Mosquito (Diptera: Culicidae) diversity along a rainy season and edge effects in a riparian forest in Southeastern Brazil

Knowledge on the distribution of mosquito communities over time and across human-modified landscapes is important in determining the risk for vector-borne disease. The diversity of mosquitoes along a rainy season and edge effects were evaluated in a riparian forest in the Cerrado biome, Southeastern Brazil. Mosquito communities were sampled with Shannon traps in three distinct habitats (forest interior, forest edge and pasture) throughout an entire rainy season, comprising five sampling months (December 2015 to April 2016). A total of 13 549 mosquitoes belonging to 54 species were sampled. Mosquito species richness and abundance were greater in February, which coincided with the middle of the rainy season and just after the months with greater rainfall. Mosquito species richness did not differ among habitats for any particular month. In February, month when 74% of individuals were recorded, mosquito abundance was lower in the pasture compared with the forest edge and interior, which did not differ statistically from each other. Four of the six most abundant mosquito species (which account for 93.5% of the sampled individuals) had more individuals collected in the forest edge, and 28 species were more abundant at the edge compared with 15 species in the forest interior. Months with high rainfall probably allowed the availability and maintenance of high-water level in breeding sites leading to a further increase in mosquito populations. While the pasture did not seem to have the ideal abiotic conditions and/or resources (e.g. food and breeding sites) for mosquito species, edge effects appear to favour mosquito populations. Therefore, the risk of mosquito-borne diseases is expected to be greater in the middle of the rain season at the riparian forest-pasture edge, when and where a greater number of disease-vectoring species are present.     

Optimising sampling methods for small mammal communities in Neotropical rainforests

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Influence of season on leaf litter ant (Hymenoptera: Formicidae) diversity in the locality of Minko'o (Southern,Cameroon)

Seasonality is known to influence ant activity in many tropical rain forests in the world such as South America and Africa. We surveyed ant fauna in the leaf litter in the locality of Minko'o. The work aimed to evaluate the effect of seasonal variation on the diversity and composition of litter ants. Ants were sampled from November 2015 to June 2017, using four sampling methods: visual capture, bait, pitfall trap and extraction. Species richness, Shannon diversity index and analysis of similarities were used to characterise diversity of ant communities between seasons. We collected 306 ant species, shared out between 56 genera and 11 subfamilies. Subfamilies Myrmicinae, Ponerinae, Dolichoderinae, Formicinae, Dorylinae, Cerapachyinae and Pseudomyrmecinae occurred in all the seasons. Species richness was highest in major dry season with 243 species followed by minor rainy season with 188, major rainy season with 177 species and finally minor dry season that recorded the lowest with 155 species. Kruskal–Wallis test showed that ant species richness did not differ between seasons (p > 0.05). Species diversity index indicated that diversity was the highest during minor dry season (H′ = 4.24), followed by the major dry season (H′ = 4.23), minor rainy season (H′ = 4.21) and lowest during major rainy season (H′ = 4.06). Eight most frequents ants have been recorded: Axinidris sp.1, Camponotus flavomarginatus, Monomorium guineense, Myrmicaria opaciventris, Odontomachus troglodytes, Carebara perpusilla, Paltothyreus tarsatus and Pheidole megacephala. Assessment of the seasonal effect on diversity reveals that dry season is richer and more diverse than rainy season and the season significantly influence the diversity of litter ants.     

Environment heterogeneity and seasonal effects in ground-dwelling ant (Hymenoptera: Formicidae) assemblages in the Parque Estadual do Rio Doce, MG, Brazil

This work aimed to explore the response of ant species assemblage to contrasting types of forests in a semideciduous stationary rainforest, in the Parque Estadual do Rio Doce, South Eastern Brazil. We compared antropomorphic borders of this park and natural ecotones, such as lake margins continuous with forests, as well as preserved forests far from ecotones. We investigated whether ground-dwelling ant species richness, abundance and composition would change according to forest types and ecotones. We expected greater species richness in interior tall forest, compared with low forest or ecotone habitats. In addition, we tested the effect of climate seasonality on ant assemblages found in each studied vegetation type. Each forest type was surveyed based on a minimum transect sampling unit of 150 m long summing up 30 pit-falls per unit. Two sampling events, one in dry season (September of 2001) and another in the rainy season (January of 2002) were performed. For both seasons, tall forest presented greater total number of ant species, however lower mean ant species and abundance per trap than other forest types, thus corroborating the prediction that ecotones might present high alpha diversity. Mean species richness and abundance did not differ between interior low forest and lake edge, or between these habitats and reserve border. In general, species composition were not clearly defined by forest types. Results here found suggest that species loss or community dominance by generalist species, eventually due to deforestation, is probably a much greater problem than previously thought. However, to understand patterns of insect species diversity and distribution in tropical ecosystem should be taken in account much more comprehensive, spatially explicit sampling designs.     

