Understory Birds Research Articles

Effects of roadside edge on nest predators and nest survival of Asian tropical forest birds

Creation of roadside forest edges can have indirect effects on forest bird communities, as edges can promote species detrimental to forest-nesting birds such as nest predators. We assessed species-specific rates of nest survival of understory birds, relative abundances of specific nest predators and predator-specific rates of nest predation relative to the distance from roadside forest edge in a dry evergreen forest in northeastern Thailand. During the breeding seasons (February–August) of 2014–2016 we searched for nests along two, 1-km transects which ran perpendicular from the edge of a five-lane highway into the forest interior. To assess nest predator species, video cameras were placed on active nests of understory birds and multiple techniques were used to assess the relative abundances of the documented nest predators. We found 306 active nests of 26 species and recorded 179 predation events from 13 species of nest predators. Distance to edge influenced the daily nest survival rates for four of seven focal bird species, with three species having higher survival rates nearer to the edge. Four of six predators had higher relative abundances in the forest interior. Rats and the Common Green Magpie (Cissa chinensis) had higher abundances nearer the edge. Snake detections were too few to assess statistically. Nest predation rates for the top three predators, Northern Pig-tailed Macaque (Macaca leonina), Green Cat Snake (Boiga cyanea) and Crested Goshawk (Accipiter trivirgratus) were significantly greater in the forest interior. The fourth-most important, Common Green Magpie, was the only predator responsible for more nest predation events closer to habitat edge compared to interior. Our study suggests that the impacts of edges on nesting success are highly dependent on the nest predator community and the species-specific responses of predators to edges.

<b>Structure of understory bird communities in Atlantic Forest Remnants in Northeastern Brazil

The Atlantic Forest in the State of Paraiba integrates the Pernambuco Center of Endemism. The present work investigated understory bird communities of three of its remnants using ten mist nets installed at eight different points of the forest understory of each area. We captured 333 birds of 44 species and 19 families. Bird richness and abundance did not differ between the three remnants (KW = 6.08; p = 0.04 and KW = 10.54; p = 0.004). The composition was little similar among them, and each area presented high species diversity and evenness. The most captured species were Arremon taciturnus (n = 40), Chiroxiphia pareola (n = 32) and Conopophaga melanops (n = 28). C. melanops has a local threat status of “vulnerable” and is considered endemic. Endangered and endemic species each represented 15.91% of the captures. Both Reserva Biologica Guaribas areas had the highest number of threatened species, while Reserva Particular do Patrimonio Natural Engenho Gargau showed the highest number of endemic and understory insectivorous species, which indicates a better quality status in comparison to the other two. These results show the importance of the remnants to bird conservation in Northeastern Brazil.

Matrix and area effects on the nutritional condition of understory birds in Amazonian rainforest fragments

Forest fragmentation, a result of deforestation, not only decreases the amount of habitat available for wildlife, but also increases the isolation of the remaining fragments and the area of edges surrounding them. Also, deforestation often leads to the creation of a dynamic regenerating matrix where cleared land is subsequently abandoned. Here we examine the effects of fragmentation and landscape change on the nutritional condition of Amazonian rainforest birds at the Biological Dynamics of Forest Fragments Project, near Manaus, Brazil. We analyzed ptilochronology-based measurements of feather growth rate in 12 species living in fragments within a dynamic landscape over 21 years. Ptilochronology serves as an index of nutritional condition by revealing energy available for maintenance over 1–2 weeks while the feather is grown, allowing intraspecific comparison across treatments. Feather growth rate decreased in fragments surrounded by young second-growth borders but increased as fragment size and age of adjacent second-growth vegetation increased. Results from this simple, yet informative, measure of nutritional condition reveal physiological impacts of land cover change, including the response of birds to changes occurring at both local and landscape levels. Our results highlight the importance of looking beyond presence/absence data to describe fragmentation effects, and support the value of landscape-scale approaches for the conservation of tropical forest biodiversity.

Does scale matter? The influence of three-level spatial scales on forest bird occurrence in a tropical landscape.

