39 research outputs found

    Aspects of behavioral ecology of Sotalia guianensis in Sepetiba Bay, southeast Brazil

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    Boat-based surveys were conducted from August 2002 to July 2003 to study the activity patterns, spatial pattern of area use, and group characteristics of Sotalia guianensis in Sepetiba Bay, southeast Brazil. Predetermined routes covered the entrance and interior of the bay, resulting in 210 dolphin sightings during 3,300 km total effort. Data on activity were collected using scan group sampling with instantaneous recording after 5 min of observation. Dolphins were sighted more frequently in the entrance of the bay, where water is deeper, and salinity and transparency are higher, than in the interior of the bay, where the environment is more influenced by freshwater inputs. Foraging and feeding were the most frequent activities, and occurred predominantly between 0600 and 1000. Foraging and feeding peaked during ebbing, low, and flooding tides, while socializing predominated at high tide. Mean group size was larger in the interior of the bay and when seabirds were present. Large aggregations containing >100 individuals of Sotalia guianensis seen year-round indicate that Sepetiba Bay is an important area for this species in coastal Brazil

    Noninvasive Low-cost Method to Identify Armadillos' Burrows: A Machine Learning Approach

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    Having accurate information about population parameters of armadillos (Mammalia, Cingulata) is essential for the conservation and management of the taxon, most species of which remain poorly studied. We investigated whether we could accurately identify 4 armadillo species (Euphractus sexcinctus, Dasypus novemcinctus, Cabassous tatouay, and Cabassous unicinctus) based on burrow morphometry. We first selected published studies that reported measurements of width, height, and angle of the burrows used by the 4 species of armadillos. Then, using such data we simulated burrow measurements for each of the 4 species of armadillos and we created predictive models through supervised machine learning that were capable of correctly identifying the species of armadillos based on their burrows' morphometry. By using classification algorithms such as Random Forest, K-Nearest Neighbor, Support Vector Machine, Naive Bayes, and Decision Tree C5.0, we achieved the overall accuracy for the classification task by about 71%, including an overall Kappa index by about 61%. Euphractus sexcinctus was the most difficult species to discriminate and classify (approximately 68% of accuracy), whereas C. unicinctus was the easiest to discriminate (approximately 93% of accuracy). We found that it was possible to identify similar-sized armadillos based on the measurements of their burrows described in the literature. Finally, we developed an R function (armadilloID) that automatically identified the 4 species of armadillos using burrow morphology. As the data we used represented all studies that reported the morphometry of burrows for the 4 species of armadillos, we can generalize that our function can predict armadillo species beyond our data. © 2021 The Wildlife Society

    Can Roads Be Used as Transects for Primate Population Surveys?

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    Line transect distance sampling (LTDS) can be applied to either trails or roads. However, it is likely that sampling along roads might result in biased density estimates. In this paper, we compared the results obtained with LTDS applied on trails and roads for two primate species (Callithrix penicillata and Callicebus nigrifrons) to clarify whether roads are appropriate transects to estimate densities. We performed standard LTDS surveys in two nature reserves in south-eastern Brazil. Effective strip width and population density were different between trails and roads for C. penicillata, but not for C. nigrifrons. The results suggest that roads are not appropriate for use as transects in primate surveys, at least for some species. Further work is required to fully understand this issue, but in the meantime we recommend that researchers avoid using roads as transects or treat roads and trails as covariates when sampling on roads is unavoidable. Copyright (C) 2012 S. Karger AG, Base

    Records of the giant-armadillo Priodontes maximus (Cingulata: Dasypodidae) in the Atlantic Forest: are Minas Gerais and Espírito Santo the last strongholds of the species?

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    We report 20 records of Priodontes maximus (Kerr, 1792) collected between 1990 and 2009 in three nature reserves located in forested areas of southeastern Brazil within the Atlantic Forest biome. Seventeen records were collected in Parque Estadual do Rio Doce (PERD), state of Minas Gerais, two in Reserva Biológica de Sooretama and one in Reserva Natural Vale, both located in the state of Espírito Santo. The records were burrows (n = 11), photographs from camera-traps (n = 6), sightings (n = 2) and carcass (n = 1). Given the higher number of records, the PERD seems to maintain the largest population among the three study areas. We searched the literature and found no other recent evidence of the species' presence in the Atlantic forest of Brazil. There are few Museum specimens and a general lack of information on the presence of the species in this biome as a whole. These facts suggest that the conservation status of the giant armadillo is extremely critical in the Atlantic Forest
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