Combining point counts and autonomous recording units improves survey efficacy across elevational gradients on two continents

1. Accurate biodiversity and population monitoring is a requirement for effective conservation decision-making. Survey method bias is therefore a concern, particularly when research programs face logistical and cost limitations. 2. We employed point counts (PCs) and autonomous recording units (ARUs) to survey avian biodiversity across elevational gradients in comparable temperate mountain habitats at opposite ends of the Americas (9 mountains in British Columbia (BC), Canada and 10 in southern Chile). We compared detected species richness against multi-year species inventories and examined differences in detection probability by family. By incorporating time costs, we assessed the performance and efficiency of single vs. combined methods. 3. ARUs were predicted to capture ~92% of species present in BC but only ~58% in Chile, despite Chilean mountain communities being less diverse. Community, rather than landscape composition, appears to be the driver of this dramatic difference. Chilean communities contain less-vocal species, which ARUs missed. Further, 6/14 families in BC were better detected by ARUs while 11/11 families in Chile were better detected by PCs. Where survey conditions differentially impacted methods, PC detection varied over the morning and with canopy cover in BC and ARU detection probability mostly varied seasonally in Chile. Within a single year of monitoring, neither method alone was predicted to capture the full avian community, with the exception of ARUs in the alpine and subalpine of BC. PCs contributed little to detected diversity in BC, but including this method resulted in negligible increases in total time costs. Combining PCs with ARUs in Chile significantly increased species detections, again, for little cost. 4. Combined methods were among the most efficient and accurate approaches to capturing diversity. We recommend conducting observer point counts, where possible, when ARUs are deployed and retrieved, in order to capture additional diversity and flag methodology biases with minimal additional effort.

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Survival of Greater Sage‐Grouse broods: survey method affects disturbance and age‐specific detection probability

Journal of Field Ornithology ◽

10.1111/jofo.12356 ◽

2021 ◽

Vol 92 (1) ◽

pp. 88-102

Author(s):

Ian P. Riley ◽

Courtney J. Conway ◽

Bryan S. Stevens ◽

Shane Roberts

Keyword(s):

Detection Probability ◽

Survey Method ◽

Sage Grouse ◽

Specific Detection

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Combining point counts and autonomous recording units improves avian survey efficacy across elevational gradients on two continents

Ecology and Evolution ◽

10.1002/ece3.7678 ◽

2021 ◽

Author(s):

Anna Drake ◽

Devin R. Zwaan ◽

Tomás A. Altamirano ◽

Scott Wilson ◽

Kristina Hick ◽

...

Keyword(s):

Elevational Gradients ◽

Point Counts

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KEANEKARAGAMAN JENIS JAMUR MAKROSKOPIS PADA BERBAGAI KONDISI TEMPAT TUMBUH HUTAN RAWA GAMBUT DI KAWASAN HUTAN DENGAN TUJUAN KHUSUS UNIVERSITAS TANJUNGPURA

JURNAL HUTAN LESTARI ◽

10.26418/jhl.v7i3.37277 ◽

2019 ◽

Vol 7 (3) ◽

Author(s):

Syapriadi Utama ◽

Dwi Astiani ◽

Wiwik Ekyastuti

Keyword(s):

Canopy Cover ◽

Sampling Technique ◽

Forest Products ◽

Data Retrieval ◽

Survey Method ◽

Swamp Forest ◽

Peat Swamp Forest ◽

Plot Sampling ◽

Peat Swamp ◽

Open Canopy

Tanjungpura University Forest for Special Purpose located in three districts Landak Regency, Mempawah Regency and Kubu Raya Regency. Has the potential to use and process non-timber forest products. The diversity of macroscopic fungi is not yet known as one of the potential natural biological resources of significant value. So that a mushroom inventory must be carried out to identify and assess the diversity of macroscopic fungi. The method used is the survey method. Data retrieval uses a double plot sampling technique. The size of each observation plot is 5 m × 5 m as the initial reference, four plots in the peat swamp forest area with open canopy cover conditions and also four observation plots in peat swamp forest areas with canopy cover conditions are still closed. Placement of research plots in both areas was carried out purposively in locations where there were many types of macroscopic fungi. The results showed that the types of macroscopic fungi found at the study site were 24 species. 24 species were divided into 594 individuals belonging to 23 genera and 9 families. Macroscopic fungi found in open canopy cover were found in 17 species, while in closed canopy cover there were 13 species. In both types of conditions the place to grow has the same 6 types of fungi. The degree of diversity of macroscopic fungi in various conditions the peat swamp in Tanjungpura University Forest for Special Purpose is low.Keyword: Macroscopic fungi, peat swamp forest, Tanjungpura University Forest for Special Purpose.