Consequences of habitat fragmentation for species occurrence are amongst the most important issues in landscape and conservation ecology. Empirical and theoretical studies have demonstrated that the total amount of habitat, patch size and connectivity have nonlinear effects on species survival on multiple spatial and temporal scales. Therefore, population models need to incorporate multiple scales, which can be extremely valuable to prioritizing conservation efforts in these changing landscapes. We tested how the amount and configuration of habitat affect understory bird species occurrence using fine to broad-scale habitat features. We used playback to sample birds in 13 Atlantic Forest fragments in Southeast Brazil. Microhabitat, local and regional landscape variables were tested against bird occurrence. Our results demonstrate that different bird species respond to different habitat scales. Sclerurus scansor, Xiphorhynchus fuscus, Automolus leucophthalmus, Drymophila ochropyga, Mackenziaena leachii, and Chiroxiphia caudata were most influenced by tree height and diameter (microhabitat characteristics), S. scansor, F. serrana and Pyriglena leucoptera were most influenced by forest cover and red-edge reflectance(local-scale metrics) and S. scansor, X. fuscus, D. ochropyga, P. leucoptera, F. serrana and M. leachii had area, core area and functional connectivity index (landscape features) as stronger predictors of species occurrence. Small forest fragments acted as corridors and increased overall connectivity of the entire community. The most effective means of maintaining long-term population connectivity of understory birds involves retaining both large and small areas, including forests with different micro-habitat characteristics. No management approach based on a single-scale would benefit all species. Implementing multiscale conservation strategies are necessary for maintaining long-term viability of forest birds on tropical landscapes.

Tree monocultures in a biodiversity hotspot: Impact of pine plantations on mammal and bird assemblages in the Atlantic Forest

Forest plantations of fast-growing exotic species constitute an important economic activity in tropical and temperate regions of developing countries. Large areas of native forests and grasslands are being turned into tree plantations without assessing their impacts on natural communities. We evaluated the effects of replacing native forests by non-native pine (Pinus taeda) plantations on the diversity and composition of assemblages of terrestrial mammals and ground-dwelling and understory birds, in a forest productive landscape of the Upper Paraná Atlantic Forest of Misiones, Argentina. Camera-trap stations were deployed in three different “environments”: 53 in a continuous forest, 69 in forest fragments, and 62 in tree plantations. The evaluation focused on the effect of the environment, the structural complexity of the vegetation, the cost-distance (distance weighted by connectivity) to the continuous forest, the percentage of native forest within different radii, and the cost of human access (as a proxy for hunting pressure) on both mean species richness per station and species composition. Alpha diversity of the assemblages of each environment was estimated using Hill numbers (effective number of species): q0 = richness, q1 = number of common species and q2 = number of dominant species. Changes in community composition were evaluated by comparing the assemblages of the three environments using three similarity indices: Sorensen (q0 = similarity in species identity), Horn (q1 = similarity in common species), and Morisita-Horn (q2 = similarity in dominant species). For mammals and birds, richness was significantly higher in forest stations (both continuous and fragmented) than in those located in plantations. For both taxa, it also decreased with the distance to the continuous forest (but with a negative quadratic term in birds). Tree plantation stands contained biased and impoverished subsets of the original assemblages. Mammal composition was affected by the environment, the distance to the continuous forest, the proportion of native forest in the landscape, and human access. The bird assemblages of plantations were seriously affected, and their composition was also influenced by changes in vegetation structure. Alternative management practices (e.g. pruning, thinning) and landscape features can partially mitigate the negative effect of tree plantations on mammal and bird assemblages. Large areas of forest that function as population sources and forest fragments immersed in the matrix of plantations are strictly necessary to preserve the original native mammal and bird assemblages in the productive landscape. Promoting connectivity and improving hunting controls will also support their conservation.

Canopy bird assemblages are less influenced by habitat age and isolation than understory bird assemblages in Neotropical secondary forest.

