Prediction of suitable habitats for the Indo-Pacific humpback dolphin (Sousa chinensis) in the Beibu Gulf of China and Vietnam

2020 ◽  
Author(s):  
Caiwen Wu ◽  
Fan Zeng ◽  
Rui Liu ◽  
Xiuqing Hao ◽  
Xuyang Chen ◽  
...  
Keyword(s):  
Anthropogenic Activities ◽  
River Estuary ◽  
Line Transect ◽  
Suitable Habitat ◽  
Beibu Gulf ◽  
Wet Season ◽  
Protection Measures ◽  
Maximum Entropy Modeling ◽  
Sousa Chinensis ◽  
Suitable Habitats

The Indo-Pacific humpback dolphin (Sousa chinensis) is a threatened coastal flagship species in Asian marine ecosystems, but the distribution of its suitable habitat remains unclear. In the present study, we characterized habitat relationships and predicted potential suitable habitats for humpback dolphins in the Beibu Gulf of China and Vietnam. Maximum entropy modeling identified six discontinuous areas in the Beibu Gulf, with a total area of 4396.8 km2, as suitable habitats for humpback dolphins. Of these, three suitable habitats covering 3948.8 km2 were known habitats, and three others covering an area of 448.1 km2 at the border of China and Vietnam or in Vietnamese waters (Beilun River Estuary, Qinghua, and Rongshi) were newly identified. Exploratory line-transect surveys are strongly recommended to determine whether dolphins are present in these three areas. The predicted suitable habitat showed seasonal variation, which increased slightly in the dry season compared with that in the wet season. Bathymetry is the most important predictor for habitat suitability, in line with the known coastal distribution of humpback dolphins. Our research predicted specific suitable habitat distributions, which can be used to develop practical protection measures, such as the establishment of marine protected areas for this species to monitor, mitigate, or prohibit harmful anthropogenic activities.

scholarly journals Birds species composition and abundance of a relativelly undisturbed vegetation at Mount Pati, Lokoja, Kogi State

2019 ◽  
Vol 6 (12) ◽  
pp. 271-282
Author(s):  
Dauda Tanko ◽  
Rita Chinweuba
Keyword(s):  
State Government ◽  
Diversity Index ◽  
Anthropogenic Activities ◽  
Bird Species ◽  
Activity Level ◽  
Line Transect ◽  
Biological Factors ◽  
Wet Season ◽  
Fuel Wood ◽  
Wiener Diversity Index

Avifauna of a relatively undisturbed vegetation at Mount Patti of Lokoja was surveyed from January to June, 2018. Line transect and point count techniques were used for data collection. This was done by weekly visits to the site between 6:00 h and 10:00 h of the day. Bird identification was done with the aid of a pair of binoculars, Field Guide of birds of western Africa and recorded bird calls. Monthly variation and season variation in bird composition and abundance were compared using Shannon-Wiener diversity index and equitability index. There were 39 species in 21 families encountered during the survey. The Family Nectarinidae had the highest number of 5 species, followed by Columbidae and Estrildidae with 4 species each. A total of 1,148 individuals were encountered during the six months survey with village weaver having the highest encountered rate of 107 while yellow-throated Long-claw had the least encountered rate of 4 individuals. Fluctuation was observed in the monthly encountered rate of the birds. Diversity and equitability indices had their highest values of 5.24 and 1.51 in January. More birds (696) were encountered in the wet season than the dry season (452). Four species were seen only in the wet season. Species effort curve showed that there are more species to be discover. The number of species encountered in this study revealed that the mountain is rich composition of bird species, even though the site seems to favour species that show preference to disturbed areas. The on-going anthropogenic activities probably paved way to these species to move in. Monthly and seasonal fluctuation of bird species diversity and abundance may be due to a combination of physical and biological factors. The physical and biological factors observed at the site which we speculate could be reasons for the observed fluctuations include slash and burnt system of farming, fuel-wood harvesting, intensive sporting activities creation of foot paths etc. High encountered rate indicate abundance and high activity level of the species. The village weaver was the most encountered species probably because they are known to be lousy, move in flocks and breed in colonies. In view of the rich composition and abundance of bird species on Mount Patti and the site being a suitable breeding site for the weavers. We recommend further study of the place as there are yet more species to be discovered as indicated by the species effort curve. There is need for conservation procedures to be initiated at the place and this study should serve as a baseline to initiate such programme by the state government.

