Forest Bird Species Research Articles

Effects of Forestry Transformation on the Species Level of Biodiversity in Poland’s Forests

Forest biodiversity is of particular importance for the world’s natural resources and for humans, so it is essential to observe the impact of forest management on its state. In this paper, the effects of Poland’s forestry evolution after 1945 on the forest biodiversity at the species level are interpreted based on four indicators (deadwood, species composition of forest stands, introduced tree species, and common forest bird species) and considering the two politically and economically different eras. In the era of socialism (1945–1989), the area share of broadleaved tree species increased intensively, with a steady predominance of single-species stands, the ongoing removal of deadwood, and a relatively slow increase in the area occupied by alien tree species. In the era of democracy (ongoing since 1990), there was a less intensive increase in the proportion of broadleaved species, an intensive increase in the stock of deadwood, an increase in the area of multi-species stands over that of single-species stands, as well as an increase in the value of the Forest Bird Index. However, an intensive increase in the area occupied by alien tree species, especially invasive ones, which negatively impact native wildlife, was also noticeable in the era of democracy. The dilemmas and problems related to the amount of deadwood in forests; the continued conversion of stands towards more complex ones; the presence of other invasive species; the consequences of climate change; the reduction in migration barriers for forest animals; and the provision of funding for biodiversity conservation activities need to be discussed and resolved or implemented further.

Protected Areas Do Not Outweigh the Species Richness or Functional Diversity and Traits of Birds in Brazil

Protected areas (PAs) are widely recognized as being essential for maintaining global biodiversity. In this study, I aimed to determine whether PAs support a greater richness of forest bird species than unprotected habitats and whether they exhibit functional diversity indices and traits comparable to those found in protected forests in the eastern Brazilian Semideciduous Atlantic Forest. I conducted bird surveys across 20 forest fragments of varying sizes (43 to 37,000 ha), 12 of which were legally designated as PAs. The results indicated that species richness was not significantly higher in PAs and that there were no significant differences in functional diversity indices and traits between unprotected and protected forests. In eastern Brazil, some forest remnants were designated as PAs merely because they were among the last remaining patches within a heavily fragmented landscape. Therefore, protected areas do not necessarily serve as accurate proxies for well-preserved habitats.

Comparing Historical and Contemporary Observations of Avian Fauna on the Yáláƛi (Goose Island) Archipelago, British Columbia, Canada.

In an era of global change, historical natural history data can improve our understanding of ecological phenomena, particularly when evaluated with contemporary Indigenous and place-based knowledge. The Yáláƛi (Goose Island) Archipelago is a group of islands in Heiltsuk (Haíɫzaqv) territory on the Central Coast of British Columbia, Canada. Not only has this region been important to the Heiltsuk for millennia but also it is both a federally and internationally recognized important bird area. In this study, we compare data collected by Charles J. Guiguet, a biologist who documented bird communities at Yáláƛi in the summer of 1948, to three different contemporary surveys and to citizen-science data. We find that the relative abundances of forest bird species (i.e., birds that use the terrestrial island ecosystems) in 1948 differed to those observed in systematic surveys in 2011. While Orange-crowned Warblers, Dark-eyed Juncos, and Red Crossbills comprised 55% of detections by Guiguet in 1948, the three most abundant species in 2011 were Bald Eagles, Varied Thrushes, and Pacific Wrens, and these accounted for only 25% of detections. Although we could not make a quantitative comparison, we provide summaries of each species observed in surveys or reported on eBird. We also incorporate Heiltsuk place-based knowledge to enrich our discussion of the variability in bird communities over time, from how changes in mammal communities and human use may have shaped vegetation dynamics to how large-scale natural phenomena impacted topography. To understand which birds are present and how their communities are changing over time, we recommend continued monitoring of the bird communities at Yáláƛi.

