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1.
Tshering Dema Michael Towsey Sherub Sherub Jigme Sonam Kinley Kinley Anthony Truskinger Margot Brereton Paul Roe 《Freshwater Biology》2020,65(1):153-164
- Growing developmental activities, such as hydropower construction, farm roads, and other human activities, are affecting the critically endangered white-bellied heron (WBH). Out of a known global population of 60, 28 individuals inhabit the river basin area and freshwater lakes and ponds of Bhutan. Several constraints impede continuous monitoring of endangered species, such as the isolated and cryptic nature of the species and the remoteness of its habitat; to date, there are no long-term reference data or techniques implemented for continuous monitoring of this species.
- In this study, we designed acoustic detection and habitat characterisation methods using long-duration recordings from three habitat areas in Bhutan. Acoustic indices were extracted and used to implement a species-specific call detector and to generate habitat soundscape representations. Using WBH calls annotated in month-long recordings from a known site, a novel indices-based detector was implemented and tested. A total of 960 hr of continuous audio recordings from three habitats in Bhutan were analysed.
- We found that a species call detector implemented using a combination of acoustic indices (that includes measures of spectral and temporal entropy and different angles of spectral ridges) has a correct detection rate of 81%. Additionally, visual inspection of the species’ acoustic habitat using long-duration false-colour spectrograms enabled qualitative assessment of acoustic habitat structure and other dominant acoustic events.
- This study proposes a combined approach of species acoustic detection and habitat soundscape analysis for holistic acoustic monitoring of endangered species. As a direct outcome of this work, we documented acoustic reference data on the critically endangered WBH from multiple habitat areas and have analysed its temporal vocalisation patterns across sites.
2.
Scott A. Rush Tom Maddox Aaron T. Fisk Mark S. Woodrey Robert J. Cooper 《Journal of Field Ornithology》2009,80(2):193-197
ABSTRACT. Relationships between egg volume and an array of life-history traits have been identified for many bird species. Despite the importance of egg volume and the need for precise and accurate measurements, egg volume is usually estimated using a mathematical model that incorporates length and width measurements along with a shape variable. We developed an instrument that provides precise estimates of egg volume and can be easily used in the field. Using Clapper Rail ( Rallus longirostris ) eggs, we compared egg volumes measured using our instrument with estimates based on linear measurements. We found our instrument to be both precise and accurate. Compared with a method based on linear measurements of eggs, use of our instrument reduced variation in egg volume estimates by 1.6 cm3 , approximately 8% of the volume of a Clapper Rail's egg. Further advantages of our technique include ease of use, increased accuracy of field-based volume estimates, and increased resolution of variation in egg volume estimates. In addition, our technique does not require postdata collection processing time and did not influence hatching success. Also, for Clapper Rails and similar species, our technique can be combined with other techniques (e.g., egg flotation) so that both egg volume and embryonic stage can be estimated at the same time. 相似文献
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ABSTRACT The migratory population of the king rail (Rallus elegans) has declined dramatically during the past 40 years, emphasizing the need to identify habitat requirements of this species to help guide conservation efforts. To assess distribution and habitat use of king rails along the Illinois and Upper Mississippi valleys, USA, we conducted repeated call-broadcast surveys at 83 locations in 2006 and 114 locations in 2007 distributed among 21 study sites. We detected king rails at 12 survey locations in 2006 and 14 locations in 2007, illustrating the limited distribution of king rails in this region. We found king rails concentrated at Clarence Cannon National Wildlife Refuge, an adjacent private Wetlands Reserve program site, and B. K. Leach Conservation Area, which were located in the Mississippi River floodplain in northeast Missouri. Using Program PRESENCE, we estimated detection probabilities and built models to identify habitat covariates that were important in king rail site occupancy. Habitat covariates included percentage of cover by tall (>1 m) and short (>1 m) emergent vegetation, percentage of cover of woody vegetation, and interspersion of water and vegetation (2007 only) within 50 m of the survey location. Detection probability was 0.43 (SE = 0.12) in 2006 and 0.35 (SE = 0.03) in 2007 and was influenced by observer identity and percentage of cover by tall herbaceous vegetation. Site occupancy was 0.11 (SE = 0.04) in 2006 and 0.14 (SE = 0.04) in 2007 and was negatively influenced most by percentage of cover by woody vegetation. In addition, we found that interspersion of vegetation and water was positively related to occupancy in 2007. Thus, nesting king rails used wetlands that were characterized by high water-vegetation interspersion and little or no cover by woody vegetation. Our results suggest that biologists can improve king rail habitat by implementing management techniques that reduce woody cover and increase vegetation-water interspersion in wetlands. 相似文献
4.