Secondary forest habitats are increasingly recognized for their potential to conserve biodiversity in the tropics. However, the development of faunal assemblages in secondary forest systems varies according to habitat quality and species‐specific traits. In this study, we predicted that the recovery of bird assemblages is dependent on secondary forest age and level of isolation, the forest stratum examined, and the species’ traits of feeding guild and body mass. This study was undertaken in secondary forests in central Panama; spanning a chronosequence of 60‐, 90‐, and 120‐year‐old forests, and in neighboring old‐growth forest. To give equal attention to all forest strata, we employed a novel method that paired simultaneous surveys in canopy and understory. This survey method provides a more nuanced picture than ground‐based studies, which are biased toward understory assemblages. Bird reassembly varied according to both habitat age and isolation, although it was challenging to separate these effects, as the older sites were also more isolated than the younger sites. In combination, habitat age and isolation impacted understory birds more than canopy‐dwelling birds. Proportions of dietary guilds did not vary with habitat age, but were significantly different between strata. Body mass distributions were similar across forest ages for small‐bodied birds, but older forest supported more large‐bodied birds, probably due to control of poaching at these sites. Canopy assemblages were characterized by higher species richness, and greater variation in both dietary breadth and body mass, relative to understory assemblages. The results highlight that secondary forests may offer critical refugia for many bird species, particularly specialist canopy‐dwellers. However, understory bird species may be less able to adapt to novel and isolated habitats and should be the focus of conservation efforts encouraging bird colonization of secondary forests.

Sugarcane and Eucalyptus plantation equally limit the movement of two forest‐dependent understory bird species

AbstractHabitat fragmentation results in landscape configuration, which affects the species that inhabit it. As a consequence, natural habitat is replaced by different anthropogenic plantation types (e.g. pasture, agriculture, forestry plantations and urban areas). Anthropogenic plantations are important for biodiversity maintenance because some species or functional groups can use it as a complementary habitat. However, depending on plantation permeability, it can act as a barrier to the movement of organisms between habitat patches, such as forest fragments, reducing functional connectivity for many species. Anthropogenic plantations are becoming the most common land use and cover type in the Anthropocene and biodiversity conservation in fragmented landscapes requires information on how different plantation types affect the capacity of the species to move through the landscape. In this study, we evaluated the influence of the type and structure of plantations on the movement of two forest‐dependent understory bird species – plain antvireo (Dysithamnus mentalis) and flavescent warbler (Myiothlyps flaveola) – within a highly fragmented landscape of Atlantic Forest hotspot. Knowing that forestry plantation is assumed to be more permeable to dependent forest bird species than open ones, we selected six study areas containing a forest fragment and surrounding plantation: three with sugarcane plantation and three with Eucalyptus sp. plantation. We used playback calls to stimulate the birds to leave forest fragments and traverse the plantations. Control trials were also carried out inside the forest fragments to compare the distances crossed. We observed that individuals moved longer distances inside forest than between plantation types, which demonstrate that plantations do constrict the movements of both species. The two plantation types equally impeded the movements of the species, suggesting the opposite of the general assumption that forestry plantations are more permeable. Our results indicate that, for generalist species, plantation type does not matter, but its presence negatively impacts movement of these bird species. We highlight that plantations have negative influences on the movements of common bird species, and discuss why this is important when setting conservation priorities.

The abundance of bird species in three sections of Kwale District's coastal forests in Kenya

Abstract. Musila SN, Manohar S, Mango N. 2017. The abundance of bird species in three sections of Kwale District's coastal forests in Kenya. Ocean Life 1: 69-83. Specifically, the diversity of bird species in the three coastal forests of Kaya Gandini Important Bird Area, Kaya Mtswakara, and Mwache Forest Reserve, Kenya, was studied between October 2007 and August 2008. To survey the understory birds of each forest, three ringing stations separated by 200-500 m and two net lines (60 m (18m x 2, 12m x 2)) and (54m (18m x 3)) separated by 60 m were utilized. Twenty-two Timed Species Counts (TSCs) were conducted in the treetops of each forest to determine the bird population. 10 m2 plots were established at 50-meter intervals around the ringing locations and TSCs survey routes, with the plot centers 10 meters perpendicular to the paths. One hundred forty-one different bird species were documented across all locations; 93 were found in Gandini, 88 in Mtswakara, and 91 in Mwache. Common to all three sections were 41 bird species types (29%), accounting for 44%, 47%, and 45% of all bird species documented in Gandini, Mwache, and Mtswakara, respectively. Overall, 38 species of forest birds were registered across all forests, including 34 in Gandini and 25 in both Mtswakara and Mwache. Four globally endangered bird species and 14 endemics to the East African Coastal Biome were discovered across all forest types. There were no migrating birds in any of the three areas, even though they were all a part of the same forest. Although Gandini and Mtswakara were the most similar, all three locations shared a similar habitat structure. Bird populations in Mwache were affected by human activities such as firewood collecting, extraction of building poles (5-10 cm DBH) for domestic and commercial use, and quarrying. Gandini stands out as the most crucial location for avifauna conservation due to its greater diversity of Forest Specialist (FF), Forest Generalist (F), understory, globally threatened birds and EACB species. Due to their close vicinity and the significant number of overlapping forest birds and internationally vulnerable bird species, all three forests should be conserved or maintained as a single forest block to ensure the survival of the greatest possible number of bird species.

