Point Count Sampling Research Articles

Effects of management practices on Northern Bobwhite Colinus virginianus density in privately owned working forests across the Southeastern United States

Abstract Obtaining rigorous baseline density estimates of species of conservation interest is key when assisting landowners to achieve management goals on private lands. Northern bobwhite (Colinus virginianus) populations are declining throughout their range and despite being the focus of numerous private land conservation initiatives, baseline density estimates in privately owned pine forests are lacking. We sought to address this knowledge gap across the Southeastern United States by sampling 105 privately owned pine stands throughout 2018 to 2020 using observer point count and autonomous recording unit (ARU) sampling data. Using Bayesian hierarchical models, we investigated the influence of stand management (brush management or applied fire) on bobwhite density, as well as four landscape‐scale environmental variables. These included percentage cover of forest, herbaceous, agricultural or burnt land area across six different spatial scales ranging from 500‐m to 10‐km around each pine stand. Baseline density on sites with no management was estimated to be 2.24 coveys per 100 ha (1.00–5.03, 95% BCI), with little impact of applying brush management, but a trend for a positive effect of fire management (0.19, −0.01 to 0.38 95% BCI). This impact of fire was seen at both the stand‐scale, correlated with an increase in acreage of applied prescribed burn management, and across the greater landscape area, correlated with cover of burnt area within a 2‐km buffer around each site. There were also strong positive influences of herbaceous vegetation and a strong negative influence of forest cover on bobwhite density. Practical implication: our sampling efforts fill an important information gap regarding densities throughout private lands in the Southeastern United States. Our study also highlights the necessity of landscape scale planning for Northern Bobwhite conservation initiatives because the efficacy of conservation practices (i.e. prescribed fire and brush management) could be altered by the landscape surrounding the treated forest stand.

Confirmation of Skywalker Hoolock Gibbon (Hoolock tianxing) in Myanmar Extends Known Geographic Range of an Endangered Primate

Characterizing genetically distinct populations of primates is important for protecting biodiversity and effectively allocating conservation resources. Skywalker gibbons (Hoolock tianxing) were first described in 2017, with the only confirmed population consisting of 150 individuals in Mt. Gaoligong, Yunnan Province, China. Based on river geography, the distribution of the skywalker gibbon has been hypothesized to extend into Myanmar between the N’Mai Kha and Ayeyarwaddy Rivers to the west, and the Salween River (named the Thanlwin River in Myanmar and Nujiang River in China) to the east. We conducted acoustic point-count sampling surveys, collected noninvasive samples for molecular mitochondrial cytochrome b gene identification, and took photographs for morphological identification at six sites in Kachin State and three sites in Shan State to determine the presence of skywalker gibbons in predicted suitable forest areas in Myanmar. We also conducted 50 semistructured interviews with members of communities surrounding gibbon range forests to understand potential threats. In Kachin State, we audio-recorded 23 gibbon groups with group densities ranging between 0.57 and 3.6 group/km2. In Shan State, we audio-recorded 21 gibbon groups with group densities ranging between 0.134 and 1.0 group/km2. Based on genetic data obtained from skin and saliva samples, the gibbons were identified as skywalker gibbons (99.54–100% identity). Although these findings increase the species’ known population size and confirmed distribution, skywalker gibbons in Myanmar are threatened by local habitat loss, degradation, and fragmentation. Most of the skywalker gibbon population in Myanmar exists outside protected areas. Therefore, the IUCN Red List status of the skywalker gibbon should remain as Endangered.