ABSTRACT Tropical forests have exceptional woodpecker diversity, but little is known about the abundance and diversity of woodpeckers in the Indian subcontinent, particularly for the Shorea robusta‐dominated moist deciduous forests of northern India. Our objective was to compare the number of woodpecker species and number of individuals detected using playback surveys and visual/aural transect surveys at five sites. Each site was surveyed 5–6 times along a 2000‐m transect, with woodpeckers detected using two methods: (1) visual and aural cues, and (2) playing back calls of 13 species at 400‐m intervals. Both methods involved similar effort per survey (100–110 min). During surveys, we detected 11 species of woodpeckers. More species and more than twice as many individuals were detected during playback surveys than during visual/aural surveys. In addition, species accumulation curves showed that we detected the species known to be present based on previous work faster with playback surveys than with visual/aural surveys at four of the five sites. During field trials, 97% of targeted individuals (N= 269) of 12 species responded to playback, and 83% of the responses occurred within 1 min of broadcast. The number of species of woodpeckers in our study area (11 species) was typical for a structurally diverse, tropical/subtropical moist broad‐leaved forest. Our results demonstrate that playback surveys are more efficient and accurate than visual/aural surveys, and that playback surveys can be useful for assessing and monitoring woodpecker diversity in tropical forests. 相似文献
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ABSTRACT Amphibian monitoring programs rarely question the quality of data obtained by observers and often ignore observer bias. In order to test for bias in amphibian call surveys, we sampled 29 clusters of wetlands from the Rainwater Basin, Nebraska, USA, totaling 228 functionally connected wetlands. Sampling consisted of 3-minute stops where volunteers recorded species heard and made digital recordings. Based on 627 samples, we examined 3 types of observer bias: omission, false inclusion (commission), and incorrect identification. Misidentification rates ranged from 4.2% to 18.3%. Relatively high and unquantified error rates can negatively affect the ability of monitoring programs to accurately detect the population or abundance trends for which most were designed. 相似文献
6.
André H. Zambolli Maria Carolina R. Manzano Laura Kyoko Honda Gabriela C. Rezende Laurence Culot 《American journal of primatology》2023,85(1):e23454
Information about species distribution is important for conservation but the monitoring of populations can demand a high sampling effort with traditional methods (e.g., line transects, sound playback) that are poorly efficient for cryptic primates, such as the black lion tamarin (Leontopithecus chrysopygus). Here we investigated the effectiveness of passive acoustic monitoring (PAM) as an alternative method to identify the presence of vocalizing lion tamarins in the wild. We aimed to: (1) determine the maximum distance at which autonomous recorders (Song Meter 3) and Raven Pro acoustic software can respectively detect and identify lion tamarin long calls emitted by two captive subjects (ex situ study); and (2) determine the sampling effort required to confirm the presence of the species in the wild (in situ study). In captive settings, we recorded lion tamarin long calls with one to two autonomous recorders operating at increasing distances from the animals' enclosure (8−202 m). In a 515 ha forest fragment, we deployed 12 recorders in a grid, 300 m apart from each other, within the estimated 100 ha home range of one group, and let them record for 10 consecutive days, totaling 985 h. In the ex situ study, hand-browsing of spectrograms yielded 298 long calls emitted from 8 to 194 m, and Raven's Template Detector identified 54.6% of them, also emitted from 8 to 194 m. In the in situ study, we manually counted 1115 long calls, and the Raven's Template Detector identified 44.75% of them. Furthermore, the presence of lion tamarins was confirmed within 1 day using four randomly sorted recorders, whereas 5 days on average were necessary with only one device. While specific protocols still need to be developed to determine primate population size using this technology, we concluded that PAM is a promising tool when considering long term costs and benefits. 相似文献
7.