Building biodiversity: drivers of bird and butterfly diversity on tropical urban roof gardens

AbstractConservation of faunal diversity in highly urbanized landscapes is facilitated through the integration of anthropogenic and natural elements in urban green spaces. Roof gardens have the potential to provide resources for urban wildlife populations, yet they typically offer marginal ecological conditions relative to ground‐level habitat so it is necessary to identify the factors associated with focal taxa diversity and abundance to better inform their planning, design, and management. We conducted 20 monthly surveys of diurnal bird and butterfly visitors to 30 urban roof gardens in the tropical city‐state of Singapore. Sixty‐five site variables were evaluated for their relative importance to four community diversity metrics (species richness, Simpson's diversity, abundance, and functional dispersion) using a conceptual framework relevant to key stakeholders involved in roof garden planning, design, and management. Surveys from a total of 80 observation hours per site recorded more than 23,000 independent bird and butterfly encounters, comprising 53 bird and 57 butterfly species, which represents 13% and 18% of the avifauna and butterfly fauna in Singapore, respectively. Twenty‐four species (12 birds, 12 butterflies) were considered uncommon or rare. Reproductive behaviors (courtship, mating, or nesting) were noted in 35 species (20 birds, 15 butterflies). Understory birds were under‐represented, whereas understory butterflies were over‐represented compared to the overall Singapore fauna. Early morning noise showed strong negative linear correlations with diversity of both taxa, but this variable was also negatively associated with planted area, perhaps indicating proxy effects. Faunal diversity decreased asymptotically with height. Both managed and spontaneous floral diversity had clear positive effects on bird and butterfly diversity. Our results provide clear indication that tropical urban roof gardens can support a diverse subset of the bird and butterfly species assemblages. Site height, site area, and plant selection are suggested to play dominant roles in determining the attractiveness of roof gardens for wildlife. To a first approximation, roof gardens should be built lower than 50 m in height and contain planted areas larger than 1100 m2, as well as shrubs for birds and both managed and spontaneous nectar plant species for butterflies.

Seasonal variation of understory insectivorous birds and arthropods in an area of secondary Atlantic Forest, southeast Brazil

Seasonal variation of understory insectivorous birds and arthropods was investigated in an area of secondary Atlantic Forest, in southeast Brazil. Birds were captured with mist-nets and arthropods collected on the ground and foliage. A total of 348 captures of 243 individuais belonging to 15 bird species were obtained. Among 3416 arthropods, 1782 were collected on the ground and 1634 on the foliage. There was no significant variation in numbers of captures, individuais and bird species between dry and rainy seasons. However, arthropods were more abundant on the foliage during the dry season and on the ground in the rainy season. In this way, although the number of arthropods varied between seasons, it seems to be a sufficient resource to insectivorous birds feeding along the year. Besides, these birds can present some plasticity, changing the frequency of their foraging tactics repertoire in search of this feeding resource.

The importance of various stages of succession in preservation of biodiversity among riparian birds in northern Iran.

Every stage of succession may provide certain species with habitat requirements which are impossible in other stages of succession. This study attempts to evaluate the different stages of succession in terms of composition and structure of bird populations in Hyrcanian forests. Bird-habitat relationships were investigated by comparing vegetation characteristics in three successional stages including late, initial stage, and urban areas. Bird richness, diversity, and abundance were measured within a 25-m radius of each of the 120 sampling points in various stages of succession and urban areas from May to April (2014) in the Ziarat catchment. This study indicated that every stage of succession may support certain species. Based on bird-habitat associations along the various stages of succession, two groups were distinguished. Conventional comparative analysis separated two groups of understory birds: interior specialists and edge specialists. The interior-specialist group was positively correlated with the number of dead trees, tall trees with high values of dbh and height and canopy cover. In contrast, edge specialists groups mainly included terrestrial insectivores and were positively correlated with open area and shrub cover, and percentage of shrub cover between 1 and 2m in height. In summary, bird communities in Hyrcanian forests are highly dynamic in different vegetation covers suggesting that it is critical to increase diverse and abundant bird populations by conserving forests composed of mosaics of differently disturbed stands and mature forest patches.