Essential steps for establishing a large‐scale passive acoustic monitoring for an elusive forest bird species: the Eurasian Woodcock (Scolopax rusticola)

In light of global biodiversity loss, comprehensive monitoring of species and biodiversity is fundamental for effective conservation management. Technology‐driven approaches, particularly in the field of bioacoustics, have gained importance, with autonomous recording units (ARUs) such as the AudioMoth being a notable example. However, a systematic application of this technology in large‐scale passive acoustic monitoring (PAM) schemes is challenging because of a lack of species‐specific calibration techniques and information on survey design. Using Eurasian Woodcock Scolopax rusticola as our focal species, we present application‐oriented guidelines for testing and implementing a terrestrial, single‐species PAM scheme. In this process, we assessed the species‐specific detection space of AudioMoths, considering the influence of recording setup and location. ARUs had similar detection rates as a human observer when set up in locations with low vegetation. A further comparative analysis of bioacoustic and traditional roding surveys confirmed the comparability of the two methods. The last step comprised an evaluation of BirdNET as a means of automated species detection. Although BirdNET reliably detected Woodcock occurrence, our results underline the need for rigorous testing of computer‐aided data analysis as well as recording hardware before establishing PAM. We demonstrate that low‐cost open source ARUs and open access analysis tools can yield results on a par with traditional survey methods, and we provide specific recommendations for PAM for Eurasian Woodcock.

Temporal dynamics of acoustic diversity in managed forests

IntroductionIn production forests, management can have cascading effects on biodiversity and ecosystem services. Acoustic diversity reflects the diversity of vocalizing animals and has also considerable recreational value for human well-being, but the relationship between acoustic diversity and forest management remains largely unexploredMethodWe recorded acoustic diversity on forest plots along a gradient of silvicultural management intensity (SMI) in three regions of Germany. We explored the diurnal and seasonal temporal dynamics in acoustic diversity index (ADI) from March to July using generalized additive mixed models (GAMMs). We further investigated the interrelation between acoustic diversity and silvicultural management intensity, forest structural diversity, as well as tree diversity, bird species richness and abundance using structural equation modeling (SEM).ResultsSilvicultural management intensity had significant effects on the temporal dynamics of ADI in May and June from dawn till dusk, but variance explained by SMI was low. We confirmed our hypothesis that ADI was reduced by SMI due to its cascading effects on forest structural diversity and bird species richness and abundance.DiscussionAcoustic diversity indices can provide valuable insights into how forest management affects the acoustic activity of soniferous communities. We discuss how this can indicate both changes in species diversity as well as their vocal activity. We further address potential implications for forest management.

Stronger together: different community science platforms all contribute to wildlife research

Context Engaging the general public can increase spatio-temporal coverage of wildlife monitoring. Given the potentially substantial costs, we need to evaluate the contribution of known and planned initiatives and confirm whether multiple platforms increase the efficiency of data collection. As observer behaviour affects data quantity and quality, users of specialised and generalist platforms are expected to behave differently, resulting in more connected networks for specialised and higher nestedness for generalist platforms. Specialist observers are expected to contribute a balanced ratio of rare and common species, whereas non-specialist contribution will depend more on species detectability. Aims We aim to evaluate whether the combined contribution of observers from different platforms can improve the quality of occurrence and distribution data of 218 endemic Atlantic Forest bird species in Brazil. We also describe and compare observer-bird species interaction networks to illustrate observer behaviour on different platforms. Methods On the basis of data from five community science platforms in Brazil, namely, eBird, WikiAves, Biofaces, iNaturalist and Táxeus, we compared the spatial distribution of bird observations, the number of observers, the presence of the same observers on various platforms, bird species coverage, and the proportion of duplicate observations within and among platforms. Key results Although species coverage of the joint dataset increased by up to 100%, spatial completeness among the five platforms was low. The network of individual platforms had low values of clustering, and the network of the joint dataset had low connectance and high nestedness. Conclusions Each platform had a somewhat unique contribution. Pooling these datasets and integrating them with standardised data can inform our knowledge on bird distributions and trends in this fragile biome. Nevertheless, we encourage observers to provide precise coordinates, dates and other data (and platforms to accommodate such data) and recommend submitting data from all platforms into the Global Biodiversity Information Facility to support wildlife research and conservation. Implications If new platforms engage more and different people, new initiatives can cover poorly represented areas and successfully expand monitoring effort for Atlantic Forest endemic bird species.

