Acoustic monitoring of black-tufted marmosets in a tropical forest disturbed by mining noise

Simple Summary: Communication is one way that animals use to obtain and defend resources, escape predators and attract sexual partners. However, this process can be disrupted by anthropogenic noise, which often differs from natural sounds in frequency, duration and intensity. This study aimed to understand whether, and how, calls emitted by black-tufted marmosets (Callithrix penicillata) are affected by mining noise. We compared ambient noise and the acoustic parameters of the contact calls of these animals in two study areas, one near and one far from the Brucutu Mine, Minas Gerais, Brazil. We found background noise to be higher in the area near the mine, and marmoset vocalizations more frequent, compared to the far area. Calls emitted in the near area also differed in spectral parameters from the far area, which suggests an effort by the animals to adapt their vocal activity to a noisier environment. Our results indicate that mining noise may affect the acoustic communication of black-tufted marmosets. These results may be taken as a starting point for establishing public policies to promote preventive and/or mitigative measures to protect wildlife around sites of mining activity. Moreover, measures to regulate any noisy activities in relation to wild animals are pressing since these are lacking in Brazil. Abstract: All habitats have noise, but anthropogenic sounds often differ from natural sounds in terms of frequency, duration and intensity, and therefore may disrupt animal vocal communication. This study aimed to investigate whether vocalizations emitted by black-tufted marmosets (Callithrix penicillata) were affected by the noise produced by mining activity. Through passive acoustic monitoring, we compared the noise levels and acoustic parameters of the contact calls of marmosets living in two study areas (with two sampling points within each area)—one near and one far from an opencast mine in Brazil. The near area had higher anthropogenic background noise levels and the marmosets showed greater calling activity compared to the far area. Calls in the near area had significantly lower minimum, maximum and peak frequencies and higher average power density and bandwidth than those in the far area. Our results indicate that the mining noise affected marmoset vocal communication and may be causing the animals to adjust their acoustic communication patterns to increase the efficiency of signal propagation. Given that vocalizations are an important part of social interactions in this species, concerns arise about the potential negative impact of mining noise on marmosets exposed to this human activity

Determining temporal sampling schemes for passive acoustic studies in different tropical ecosystems

Among different approaches to exploring and describing the ecological complexity of natural environments, soundscape analyses have recently provided useful proxies for understanding and interpreting dynamic patterns and processes in a landscape. Nevertheless, the study of soundscapes remains a new field with no internationally accepted protocols. This work provides the first guidelines for monitoring soundscapes in three different tropical areas, specifically located in the Atlantic Forest, Rupestrian fields, and the Cerrado (Brazil). Each area was investigated using three autonomous devices recording for six entire days during a period of 15 days in both the wet and dry seasons. The recordings were processed via a specific acoustic index and successively subsampled in different ways to determine the degree of information loss when reducing the number of minutes of recording used in the analyses. We describe for the first time the temporal and spectral soundscape features of three tropical environments. We test diverse programming routines to describe the costs and the benefits of different sampling designs, considering the pressing issue of storing and analyzing extensive data sets generated by passive acoustic monitoring. Schedule 5 (recording one minute of every five) appeared to retain most of the information contained in the continuous recordings from all the study areas. Less dense recording schedules produced a similar level of information only in specific portions of the day. Substantial sampling protocols such as those presented here will be useful to researchers and wildlife managers, as they will reduce time- and resource-consuming analyses, whilst still achieving reliable results

Positive and negative interactions with humans concurrently affect vervet monkey, Chlorocebus pygerythrus, ranging behavior

Many non-human primates adjust their behavior and thrive in human-altered habitats, including towns and cities. Studying anthropogenic influences from an animal’s perspective can increase our understanding of their behavioral flexibility, presenting important information for human-wildlife cohabitation management plans. Currently, research on anthropogenically disturbed wildlife considers either positive or negative aspects of human-wildlife encounters independently, highlighting a need to consider potential interactions between both aspects. Vervet monkeys, Chlorocebus pygerythrus, are a suitable species to address this gap in research as they tolerate urbanization, however, they are understudied in urban landscapes. We conducted this in KwaZulu-Natal, South Africa, where vervet monkeys are commonly found throughout the anthropogenic landscape. Here we determined, from a monkey’s perspective, how the frequency and nature of human-monkey interactions, both positive (food-related) and negative (human-monkey conflict), affected vervet monkey ranging patterns in an urban environment. Over a year, we assessed the movement patterns of three groups of urban vervet monkeys over one year, analyzing both 95% and 50% kernel density estimates of their home ranges alongside daily path lengths and path sinuosities every month using generalized linear mixed models. Overall, we found that human interactions within the urban landscape affected all measures of ranging to some degree. The core home ranges of vervet monkeys increased with a higher rate of positive human encounters and their total home range increased with an interaction of both positive and negative human encounters. Furthermore, vervet monkeys were less likely to respond (i.e. increase daily path length or path sinuosity) to human aggression when food rewards were high, suggesting that effective management should focus on reducing human-food foraging opportunities. Our results highlight the complex interplay between positive and negative aspects of urban living and provide guidance for managers of human-nonhuman primate interactions