A comparison of pitfall traps with bait traps for studying leaf litter ant communities.

A comparison of pitfall traps with bait traps for sampling leaf litter ants was studied in oak-dominated mixed forests during 1995-1997. A total of 31,732 ants were collected from pitfall traps and 54,694 ants were collected from bait traps. They belonged to four subfamilies, 17 genera, and 32 species. Bait traps caught 29 species, whereas pitfall traps caught 31 species. Bait traps attracted one species not found in pitfall traps, but missed three of the species collected with pitfall traps. Collections from the two sampling methods showed differences in species richness, relative abundance, diversity, and species accumulation curves. Pitfall traps caught significantly more ant species per plot than did bait traps. The ant species diversity obtained from pitfall traps was higher than that from bait traps. Bait traps took a much longer time to complete an estimate of species richness than did pitfall traps. Little information was added to pitfall trapping results by the bait trapping method. The results suggested that the pitfall trapping method is superior to the bait trapping method for leaf litter ant studies. Species accumulation curves showed that sampling of 2,192+/-532 ants from six plots by pitfall traps provided a good estimation of ant species richness under the conditions of this study.     

Are conservation units in the Caatinga biome,Brazil, efficient in the protection of biodiversity? An analysis based on the drosophilid fauna

Biodiversity is believed to be low in regions with vegetation that has adapted to water stress. Additionally, there is little interest by authorities in establishing and expanding conservation units in these areas. In Brazil, the Caatinga and the Cerrado biomes comprise this xerophilous vegetation. In both, climate is tropical and the dry season is long and well-defined. The Caatinga is the Brazilian biome with the smallest area protected by conservation units. This study evaluates the efficacy of conservation units in the Caatinga biome based on abundance and richness of drosophilids. Flies were collected inside and outside these areas. In total, approximately 23,000 flies of 32 species were collected in six conservation and six non-conservation sites. Two non-described species occurred exclusively inside protected areas, underlining the importance of conservation efforts in the maintenance of biodiversity. Other species were recorded exclusively outside conservation areas, which emphasizes the importance of establishing and expanding conservation units in the Caatinga. Native species were significantly more abundant inside conservation units, though the richness was similar in protected and non-protected areas. Abundance of exotic species outside conservation areas was statistically different in comparison with that of native ones.     

北京市珍珠泉乡不同昆虫采集方法采集效果对比分析

为了探究科研调查中不同昆虫采集方法的采集效率差异,在北京珍珠泉乡不同的生境类型中,采用样线法、马氏网法、灯诱法、陷阱法(糖醋液)4种采集方法进行昆虫采集,按生境类型对不同采集方法采集的昆虫进行统计分析.在实验中共采集昆虫3996头,隶属12目87科,其中在昆虫种类数量上,鳞翅目最多,其次是半翅目和鞘翅目;在数量上,半翅...     

Multi‐scale ant diversity in savanna woodlands: an intercontinental comparison

Ecological patterns and processes are highly scale‐dependent, but few studies have used standardized methodology to examine how scale dependency varies across continents. This paper examines scale dependency in comparative ant species richness and turnover in savannas of Australia and Brazil, which are well‐matched climatically but whose ant faunas have contrasting biogeographic origins. The study was conducted in savanna woodland near Darwin in northern Australia and Uberlândia in central Brazil. The sampling design consisted of eight 400‐m line transects, four in each continent, with eight pitfall traps located on and around each of 20 trees evenly spaced along each transect. Ant richness and species turnover were compared at three spatial scales: pitfalls associated with a tree, trees within a transect and transects within a savanna. The composition of the Australian and Brazilian savanna ant faunas was broadly similar at the subfamily level, despite the very low proportion of shared genera and species. The ground and arboreal ant faunas were very distinct from each other in both savannas, but especially in Brazil. Overall ant abundance was almost three times higher in Australia than in Brazil, both on the ground and on vegetation, but overall species richness was higher in Brazil (150 species) than in Australia (93). There was no significant difference in the mean number of species per pitfall trap, but the mean species richness was significantly higher in Brazil than in Australia at both the tree and transect scales. We attribute these scale‐dependent intercontinental differences to biogeographical and historical factors in Brazil that have led to a large regional pool of arboreal species of rainforest origin. Our study underlines the importance of biogeographical context when conducting comparative analyses of community structure across biogeographical scales, and highlights the importance of process acting at regional scales in determining species richness in ant communities.     