Samantha L. Rogers Jaime A. Collazo Christina A. Drew 《Journal of Field Ornithology》2013,84(4):355-366
Prescribed burning maintains marsh habitat, but its impact on breeding King Rails (Rallus elegans) is poorly understood. This practice may serve as a means to enhance populations of a species whose numbers are declining in the southeastern United States. We used call‐broadcast surveys and nest searches to categorize the state of occupied plots by the presence or non‐presence of nesting activity in the Back Bay region, North Carolina and Virginia, in 2010. We also used nest video surveillance to estimate nest survival in 2009 and 2010. The probabilities that a surveyed plot was occupied (1) and contained an active nest (2) were higher in recently burned marsh plots (0–1 year‐since‐burn [YSB]) than in plots with ≥2 YSB at Mackay Island and Back Bay National Wildlife Refuges (NWRs). Highest probabilities were recorded in 0–1 YSB plots at Mackay Island NWR ( = 0.96 ± 0.04, = 0.75 ± 0.18), and the lowest in ≥2 YSB plots at Back Bay NWR ( = 0.21 ± 0.10, = 0.03 ± 0.04). Nest survival from egg laying to hatching (31 d) was 0.48 (95% confidence interval [CI] = 0.06–0.83), with an estimated 0.79 (95% CI = 0.29–0.96) survival rate for the incubation stage (21 d). These nest survival estimates for King Rails in fire‐managed marshes were similar to estimates for other populations. Measures of vegetation cover, proxies for concealment, did not differ between nest sites and unused sites, even within recently burned marshes. This lack of differences in vegetation structure suggests that regrowth occurs rapidly during the period between burning (winter months) and the onset of reproduction (late April). Thus, recently burned marshes may benefit nesting King Rails by providing nest concealment. In addition, burned marshes may enhance availability of many invertebrates. Although we found that the probability that surveyed plots contained active nests was higher in recently burned marsh plots, estimates of fledging success are needed before marsh burns can be considered an effective means of fostering population growth. 相似文献
8.
Ikkyu Aihara Priyanka de Silva Ximena E. Bernal 《Ethology : formerly Zeitschrift fur Tierpsychologie》2016,122(2):105-113
In many animals, males aggregate to produce mating signals that attract conspecific females. These leks, however, also attract eavesdropping predators and parasites lured by the mating signal. This study investigates the acoustic preferences of eavesdroppers attracted to natural choruses in a Neotropical frog, the túngara frog (Engystomops pustulosus). In particular, we examined the responses of frog‐biting midges to natural variation in call properties and signaling rates of males in the chorus. These midges use the mating calls of the frogs to localize them and obtain a blood meal. Although it is known that the midges prefer complex over simple túngara frog calls, it is unclear how these eavesdroppers respond to natural call variation when confronted with multiple males in a chorus. We investigated the acoustic preference of the midges using calling frogs in their natural environment and thus accounted for natural variation in their call properties. We performed field recordings using a sound imaging system to quantify the temporal call properties of males in small choruses. During these recordings, we also collected frog‐biting midges attacking calling males. Our results revealed that, in a given chorus, male frogs calling at higher rates and with higher call complexity attracted a larger number of frog‐biting midges. Call rate was particularly important at increasing the number of midges attracted when males produced calls of lower complexity. Similarly, call complexity increased attractiveness to the midges especially when males produced calls at a low repetition rate. Given that female túngara frogs prefer calls produced at higher repetition rates and higher complexity, this study highlights the challenge faced by signalers when increasing attractiveness of the signal to their intended receivers. 相似文献
9.
