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Monitoring the vocal behavior of owls is challenging because of their nocturnal habits and limited vocal activity. Here, we evaluated the use of passive acoustic monitoring coupled with automated signal recognition software to monitor the spontaneous vocal activity of the Ferruginous Pygmy-Owl (Glaucidium brasilianum) over a complete annual cycle at five recording stations in the Brazilian Pantanal. The vocal behavior of this species was concentrated during the crepuscular periods, with highest vocal activity in the hours prior to sunrise. The Ferruginous Pygmy-Owl was vocally active throughout the year, but the species showed a peak of activity from June to August. Paired Ferruginous Pygmy-Owl males tend to perform territorial calls less often during the nestling period, which may partly explain the significant decrease in the vocal activity after August. Our results suggest that the breeding period of the species starts in June, and the nesting phase probably occurs from September onwards, when the wet season starts. The first rains in seasonal tropical areas are usually associated with an increase in food availability, which may explain the species´ breeding period onset. Future surveys aiming to monitor the species, avoiding the use of broadcast calls, should be performed before sunrise between June and August, when the vocal activity was maximal. [ABSTRACT FROM AUTHOR]

Small, volant and nocturnal, bats face strong challenges to avoid heat loss. Among aerial insectivores, body mass varies by two orders of magnitude between the smallest and the largest species. At low temperatures, physiological constraints should be harsher for smaller bats, as they lose more heat through their body surface than larger species. So, temperature variations should lead to distinct behavioural responses by bats of different body masses. Also, because they feed on arthropods, dependent on ambient temperature, aerial insectivores should halt feeding at low temperatures. Using ultrasound detectors and temperature and humidity sensors, we investigated how aerial insectivores of the coldest region in austral Brazil respond to nightly temperature variations and compared those responses between guilds of distinct body masses. We predict that smaller bats reduce their activity faster than larger bats, but that foraging should reduce simultaneously in the two guilds, as they depend on ectothermic prey. Bat activity reduced significantly below 12 °C. Larger bats maintained their activity at temperatures where the activity of smaller bats had already halted. However, larger bats foraged mostly during the first half of the night, at higher temperatures than those chosen by smaller bats to forage. We associate these differential responses to the thermal convection process, which may increase prey availability at higher altitudes, where larger molossids are known to forage. Smaller species, mostly edge-space hunters, probably take advantage of less variable prey availability during the night, resulting in a more regular behavioural pattern of navigation and foraging. [ABSTRACT FROM AUTHOR]

The ecology of tropical wildlife remains unknown for most nocturnal species owing to difficulties in performing night surveys. To improve our understanding of the ecology of nocturnal tropical birds, we monitored the calling activity of two Neotropical nightjars, the Little nightjar (Setopagis parvula) and the Common pauraque (Nyctidromus albicollis), over an annual cycle at four sites in the Brazilian Pantanal. The calling activity of both species was restricted to the nocturnal period and showed peaks of activity just before dawn and just after dusk. The Little nightjar was detected from early June to late January owing to the migratory habits of the species, while the Pauraque was detected throughout the year. Our results suggest that the breeding season of both species starts in August, and the nesting phase probably takes place in September at the end of the dry season. This might be related to the typical increase in arthropod abundance after the first rains in tropical habitats with seasonal rainfall. Future surveys of these species should be performed in the last fortnight of August at 5 am, a period during which the calling activity of both nightjars was maximum. Autonomous sound recorders should be left in the field for a minimum of 9 days to record a reliable vocal activity rate. Acoustic monitoring, coupled with automated signal recognition, has proven to be a useful tool for monitoring tropical nightjars and may be useful to increase our knowledge about the ecology of other nocturnal tropical species. [ABSTRACT FROM AUTHOR]

Acoustic monitoring provides the opportunity to study ecological processes that are difficult to assess with traditional surveys. Elachistocleis matogrosso is an anuran species, described in 2010, for which limited biological information is available. This study investigated the calling activity of the species in the north-eastern portion of the Pantanal, Brazil, a wetland area with marked seasonality between the dry and wet seasons. The calling activity of E. matogrosso was monitored using automated digital recorders in combination with automated signal recognition software over two different annual cycles. The species was vocally active only during the wet season (October – April), with a peak in November-December during the 2013–2014 annual cycle and in February-March during the 2015–2016 annual cycle. The peak calling activity occurred at dusk. This species has nocturnal habits and an explosive breeding activity. The detection of the species was intermittent, which suggests that environmental predictors or site-specific conditions might play an important role in species detection. Moreover, this intermittent occupancy indicated that surveys that employ traditional field techniques would likely fail to detect this species. We describe an effective protocol for detecting E. matogrosso with acoustic monitoring, which requires recording during 20 days in February from 17:01 to 05:00. Our procedure would be easy to adapt to other anuran species, and it could be used for investigating new localities and assessing population changes over time. [ABSTRACT FROM AUTHOR]

