Distribution Of Migratory Birds Research Articles

Serological analysis in humans in Malaysian Borneo suggests prior exposure to H5 avian influenza near migratory shorebird habitats

Cases of H5 highly pathogenic avian influenzas (HPAI) are on the rise. Although mammalian spillover events are rare, H5N1 viruses have an estimated mortality rate in humans of 60%. No human cases of H5 infection have been reported in Malaysian Borneo, but HPAI has circulated in poultry and migratory avian species transiting through the region. Recent deforestation in coastal habitats in Malaysian Borneo may increase the proximity between humans and migratory birds. We hypothesise that higher rates of human-animal contact, caused by this habitat destruction, will increase the likelihood of potential zoonotic spillover events. In 2015, an environmentally stratified cross-sectional survey was conducted collecting geolocated questionnaire data in 10,100 individuals. A serological survey of these individuals reveals evidence of H5 neutralisation that persisted following depletion of seasonal H1/H3 HA binding antibodies from the plasma. The presence of these antibodies suggests that some individuals living near migratory sites may have been exposed to H5 HA. There is a spatial and environmental overlap between individuals displaying high H5 HA binding and the distribution of migratory birds. We have developed a novel surveillance approach including both spatial and serological data to detect potential spillover events, highlighting the urgent need to study cross-species pathogen transmission in migratory zones.

Impacts of changing climate on the distribution of migratory birds in China: Habitat change and population centroid shift

Climate changes are related to the changes in the distribution of migratory species, which irreparably harm biodiversity. In this study, we evaluated the habitat change and population centroid shift for 7 orders and 23 different species on the IUCN (International Union for the Conservation of Nature and Natural Resources) Red List of migratory birds from 2014 to 2017 in current to mid-21st (2041–2700) century by Maximum Entropy method (MaxEnt) model. We found that there is significant spatial variability in geographical suitability, with the Yangtze River basin losing 9.74% of suitable habitat and the Pearl River basin losing 13% of habitat. The area of suitable habitat decreases over 3% of total habitat area in China under the RCP 2.6, and decreases about 10% of total habitat area in China under RCP 8.5 scenario, with the population centroid of habitat moving about 50 km to northeast on average. Furthermore, the mean suitability of migratory birds will decrease over 3% in the future, which means environmental variables are changing in directions that are not suitable for birds. Migratory birds will change their habitat and growth cycle in response to the climate change. The direction and distance of the population centroid are different for every species. Most of the individual species in the study will move over 50 km and all the species will move to places with higher suitability. For the whole of China, the constraint for migratory birds is tmin (Minimum temperature). The dominant variable in southeast China is NDVI (Normalized Difference Vegetation Index), while alt (altitude) in the north China. The decline in the suitable habitat area and shift in the population centroid will lead to the changes in the time and distance of the migration process, resulting in more adverse conditions for the survival of migratory birds. Our study proves the adverse role of climate change in species distribution which is a prerequisite for protecting species in the future.

Identifying key bird species and geographical hotspots of avian influenza A (H7N9) virus in China

BackgroundIn China since the first human infection of avian influenza A (H7N9) virus was identified in 2013, it has caused serious public health concerns due to its wide spread and high mortality rate. Evidence shows that bird migration plays an essential role in global spread of avian influenza viruses. Accordingly, in this paper, we aim to identify key bird species and geographical hotspots that are relevant to the transmission of avian influenza A (H7N9) virus in China.MethodsWe first conducted phylogenetic analysis on 626 viral sequences of avian influenza A (H7N9) virus isolated in chicken, which were collected from the Global Initiative on Sharing All Influenza Data (GISAID), to reveal geographical spread and molecular evolution of the virus in China. Then, we adopted the cross correlation function (CCF) to explore the relationship between the identified influenza A (H7N9) cases and the spatiotemporal distribution of migratory birds. Here, the spatiotemporal distribution of bird species was generated based on bird observation data collected from China Bird Reports, which consists of 157 272 observation records about 1145 bird species. Finally, we employed a kernel density estimator to identify geographical hotspots of bird habitat/stopover that are relevant to the influenza A (H7N9) infections.ResultsPhylogenetic analysis reveals the evolutionary and geographical patterns of influenza A (H7N9) infections, where cases in the same or nearby municipality/provinces are clustered together with small evolutionary differences. Moreover, three epidemic waves in chicken along the East Asian–Australasian flyway in China are distinguished from the phylogenetic tree. The CCF analysis identifies possible migratory bird species that are relevant to the influenza A(H7N9) infections in Shanghai, Jiangsu, Zhejiang, Fujian, Jiangxi, and Guangdong in China, where the six municipality/provinces account for 91.2% of the total number of isolated H7N9 cases in chicken in GISAID. Based on the spatial distribution of identified bird species, geographical hotspots are further estimated and illustrated within these typical municipality/provinces.ConclusionsIn this paper, we have identified key bird species and geographical hotspots that are relevant to the spread of influenza A (H7N9) virus. The results and findings could provide sentinel signal and evidence for active surveillance, as well as strategic control of influenza A (H7N9) transmission in China.

Attribution index for changes in migratory bird distributions: The role of climate change over the past 50 years in China

To examine whether changes in the distribution of migratory birds can be attributed to climate change, we analyzed the changes in the distributions of the species relative to climate change over the past 50years in China. Long-term distribution records of 14 species or subspecies of migratory birds were used together with grey relationship analysis, fuzzy sets classification techniques, the consistency index and the attribution index. Over the past 50years, edges of distributions expanded. Different species expanded to different directions driven directly by the climate change or driven secondary by the climate change or other habitat changes, and for the majority of birds, these changes were mainly related to the thermal index. Driven by climatic factors over the past years, the northern limits of more than one-half of the birds shifted northward with fluctuations. In addition, the consistency indices of observed vs. predicted changes in the distribution boundaries or the distribution centers were higher for particular migratory birds. The changes in the center latitude or longitude of the distribution of 4 species or subspecies, the northern boundary of 6 species or subspecies, the southern boundary of 1 subspecies, the eastern boundary of 5 species or subspecies and the western boundary of 3 species or subspecies can be attributed to climate change.

Carex Dynamics as an Environmental Indicator in the Poyang Lake Wetland Area: Remote Sensing Mapping and GIS Analysis

It is of considerable importance to analyze the changes in Carex distribution and environmental elements in order to protect and exploit the wetland resources of the Poyang Lake wetland area, one of the most important wetlands in the world. Employing multitemporal remote sensing images acquired on October 31st, 2005 and December 10th, 1999, the authors determined the dynamic distribution of Carex by combining spectral angle mapping technologies. Then, for the first time, Arc View GIS-based statistical analysis was performed on the Carex dynamics. Finally, the relationship between the Carex dynamics and delta change, and the landscape fragmentation index of Carex were further analyzed. It was found that: (1) the extent of Carex in the Gan River delta, particularly in the north distributary of the river, was directly correlated to lake sedimentation and regional drought in the same year; (2) the distribution of migratory birds is influenced by factors additional to the distribution of Carex; and (3) the wetland landscape ecology of the Poyang Lake wetland area is facing threats from human disturbance and needs further attention if it is to retain its status as an important bird habitat.