Erica Fleishman Danielle Cholewiak Douglas Gillespie Tyler Helble Holger Klinck Eva-Marie Nosal Marie A. Roch 《Biological reviews of the Cambridge Philosophical Society》2023,98(5):1633-1647
Monitoring on the basis of sound recordings, or passive acoustic monitoring, can complement or serve as an alternative to real-time visual or aural monitoring of marine mammals and other animals by human observers. Passive acoustic data can support the estimation of common, individual-level ecological metrics, such as presence, detection-weighted occupancy, abundance and density, population viability and structure, and behaviour. Passive acoustic data also can support estimation of some community-level metrics, such as species richness and composition. The feasibility of estimation and certainty of estimates is highly context dependent, and understanding the factors that affect the reliability of measurements is useful for those considering whether to use passive acoustic data. Here, we review basic concepts and methods of passive acoustic sampling in marine systems that often are applicable to marine mammal research and conservation. Our ultimate aim is to facilitate collaboration among ecologists, bioacousticians, and data analysts. Ecological applications of passive acoustics require one to make decisions about sampling design, which in turn requires consideration of sound propagation, sampling of signals, and data storage. One also must make decisions about signal detection and classification and evaluation of the performance of algorithms for these tasks. Investment in the research and development of systems that automate detection and classification, including machine learning, are increasing. Passive acoustic monitoring is more reliable for detection of species presence than for estimation of other species-level metrics. Use of passive acoustic monitoring to distinguish among individual animals remains difficult. However, information about detection probability, vocalisation or cue rate, and relations between vocalisations and the number and behaviour of animals increases the feasibility of estimating abundance or density. Most sensor deployments are fixed in space or are sporadic, making temporal turnover in species composition more tractable to estimate than spatial turnover. Collaborations between acousticians and ecologists are most likely to be successful and rewarding when all partners critically examine and share a fundamental understanding of the target variables, sampling process, and analytical methods. 相似文献
10.
Laura E. D'Acunto Benjamin P. Pauli Mikko Moy Kiara Johnson Jasmine Abu‐Omar Patrick A. Zollner 《Ecology and evolution》2018,8(6):3152-3160
Mobile acoustic surveys are a common method of surveying bat communities. However, there is a paucity of empirical studies exploring different methods for conducting mobile road surveys of bats. During 2013, we conducted acoustic mobile surveys on three routes in north‐central Indiana, U.S.A., using (1) a standard road survey, (2) a road survey where the vehicle stopped for 1 min at every half mile of the survey route (called a “start‐stop method”), and (3) a road survey with an individual using a bicycle. Linear mixed models with multiple comparison procedures revealed that when all bat passes were analyzed, using a bike to conduct mobile surveys detected significantly more bat passes per unit time compared to other methods. However, incorporating genus‐level comparisons revealed no advantage to using a bike over vehicle‐based methods. We also found that survey method had a significant effect when analyses were limited to those bat passes that could be identified to genus, with the start–stop method generally detecting more identifiable passes than the standard protocol or bike survey. Additionally, we found that significantly more identifiable bat passes (particularly those of the Eptesicus and Lasiurus genera) were detected in surveys conducted immediately following sunset. As governing agencies, particularly in North America, implement vehicle‐based bat monitoring programs, it is important for researchers to understand how variations on protocols influence the inference that can be gained from different monitoring schemes. 相似文献
11.
