes in the abundance of vertebrate and invertebrate populations relative to undisturbed old-growth forests. A key unresolved question is understanding which physiological mechanisms underlie different responses of species and functional groups to selective logging. Regulation of oxidative status is thought to be one major physiological mechanism underlying the capability of species to cope with environmental changes. Using a correlational cross-sectional approach, we compared a number of oxidative status markers among 15 understorey bird species in unlogged and selectively logged forest in Borneo in relation to their feeding guild. We then tested how variation of markers between forest types was associated with that in population abundance. Birds living in logged forests had a higher activity of the antioxidant enzyme superoxide dismutase and a different regulation of the glutathione cycle compared to conspecific birds in unlogged forest. However, neither oxidative damage nor oxidized glutathione differed between forest types. We also found that omnivores and insectivores differed significantly in all markers related to the key cellular antioxidant glutathione irrespective of the forest type. Species with higher levels of certain antioxidant markers in a given type of forest were less abundant in that forest type compared to the other. Our results suggest that there was little long-term effect of logging (last logging rotation occurred ~15years prior to the study) on the oxidative status of understorey bird species. However, it is unclear if this was owing to plasticity or evolutionary change. Our correlative results also point to a potential negative association between some antioxidants and population abundance irrespective of the forest type.

Selective predation by the White-browed Warbler (Myiothlypis leucoblephara), a Neotropical understorey insectivorous bird

ABSTRACT The diet composition and feeding preference of Myiothlypis leucoblephara (White-browed Warbler, Parulidae) were investigated in an area of the Atlantic Forest, Brazil, based on fecal samples and availability of field arthropods. Hymenoptera Formicidae and Coleoptera were the predominant taxa in the diet, corresponding to more than 70% of all items. Myiothlypis leucoblephara exhibited a preference for prey types, mainly Formicidae and Coleoptera (λ = 0.123, p = 0.01), which are the proportionally more consumed taxa when compared to other types of prey. The species also showed preference for prey sizes, with arthropods of the size classes between 2 mm-6 mm being proportionally more consumed (λ = 0.214, p = 0.001). Although it forages predominantly on the ground, M. leucoblephara also preys on arthropods regularly on the foliage, which allows expanding the range of substrates exploited as well as obtaining different types of prey, probably favoring the differential consumption. On the other hand, the preference for intermediate size prey suggests foraging optimization, consuming feeding items with high energy-intake rate in relation to costs of predation. Whether the preference results from active selection by the birds or simply by the difficulty of finding less abundant items needs to be investigated.

Glucocorticoids link forest type to local abundance in tropical birds

Abstract Selective logging is a major driver of environmental changes in the tropics. Recently, there has been increasing interest in understanding which traits make bird species resilient or vulnerable to such changes. Physiological stress mediated by the steroid hormone corticosterone (CORT) might underlie changes in local abundance of species because it regulates a range of body functions and behaviours to maintain homeostasis in changing environments. We conducted a 3‐year study to assess (a) the variation in CORT levels in feathers (where CORT is deposited during the moult) of 10 understorey bird species across both unlogged old‐growth forest and selectively logged forest in Borneo, (b) how this variation is associated with within‐year variation in population abundance between forest types and (c) whether the difference in feather CORT (fCORT) between co‐specific populations living in unlogged and logged forests in 1 year is related with their difference in population abundance the following year. We used effect size estimates to measure standardized magnitude and direction of fCORT changes between unlogged and selectively logged forest. We found small to large effect sizes, indicating large among‐species variation in physiological acclimatization to changes in forest conditions. In 2016 and 2018, species with relatively higher fCORT in unlogged forest were relatively more abundant in logged forest in the same year; in 2017, species with relatively higher fCORT in logged forest were relatively more abundant in logged forest. Importantly, we found that for a given species, the difference in fCORT at year (x) between unlogged and logged forests was negatively related with a difference in its local abundance between the two forest types in the following year (x + 1). Our results point to glucocorticoid hormones as potential mediators of carry‐over effects on population abundance due to direct and indirect effects of silvicultural practices in tropical forests of Borneo, suggesting fCORT as a potential marker of population changes. A free Plain Language Summary can be found within the Supporting Information of this article.