Responses of bird functional communities to anthropogenic disturbances in the naturally fragmented Southern Mistbelt Forests in the Midlands of KwaZulu-Natal, South Africa

Forest disturbance poses major threats to biodiversity and forest ecosystem processes. Understanding bird species’ responses to disturbed forests is important for species conservation and forest management. Here, we assessed the impact of selective logging history (∼150 years), livestock grazing, alien plant invasion and adjacent matrix-type surrounding forest patches on bird species richness and functional diversity in 14 Southern Mistbelt Forest patches in the Midlands of KwaZulu-Natal, South Africa. The bird communities were surveyed using fixed-radius point-counts. We quantified functional diversity using three functional indices functional richness, functional divergence, and functional evenness. None of the disturbance types assessed affected the richness of bird species. The size of the forest patch affected bird species. For functional diversity, FRic was significantly higher in disturbed forest patches for forest specialists, insectivores and cup or ball-nesting birds. Functional evenness for the forest-sensitive groups, like forest specialists and insectivores, was significantly lower in disturbed sites. The results of this study showed that responses of functional communities and forest specialist bird species varied depending on disturbance type and intensity. We recommend that future studies assessing forest disturbance impacts on bird species use taxonomic proxies with different functional diversity indices for forest bird species conservation and management.

Beta diversity partitioning reveals homogenization in bird community composition within the forest-agriculture landscape of the northern Taiwan coast

ContextThis study examined how human-induced landscape changes affected bird diversity in mountain villages with mixed forests and cultivated fields.ObjectivesWe focused on the bird species composition (beta diversity) to determine whether species homogenization varied with forest cover differences. This study developed it as a novel metric potentially quantifying homogenization level comparison in species functional groups.MethodsBird surveys were conducted at 27 sites with forest cover scattered from 0 to 100%. Bird species were divided into forest birds and nonforest birds. Beta diversity was partitioned into turnover and nestedness-resultant components, and their contribution ratio to Sørensen beta was used to examine the effect of forest cover and pairwise cover difference.ResultsOur results indicated that forest birds exhibited low turnover and low nestedness, whereas nonforest birds exhibited nestedness distribution characteristics. The nestedness-resultant contribution ratio of nonforest birds was higher, driven by forest cover difference (slope = 0.0080, Pseudo R2 = 0.35**) than that of forest birds (slope = 0.0018, Pseudo R2 = 0.02**). Thus, we quantify the result of forest cover decreased lead to the dominated by nestedness species in nonforest birds.ConclusionsThese findings highlight the distinct effects of environmental changes on these two bird functional groups. Although the Sørensen beta diversity increases with forest cover decrease, most are contributed by nestedness-resultant nonforest birds and lead to homogenization. Thus, it is recommended that conservation plans should separately address forest and nonforest bird species to avoid the risk of underestimating species homogenization due to anthropogenic land-use and habitat degradation.

Guidelines for the use of spatially varying coefficients in species distribution models

AbstractAimSpecies distribution models (SDMs) are increasingly applied across macroscales using detection‐nondetection data. These models typically assume that a single set of regression coefficients can adequately describe species–environment relationships and/or population trends. However, such relationships often show nonlinear and/or spatially varying patterns that arise from complex interactions with abiotic and biotic processes that operate at different scales. Spatially varying coefficient (SVC) models can readily account for variability in the effects of environmental covariates. Yet, their use in ecology is relatively scarce due to gaps in understanding the inferential benefits that SVC models can provide compared to simpler frameworks.InnovationHere we demonstrate the inferential benefits of SVC SDMs, with a particular focus on how this approach can be used to generate and test ecological hypotheses regarding the drivers of spatial variability in population trends and species–environment relationships. We illustrate the inferential benefits of SVC SDMs with simulations and two case studies: one that assesses spatially varying trends of 51 forest bird species in the eastern United States over two decades and a second that evaluates spatial variability in the effects of five decades of land cover change on grasshopper sparrow (Ammodramus savannarum) occurrence across the continental United States.Main conclusionsWe found strong support for SVC SDMs compared to simpler alternatives in both empirical case studies. Factors operating at fine spatial scales, accounted for by the SVCs, were the primary divers of spatial variability in forest bird occurrence trends. Additionally, SVCs revealed complex species–habitat relationships with grassland and cropland area for grasshopper sparrow, providing nuanced insights into how future land use change may shape its distribution. These applications display the utility of SVC SDMs to help reveal the environmental factors that drive species distributions across both local and broad scales. We conclude by discussing the potential applications of SVC SDMs in ecology and conservation.