Biodiversity Conservation in Mining Landscapes: a Systematic Review of Assessment Approaches in the Philippines

Mining is an important sector of the Philippine economy, but it often results in negative impacts on biodiversity. To mitigate these impacts, it is crucial to assess biodiversity in mining areas and integrate conservation efforts into mining operations. As part of the national policy guidelines on biodiversity compliance for mining companies, this study has conducted a systematic review to examine the various biodiversity assessment methods, tools, sampling designs, diversity parameters, values, and indices used in the Philippines' mining sites. Search engines and research databases were utilized in identifying diversity assessment-related research. Based on the eligibility criteria, only 25 of the 100 papers downloaded and two project terminal reports were eligible and considered in the review. It was found that authors commonly used transect line and quadrat methods for floral studies and transect line, mist netting, point count, and opportunistic sampling for faunal studies. Species abundance, relative abundance, dominance, frequency, relative frequency, density, relative density, percent cover, and importance value were the most frequently assessed biodiversity parameters, whereas the Shannon-Wiener diversity index, Simpson index, species richness, and evenness were the most commonly used indices. Endemism, economic importance, invasiveness, and conservation status were additional factors evaluated. Overall, this review provides an overview of the various biodiversity assessment methods used in the country's mining areas and offers guidance for future assessments in other mining landscapes. The limited number of studies related to biodiversity assessment in mining areas in the Philippines over the last decade highlights the urgent need for more research in this field.

Estimating species richness and density of a bird community in a coastal lagoon on the Mexican Pacific

In this study we assess the bias in estimates of bird richness in a tropical wetland. We used 18 months of data from point counts to estimate the species richness in a coastal lagoon in Oaxaca and computed eight species richness estimators. We evaluated estimate inaccuracy using the sum of total richness that we obtained with combined sampling techniques between 2006 and 2010. We selected the richness estimator of minimum inaccuracy and used randomized species accumulation curves to investigate differences in species densities obtained with 10 and 20-minute counts. To ascertain if habitat type influenced richness estimates, we compared the bird diversity associated with contrasting mangrove and estuarine environments. The total richness for the lagoon was 185 species and the jackknife 2 richness estimator showed the minimum inaccuracy. The randomized accumulation curves of 10 and 20 minutes displayed partially overlapping confidence intervals and an increasing time lag between the count durations at equivalent densities. The rarefaction curves from contrasting habitat types showed significantly higher richness and species density in the estuary while the jackknife 2 estimator indicated similar sample coverage in both habitats. We identify important consequences of the sampling methodology that we used and conclude that point count sampling resulted in incomplete species detection but facilitated comparative analyses.

Assessment of Population Abundance, Density and Habitat Preference of Sclater’s Guenon (Cercopithecus sclateri Pocock 1904) in Aboh-Mbaise Communal Forest, Imo State, Nigeria

Aims: We assessed the population abundance, density and habitat preference of sclater’s guenon (Cercopithecus sclateri) in Aboh-Mbaise communal forest to inform conservation efforts for the species now and in the future.
 Study Design: We used the point count sampling method to estimate population size.
 Place and duration of study: The study was carried out in Lagwa communal forest, Aboh-Mbaise Local Government Area, Imo State, between December 2019 and November 2021.
 Methodology: We laid-out eight 2.5-km transects in a land area of 28,500km2. We enumerated and measured trees using the point-centered quarter method. 
 Results: Results of this study indicated that they were 738 individual monkeys, 392 in dry and 346 in the wet seasons. The population density was 0.04 ± 0.01 individuals/km2, with troop sizes of 4.09±0.83 and 3.68 ± 0.75 for dry and wet seasons, respectively. The monkeys were sighted mostly in secondary forest, sacred groves, and economic trees. Most of the trees were within the diameter-at-breast-height class of 21cm-30 cm. A total of (304) plant species were used by the monkeys for cover in both seasons; these included Dacryodes edulis, Elaeis guinensis, Magnifera indica, Treculia africana and Pterocarpus erinaceous.
 Conclusion: The findings of this research is a prelude to understanding the population dynamics and habitat structure of the sclater’s guenon in the study area. Massive sensitization of the locals, regeneration of the remaining fragmented habitat and establishment of a wildlife sanctuary are needed to allow conservation of the species and its habitat.