Comparing contact calling between black tufted-ear marmosets (Callithrix penicillata) in a noisy urban environment and in a quiet forest

All habitats have some level of noise but anthropogenic sounds such as those produced by traffic are structurally different from natural sounds, and could cause organisms living in noisy urban areas to modify their vocal communication. We compared temporal and spectral parameters of contact calls in black tufted-ear marmosets (Callithrix penicillata) living in a noisy and a quiet area. From February 2009 to March 2012 we recorded spontaneously produced phee vocalizations by marmosets in two areas in Minas Gerais, Brazil: a noisy urban park (N = 581) in Belo Horizonte, and a quiet natural forest, on Cauaia farm in Matozinhos city (N = 560). We measured the duration, frequencies, and rate of phee vocalizations. We found that marmosets’ phee vocalizations were significantly longer in the noisy area than in the quiet area. The low, high, and dominant frequencies were significantly lower in the noisy area than in the quiet area, and contact calling was less frequent in the noisy area than in the quiet area. We suggest that the differences between marmoset contact calls from noisy and quiet areas are influenced by anthropogenic noise

Changes on soundscapes reveal impacts of wildfires in the fauna of a Brazilian savanna

Wildfire is a natural process in Brazilian savannas, but human activities alter fire regimes and threaten biodiversity. In this study, we used an ecoacoustics approach to assess fauna responses and recovery after wildfire in a Brazilian savanna. Six passive acoustic monitoring devices were used to record soundscapes before and after a wildfire a at burned and non-burned sites for one year and one month (September 2012 to September 2013). Power Spectral Density and the Acoustic Complexity Index were used to track biophony. Before the fire, the two sites had similar biophonic patterns (PSD: T = 1136, Z = 1.52, P = 0.12; ACI: T = 1117, Z = 1.10, P = 0.26) and soniferous species richness (Site 1 = 52 and Site 2 = 49). However, in the first two sessions of recordings after the fire, biophony became higher at the burned site during the day (PSD: T = 211 and 233; Z = 4.13 and 6.41; ACI: T = 120 and 469, Z = 5.14 and 7.07; all P < 0.00). During the night, biophony was usually higher at the non-burned site until May 2013 (PSD: T = 0 to 453; Z = 3.30 to 5.90; ACI: T = 333 to 491, Z = 3.80 to 4.93; all P < 0.00). Biophony became similar (P = 0.17 to 0.38) at the two sites or higher (P = 0.00 to 0.01) at the burned site from July to September 2013 (PSD: T = 55 to 1167; Z = 1.35 to 6.89; ACI: T = 719 to 1365, Z = 0.87 to 3.04). After the fire, a reduction of soniferous species at the burned site was observed for insects and bats. Both biophonic activity and soniferous species showed a tendency to recover one year after the fire, but there were still less species in September 2013 (non-burned = 43 and burned = 37) when compared to September 2012 at both sites (Site 1 = 52 and Site 2 = 49). Our results showed that changes in the natural regimes of fire can negatively impact the biodiversity and reinforce the need for monitoring protocols and inspection of wildfires. [Abstract copyright: Copyright © 2021 Elsevier B.V. All rights reserved.

Low welfare impact of noise : assessment in an experimental model of mice infected by Herpes simplex-1

The breeding practices adopted and the equipment typically found in animal facilities produce sounds at frequencies within the auditory range of the mice (1 to 100 kHz), which can cause hearing and other non-hearing effects. Another aspect that could potentially affects the welfare of experimental animals would be their impaired health condition, since in addition to all the variables present in the environment, some of them are deliberately infected with pathogens. This study aimed to evaluate the possible effects of the chronic exposure of C57BL/6 and Tlr2/Tlr9(−/−) mice, uninfected and infected, with a low m.o.i. of Herpes simplex-1, at different noise levels present in the “Quiet” and “Noisy” rooms. Considering all procedures, a total of 51 male mice were used, 27 of the C57BL/6 and 24 of the Tlr2/Tlr9(−/−) strains. Physiological parameters such as weight gain, hemogram, cholesterol, glucose,corticosterone and cytokines involved in the immune response were evaluated together with the animals’ behavioral responses in Open Field and Light/Dark tests. In relation to the physiological parameters in C57BL/6, there was infection x noise interaction (P <  0.05) with greater weight gain by the infected “Quiet” group (P <  0.05) when compared to the infected “Noisy” group. In the hemogram of C57BL/6 there was infection x noise interaction (P <  0.01) in the platelets, with increase by the infected “Quiet” group when compared to the control “Quiet” and infected “Noisy” group (P <  0.05). No significant differences were found between the groups in the cholesterol, glucose and corticosterone concentrations. Regarding the production of cytokines in C57BL/6 there was infection x noise interaction (P <  0.05), with a lower production of gamma interferon in control “Quiet” group when compared to the infected “Quiet” group and to the control “Noisy” group (all P <  0.05). In behavioral tests there was no difference between the groups. Our results demonstrated that although the noise and infection influence have caused changes in some physiological and immunological parameters, they were not sufficient to promote measurable change in the stress parameters evaluated, since that corticosterone concentration and the responses of the animals from different groups in the behavioral tests were not different. This study demonstrated that the noise level found in the animal facility caused a low impact on the welfare of experimental mice