Ant diversity decreases during the dry season: A meta-analysis of the effects of seasonality on ant richness and abundance

Tropical studies traditionally describe insect diversity variation throughout the year. The temporally structured responses of insect assemblages to climate seasonality vary across ecosystems due to gradients of resource availability and limiting ecological factors. These idiosyncratic responses might be particularly true across the vast geographical range of the Brazilian territory, including various environments that harbor one of the most diverse ant faunas worldwide. This study addressed the relationship between ant diversity and climatic seasonality, performing a quantitative review of the published data on ant diversity collected in Brazil. We investigated the seasonality effect on ant abundance and richness described in the literature in 47 papers published between 2000 and 2018. These studies were developed mainly in the Atlantic Forest biome and collected ants with pitfall traps on the soil/litter stratum. We initially carried out a vote-counting procedure by comparing the number of significant results describing seasonal differences in the ant assemblage. We found that most papers described a similar pattern of ant abundance, richness, and species composition between seasons. However, when we performed a meta-analysis, we observed a clear pattern of higher ant abundance and richness in the wet/summer season compared with the dry/winter season. Our meta-analysis reveals that the ant diversity decreases in the dry season, strongly in the Cerrado biome. Additionally, we point out differences in the sampling effort across biomes, indicating the need for further investments in studies focused on temporal diversity patterns, including seasonal effects, on the insect assemblage in biomes less investigated so far. Abstract in Portuguese is available with online material.     

Rainfall Influences Ant Sampling in Dry Forests

The standardized 'Ants of the Leaf Litter' protocol aims to facilitate the use of ground-foraging and litter-dwelling ants in biodiversity assessment and monitoring programs. It was initially developed to characterize assemblages from tropical rain forests and is based on two main techniques: Winkler extractions and pitfall traps. Here, we tested to what extent this protocol was adapted to tropical dry forests and affected by the rainfall regime. Our 10 study sites were located along an aridity gradient (average annual rainfall: 350–1300mm) in the Gran Chaco. The number of species collected per sampling effort increased with aridity for pitfalls but followed an opposite trend for Winkler samples. This trend could be explained by the low daytime foraging activity in the leaf litter during drought periods. In arid and semiarid regions the good performance of pitfalls was probably related to their 24-h operation and to the attractiveness of the water they contained. Our results stress that the Winkler method used in the Ants of the Leaf Litter protocol may not be cost-effective during periods of drought and may lead to severe underestimations of litter ant diversity in tropical dry forests.     

Effects of Season and Vegetation Type on Community Organization of Dung Beetles in a Tropical Dry Forest1

Dung beetles are important components of most terrestrial ecosystems. In tropical rain forests, dung beetle communities can be very rich in number of species and individuals, and they are known to be useful bioindicators of habitat disturbance. In contrast, very little is known about the organization of dung beetle communities in tropical dry forests. The aim of this study was to describe in detail the dung beetle community of a Mexican tropical dry forest and to assess the relative importance of rainfall seasonality and forest structure in affecting the temporal and spatial dynamics of this community. Dung beetles were captured with pitfall traps at the beginning of the rainy season, the middle of the rainy season, and the middle of the dry season, in two distinct forest types: deciduous forest (DF) and semideciduous forest (SDF) at the Estación de Biología Chamela. Both rainfall seasonality and forest structure affected the community organization of dung beetles. During both rainy periods, 14 species were captured, but only three during the dry season. Dung beetles captured during the dry season were only found in the SDF. When comparing the beginning and the middle of the rainy season, differences in abundance and guild structure were also observed between both periods and between forest types, but these differences were much less pronounced.     

Is pitfall trapping a valuable sampling method for grassland Orthoptera?