scholarly journals Population characteristics and habitat suitability of Asian elephants (Elephas maximus Linnaeus, 1758) in the Khao Yai National Park, Thailand

2019 ◽  
Vol 5 (2) ◽  
pp. 62-71
Author(s):  
Mananya Pla-ard ◽  
Ronglarp Sukmasuang ◽  
Khanchit Srinopawan
Keyword(s):  
Population Structure ◽  
Habitat Suitability ◽  
National Park ◽  
Population Characteristics ◽  
Line Transect ◽  
Suitable Habitat ◽  
Annual Data ◽  
Wet Season ◽  
Khao Yai National Park ◽  
Combined Data

Abstract The aim of this study was to investigate the population and habitat of wild elephants in the Khao Yai National Park, to provide elephant population densities using the line transect method. Habitat suitability was also assessed based on the data obtained from the location of the species during monthly ranger patrol across the park area, with the rate of dung decay used for population calculation. The population structure and age class were studied by direct observation to estimate the population trend. On the basis of 116 systematic transect lines that were 2 km in length and separated by 500-m intervals, a total of 1,209 elephant dung piles were found in more than 213.20 km. The analysis of the combined data showed that the dung density was 531.49 dung piles/km2, with a decay rate of 0.0039 dung piles/day based on 56 dung piles checked every 7 days. The annual data showed that the population density was 0.15 individuals/km2. The population structure comprising calf:juvenile:subadult:adult was 1: 1.09:1.14:2.10; the sex ratio of adult male to adult female elephants was 1:1.10; and the ratio of reproductive ability among adult females, juveniles, and calves was 1.00:0.99:0.90. The combined data also showed that the main environmental factor affecting the presence of the animals was salt lick sites. The pooled data analysis found that the habitat most suitable for the elephants covered an area of 220.59 km2. The habitat suitability, based on the dry season appearance data, covered an area of 258.64 km2, whereas during the wet season, it covered an area of 517.45 km2. As the most suitable habitat for elephants appears around the park boundary, habitat improvements for wild elephants should address the central areas of the national park. A greater emphasis should be placed on creating salt licks, being far from human activity sites.

Seasonal group characteristics and occurrence patterns of Indo-Pacific humpback dolphins (Sousa chinensis) in Xiamen Bay, Fujian Province, China

2016 ◽  
Vol 97 (4) ◽  
pp. 1026-1032 ◽  
Author(s):  
Xianyan Wang ◽  
Fuxing Wu ◽  
Samuel T. Turvey ◽  
Massimiliano Rosso ◽  
Qian Zhu
Keyword(s):  
River Estuary ◽  
Wet Season ◽  
Jiulong River Estuary ◽  
Xiamen Bay ◽  
Encounter Rates ◽  
Dry Seasons ◽  
Sousa Chinensis ◽  
Peripheral Areas ◽  
Occurrence Patterns ◽  
Group Characteristics

Abstract Monthly field surveys were conducted between August 2010 and July 2015 to explore seasonal group characteristics and occurrence patterns of Indo-Pacific humpback dolphins (Sousa chinensis) in Xiamen Bay, China. Dolphins formed larger groups in winter and spring (dry seasons) than in summer and autumn (wet seasons; U = 1,564.00, P < 0.001). Sighting encounter rates were higher during the wet season than during the dry season (U = 181.00, P < 0.001), while individual encounter rates were not significantly different between seasons (F = 0.494, d.f. = 3, P = 0.688). Dolphin sightings and the foraging events were mainly found in inner harbors (Western Harbour and Tongan Bay) during the dry seasons and in peripheral areas (Jiulong River Estuary, Wuyu, and Dadeng-Xiaodeng) during the wet seasons. Seasonal occurrence patterns may be associated with the seasonal prey shifts between these different environments.