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Singing in the suburbs: point count surveys efficiently reveal habitat associations for nocturnal Orthoptera across an urban-to-rural gradient

Journal of Insect Conservation ◽

10.1007/s10841-020-00273-9 ◽

2020 ◽

Vol 24 (6) ◽

pp. 1031-1043

Author(s):

Darin J. McNeil ◽

Christina M. Grozinger

Keyword(s):

Site Occupancy ◽

Habitat Associations ◽

Survey Method ◽

Population Declines ◽

Detection Rates ◽

Point Count ◽

Point Counts ◽

Focal Species ◽

Habitat Gradient ◽

Count Surveys

Abstract As evidence for global insect population declines continues to amass, several studies have indicated that Orthoptera (grasshoppers, crickets, and katydids) are among the most threatened insect groups. Understanding Orthoptera populations across large spatial extents requires efficient survey protocols, however, many previously established methods are expensive and/or labor-intensive. One survey method widely employed in wildlife biology, the aural point count, may work well for crickets and katydids (suborder: Ensifera) because males produce conspicuous, species-specific mating calls. We conducted repeated point count surveys across an urban-to-rural gradient in central Pennsylvania. Occupancy analyses of ten focal species indicated that, although detection probability rates varied by species from 0.43 to 0.98, detection rates compounded over five visits such that all focal species achieved cumulative > 0.90. Factors associated with site occupancy varied among species with some positively associated with urbanization (e.g., Greater Anglewing, Microcentrum rhombifolium), some negatively associated with urbanization (e.g., Sword-bearing Conehead, Neoconocephalus ensiger), and others exhibiting constant occupancy across a habitat gradient (e.g., Common True Katydid, Pterophylla camellifolia). Our community-level analysis revealed that different species’ habitat associations interacted such that intermediate levels of urbanization (i.e., suburbs) hosted the highest number of species. Implications for insect conservation Ultimately, our analyses clearly support the concept that aural point counts paired with static occupancy modeling can serve as an important tool for monitoring night-singing Orthoptera populations. Applications of point count surveys by both researchers and citizen scientists may improve our understanding Ensifera populations and help in the global conservation of these threatened insects.

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Estimating Detection Probability and Density from Point-Count Surveys: A Combination of Distance and Double-Observer Sampling

The Auk ◽

10.1093/auk/123.3.735 ◽

2006 ◽

Vol 123 (3) ◽

pp. 735-752 ◽

Cited By ~ 8

Author(s):

Michelle L. Kissling ◽

Edward O. Garton

Keyword(s):

Detection Probability ◽

Survey Methods ◽

Effective Area ◽

Survey Method ◽

Density Estimates ◽

Point Count ◽

Detection Probabilities ◽

Fixed Radius ◽

Count Surveys ◽

Double Observer

Abstract Point counts are the method most commonly used to estimate abundance of birds, but they often fail to account properly for incomplete and variable detection probabilities. We developed a technique that combines distance and double-observer sampling to estimate detection probabilities and effective area surveyed. We applied this paired-observer, variable circular-plot (POVCP) technique to point-count surveys (n = 753) conducted in closed-canopy forests of southeast Alaska. Distance data were analyzed for each species to model a detection probability for each observer and calculate an estimate of density. We then multiplied each observer's density estimates by a correction factor to adjust for detection probabilities <1 at plot center. We compared analytical results from four survey methods: single-observer fixed-radius (50-m) plot; single-observer, variable circular-plot (SOVCP); double-observer fixed-radius (50-m) plot; and POVCP. We examined differences in detection probabilities at plot center, effective area surveyed, and densities for five bird species: Pacific-slope Flycatcher (Empidonax difficilis), Winter Wren (Troglodytes troglodytes), Golden-crowned Kinglet (Regulus satrapa), Hermit Thrush (Catharus guttatus), and Townsend's Warbler (Dendroica townsendi). Average detection probabilities for paired observers increased ≈8% (SE = 2.9) for all species once estimates were corrected for birds missed at plot center. Density estimators of fixed-radius survey methods were likely negatively biased, because the key assumption of perfect detection was not met. Density estimates generated using SOVCP and POVCP were similar, but standard errors were much lower for the POVCP survey method. We recommend using POVCP when study objectives require precise estimates of density. Failure to account for differences in detection probabilities and effective area surveyed results in biased population estimators and, therefore, faulty inferences about the population in question. Estimaciones de la Densidad y de las Probabilidades de Detección a Partir de Muestreos Utilizando Conteos en Puntos: Una Combinación de Muestreos de Distancia y de Doble Observador

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Power to Detect Trend in Short-Term Time Series of Bird Abundance

The Condor ◽

10.1093/condor/109.4.943 ◽

2007 ◽

Vol 109 (4) ◽

pp. 943-948

Author(s):

Wayne E. Thogmartin ◽

Brian R. Gray ◽

Maureen Gallagher ◽

Neal Young ◽

Jason J. Rohweder ◽

...