Common methods to assess diversity and abundance of Orthoptera are sweep netting, transect counts and box-quadrat sampling. Pitfall trapping, by contrast, is rarely used, and the value of this method is still being questioned. In 2008, we studied Orthoptera species richness and abundance in five vegetation types along a gradient of dune succession on the Baltic Sea island of Hiddensee (NE Germany) by comparing transect-count and pitfall-trapping data. Using transect counts, 12 species were detected in the study area. With pitfall traps, three chorto- and thamnobiont Ensifera species (C. dorsalis, M. roeselii and T. viridissima) were not caught at all, and it was only in low-growing and sparsely-vegetated grey dunes that all present species were detected. With pitfall traps, the proportion of present species recorded strongly declined with increasing height and density of the vegetation type. Assuming that transect counts are a good proxy for relative Orthoptera densities, densities ascertained by pitfall traps are strongly biased by vegetation structure and locomotive behaviour of the species. More than 80% of all individuals were caught in sparsely-vegetated grey dunes. Frequency patterns of the species also differed. Using pitfall traps, especially chortobiont species were significantly underrepresented. Qualitative and quantitative sampling of Orthoptera using pitfall traps seems only reasonable in habitats with low and sparse vegetation and a high proportion of geobiont species.     

Using dung beetles to evaluate the conversion effects from native to introduced pasture in the Brazilian Pantanal

The Pantanal is the largest Neotropical seasonal freshwater wetland on Earth. Extensive livestock production has been the dominant economic land use activity of the Pantanal, where approximately 80 % of the land is occupied by native and introduced pastures. However, the impact of native pasture conversion into introduced pasture on the biodiversity of this biome is little understood. Here we evaluate the effect of native pasture to introduced pasture conversion on dung beetle communities. We sampled dung beetles in July 2011 (dry season) and January 2012 (rainy season), at four native pasture sites and four introduced pasture sites in Aquidauana, Mato Grosso do Sul, Brazil. The sampling was carried out using pitfall traps baited with three different bait types: carrion, cattle dung, and human feces. We sampled 7086 individuals, belonging to 32 species of 16 genera and six tribes of dung beetles. The abundance was similar among the pasture types. However, a higher species richness was found on the native pasture. Species composition also differed between the two pasture types in each sampling season. Additionally, the dominant functional guilds were different in the two landscapes. The result shows that the conversion of native grasslands into introduced pasture results in a decrease of species number and changes in species composition. These findings highlight the importance on native pasture to the conservation of dung beetle biodiversity in this ecosystem.     

Removing understory vegetation in oil palm agroforestry reduces ground-foraging ant abundance but not species richness

Ants are known to provide valuable ecosystem services in agricultural landscapes, including oil palm plantations. Their communities are less diverse and more uneven in oil palm compared with forest, and this may increase their vulnerability to disturbance. This study quantifies ant communities in oil palm agroforestry and experimentally tests their robustness to a common-practice high-disturbance management intervention: removing understory vegetation.Fieldwork was based at the Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) Understory Vegetation Project in Sumatra, Indonesia, where three treatments varying in their degree of understory vegetation management were established in 2014: (1) widespread herbicide was applied removing all understory vegetation (Reduced); (2) herbicide was applied to the harvesting paths and circles, and other vegetation was allowed to grow (Normal – control); (3) no herbicide was applied (Enhanced). We measured ground-foraging ant communities before and after the treatments were implemented, using pitfall traps over 324 trap-nights (a trap-night is one trap set for one night). We investigated how ant abundance, species richness, species evenness, beta diversity, and community composition differed between the treatments.We found 3507 ants across 68 species or morphospecies. Seven of these were highly abundant and accounted for 78% of individuals. Post-treatment ant abundance was lower in the reduced treatment (mean per plot: 84) than in the normal (159) and enhanced (131) treatments, which did not differ from each other. Species richness, species evenness, beta diversity and community composition were not affected by the vegetation treatments.We recommend that oil palm growers maintain understory vegetation in oil palm plantations to support ground-foraging ants. Though not tested here, this may also improve ant-mediated ecosystem services, such as pest control, seed dispersal, nutrient redistribution, and the maintenance of soil health. This study demonstrates that enhancing habitat complexity through management practices can support biodiversity in monocrop landscapes.     