Interspecific information use by army-ant–following birds

ABSTRACT Many animals use cues from other species to gather information about foraging opportunities, but engaging in such behavior requires balancing the potential benefits with the risks of increased competition. Neotropical birds that follow army ants are an appropriate system within which to study such eavesdropping behavior. Mixed-species groups of these understory birds congregate around ant swarms, where they forage on insects flushed by the ants. Obligate ant-followers have specialized behaviors to track ant swarms and may serve as information sources for facultative ant-followers. Owing to strong dominance hierarchies among species, however, the value of the information likely depends on the competitive relationship between the information provider and the eavesdropper. I investigated whether ant-following birds preferentially followed the songs of some antbird species over others, testing the prediction that the vocalizations of small (subordinate) ant-following species would attract more indivi...

Effect of human-induced forest edges on the understory bird community in Hyrcanian forests in Iran: Implication for conservation and management

Understanding bird species responses to edge effect is critical for effective forest ecosystem management. We studied changes in diversity, density and abundance of bird communities and environmental variables along an edge-interior gradient in the Saadabad-Naharkhoran forested area located within the Hyrcanian forests in Iran. Bird species and environmental variables were recorded within a 25m radius of 81 sampling points. Distance from the edge had significant impact on the abundance of some species including Great Spotted Woodpecker, Nuthatch, Treecreeper and bark gleaning birds. Among diversity and evenness indices, Simpson diversity index, Shannon diversity index, and N1 and N2 indices showed significant differences. Bird species showed different density patterns in our study. Some species such as Great Tit, Nightingale, Carrion Crow and Black Bird responded positively, and Great Spotted Woodpecker, Nuthatch, Wren and Blue Tit responded negatively to forest edge conditions. Bird community analysis divided bird species into two main groups. The first group includes Pheasant, Nightingale, Jay and Blackbird which showed positive responses to edge effect and had a high correlation with variables such as ground cover, number of trees with dbh 12–20cm and temperature. The second group consisted of Treecreeper, Great Spotted Woodpecker, Green Woodpecker, and Nuthatch which showed a negative response to the edge effect and a positive correlation with snag and log dbh, snag and log height, the number of trees with dbh 100–300cm, canopy cover, life litter depth and dbh of the trees. Results obtained from this study can be important in conservation and management of bird communities in remnant Hyrcanian forests. Also, protected areas in some parts of Hyrcanian forests can be selected based on environmental variables with a positive correlation with edge-eluding species.

IMPACT OF INTENSIVE SYLVICULTURE SYSTEM (TPTII/SILIN) ON UNDERSTORY BIRD COMMUNITY AT TRIWIRA ASTA BHARATA FOREST CONCESSION, EAST KALIMANTAN

The objective of the research is to identify the impact of Intensive Indonesian Selective Cutting and Replanting System (TPTII/SILIN) at dipterocarp production forest on understory birds community. Two forest blocks were compared, one with TPTII/SILIN and the other with Indonesian Selective Cutting and Replanting System (TPTI). At each forest block, 10 of 4 x 10 m mist nets were installed for three days and then they were moved to other spot for other three days. Mist nets were opened from 06:00 to 17:00 and monitored every 15 minutes. The trapped bird was identified and body size measured, then subsequently released. Data was analyzed by using Important Value Index, Shannon-Weinner Diversity Index, Margalef Species Richness Index, Simpson Dominance Index, and Sorensen Similarity Index. Number of individu, number of species, Shanon-Wiener Diversity Index were compared statistically using student t-test. The result showed that Ceyx erithacus and Arcahnotera longirostra hold the highest important value index in TPTI and TPTII/SILIN respectively. Bird abundance, Shannon-Weinner Diversity Index and Margalef Species Richness Index were lower in TPTI than TPTII/SILIN. Meanwhile Simpson Dominance Index was higher at TPTI than TPTII/SILIN. Statistical analysis for the data of the two forest blocks showed significant differences on number of individual, number of species and Shannon-Weiner Diversity Index. TPTII/SILIN was better in supporting understory birds community than those of TPTI.