Species Richness and Composition of Forest Birds in Urban Parks and Reserves of Buenos Aires City, Argentina.

Urbanization is among the main factors of ecosystem transformation and threats to global biodiversity. Urban green spaces provide multiple services, being important for biodiversity and human well-being. However, the relationship between green spaces and forest birds has been scarcely studied in the Global South. In this work, we used citizen science data (eBird) to assess the variation in the species richness and composition of forest birds in two types of public urban green spaces characterized by different vegetation composition and management: parks and reserves. In general, reserves had more native and unmanaged vegetation than parks. We selected parks and reserves located in the coastal area of the Metropolitan Area of Buenos Aires, Argentina. Sampling effort was considered as the number of checklists for each site. The database allowed information to be extracted from 12 sites and 33 species. The most common species were the Green-barred Woodpecker (Colaptes melanochloros), the Narrow-billed Woodcreeper (Lepidocolaptes angustirostris), and the White-crested Tyrannulet (Serpophaga subcristata). Bird species richness was higher in reserves than in parks and was positively related to sampling effort. The forest bird species composition varied according to the type of green area and sampling effort. Species composition showed a significant nestedness, with the least rich sites being a subset of species from the richest sites. Reserves and sites with the highest sampling effort concentrated all species. The results obtained show the importance of urban reserves in the conservation of forest birds.

Elevational differences in territory defence response in native (endemic and non-endemic) forest birds on Viti Levu Island, Fiji

ABSTRACT Experimental approaches to measure territory defence can be used to interpret the relative magnitude of intraspecific aggression in different ecological contexts. The aim of this study is to examine the response of Fijian forest bird species to conspecific intruders using playback of previously recorded songs along an elevational gradient. We address two questions: Do different foraging guilds in Fiji’s forest birds show different patterns of territorial defence behaviour towards conspecific intruders? Secondly, do Fiji’s forest birds show stronger territorial defence at higher elevations? We explore these questions across two foraging guilds (insectivore and omnivore) on Viti Levu Island, Fiji. All four focal species had a stronger response at the highest elevation, and the endemic insectivore had the strongest response. Perhaps high elevation insects are less abundant and hence increased aggressiveness is favoured to defend the territory, and/or perhaps in general more aggressive birds colonise higher elevation areas, both ideas that require further testing. This study provides first insights into response to conspecifics in Fiji’s forest birds that can be explored in relation to avian behaviour also in the context of human activity, human disturbance and threats to the persistence of birds across elevational gradients.

Detection ranges of forest bird vocalisations: guidelines for passive acoustic monitoring

Passive acoustic monitoring has proven to have many advantages for monitoring efforts and research activities. However, there are considerations to be taken into account regarding the placement of autonomous sound recorders. Detection ranges differ among species and in response to variable conditions such as weather or the location of vocalising animals. It is thus important to the success of a research project to understand, with a certain degree of confidence, the distances at which birds might be detected. In two types of forests in Poland, we played back the vocalisations of 31 species of European forest birds exemplifying different singing characteristics. Based on recordings obtained along a 500-m transect, we estimated the probability of detection and maximum detection distance of each vocalisation. We broadcasted the recording at three heights of singing and repeated playbacks three times during the breeding season to evaluate the effect of vegetation growth. Our results revealed that environmental and meteorological factors had a significant influence on both detection probability and maximum detection distances. This work provides comprehensive measurements of detection distance for 31 bird species and can be used to plan passive acoustic monitoring research in Europe, taking into account species traits and individual characteristics of the study area.