scholarly journals Modeling habitat suitability of the Red-backed Shrike (Lanius collurio) in the Irano-Anatolian biodiversity hotspot

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Sayyad Sheykhi Ilanloo ◽  
Sohrab Ashrafi ◽  
Afshin Alizadeh Shabani
Keyword(s):  
Population Size ◽  
Habitat Suitability ◽  
Anthropogenic Activities ◽  
Important Variable ◽  
Biodiversity Hotspot ◽  
Mean Annual Temperature ◽  
Suitable Habitat ◽  
Suitable Model ◽  
Western Palearctic ◽  
Suitable Habitats

Identifying suitable habitats of species is essential knowledge to conserve them successfully. Human activities causes the reduction of population size and habitat suitability of many species. Red-backed Shrike is a widespread in western Palearctic. However, the population of this specie has declined in its geographical range due to the loss of suitable habitats. Therefore, it is necessary to identify its suitable habitats and factors affecting species habitat suitability and to protect its reduction population size. The aim of the present study was to identify the suitable habitat of the Red-backed Shrike and determine the most important predictors of its suitable habitat in Irano-Anatolian biodiversity hotspot. To achieve this goal, species presence points were first collected and seven environmental variables related to climate, topography and anthropogenic activities, were used to construct the species habitat suitable model. Models were built using five distribution modeling methods: Maxent, GAP, GLM, RF and GBM in sdm package. Then the models were Ensemble from 5 different models and the final model was constructed. The results of this study showed that the most suitable habitats of this species are in the western and northern parts of the area of study. The mean annual temperature with 41% contribution was the most important variable in constructing the habitat suitability model for this specie. In addition, climate variables with 75% contribution were identified as the most important habitat suitability factor for this specie. Also in relation to conservation of the Red-backed Shrike species in the Irano-Anatolian region, it can be stated that the extent of distribution and presence of this specie has been extended to the northern latitudes due to climate change. As a result, the temperature and climate factor should be given special attention in the management of bird habitats in this area. 

scholarly journals Predictive modeling of suitable habitats for threatened marine invertebrates and implications for conservation assessment in Brazil

2010 ◽  
Vol 58 (spe4) ◽  
pp. 57-68 ◽  
Author(s):  
Rafael A. Magris ◽  
G. F. G. Déstro
Keyword(s):  
Threatened Species ◽  
Marine Invertebrates ◽  
Current Knowledge ◽  
Distribution Data ◽  
Suitable Habitat ◽  
Conservation Assessment ◽  
Modeling Tools ◽  
Maximum Entropy Modeling ◽  
Gis Applications ◽  
Suitable Habitats

Spatial analysis and modeling tools were employed to predict suitable habitat distribution for threatened marine invertebrates and estimate the overlap between highly suitable areas for these species and the Brazilian marine protected areas (MPAs). Records of the occurrence of species were obtained from the collections included in the Ocean Biogeographic Information System (OBIS-Brazil), with additional records culled from the literature. The distribution data of 16 out of 33 threatened species, with at least ten occurrences in the available records, were selected for modeling by Maxent algorithm (Maximum Entropy Modeling) based on environmental variables (temperature, salinity, bathymetry and their derivatives). The resulting maps were filtered with a fixed threshold of 0.5 (to distinguish only the highly suitable areas) and superimposed on MPA digital maps. The algorithm produced reasonable predictions of the species' potential distributions, showing that the patterns predicted by the model are largely consistent with current knowledge of the species. The distribution of the highly suitable areas showed little overlapping with Brazilian MPAs. This study showed how the habitat suitability for threatened species can be assessed using GIS applications and modeling tools.