Targeted reforestation could reverse declines in connectivity for understory birds in a tropical habitat corridor.

Re-establishing connectivity between protected areas isolated by habitat clearing is a key conservation goal in the humid tropics. In northeastern Costa Rica, payments for environmental services (PES) and a government ban on deforestation have subsidized forest protection and reforestation in the San Juan-La Selva Biological Corridor (SJLSBC), resulting in a decline in mature forest loss and the expansion of tree plantations. We use field studies and graph models to assess how conservation efforts have altered functional connectivity over the last 25years for four species of insectivorous understory birds. Field playback studies assessed how reforestation habitat quality affected the willingness of Myrmeciza exsul, Henicorhina leucosticta, Thamnophilus atrinucha, and Glyphorynchus spirurus to travel outside forest habitat for territorial defense. Observed travel distances were greatest in nonnative and native tree plantations with high understory stem density, regardless of overstory composition. In contrast, tree plantations with low stem density had travel responses comparable to open pasture for three of the four bird species. We modeled landscape connectivity for each species using graph models based on varying possible travel distances in tree plantations, gallery forests, and pastures. From 1986 to 2011, connectivity for all species declined in the SJLSBC landscape (5825km2 ) by 14% to 21% despite only a 4.9% net loss in forest area and the rapid expansion of tree plantations over 2% of the landscape. Plantation placement in the landscape limited their potential facilitation of connectivity because they were located either far from forest cover or within already contiguous forest areas. We mapped current connectivity bottlenecks and identified priority areas for future reforestation. We estimate that reforestation of priority areas could improve connectivity by 2% with only a 1% gain in forest cover, an impressive gain given the small area reforested. Results indicate key locations where spatial targeting of PES within the SJLSBC study region would protect existing forest connectivity and enhance the connectivity benefits of reforestation.

Functional Traits, Flocking Propensity, and Perceived Predation Risk in an Amazonian Understory Bird Community.

Within a community, different species might share similar predation risks, and, thus, the ability of species to signal and interpret heterospecific threat information may determine species' associations. We combined observational, experimental, and phylogenetic approaches to determine the extent to which evolutionary history and functional traits determined flocking propensity and perceived predation risk (response to heterospecific alarm calls) in a lowland Amazonian bird community. We predicted that small birds that feed myopically and out in the open would have higher flocking propensities and account for a higher proportion of positive responses to alarms. Using generalized linear models and the incorporation of phylogeny on data from 56 species, our results suggest that phylogenetic relationships alongside body size, foraging height, vegetation density, and response to alarm calls influence flocking propensity. Conversely, phylogenetic relationships did not influence response to heterospecific alarm calls. Among functional traits, however, foraging strategy, foraging density, and flocking propensity partially explained responses to alarm calls. Our results suggest that flocking propensity and perceived predation risk are positively related and that functional ecological traits and evolutionary history may explain certain species' associations.

DIVERSIDAD DE AVES DE SOTOBOSQUE EN BOSQUES TROPICALES, ÁREAS DE REGENERACIÓN NATURAL Y CULTIVOS DE PALMA AFRICANA EN HUMEDALES DEL LAGO DE IZABAL, GUATEMALA

Diversity of understory birds in tropical forests, natural recovery areas, and African oil palm crops in wetlands of the Izabal Lake, Guatemala. – African oil palm (Elaeis guineensis) crops have been identified as one of the most important threats to biodiversity of tropical forests. By mean of mist nets, species richness, diversity and structure of understory bird communities were studied in three vegetation types of a Neotropical wetland: humid tropical forest remnants, natural regeneration sites (“guamiles”), and African oil palm plantations. We captured a total of 734 birds of 106 species, belonging to 22 families. The habitat with highest diversity was forest (63 species and 329 individuals), followed by guamiles (62 species and 368 individuals) and finally oil palm plantations (11 species and 37 individuals). As expected, statistical differences were found among the studied habitats. Only 11% of species and 5% of the total captured birds were recorded in the African oil palm plantations. Our data show that oil palm cultivation represents a serious threat to biological diversity, making it a priority to generate guidelines based on scientific and conservation criteria.