Monitoring the abundance of cryptic species inevitably relies on the use of index methods. Unfortunately, detectability is often confounded by unidentified covariates. One such species is the critically endangered Australasian Bittern Botaurus poiciloptilus. Current monitoring relies upon the ability to count males based on the conspicuous breeding calls of males. However, as in many vocal species, calling rates vary spatially and temporally, making it necessary to account for this when using call counts to index abundance. We undertook 461 15‐min call counts of Australasian Bitterns, in a range of conditions, during two breeding seasons at Whangamarino wetland, New Zealand. We fitted a range of generalized linear mixed models to these data to determine which factors were the best predictors of calling rate per individual Bittern (CRPI), allowing us to make recommendations regarding the optimum time and conditions for monitoring. Bittern CRPI was predictable in terms of time of day, month, cloud cover, rainfall and certain moon parameters, but some spatial and temporal variation remained unexplained. Results showed that the best time to detect Australasian Bitterns was 1 h before sunrise, in September (austral spring), on a moonlit night with no cloud or rain. Such models are useful for identifying times and conditions when counts are the highest and least variable, and could be applied to any species or cue count monitoring method where detection depends on counting calling individuals. Results can be used to standardize index counts, or sensibly to adjust and compare counts from different times. Standardizing monitoring in this way can lead to the development of monitoring methods that have a greater power to show population changes across shorter time periods. Moreover, the use of modelling processes to estimate effect sizes creates potential for such methods to be applied in circumstances where monitoring conditions are rarely optimum and standardization creates logistical trade‐offs, something that is particularly common in studies of cryptic species. 相似文献
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13.
The ethological approach has already provided rich insights into the auditory neurobiology of a number of different taxa (e.g. birds, frogs and insects). Understanding the ethology of primates is likely to yield similar insights into the specializations of this taxa's auditory system for processing species-specific vocalisations. Here, we review the recent advances made in our understanding of primate vocal perception and its neural basis. 相似文献
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15.
ABSTRACTAutomated recognition is increasingly used to extract information about species vocalizations from audio recordings. During processing, recognizers calculate the probability of correct classification (“score”) for each acoustic signal assessed. Our goal was to investigate the implications of recognizer score for ecological research and monitoring. We trained four recognizers with clips of Common Nighthawk (Chordeiles minor) calls recorded at different distances: near, midrange, far, and mixed distances. We found distance explained 49% and 41% of the variation in score for the near and mixed-distance recognizers, but only 3% and 6% of the variation for the midrange and far recognizers. We calculated detection functions for each of the recognizers at various score thresholds and found that the detection function for the near and mixed-distance recognizers satisfied the assumptions of density estimation for most score thresholds, while the detection function for the midrange and far recognizers did not. The detection functions also showed that score threshold choice is a decision about sampling area, not just about the balance between recall and precision. Overall, we showed that training recognizers with ‘high-quality’ clips that were recorded at close range will improve the utility of the data without affecting how many true positives the recognizer detects. 相似文献
16.
MATHEW W. ALLDREDGE THEODORE R. SIMONS KENNETH H. POLLOCK 《The Journal of wildlife management》2007,71(8):2759-2766
ABSTRACT Detection distance is an important and common auxiliary variable measured during avian point count surveys. Distance data are used to determine the area sampled and to model the detection process using distance sampling theory. In densely forested habitats, visual detections of birds are rare, and most estimates of detection distance are based on auditory cues. Distance sampling theory assumes detection distances are measured accurately, but empirical validation of this assumption for auditory detections is lacking. We used a song playback system to simulate avian point counts with known distances in a forested habitat to determine the error structure of distance estimates based on auditory detections. We conducted field evaluations with 6 experienced observers both before and after distance estimation training. We conducted additional studies to determine the effect of height and speaker orientation (toward or away from observers) on distance estimation error. Distance estimation errors for all evaluations were substantial, although training reduced errors and bias in distance estimates by approximately 15%. Measurement errors showed a nonlinear relationship to distance. Our results suggest observers were not able to differentiate distances beyond 65 m. The height from which we played songs had no effect on distance estimation errors in this habitat. The orientation of the song source did have a large effect on distance estimation errors; observers generally doubled their distance estimates for songs played away from them compared with distance estimates for songs played directly toward them. These findings, which we based on realistic field conditions, suggest measures of uncertainty in distance estimates to auditory detections are substantially higher than assumed by most researchers. This means aural point count estimates of avian abundance based on distance methods deserve careful scrutiny because they are likely biased. 相似文献
17.