Species composition and ecological groupings of birds of extrazonal transformed landscapes of Yenisei Siberia in the spring and summer period

The article presents the results of a pilot study conducted in May–June 2022 in the places of interpenetration of the Krasnoyarsk forest-steppe and subtaiga, where extrazonal transformed landscapes were formed. An important role in this was played by such factors as the location of the territory on the border of natural zones, the dismembered hilly-rocky terrain, active human economic activity, which also caused the high mosaic of biotopes. As a result, there is an overlap of ranges of typically forest and steppe bird species, as well as their nesting in close proximity to each other, which is explained by their ecological specialization. During this period, 105 species and subspecies of birds belonging to 13 groups were noted. All the diversity is distributed by ecological groups that correspond to the large biotopes identified in the study area: small-leaved birch and mixed forests; forest edges, felling and chopping; coniferous forests; high-stemmed and shrubby floodplain forests; residential landscapes; wetland complex; high-grass and low-grass open areas. Some phenological data, information on the biotopic placement, abundance and nesting of birds collected in the process of route hiking are presented.

Effects of habitat heterogeneity on bird communities in the forests of northeastern Germany

Habitat heterogeneity is a key factor for regulating biodiversity in temperate lowland forests. Specifically, stands associated with late forest development phases provide important habitat structures for many rare and threatened forest bird species. However, how forest stands that differ in their structural complexity, canopy conditions and tree species composition affect forest bird assemblages both at the local and landscape scale remains largely unclear. In a young moraine lake landscape of northeastern Germany, we assessed correlations of bird diversity and bird composition with stand properties. We used data from 48 transects (400 m) established in (1) unmanaged, closed-canopy, mature stands that were dominated by Fagus sylvatica (UDS), and (2) diverse managed, mixed coniferous stands with a mosaic of open and closed canopy patches (MCS). We found that bird communities of the UDS strongly differed from those in the MCS, with open habitat species being more frequent in the MCS. By contrast, differences in diversity measures were less distinct. Moreover, we identified nine indicator species for the UDS (Columba oenas, Cyanistes caeruleus, Muscicapa striata, Leiopicus medius, Certhia brachydactyla, Ficedula parva, Dryobates minor, Sturnus vulgaris, Ficedula hypoleuca) and seven indicator species for the MCS (Periparus ater, Pyrrhula pyrrhula, Regulus regulus, Prunella modularis, Lophophanus cristatus, Emberiza citronella, Anthus trivialis). Several famous ancient beech forest patches in Müritz National Park and the UNESCO Biosphere Reserve “Schorfheide-Chorin” were found to harbour the set of the UDS indicator species. The UDS support of bird coenosis is typical for old mature broadleaved forests and can be considered as an effective tool for bird conservation. Our results further indicate that the combination of unmanaged and managed stands associated with different habitat complexities would benefit forest bird assemblages at the landscape scale. Key words: forest specialist birds, bird conservation, non-managed forests, old-growth patches, Ficedula parva, Leiopicus medius, coniferous forest

Forest Bird Populations at the Big Island National Wildlife Refuge Complex, Hawai‘i