Structure des communautés de Phanaeini (Coleoptera : Scarabaeidae) de Guyane : étude par échantillonnage massif au piège d’interception

Summary

Seasonality and community structure of Phanaeini (Coleoptera: Scarabaeidae) in French Guiana : study by mass sampling using large flight interception traps. Phanaeini is a neotropical tribe of scarabs mostly dung or carrion feeders, generally of large size. This paper analyses data collected with large window flight interception traps set on nine forest sites in French Guiana with a primary goal of biotic inventory. The study deals with three main questions: 1) What is the spatial structure of communities and are there some species indicators of secondary forests and others of pristine conditions? 2) What is the temporal structure of the community and is there a stable pattern of seasonality between years and sites? 3) Between close species, is there a temporal asynchrony? Our samples contain more than 9,700 identified specimens, nine complete year series on four sites including a four years continuous survey near Cayenne. We found a significantly lower diversity (Shannon and Simpson index) on the most fragmented and hunted sites. A more equitable repartition of species and a relative abundance of the larger species appear typical of undisturbed sites. Other observations reinforce the hypothesis that there is a fast and huge modification in Phanaeini community structure on the most accessible and disturbed sites. Seasonal pattern shows an abundance peak at the beginning of the rainy season (December or January), a medium abundance during the rainy season with sometimes secondary peaks and a low to very low activity during the dry season. The pattern is rather consistent between years but changes with sampling site. It is however different from the results of other studies using pitfall baited traps in Amazonian and Guyanese forests. These studies show much less clear temporal pattern or no seasonal change. There is no obvious pattern of niche sharing by phenological differences between species. The methodological differences of sampling between baited traps and window flight traps are eventually discussed. Due to its passive way of collecting, interception trap is considered as quite relevant for studying flight activity spatio-temporal patterns of Scarabaeinae. This aspect may explain some differences in seasonality patterns compared to other studies.     

Patterns of Ant (Hymenoptera: Formicidae) Richness and Relative Abundance along an Aridity Gradient in Western Venezuela

In xeric ecosystems, ant diversity response to aridity varies with rainfall magnitude and gradient extension. At a local scale and with low precipitation regimes, increased aridity leads to a reduction of species richness and an increased relative abundance for some ant species. In order to test this pattern in tropical environments, ant richness and relative abundance variation were evaluated along 35 km of an aridity gradient in the Araya Peninsula, state of Sucre, Venezuela. Three sampling stations comprising five transects each were set up. Pitfall traps and direct collecting from vegetation were assessed per transect. Overall, 52 species, 23 genera, and 7 subfamilies of ants were recorded in the peninsula. The total number of species and genera recorded by both sampling stations and transects decreased linearly with increasing aridity. Total relative abundance was highest in the most arid portion of the peninsula, with Crematogaster rochai (Forel) and Camponotus conspicuus zonatus (Emery) (Hymenoptera: Formicidae) being the numerically dominant species. Spatial and multivariate analyses revealed significant changes in ant composition every 11 km of distance, and showed a decrease of ant diversity with the increase of harsh conditions in the gradient. Here, we discuss how local geographic and topographic features of Araya originate the aridity gradient and so affect the microhabitat conditions for the ant fauna.     

Effect of rain on trap building by Myrmeleon brasiliensis in a riparian woodland from the Cerrado biome in Brazil

In areas of the Cerrado biome (Brazilian savanna) with well‐defined rainy and dry seasons, changes in climate and landscape affect the abundance and seasonality of insects. Larvae of the antlion Myrmeleon brasiliensis (Návas) (Neuroptera: Myrmeleontidae) are predators that build traps in dry sandy soil to capture prey. Here we determined the effect of rain on trap building by M. brasiliensis larvae in a riparian forest in the Cerrado biome. Differences in population size and developmental stage were found between the rainy and dry seasons. In the laboratory, the effect of rain‐soaked soil on trap building was evaluated. Fewer antlion larvae were found in the rainy season. Moreover, a greater abundance of larvae in the final stage of development (third instar) was found in the dry season, whereas more first instars were found in the rainy season. The latter revealed that wet soil affects the trap building of the larvae, as smaller traps were built in the treatment with soaked soil (simulated rain), whereas the larvae in the control treatment (no rain) continued building traps with no change in size. The findings indicate that seasonality in the Cerrado biome exerts a short‐term influence on M. brasiliensis larvae (larvae build fewer traps) as well as a long‐term influence (association with life cycle).     