Noise pollution effect on composition of avian structure in different urban gradients

Extreme urbanization producing high noise level reduces species richness across different taxa. The present study is an effort to document the noise level of two urban educational campuses of Bhubaneswar and its effect on avifaunal composition. Point count sampling method was found to be most suitable. Around 49 species of birds including 6 migratory belonging to 9 orders and 28 families were recorded. Campus 1 was recorded higher noise level than campus 2. The higher bird species richness and abundance in Campus 2 predicts that the urban environment with green space provides a better habitat for birds due to more structured vegetation cover as well as less noise level. Noise level found to be negatively correlated with bird richness and abundance, which explaining, higher the noise level, lower the bird richness. This knowledge can help the city planners to select suitable place for making green spaces and sustainable habitat for the birds.

Avian congregation sites in the Gulf of Kachchh, Gujarat, India

he present study deals with the congregation of avifauna at various locations in Gulf of Kachchh (GoK), Gujarat, India. The study was conducted between 2011 and 2014. A total of 14 sites were identified in Gulf of Kachchh which had regular and remarkable congregation of mono-species or multi-species of waterbirds. The observations were made through line transects and point count sampling methods. The largest congregation sites were Bhaidar and Pirotan Islands with more than 5,000 individuals of waterbirds. Khijadiya wetland was also recorded with a remarkable number of birds in the congregation, i.e., more than 4,000 individuals. The identified congregation sites were found to be distributed throughout the southern part of GoK. Such sites were intertidal areas, freshwater bodies, saltpans etc. The bird congregations comprised resident and migratory waterbirds and coastal birds.

Assessing tropical forest restoration after fire using birds as indicators: An afrotropical case study

The necessity to restore rainforest habitats degraded by anthropogenic fires is widely recognized, however, research on restoration approaches has mainly centred on the recovery of forest structural complexity. There is insufficient evidence on the efficacy of restoration methods in the recovery of the faunal diversity and features linked to key ecosystem functions. We assessed the taxonomic diversity and functional trait structure of bird assemblages in undisturbed primary forest and fire-affected habitats undergoing natural regeneration, as well as areas of assisted natural regeneration, in Nyungwe National Park, Rwanda. We compiled bird occurrence data from point-count sampling, and obtained morphological traits for all species in our assemblages using measurements taken from wild birds and museum specimens. We found marked differences in species composition between primary forest habitats and regenerating forest, with similarity increasing over time since perturbation. Taxonomic diversity was higher in primary forest, and similar between the two restoration approaches. Functional diversity was lower in assisted naturally regenerated habitats, although separate analyses within dietary guilds revealed no differences across habitats. Among desired restoration outcomes, tree species diversity was the leading positive driver of avian species diversity, fern coverage exerted negative effects, while canopy cover had a positive but weak influence. Our findings underscore the importance of preventing anthropogenic fires in tropical rainforest since their impacts on ecological processes are not easily reversed, as shown by the lack of improvement in avian diversity metrics under assisted naturally regeneration in relation to natural regeneration. We stress the need to document both floral and faunal recovery in order to aid informed decision-making on restoration methods.

Birds’ gap-crossing in open matrices depends on landscape structure, tree size, and predation risk

Scattered trees are frequently considered “keystone structures” due to their disproportionate contribution in facilitating movement across the landscape. However, which landscape structure scattered trees best facilitate animal movement in the most effective manner remains poorly understood in the literature. Here, we tested three hypotheses examining how scattered trees influenced natural bird movement across an open matrix. We used three bird sampling methods: line transect, point count, and focal tree sampling. Our results showed that the efficacy of scattering trees as stepping stones and/or as a source of resources is mainly conditioned by three factors: predation risk, tree size, and landscape context in which the trees are inserted in an open matrix. In general, movement between habitat patches (gap-crossings) were more frequent in shorter distances (mean=10.9m). For larger gaps, the addition of scattered trees as stepping stones in the movement path is essential in reaching the neighboring habitat patches. The functional drivers of scattered trees are mainly related to perching, eating, and reproducing. Their functions increase with tree size and distance to the nearest patch. In relation to landscape context, birds prefer scattered trees surrounded by higher amounts of forest cover or with a network of higher aggregation trees. All these decision-making outcomes suggest antipredatory strategies during bird movement across landscapes including: (1) reducing the distance required to reach safer shelter; (2) choosing larger scattered trees as stepping stones, which improves a birds’ ability to detect predators, before deciding on the next movement; (3) choosing the movement path in the landscape context that most reduces the ability of predators to detect them or that increases the probability of escape from a predator. Land managers who wish to facilitate bird movements in open matrices should ensure gaps between landscape elements are less than 40m; preserve and actively plant arboreal individuals of tree species (height>15m) in open matrices; increase spatial aggregation of scattered trees or use them in landscapes with higher amounts of forest cover.