Abstract Endemic Hawaiian forest birds have experienced dramatic population declines. The Big Island National Wildlife Refuge Complex (Refuge Complex) was established for the conservation of endangered forest birds and their habitats. Surveys have been conducted at two units of the Refuge Complex to monitor forest bird populations and their response to management actions. We analyzed survey data from 1987 to 2019 at the Hakalau Forest Unit (HFU) and from 1995 to 2019 at the Kona Forest Unit (KFU). We analyzed three strata at HFU: open-forest, closed-forest, and afforested-pasture, and two strata at KFU: upper (>1,524 m elevation) and lower (<1,524 m). In all years, ‘i‘iwi Vestiaria coccinea, ‘apapane Himatione sanguinea, and Hawai‘i ‘amakihi Chlorodrepanis virens virens were the most abundant species at HFU. Three endangered forest bird species, Hawai‘i ‘ākepa Loxops coccineus, ‘alawī Loxops mana (also known as Hawai‘i creeper) and ‘akiapōlā‘au Hemignathus wilsoni, had much lower densities. The most abundant species at KFU was ‘apapane, followed by Hawai‘i ‘amakihi at much lower densities. We found a continuation of several trends observed in previous analyses at HFU up to 2012, with most species’ trends upward in afforested-pasture stratum, stable in the open-forest stratum, and downward in the closed-forest stratum. However, more species were showing downward trends in all three strata during the most recent decade. Results were mixed at KFU, with most species’ trends downward in the upper stratum and upward in the lower stratum. Populations of endangered species were either locally extirpated at KFU or in numbers too low to reliably estimate population abundance. The Refuge Complex is important for conservation of forest birds on Hawai‘i Island. Our results show that HFU supports the majority of three endangered forest bird species. Threats to forest birds at the Refuge Complex appear to be having a negative impact. These threats include habitat loss, disease, feral ungulates, and nonnative predators. Continuing and enhancing management actions, such as forest restoration and removal of invasive species, could help mitigate these impacts and allow the Refuge Complex to remain a key site for forest bird conservation in Hawai‘i.

Documenting birds over two centuries of deforestation in an Atlantic Forest region of Brazil

ABSTRACT The first ornithological record from Paraná State, Southern Brazil, dates from 1820, when forests covered 83% of the area. There is a lack of studies evaluating how knowledge on species richness increased over time, together with a massive deforestation process. We aimed to describe the changes, by decade, in forest species richness since that time, and to determine how field effort hours were distributed. We reviewed published studies using online databases. We compared forest bird communities between decades with Jaccard Dissimilarity Indices and compared communities’ composition among decades with Analysis of Similarity. In 200 years, 421 forest bird species were mentioned. Most of the species were detected until 1980, a likely subset of the avifauna before habitat loss; fewer species (108) were recorded afterward. An increasing number of species (8–20) stopped being recorded by decade from the 1980s. Field effort hours were mentioned in 1984, remaining temporally and spatially uneven. More than 1,000 localities have been inventoried, but most species reports are from Eastern municipalities. Areas within Serra do Mar, Curitiba, and Londrina stand out as protected forests and well-known academic centers. Cerrado endemics corroborated the relevance of exploring different regions, but further studies in this domain are strongly recommended.

Landscape configuration alters movement behavior and space‐use of a Hawaiian forest bird community

Habitat loss and fragmentation are considered the greatest threats to ecosystems worldwide. Movement reveals how individuals meet their habitat requirements and respond to environmental heterogeneity, and thus can provide a powerful tool for investigating how animals respond to changes in landscape configuration. In our study, we examined the effects of landscape configuration on the space use and movement strategies of four endemic Hawaiian forest bird species spanning a range of foraging guilds (i.e. frugivore, nectivore, generalist). We used a landscape‐level automated radio tracking system to measure location data of 127 individuals tracked on Hawaiʻi Island in a naturally fragmented landscape created by volcanic activity in the mid‐ to late‐1800s and a nearby continuous landscape. We found that landscape configuration had a strong effect on movement patterns and space‐use of all four species. In the fragmented landscape, all species predominately occupied a single forest patch, displayed a high degree of area‐restricted search behavior, with few long‐distance movements away from their primary forest patch. These patterns contrasted significantly with those of conspecifics in the continuous landscape which exhibited relatively unconstrained movements across the forested landscape and had 3‐ to 12‐fold larger home ranges. Our findings indicate that landscape structure plays a strong role in shaping movement behavior of a tropical bird community and provides valuable insights into the behavioral mechanisms that may be important for species to persist within fragmented landscapes.

The critical role of coastal protected areas in buffering impacts of extreme climatic conditions on bird diversity and their ecosystem services' provisioning in the Eastern Cape Province, South Africa.