Keyword(s):

Sample Size ◽

Short Duration ◽

Bird Species ◽

Population Monitoring ◽

Short Term ◽

Wet Prairie ◽

Bird Abundance ◽

Point Counts ◽

Study Sites ◽

Species Specific

Abstract Avian point counts for population monitoring are often collected over a short timespan (e.g., 3–5 years). We examined whether power was adequate (power ≥0.80) in short-duration studies to warrant the calculation of trend estimates. We modeled power to detect trends in abundance indices of eight bird species occurring across three floodplain habitats (wet prairie, early successional forest, and mature forest) as a function of trend magnitude, sample size, and species-specific sampling and among-year variance components. Point counts (5 min) were collected from 365 locations distributed among 10 study sites along the lower Missouri River; counts were collected over the period 2002 to 2004. For all study species, power appeared adequate to detect trends in studies of short duration (three years) at a single site when exponential declines were relatively large in magnitude (more than −5% year−1) and the sample of point counts per year was ≥30. Efforts to monitor avian trends with point counts in small managed lands (i.e., refuges and parks) should recognize this sample size restriction by including point counts from offsite locations as a means of obtaining sufficient numbers of samples per strata. Trends of less than −5% year−1 are not likely to be consistently detected for most species over the short term, but short-term monitoring may still be useful as the basis for comparisons with future surveys.

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Treeline ecotones shape the distribution of avian species richness and functional diversity in south temperate mountains

Scientific Reports ◽

10.1038/s41598-020-75470-2 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Tomás A. Altamirano ◽

Devin R. de Zwaan ◽

José Tomás Ibarra ◽

Scott Wilson ◽

Kathy Martin

Keyword(s):

Species Richness ◽

Functional Diversity ◽

Functional Traits ◽

Habitat Structure ◽

Environmental Gradients ◽

Montane Forest ◽

Avian Species ◽

Point Counts ◽

Mountain Habitats ◽

Elevational Range

Abstract Mountains produce distinct environmental gradients that may constrain or facilitate both the presence of avian species and/or specific combinations of functional traits. We addressed species richness and functional diversity to understand the relative importance of habitat structure and elevation in shaping avian diversity patterns in the south temperate Andes, Chile. During 2010–2018, we conducted 2202 point-counts in four mountain habitats (successional montane forest, old-growth montane forest, subalpine, and alpine) from 211 to 1,768 m in elevation and assembled trait data associated with resource use for each species to estimate species richness and functional diversity and turnover. We detected 74 species. Alpine specialists included 16 species (22%) occurring only above treeline with a mean elevational range of 298 m, while bird communities below treeline (78%) occupied a mean elevational range of 1,081 m. Treeline was an inflection line, above which species composition changed by 91% and there was a greater turnover in functional traits (2–3 times greater than communities below treeline). Alpine birds were almost exclusively migratory, inhabiting a restricted elevational range, and breeding in rock cavities. We conclude that elevation and habitat heterogeneity structure avian trait distributions and community composition, with a diverse ecotonal sub-alpine and a distinct alpine community.

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Variation in herpetofauna detection probabilities: implications for study design

Environmental Monitoring and Assessment ◽

10.1007/s10661-021-09424-0 ◽

2021 ◽

Vol 193 (10) ◽

Author(s):

Jeremy A. Baumgardt ◽

Michael L. Morrison ◽

Leonard A. Brennan ◽

Madeleine Thornley ◽

Tyler A. Campbell

Keyword(s):