Diversity and structure of bird assemblages along urban-rural gradient in Kolkata, India

This study examined the bird assemblages by comparing the bird species diversity, composition, guild structure, and habitat and height utilization along the urban-rural gradient. Birds were surveyed from January 2008 to December 2009 using fixed-radius point counts in 20 sampling points randomly selected within four different habitat. A total of 134 species were recorded from 160 point count sampling plots. Of all the species recorded, 37 (28%) were found in all habitats and 35 (26%) found exclusively in some of the habitats. Out of 35 exclusive species, 30 (22%) were found in rural and semi-rural habitat, 5 (4%) were found in urban parks, and no exclusive species were found in high-density residential habitat. The species and guild composition in rural natural sites showed dissimilar assemblages in comparison to other habitat types, for example, the decline of insectivorous birds in response to increasing urbanization. The observed differences in bird assemblages reflect the differential availability of resources along the urbanization gradient. The results of this study support to the hypothesis that avian species richness or diversity failing to respond to urbanization linearly, but instead peaks at a level of intermediate disturbance or development.

Avian Community Structure as a Function of Season, Habitat Type, and Disturbance, in Mole National Park, Northern Region (Ghana)

The study assessed factors that influenced bird-habitat preference, diversity, and spatial distribution in Mole National Park. Birds were identified using point count sampling method, while ordination techniques were performed to determine the influence of environmental factors on bird-habitat preference. A total of 4951 individuals belonging to 131 species were identified across the four habitat types in the wet (n= 3033) and dry (n= 1648) seasons. Despite the high abundance and richness of birds in the woodland and shrubland habitats, grassland habitat was the most diverse, due to the high spatial evenness distribution of the birds. Bushfire, patchiness, and animal trampling were the key environmental determinants in bird assemblages and habitat preferences and accounted for 62.02% and 81.82% variations in the two seasons. Rarer birds like White-Backed Vulture (NT) and White-Headed Vulture (CR), Bateleur Eagle (NT), and Woolly-Necked Stork (VU), with high conservation concern, suggest intensification of conservation effort, while the dominance of Sahel Bush-sparrow was probably due to their broad range habitat preferences and ability to adapt to environmental conditions across these habitats. These species could be used as indicators of habitat quality, if future scenarios restrict their movement or distribution in narrow range habitats.

The utility of point count surveys to predict wildlife interactions with wind energy facilities: An example focused on golden eagles

Wind energy development is rapidly expanding in North America, often accompanied by requirements to survey potential facility locations for existing wildlife. Within the USA, golden eagles (Aquila chrysaetos) are among the most high-profile species of birds that are at risk from wind turbines. To minimize golden eagle fatalities in areas proposed for wind development, modified point count surveys are usually conducted to estimate use by these birds. However, it is not always clear what drives variation in the relationship between on-site point count data and actual use by eagles of a wind energy project footprint. We used existing GPS-GSM telemetry data, collected at 15 min intervals from 13 golden eagles in 2012 and 2013, to explore the relationship between point count data and eagle use of an entire project footprint. To do this, we overlaid the telemetry data on hypothetical project footprints and simulated a variety of point count sampling strategies for those footprints. We compared the time an eagle was found in the sample plots with the time it was found in the project footprint using a metric we called “error due to sampling”. Error due to sampling for individual eagles appeared to be influenced by interactions between the size of the project footprint (20, 40, 90 or 180 km2) and the sampling type (random, systematic or stratified) and was greatest on 90 km2 plots. However, use of random sampling resulted in lowest error due to sampling within intermediate sized plots. In addition sampling intensity and sampling frequency both influenced the effectiveness of point count sampling. Although our work focuses on individual eagles (not the eagle populations typically surveyed in the field), our analysis shows both the utility of simulations to identify specific influences on error and also potential improvements to sampling that consider the context-specific manner that point counts are laid out on the landscape.