In this study, we documented the diversity of bird species in the Eastern Cape coastal nature reserves (i.e., Hluleka, Dwesa, Silaka and Mkhambati nature reserves), and determined the potential role of each bird species in habitat maintenance using two functional traits (i.e., body mass and feeding mode) as the function's proxy. We applied the timed species count approach during bird observations, coupled with drive-by surveys to maximise spatial coverage of each nature reserve over four years. To evaluate functional diversity, bird species were classified based on functional traits such as the adult body, and their potential ecological role derived from their feeding mode and habitat associations. Over 864 h, we accumulated 818 bird records containing 178 different bird species that were classified into 58 families with 32 species occurring in all nature reserves. Shannon-Wiener Diversity Indices showed very high overall species diversity across the nature reserves (H > 3.5) with no differences detected across sites. Although no significant correlations between vegetation changes measured through Normalised Difference vegetation Index (NDVI) in each nature reserve and the number of bird records, forest bird species were dominant (42.1%; N = 178) throughout years of observation and diversity remained high (H > 3.5). Bird species abundance only increased significantly across all nature reserves during 2018-2019. All four nature reserves had a similar distribution of bird functional traits with both high functional richness (FRic = 1), and divergence (FDiv = 0.8) and moderate evenness (FEve = 0.4). Multiple Correspondence Analysis (MCA) demonstrated a positive correlation between bird sizes and functions with large birds mainly associated with predators and carrion. Small birds and medium birds had a similar composition of species in terms of functionality being seed dispersers across the nature reserves. A significant effect that insectivores and carrions displayed in MCA plots, suggest the availability of indirect pollination services. Despite extreme drought conditions across the country in 2019, NDVI levels remained largely consistent over time in these four reserves; and thus, they offer important refuge for birds during extreme climatic conditions such as drought.

What's the rumpus? Resident temperate forest birds approach an unfamiliar neotropical alarm call across three continents.

Alarm signals have evolved to communicate pertinent threats to conspecifics, but heterospecifics may also use alarm calls to obtain social information. In birds, mixed-species flocks are often structured around focal sentinel species, which produce reliable alarm calls that inform eavesdropping heterospecifics about predation risk. Prior research has shown that Neotropical species innately recognize the alarm calls of a Nearctic sentinel species, but it remains unclear how generalizable or consistent such innate signal recognition of alarm-calling species is. We tested for the responses to the alarm calls of a Neotropical sentinel forest bird species, the dusky-throated antshrike (Thamnomanes ardesiacus), by naive resident temperate forest birds across three continents during the winter season. At all three sites, we found that approaches to the Neotropical antshrike alarm calls were similarly frequent to the alarm calls of a local parid sentinel species (positive control), while approaches to the antshrike's songs and to non-threatening columbid calls (negative controls) occurred significantly less often. Although we only tested one sentinel species, our findings indicate that temperate forest birds can recognize and adaptively respond globally to a foreign and unfamiliar tropical alarm call, and suggest that some avian alarm calls transcend phylogenetic histories and individual ecological experiences.

Hearing to the Unseen: AudioMoth and BirdNET as a Cheap and Easy Method for Monitoring Cryptic Bird Species.

The efficient analyses of sound recordings obtained through passive acoustic monitoring (PAM) might be challenging owing to the vast amount of data collected using such technique. The development of species-specific acoustic recognizers (e.g., through deep learning) may alleviate the time required for sound recordings but are often difficult to create. Here, we evaluate the effectiveness of BirdNET, a new machine learning tool freely available for automated recognition and acoustic data processing, for correctly identifying and detecting two cryptic forest bird species. BirdNET precision was high for both the Coal Tit (Peripatus ater) and the Short-toed Treecreeper (Certhia brachydactyla), with mean values of 92.6% and 87.8%, respectively. Using the default values, BirdNET successfully detected the Coal Tit and the Short-toed Treecreeper in 90.5% and 98.4% of the annotated recordings, respectively. We also tested the impact of variable confidence scores on BirdNET performance and estimated the optimal confidence score for each species. Vocal activity patterns of both species, obtained using PAM and BirdNET, reached their peak during the first two hours after sunrise. We hope that our study may encourage researchers and managers to utilize this user-friendly and ready-to-use software, thus contributing to advancements in acoustic sensing and environmental monitoring.