Susan C. Walls J. Hardin Waddle Robert M. Dorazio 《The Journal of wildlife management》2011,75(4):751-761
Effective monitoring programs are designed to track changes in the distribution, occurrence, and abundance of species. We developed an extension of Royle and Kéry's (2007) single species model to estimate simultaneously temporal changes in probabilities of detection, occupancy, colonization, extinction, and species turnover using data on calling anuran amphibians, collected from 2002 to 2006 in the Lower Mississippi Alluvial Valley of Louisiana, USA. During our 5-year study, estimates of occurrence probabilities declined for all 12 species detected. These declines occurred primarily in conjunction with variation in estimates of local extinction probabilities (cajun chorus frog [Pseudacris fouquettei], spring peeper [P. crucifer], northern cricket frog [Acris crepitans], Cope's gray treefrog [Hyla chrysoscelis], green treefrog [H. cinerea], squirrel treefrog [H. squirella], southern leopard frog [Lithobates sphenocephalus], bronze frog [L. clamitans], American bullfrog [L. catesbeianus], and Fowler's toad [Anaxyrus fowleri]). For 2 species (eastern narrow-mouthed toad [Gastrophryne carolinensis] and Gulf Coast toad [Incilius nebulifer]), declines in occupancy appeared to be a consequence of both increased local extinction and decreased colonization events. The eastern narrow-mouthed toad experienced a 2.5-fold increase in estimates of occupancy in 2004, possibly because of the high amount of rainfall received during that year, along with a decrease in extinction and increase in colonization of new sites between 2003 and 2004. Our model can be incorporated into monitoring programs to estimate simultaneously the occupancy dynamics for multiple species that show similar responses to ecological conditions. It will likely be an important asset for those monitoring programs that employ the same methods to sample assemblages of ecologically similar species, including those that are rare. By combining information from multiple species to decrease the variance on estimates of individual species, our results are advantageous compared to single-species models. This feature enables managers and researchers to use an entire community, rather than just one species, as an ecological indicator in monitoring programs. © 2011 The Wildlife Society. 相似文献
18.
Mario Penna Nelson A. Velásquez Jaime Bosch 《Biological journal of the Linnean Society. Linnean Society of London》2015,116(1):41-51
The auditory sensitivity in three species of the anuran genus Alytes (Alytidae) was examined to determine patterns of intra‐ and interspecific variation, relating these measurements to behavioural preferences measured in previous studies and to the adaptive and evolutionary significance of this sensory function. The audiograms obtained with multi‐unit recordings in the torus semicircularis of 13 Alytes cisternasii, 10 Alytes obstetricans, and eight Alytes dickhilleni show two regions of enhanced sensitivity, between approximately 100–500 and 1200–2400 Hz, with minimum thresholds at approximately 40 and 45 dB SPL, respectively. The mean and range of the high‐frequency region differed among species, although the sensitivity, measured as minimum thresholds, was similar. The region of high‐frequency sensitivity was centred at approximately the frequency of the advertisement call in A. cisternasii but, in A. obstetricans and A. dickhilleni, was centred at frequencies higher than the conspecific calls. These results contrast with preferences for lower frequencies exhibited by Alytes in female phonotactic and in male evoked vocal responses. Such loose relationships between signals and receivers suggest that the divergence of the sound communication system in Alytes has implied environmental and phylogenetic factors in addition to sexual selection processes. 相似文献
19.
Dung and nest surveys: estimating decay rates 总被引：5，自引：0，他引：5
S. E. Laing† S. T. Buckland‡ R. W. Burn§ D. Lambie¶ A. Amphlett 《Journal of Applied Ecology》2003,40(6):1102-1111
20.
Diehl RL 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2008,363(1493):965-978
Speech perception is remarkably robust. This paper examines how acoustic and auditory properties of vowels and consonants help to ensure intelligibility. First, the source-filter theory of speech production is briefly described, and the relationship between vocal-tract properties and formant patterns is demonstrated for some commonly occurring vowels. Next, two accounts of the structure of preferred sound inventories, quantal theory and dispersion theory, are described and some of their limitations are noted. Finally, it is suggested that certain aspects of quantal and dispersion theories can be unified in a principled way so as to achieve reasonable predictive accuracy. 相似文献