Leaf-cutting ant nests support less dense and impoverished seed assemblages in a human-modified Caatinga dry forest

Regenerating forests make up an increasingly large portion of tropical landscapes worldwide and regeneration dynamics may be influenced by leaf-cutting ants (LCA), which proliferate in disturbed areas and collect seeds for fungus culturing. Here, we investigate how LCA influences seed fate in human-modified areas of Caatinga dry forest. We evaluate the seed deposition and predation on Atta opaciceps nests, foraging habitat surrounding nest and control habitat away of nest influence of 15 colonies located along a forest cover gradient during the rainy and dry seasons. For each habitat, four 50-cm² plots were established and all seeds on the soil surface were collected along 1 year. We recorded 13,628 seeds distributed among 47 species and 36.57% of the total seeds did not show any sign of predation. Nest mound habitats supported low-density and species-poor seed assemblages, which were taxonomically distinct from the control habitats. These effects only occurred in the rainy season. The proportion of undamaged seeds were similar across the habitats. While forest cover did not influence seed assemblage in terms of species richness or seed predation, it did interact with habitat type via increments in seed abundance as forest cover increased across the nests. Forest cover also affected seed composition, but only in the rainy season. These results indicate that LCA decrease seed deposition in areas under their influence, particularly on the nest mounds. As LCA profit from human disturbance in the Caatinga, their role as seed ‘sinks’ should be enhanced in disturbed Caatinga patches, particularly during the rainy season, when most of the plant recruitment occurs. Our findings reinforce the importance of LCA as drivers of forest dynamics and resilience in human-modified landscapes.     

Ground spider diversity in the Kenting uplifted coral reef forest, Taiwan: a comparison between habitats receiving various disturbances

The effects of various disturbances on diversity and community structures of ground spiders in the Kenting National Park uplifted coral reef forest were investigated using pitfall traps. In each of the following five sampling sites, ten trap stations were established and were monitored once every month for a whole year: primary forest, primary forest with tourism activities, secondary forest, grassland with tourism activities and abandoned grassland. A total of 2237 adult spiders from 20 families and 110 species were collected, among which 86 (78.2%) were new or newly recorded species to Taiwan. Dominant species can be divided into two major groups according to temporal abundance variations: abundant in the dry season and abundant in the wet season. Habitat preference of 12 dominant species was assessed by comparing their relative abundance between sampling sites. Half of the species exhibited strong habitat preference and two species could only be found in habitats receiving no tourism disturbance. The Shannon–Weaver function, Simpson index and Evenness were not significantly different among the sites, suggesting that these sites had a similar community structure characterized by few dominant species and numerous rare species. However, the species composition differed considerably among the five sites. Results of a UPGMA analysis using pairwise Euclidean distance demonstrated that specimens from 50 trap stations can be divided into four major clusters: primary forest, secondary forest, grassland I and grassland II. Also, among 110 species obtained, 61 were distributed in one sampling site only, and each site had between 11 and 16 unique species. In addition to species composition, foraging guild composition also differed significantly among sampling sites. These results suggest that the diversity of ground spiders in the KTNP uplifted coral reef forest is quite heterogeneous, and any management activity should consider the uniqueness of each habitat type.     

Evidence for longitudinal migration by a “sedentary” Brazilian flycatcher,the Ash‐throated Casiornis

The digitalization of museum collections and concurrent increase in citizen‐science initiatives is ushering in an era of unprecedented availability of primary biodiversity data. These changes permit a reappraisal of phenological patterns of tropical species. I examined spatio‐temporal variation in the distribution patterns of an ostensibly sedentary endemic Brazilian flycatcher, the Ash‐throated Casiornis (Casiornis fuscus), using both specimen data from museums and sighting records and rich media data from citizen‐science initiatives. I found compelling evidence for partial intratropical longitudinal migration to Amazonia and the Cerrado biomes from the species’ core range in the semi‐desert Caatinga biome and adjacent ecotones. These records from outside of the Caatinga were distributed during the height of the dry season from April to October, although the Caatinga is not entirely vacated at this time. This pattern of partial migration leads to a doubling of the distributional range of Ash‐throated Casiornises and strongly suggests that the species is a breeding near‐endemic of the Caatinga biome. This pattern was potentially previously not apparent because of significant biases in specimen collection between biomes, giving a false sense of abundance in the Brazilian Amazon.