Diversity and Temporal Variation of Avian Fauna in a Rice Growing Landscape in Kurunegala District, Sri Lanka

Rice fields are man-made semi-aquatic ecosystems maintained for the purpose of paddy cultivation. Five contrastingly different successive culture stages viz, preparatory stage, vegetative stage, ripening stage, harvesting stage and post-harvest stage occur along a single paddy culture cycle. Although it has been recorded that a wide variety of fauna are associated with these culture stages, there is a dearth of information on the temporal variation of avian fauna along these culture stages. Therefore, a study was carried out in a rice growing landscape at Katugampola, a rural village in Kurunegala District, to investigate if there is any temporal variation of avian diversity along the culture stages of a paddy culture cycle there. It was hypothesized that the physical and biological characteristics vary along the successive culture stages, and that each culture stage offers a predictable habitat for a distinct assemblage of birds. The sampling protocol of the study included in situ observation, identification and enumeration of different bird species using the fixed radius point count sampling method, and assessing the physical and biological parameters such as the percentage area covered by paddy plants, height of the paddy plants, number of people, number of off road vehicles, number of cattle, number of dogs, sound level, wind speed and the associated insect fauna at each culture stage using appropriate standard field sampling techniques. The study was commenced in May 2014 and lasted until September 2014. Altogether 1892 bird counts were made during the study period where the birds belonged into 19 different species and to 12 different families. Physical and biological parameters also varied significantly (p<0.05 Oneway ANOVA) along the paddy culture cycle. Distinct bird assemblages characteristic to each culture stage were recorded during the study. For example, large predatory birds such as Cattle Egret, Intermediate Egret and Little Egret became abundant during the preparatory stage while small seed eating birds such as sparrows became abundant during the ripening and mature stages. Further, large seed eating birds such as Green Imperial Pigeon and Rose-ringed Parakeet became abundant both during the vegetative stage and the post-harvest stage. The temporal variation of the above bird assemblages appeared to have a direct relationship with the variation of the biological and physical parameters along the paddy culture cycle at Katugampola rice field. Keywords: Avian diversity, Rice growing landscapes, Paddy culture cycle

Image subsampling and point scoring approaches for large-scale marine benthic monitoring programs

Benthic imagery is an effective tool for quantitative description of ecologically and economically important benthic habitats and biota. The recent development of autonomous underwater vehicles (AUVs) allows surveying of spatial scales that were previously unfeasible. However, an AUV collects a large number of images, the scoring of which is time and labour intensive. There is a need to optimise the way that subsamples of imagery are chosen and scored to gain meaningful inferences for ecological monitoring studies. We examine the trade-off between the number of images selected within transects and the number of random points scored within images on the percent cover of target biota, the typical output of such monitoring programs. We also investigate the efficacy of various image selection approaches, such as systematic or random, on the bias and precision of cover estimates. We use simulated biotas that have varying size, abundance and distributional patterns. We find that a relatively small sampling effort is required to minimise bias. An increased precision for groups that are likely to be the focus of monitoring programs is best gained through increasing the number of images sampled rather than the number of points scored within images. For rare species, sampling using point count approaches is unlikely to provide sufficient precision, and alternative sampling approaches may need to be employed. The approach by which images are selected (simple random sampling, regularly spaced etc.) had no discernible effect on mean and variance estimates, regardless of the distributional pattern of biota. Field validation of our findings is provided through Monte Carlo resampling analysis of a previously scored benthic survey from temperate waters. We show that point count sampling approaches are capable of providing relatively precise cover estimates for candidate groups that are not overly rare. The amount of sampling required, in terms of both the number of images and number of points, varies with the abundance, size and distributional pattern of target biota. Therefore, we advocate either the incorporation of prior knowledge or the use of baseline surveys to establish key properties of intended target biota in the initial stages of monitoring programs.