Impacts of selective logging on avian phylogenetic and functional diversity in the Amazon

AbstractSelective logging is the most extensive land use threatening tropical forests worldwide, making our understanding of its impacts on biodiversity vital for the conservation of these hyperdiverse ecosystems. We investigated the effects of selective logging on the phylogenetic and functional diversity (FD) of Amazonian forest avifauna. We sampled the overall and the understorey bird community using point counts and mist‐netting, respectively, in logged and unlogged forests. The overall bird community showed significantly lower phylogenetic diversity (PD) and FD in logged than unlogged forests, but significantly higher standard effect size (ses) of PD, ses mean pairwise distance (MPD), mean nearest taxon distance (MNTD), ses functional MPD (sesfMPD) and functional MNTD (fMNTD) in logged sites. Evolutionary distinctiveness, sesMPD, sesFD, fMNTD and sesfMNTD of understorey birds were significantly higher in logged forests. Higher logging intensity affected some metrics negatively and others positively, although the relatively small changes in phylogenetic and FD suggest limited overall effects from logging at lower intensity. In combination, selective logging brings deleterious effects for some components of phylogenetic and FD of the overall Amazonian bird community. Nonetheless, selectively logged forests retain important avian diversity, underscoring their high conservation value. Relatively, low impacts of selective logging may be due to the reduced‐impact logging (RIL) techniques used, high connectivity with well‐preserved unlogged forests or focus on short‐term logging impacts. Because even low‐intensity RIL causes some losses in evolutionary history and functional traits, an optimal approach for conserving phylogenetic and FD requires incorporating some land‐sparing logging to protect more old‐growth patches within the logged matrix.

The effectiveness of point counts and mist-netting in surveying Afrotemperate forest bird community structure in South Africa

ABSTRACT Point counts and mist-netting are two frequently employed survey techniques used in assessing forest avian communities, although the reliability of these methods varies according to species composition and habitat. This study investigates how effectively these two methods survey forest bird community structures within South African Afrotemperate forests. Seven forests within the Eastern Cape were surveyed from 140 duplicate point count and 63 mist-netting stations. Both methods were compared for assessing species richness, as determined from bird atlas data. Generalised linear mixed-effect modelling was used to determine functional traits which most impacted species detection, and to identify detection biases for both methods. Both methods compared consistently across the seven forests, which shared similar community structure. Point counts detected 79.2% of the total diversity versus 41.0% using mist-netting, and mixed-effects modelling corroborated that species detection is more effective using point counts. All functional traits tested (body size, primary foraging stratum, feeding guild, habitat specialisation, and dispersal behaviour) affected detection outcome. Point counts better represented all aspects forest bird community structure, including mid- and understorey birds which are presumed to be better detected by mist-netting. Use of mist-netting only slightly enhanced diversity assessments, and combined survey efforts under-represented forest-edge foragers, woodland and grassland habitat generalists (~63.6% total diversity), large birds, Palaearctic migrants, and carnivores.

Fine-scale barriers to connectivity across a fragmented South-East Asian landscape in six songbird species.

Habitat fragmentation is a major extinction driver. Despite dramatically increasing fragmentation across the globe, its specific impacts on population connectivity across species with differing life histories remain difficult to characterize, let alone quantify. Here, we investigate patterns of population connectivity in six songbird species from Singapore, a highly fragmented tropical rainforest island. Using massive panels of genome‐wide single nucleotide polymorphisms across dozens of samples per species, we examined population genetic diversity, inbreeding, gene flow and connectivity among species along a spectrum of ecological specificities. We found a higher resilience to habitat fragmentation in edge‐tolerant and forest‐canopy species as compared to forest‐dependent understorey insectivores. The latter exhibited levels of genetic diversity up to three times lower in Singapore than in populations from contiguous forest elsewhere. Using dense genomic and geographic sampling, we identified individual barriers such as reservoirs that effectively minimize gene flow in sensitive understorey birds, revealing that terrestrial forest species may exhibit levels of sensitivity to fragmentation far greater than previously expected. This study provides a blueprint for conservation genomics at small scales with a view to identifying preferred locations for habitat corridors, flagging candidate populations for restocking with translocated individuals and improving the design of future reserves.