Species Composition of Tropical Understory Birds in Threatened East African Coastal Forests Based on Capture Data

The East African coastal forests are subject of haphazard modification following anthropogenic pressures including tree cutting and clearing for agriculture. These activities, which are leading cause of habitat disturbance and species loss, are the major challenge in the management of sensitive wildlife species such as forest understory birds. This study investigated species composition of understory birds in the coastal forests of northeastern Tanzania to generate information for the management of the landscape and biodiversity in the area. Using mist nets, birds were trapped from core and edge habitats of representative forest patches. Trapped birds were classified to species level and categorized into bird guilds based on their levels of forest dependence. It was found out that species richness was influenced by forest patch size rather than level of habitat disturbance. Edge habitat was also found to be important in hosting higher number of forest understory birds, especially generalists—but this should be treated with caution because following habitat destruction that is ongoing in the study area, there is a danger of generalist wiping out specialist species due to competitive exclusion. Strict control measures to stop illegal tree cutting and agricultural activities near the forests were recommended for sustainable conservation of the understory birds in the forests.

Forest recovery in post-pasture Amazonia: Testing a conceptual model of space use by insectivorous understory birds

Understanding how animals move in a complex habitat mosaic is critical to biodiversity conservation as deforested lands and secondary rainforests accumulate in landscapes previously dominated by primary forests. To visualize the spatiotemporal dynamics of secondary forest recovery after pasture abandonment, we formed a conceptual model predicting avian space use during a temporal sequence beginning with deforestation and continuing through regrowth of old secondary forest. We tested five predictions of the model at the Biological Dynamics of Forest Fragments Project near Manaus, Brazil, using 73 radio-tagged understory insectivores of three species: two woodcreepers (Glyphorynchus spirurus, Xiphorhynchus pardalotus) and a terrestrial antthrush (Formicarius colma). Both woodcreepers provided evidence to support all predictions except that of greater path tortuosity in primary forest. Woodcreepers using secondary forest had larger home ranges, larger core areas, and faster movement rates than in primary forest. Further, the proportion of all species' core areas in primary forest exceeded the proportion of home ranges in primary forest. Formicarius colma showed a fundamentally different pattern than the woodcreepers: it essentially avoided secondary forest until 27–31years after pasture abandonment, at which point movements were indistinguishable from those in primary forest. Formicarius colma and other terrestrial insectivores show implastic spatiotemporal responses to recovering secondary growth, which we suspect contributes to the sensitivity of this guild to forest disturbance. Quantifying the value of marginal (and economically inconsequential) habitats such as secondary forest will be essential as land managers strive to maintain species persistence and connectivity in increasingly heterogeneous tropical landscapes.

Tropical countryside riparian corridors provide critical habitat and connectivity for seed-dispersing forest birds in a fragmented landscape

We conducted extensive mist netting and radio tracking of common frugivorous, seed-dispersing, and tropical forest-dwelling blue-crowned manakins (Lepidothrix coronata; BCMA) and white-ruffed manakins (Corapipo altera; WRMA) to study their habitat use, movements, breeding success, and seed dispersal potential in the fragmented landscape of southern Costa Rica. We obtained 1354 GPS locations from 20 BCMAs and 4040 GPS locations from 54 WRMAs we tracked. These birds were dependent on forest remnants and rarely moved through open habitats. This was more likely for WRMAs, which were slightly more tolerant of forest fragmentation. BCMAs preferred the local Las Cruces Forest Reserve and riparian corridors to smaller (<10 ha) and more isolated forest fragments. Radio tracking showed that both species used small forest fragments less than expected based on the birds’ sites of capture. In general, age ratios were immature-biased and sex ratios were female-biased, especially in riparian corridors, which enabled movements across the highly deforested landscape. Average daily nest survival rate was 92.2 % for BCMA nests and 97.1 % for WRMA nests. Both species used riparian corridors 3–5 times more than expected based on land cover, utilizing these corridors for food, water, breeding, and for moving across a highly deforested landscape. Although most movements of both species were 100 m or less, some birds moved more than 600 m between observations, sometimes in only 15 min. These manakins are abundant in the forest understory and are capable of dispersing seeds more than 600 m, helping the regeneration of native vegetation. Tropical countryside riparian corridors provide critical habitat and connectivity for these common seed-dispersing forest understory birds in a fragmented landscape.