Variables associated with detection probability, detection latency, and behavioral responses of Golden-winged Warblers (Vermivora chrysoptera)

ABSTRACT Detection probability during point counts and its associated variables are important considerations for bird population monitoring and have implications for conservation planning by influencing population estimates. During 2008–2009, we evaluated variables hypothesized to be associated with detection probability, detection latency, and behavioral responses of male Golden-winged Warblers in pastures in the Monongahela National Forest, West Virginia, USA. This is the first study of male Golden-winged Warbler detection probability, detection latency, or behavioral response based on point-count sampling with known territory locations and identities for all males. During 3-min passive point counts, detection probability decreased as distance to a male's territory and time since sunrise increased. During 3-min point counts with playback, detection probability decreased as distance to a male's territory increased, but remained constant as time since sunrise increased. Detection probability was greater w...

Prevalence of Seed-dispersers in a Semi-deciduous Forest of Ghana

Seed dispersal is a necessary process for plant reproduction. The research seeks to give an overview of mammals and birds that exist and utilize a plantation in the semi-deciduous forest. The questions asked in this regard are: (1) which native mammalian fauna and or birds utilize the plantation area (2) what ecological roles do the mammals/bird play (3) Do different bird species inhabit the various vegetation types within the plantation. The study was carried out on a private plantation (7°3' N and 1°34' W) 42 km north of Kumasi, the Ashanti region, Ghana. An indirect questionnaire method was used to estimate the distribution of mammalian species that are good seed dispersers. Interviews were conducted with a total of 9 hunters in two near-by villages bordering the plantation area. The point count method was used for the bird survey, because it was easy to gather large amounts of data within a short period of time. A total of 45 counting stations were located in the plantation for the point count survey. Based on the evaluation of the questionnaire, eleven of the mammals were found in or around the plantation. A total of 32 bird species were sighted in the general bird survey and the point count sampling. The similarity of bird species in the remnant natural forest compared to the agro forestry area was 0.21, while that for the remnant natural forest compared to the actual plantation area was 0.18 using the Jaccards index. However the Shannon diversity index for birds calculated for the remnant natural forest was 1.682 while that of the actual plantation area and agro forestry areas are 1.693 and 2.074, respectively. It was concluded that seed-dispersal mammals and birds occurred on the plantation.

Geo-Spatial Modelling of Habitat Suitability of wildlife species of Kuno Wildlife Sanctuary

Predicting species habitat in a wildlife sanctuary is essential in management and conservation process of the species. Habitat map appear most capable of providing information on the distribution of large numbers of species in a wider variety of habitat types. Integrated GIS and Remote Sensing have already successfully been applied to map the distribution of several plant and animal species, their ecosystems, landscapes, bio-climatic conditions and factors facilitating invasions. The present study is carried out using the technologies of Remote Sensing and GIS to predict and model the habitat suitability of some herbivorous species of Kuno Wildlife Sanctuary for better management and conservation in a cost-effective way. The paper presents the habitat suitability of the various wildlife species found in the sanctuary. The sanctuary was categorized into 9 habitats - Mixed forest, Dense Forest, Open Forest, Kardhai forest, Khair- Kardhai forest, Dhawa forest, Khair forest, Dry/ Barren land and Water bodies using supervised classification. Wildlife species were surveyed using point count and distance sampling techniques while registering the coordinates with a GPS from 2008 to 2010. Geo-statistical Kriging and Co-Kriging methods were used to calculate the predictable habitat of the wild prey species encountered taking into account the proximity to water availability, habitat type, slope, aspect, distance from human habitats, etc. Keywords- Remote Sensing, GIS, Geo-statistical Kriging, Wildlife Species, Habitat Suitability Map

Alternative silvicultural practices with variable retention improve bird conservation in managed South Patagonian forests