Detection Probability ◽

Relative Effectiveness ◽

Population Monitoring ◽

Occupancy Modeling ◽

Pitfall Traps ◽

Modeling Framework ◽

Detection Probabilities ◽

Study Sites ◽

Sampling Duration ◽

Biodiversity Decline

AbstractPopulation monitoring is fundamental for informing management decisions aimed at reducing the rapid rate of global biodiversity decline. Herpetofauna are experiencing declines worldwide and include species that are challenging to monitor. Raw counts and associated metrics such as richness indices are common for monitoring populations of herpetofauna; however, these methods are susceptible to bias as they fail to account for varying detection probabilities. Our goal was to develop a program for efficiently monitoring herpetofauna in southern Texas. Our objectives were to (1) estimate detection probabilities in an occupancy modeling framework using trap arrays for a diverse group of herpetofauna and (2) to evaluate the relative effectiveness of funnel traps, pitfall traps, and cover boards. We collected data with 36 arrays at 2 study sites in 2015 and 2016, for 2105 array-days resulting in 4839 detections of 51 species. We modeled occupancy for 21 species and found support for the hypothesis that detection probability varied over our sampling duration for 10 species and with rainfall for 10 species. For herpetofauna in our study, we found 14 and 12 species were most efficiently captured with funnel traps and pitfall traps, respectively, and no species were most efficiently captured with cover boards. Our results show that using methods that do not account for variations in detection probability are highly subject to bias unless the likelihood of false absences is minimized with exceptionally long capture durations. For monitoring herpetofauna in southern Texas, we recommend using arrays with funnel and pitfall traps and an analytical method such as occupancy modeling that accounts for variation in detection.

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Kondisi mangrove di pesisir timur pulau Jemaja Kepuluan Anambas

Dinamika Lingkungan Indonesia ◽

10.31258/dli.7.2.p.70-80 ◽

2020 ◽

Vol 7 (2) ◽

pp. 70

Author(s):

Wahyudi Andrito ◽

Syafruddin Nasution ◽

Efriyeldi Efriyeldi

Keyword(s):

East Coast ◽

Good Condition ◽

Canopy Cover ◽

Coastal Areas ◽

Average Density ◽

Survey Method ◽

Mangrove Forests ◽

Bruguiera Gymnorrhiza ◽

Mangrove Species ◽

Sea Levels

Mangrove ecosystems are one of three important ecosystems in the coastal areas that supports global warming mitigation efforts. The existence of mangrove forests is needed to reduce the increased CO2 concentrations in the atmosphere. However, the rise of the water temperatures and sea levels indirectly affects the presence and condition of mangrove forests in coastal areas. The purpose of this study is to determine the condition of the mangrove community on the East Coast of Jemaja, Anambas Archipelagoes Regency. The survey method was used in this study and a series survey activities were conducted for a quadrant transect with a size of 10m by 10m in December 2019 - March 2020.The result shown that the five mangrove species were identified, such as Rhizophora apiculata, R. mucronata, Bruguiera gymnorrhiza, Ceriops tagal and Xylocarpus granatum. R. apiculata dominates with an important value index of 123.12%. While, the average density of mangroves and saplings in the study area was 3155 ± 785 individuals/ha and the average canopy cover was 84.03 ± 3.11%. With this finding, it can be concluded that the condition of mangroves in the East Coast of Jemaja is very dense and still in a good condition.

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Monitoring migratory birds in stopover habitat: assessing the value of extended duration audio recording

10.1101/2020.08.01.232215 ◽

2020 ◽

Author(s):

Ellie Roark ◽

Willson Gaul

Keyword(s):

Species Identification ◽

Relative Abundance ◽

Migratory Birds ◽

Survey Method ◽

List Type ◽

Point Counts ◽

Migration Timing ◽

Number Of Species ◽

Extended Duration ◽

Stopover Habitat

ABSTRACTBecause birds are frequently detected by sound, autonomous audio recorders (called automated recording units or ARUs) are now an established tool in addition to in-person observations for monitoring the status and trends of bird populations. ARUs have been evaluated and applied during breeding seasons, and to monitor the nocturnal flight calls of migrating birds. However, birds behave differently during migration stopover than during the breeding season. Here we present a method for using ARUs to monitor land birds in migration stopover habitat.We conducted in-person point counts next to continuously recording ARUs, and compared estimates of the number of species detected and focal species relative abundance from point counts and ARUs. We used a desk-based audio bird survey method for processing audio recordings, which does not require automated species identification algorithms. We tested two methods of using extended duration ARU recording: surveying consecutive minutes, and surveying randomly selected minutes.Desk-based surveys using randomly selected minutes from extended duration ARU recordings performed similarly to point counts, and better than desk-based surveys using consecutive minutes from ARU recordings. Surveying randomly selected minutes from ARUs provided estimates of relative abundance that were strongly correlated with estimates from point counts, and successfully showed the increase in abundance associated with migration timing. Randomly selected minutes also provided estimates of the number of species present that were comparable to estimates from point counts.ARUs are an effective way to track migration timing and intensity in remote or seasonally inaccessible migration stopover habitats. We recommend that desk-based surveys use randomly sampled minutes from extended duration ARU recordings, rather than using consecutive minutes from recordings. Our methods can be immediately applied by researchers with the skills to conduct point counts, with no additional expertise necessary in automated species identification algorithms.

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