scholarly journals The Impact of Human Pressure and Climate Change on the Habitat Availability and Protection of Cypripedium (Orchidaceae) in Northeast China

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 84
Author(s):  
Huanchu Liu ◽  
Hans Jacquemyn ◽  
Xingyuan He ◽  
Wei Chen ◽  
Yanqing Huang ◽  
...  
Keyword(s):  
Climate Change ◽  
Northeast China ◽  
Habitat Destruction ◽  
Changbai Mountains ◽  
Suitable Habitat ◽  
Human Pressure ◽  
Terrestrial Orchids ◽  
The Future ◽  
Suitable Habitats ◽  
The Impact

Human pressure on the environment and climate change are two important factors contributing to species decline and overall loss of biodiversity. Orchids may be particularly vulnerable to human-induced losses of habitat and the pervasive impact of global climate change. In this study, we simulated the extent of the suitable habitat of three species of the terrestrial orchid genus Cypripedium in northeast China and assessed the impact of human pressure and climate change on the future distribution of these species. Cypripedium represents a genus of long-lived terrestrial orchids that contains several species with great ornamental value. Severe habitat destruction and overcollection have led to major population declines in recent decades. Our results showed that at present the most suitable habitats of the three species can be found in Da Xing’an Ling, Xiao Xing’an Ling and in the Changbai Mountains. Human activity was predicted to have the largest impact on species distributions in the Changbai Mountains. In addition, climate change was predicted to lead to a shift in distribution towards higher elevations and to an increased fragmentation of suitable habitats of the three investigated Cypripedium species in the study area. These results will be valuable for decision makers to identify areas that are likely to maintain viable Cypripedium populations in the future and to develop conservation strategies to protect the remaining populations of these enigmatic orchid species.

scholarly journals Capitoline Dolphins: Residency Patterns and Abundance Estimate of Tursiops truncatus at the Tiber River Estuary (Mediterranean Sea)

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 275
Author(s):  
Daniela Silvia Pace ◽  
Chiara Di Marco ◽  
Giancarlo Giacomini ◽  
Sara Ferri ◽  
Margherita Silvestri ◽  
...  
Keyword(s):  
Population Size ◽  
Tursiops Truncatus ◽  
Site Fidelity ◽  
Bottlenose Dolphins ◽  
River Estuary ◽  
Suitable Habitat ◽  
Tyrrhenian Sea ◽  
Abundance Estimate ◽  
Photo Identification ◽  
Tiber River

Periodic assessments of population status and trends to detect natural influences and human effects on coastal dolphin are often limited by lack of baseline information. Here, we investigated for the first time the site-fidelity patterns and estimated the population size of bottlenose dolphins (Tursiops truncatus) at the Tiber River estuary (central Mediterranean, Tyrrhenian Sea, Rome, Italy) between 2017 and 2020. We used photo-identification data and site-fidelity metrics to study the tendency of dolphins to remain in, or return to, the study area, and capture–recapture models to estimate the population abundance. In all, 347 unique individuals were identified. The hierarchical cluster analysis highlighted 3 clusters, labeled resident (individuals encountered at least five times, in three different months, over three distinct years; n = 42), part-time (individuals encountered at least on two occasions in a month, in at least two different years; n = 73), and transient (individuals encountered on more than one occasion, in more than 1 month, none of them in more than 1 year; n = 232), each characterized by site-fidelity metrics. Open POPAN modeling estimated a population size of 529 individuals (95% CI: 456–614), showing that the Capitoline (Roman) coastal area and nearby regions surrounding the Tiber River estuary represent an important, suitable habitat for bottlenose dolphins, despite their proximity to one of the major urban centers in the world (the city of Rome). Given the high number of individuals in the area and the presence of resident individuals with strong site fidelity, we suggest that conservation plans should not be focused only close to the Tiber River mouths but extended to cover a broader scale of area.

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