Abstract Understanding biodiversity's responses to environmental variations is a challenging task in ecological research. Under a functional perspective, studies have shown that environmental alterations can affect organisms' traits that are related to their performance, fitness and ecological functions. In the present study, we evaluated how the diversity and functional traits of two distinct bat guilds are affected by an elevational gradient in Atlantic forest, southeastern Brazil. Indices regarded to functional diversity and to dominant functional traits (Rao Quadratic Entropy - RaoQ and Community Weighted Mean - CWM) were calculated for both bat guilds: understory and open-space bat faunas. Generalized Linear Models (GLMs) were applied to verify the relation of each metric with elevation, and the presence of non-linear relationships were tested. Results showed that each guild of the bat community reacted differently to the elevational gradient, with statistically significant results of RaoQ for understory bats and of CWM for both guilds (for aspect ratio) or for only one bat guild (mass for understory bats and wing load for open-space bats). Our results illustrate how an environmental gradient can impose different selective pressures in each bat guild and how the distinct bat groups are affected by elevation. This is the first study considering functional aspects of open-space bats in the Neotropics. Highlights • Different bat guilds (understory and open-space bats) have their functional traits affected by elevation in distinct ways. • Functional diversity of understory bats was negatively affected by elevation. • Functional diversity of open-space bats showed no relationship with elevation. • The traits body mass and aspect ratio of understory bats were affected by elevation. • In open-space bats, wing load and aspect ratio traits were related with elevation. [ABSTRACT FROM AUTHOR]

Rossi-Santos, M.R., 2015. Oil industry and noise pollution in the humpback whale ( Megaptera novaeangliae) soundscape ecology of the southwestern Atlantic breeding ground. The present work aims to assess acoustic overlapping between the humpback whale song and anthropogenic sounds around oil and gas platforms through spectral description and frequency comparison. Whales were monitored systematically in northeastern Brazil (11° S, 37° W to 14° S, 38° W). Acoustic and behavioral data were collected from 2007 to 2009, focusing on humpback occurrence around oil platforms. Diverse anthropogenic noises were registered in a similar frequency range as recorded cetacean sounds, which suggests overlapping of acoustic niches. Noise pollution from oil and gas production may potentially affect this species' communication, with implications for distribution and behavior in their breeding area. This paper is the first report of acoustic overlapping of oil platforms and cetaceans in the southwestern Atlantic Ocean. Given increasing gas and oil exploitation, efforts to improve the development and use of these acoustic methods are recommended in order to mitigate impacts on the marine life. O presente trabalho tem como objetivo acessar a sobreposição acústica entre o canto da baleia jubarte e sons antropogênicos ao redor de plataformas de petróleo e gás, através da descrição espectral e comparação de frequências. As baleias foram sistematicamente monitoradas no nordeste do Brasil (11° S, 37° W - 14° S, 38° W). Dados acústicos e comportamentais foram coletados entre 2007 e 2009, focando na ocorrência de jubarte ao redor de plataformas de petróleo. Diversos ruídos antropogênicos foram registrados em uma amplitude de frequência semelhante aos sons gravados dos cetáceos, o que sugere uma sobreposição de nichos acústicos. A poluição sonora originada na produção de petróleo e gás pode, potencialmente, afetar a comunicação desta espécie, com consequências em sua distribuição e comportamento nesta área de reprodução. Este artigo é o primeiro a trazer informações sobre a sobreposição acústica entre plataformas de petróleo e cetáceos no Oceano Atlântico Sul ocidental. Frente à crescente exploração de petróleo e gás, se faz necessário desenvolver esforços para melhorar o desenvolvimento e uso dos métodos acústicos para serem empregados como monitoramento destas atividades. [ABSTRACT FROM AUTHOR]

Temporal scale in animal communities is often associated with seasonality, despite the large variation in species activity during a diel cycle. A gap thus remains in understanding the dynamics of short-term activity in animal communities. Here we assessed calling activity of tropical anurans and addressed how species composition varied during night activity in assemblages along gradients of local and landscape environmental heterogeneity. We investigated 39 anuran assemblages in the Pantanal wetlands (Brazil) with passive acoustic monitoring during the peak of one breeding season, and first determined changes in species composition between night periods (early, mid and late) using two temporal resolutions (1- and 3-hr intervals). Then, we addressed the role of habitat structure (local and landscape heterogeneity variables from field-based and remote sensing metrics) and ecological context (species richness and phylogenetic relatedness) in determining changes in species composition (a) between night periods and (b) across days. Nocturnal calling activity of anuran assemblages varied more within the 1-hr resolution than the 3-hr resolution. Differences in species composition between early- and late-night periods were related to local habitat structure and phylogenetic relatedness, while a low variation in compositional changes across days was associated with low-heterogeneous landscapes. None of these relationships were observed using the coarser temporal resolution (3 hr). Our findings on the variation of calling activity in tropical anuran assemblages suggest potential trade-offs mediated by fine-temporal partitioning. Local and landscape heterogeneity may provide conditions for spatial partitioning, while the relatedness among co-signalling species provides cues on the ecological overlap of species with similar requirements. These relationships suggest a role of niche dimensional complementarity on the structuring of these anuran assemblages over fine-temporal scales. We argue that fine-temporal differences between species in breeding activity can influence the outcome of species interaction and thus, addressing temporal scaling issues can improve our understanding of the dynamics of animal communities., (© 2020 British Ecological Society.)