Alternative silvicultural approaches to timber management, such as regeneration treatments with different degrees of stand retention, may mitigate negative effects of clear-cutting or shelterwood cuts in forested ecosystems, including changes in old-growth forest bird communities. The aims of this work were: (a) to compare bird species richness and densities among different silvicultural designs with variable retention (dispersed and/or aggregated) and unmanaged primary forests, and (b) to assess temporal changes at community and species levels before and after treatments. A baseline avian survey was conducted prior to harvesting to evaluate canopy gap presence and forest stand site quality influences. Subsequent to harvesting, data on bird species richness and density were collected by point-count sampling during the summer season for 5 consecutive years (4 treatments × 5 years × 6 sampling points × 5 counts). Bird species richness and density (15 species and 9.2 individuals ha −1) did not change significantly with forest site quality of the stands and canopy gap presence in unmanaged forests. However, both variables were significantly modified in managed forests, increasing over time to 18 species and reaching to 39 individuals ha −1. Inside the aggregated retention, bird communities were more similar to unmanaged primary forests than those observed within the dispersed retention or in clear-cuts. Opting for a regeneration method with dispersed and aggregated retention has great potential for managing birds in Nothofagus pumilio forests. This method retained enough vegetation structure in a stand to permit the establishment of early successional birds (at least in dispersed retention), and to maintain the bird species of old-growth forests which could persisted in the retention aggregates.

Novas ocorrências e registros notáveis sobre distribuição de aves em Santa Catarina, sul do Brasil

New occurrences and noteworthy records on distribution of birds in Santa Catarina, southern Brazil. Most ornithological fi eldworks in the state of Santa Catarina concentrate on the eastern half of state, while the mid- dle-west lacks information. Between March 2000 and May 2002 a bird inventory was made in the infl uence areas of the hydroelectric power plants of Machadinho and Barra Grande, along the right banks of the Uruguai and Pelotas rivers, on Santa Catarina State territory. We carried out ad libitum surveys, point count sampling, and capture with mist nets. We present seventy-two note- worthy records for Santa Catarina, including three new occurrences for the state (Cypseloides senex, Polioptila dumicola e Procacicus solitarius),three species whose available information was only in general bibliography (Amazona pretrei, Ramphastos toco e Capsiempis fl aveola), four whose records are the fi rst in the last 40 years (Megascops sanctaecatarinae,Macropsalis forcipata Phyllomyias virescens e Corytops delalandi), and 63 species fi rst cited for the eastern section of the Uruguai river valley

A large-scale field comparison of strip transect and stationary point count methods for conducting length-based underwater visual surveys of reef fish populations

Monthly visual surveys of reef fish populations in the Florida Keys were conducted from May to September of 1999 and April to December of 2000 using both strip transect and stationary point count sampling methods. Each month divers using SCUBA conducted three 10 m × 30 m transect surveys and three 5 m radius stationary point counts at 26 sites selected using a habitat based, stratified random design procedure. During both sampling procedures divers enumerated and assigned to 5 cm size increments all groupers (Serranidae), snappers (Lutjanidae), hogfish (Labridae), angelfish (Pomacanthidae), butterflyfish (Chaetodontidae), triggerfish (Balistidae), and a few other species of recreational or commercial importance. The rationale behind this sampling design was to assess the differential vulnerability of the various species and size classes to the lower behavioral disturbance/smaller area point count technique as compared to the higher disturbance/larger area transect method, and to assess which method would produce the highest density estimates and census the largest number of individuals per unit of sampling effort for size structure determinations. Although both types of samples required about the same amount of diver effort to complete, approximately 1.5 times more individuals were recorded during transect surveys. However, since transect surveys encompassed 4.3 times as much area as point counts, observed densities averaged about three times higher for point count samples. There was considerable variation among species with respect to this pattern, with total numbers of individuals for the 10 most abundant species ranging from about equal to 4.5 times higher during transect surveys, while densities ranged from nearly equal to about 6 times higher during point counts. Length frequencies within species were generally very similar between the two methods, though a higher proportion of larger individuals was recorded for a few species during transect surveys. Since previous studies have strongly indicated that visual census techniques produce underestimates of true reef fish densities, the higher and presumably more accurate density estimates provided by the point count method, along with other factors such as presumed increases in accuracy of counts and size estimates associated with increased observation time of individual fishes, led us to select this method for our future surveys.