Habitat Selection And Foraging Strategy Of Hooded Crane On Migration Route In China

Habitat selection directly or indirectly affects the geographical distribution of population, reproductive success, survival and population density of birds. Habitat destruction and fragmentation are the two most important factors causing species extinction. So the key for species diversity conservation is protecting habitat and its integrity. The fitness of migratory birds during winter time determines their survival status, migration schedule and reproductive success of the subsequent calendar year. Food quality and foraging behavior are important parts to verify the foraging theory of migratory birds. Currently, the biggest threat is original habitat loss for global fifteen Cranes. In this case, most of the Cranes have adapted foraging in the farmland, and reducing their forgaing time in natural grassland and wetland habitats. We select Hooded Crane (Grus monacha) as our object of this study which is our national I key protected wild animals in China. It is estimated that currently the global population is about 11,600. Small part of the population breeds in Lesser Khingan region, the majority of the population migrates through the Songnen Plain, and about 1000-1500 individuals winter at the lakes and coastal region of the middle and lower reaches of Yangtze River in China. To understanding the habitat situation at different living period and provide dependable information for the conservation of Hooded Crane, Following questions are the main considerations to address in this research:1) The selection mechanism and restriction factors of nest sites selection for Hooded Cranes in Lesser Khingan region, China2) Habitat suitability evalution and threats of Hooded Crane in stopovers and wintering areas, China3) Foraging habitat utilization and foraging strategies of Hooded Crane in different wintering sites, ChinaTo this end, the investigation and sampling were developed across the breeding, stopovers and wintering areas from 2009 to 2014. The nests of Hooded Crane were searched for, and the environmental parameters around the nest-sites were investigated; the migratory and wintering distribution points from field and literatures were collected; the wintering food habitats, behavior and food resources were investigated and tested, the data combined with TreeNet, Maxent and SPSS software to analyze data, the following conclusions were obtained:1) The nesting habitat of breeding Hooded Crane was forestry wetland with some water surface, water depth and sparse shrub in Lesser Khingan region, China.Hooded Crane mainly breeds at Dazhanhe Wetland National Nature Reserve (NNR) and Xinqing Hooded Crane NNR in Heilongjiang Province, China. Seven nests were found during 2009 to 2010, and 26 nests were found in total since 2002. The nests of Hooded Crane were placed on top of the tower head within water areas, accompanied with trees such as Larix gmelini, Alnus sibirica, shrub such as Spiraea salicifolia and herbs such as Carex schmidtii, Calamagrostis angustifolia. The environmental main factors for nest-site selection by Hooded Crane were water area around the nests (greater than 23 m2), water depth around the nests (greater than 6 cm) and shrub cover (less than 0.24). The first two water factors could provide Rana chensinensis and Salamandrella keyserlingii for Hooded Crane as food, and could also prevent the invasion of Capreolus pygargus and Sus scrofa; sparse shrub cover could provide shelter and did not affect escaping from danger of Hooded Crane.2) The high suitable potential habitat of stopovers was concentrated on Songnen Plain and costal wetland of Bohai Bay; high suitable distribution of wintering habitats of Hooded Crane was at Poyang Lake and wetlands around middle and lower reaches of Yangtze River in ChinaBased on the distribution points of Hooded Crane and environmental variables, the suitable stopovers of Hooded Crane depended on elevation (38.35%), seasonal temperature (15.63%), the wettest month of precipitation (9.58%), land cover (9.49%) and other environmental variables, and the potential suitable habitat mainly concentrated on Songnen Plain, Bohai Bay and Liaodong Bay. Songnen Plain is the most important stopover where several thousand individuals of Hooded Crane stop there every year. But due to natural and artificial reasons, the wetland area is shrinking. As another suitable potential habitat, coastal beach of Bohai and Liaoning Bay had been reclaimed as a harbor and urban development.Precipitation of driest quarter (61.40%) is the most important environmental variables to affect potential wintering distribution of Hooded Crane. The suitable wintering grounds are mainly concentrated at middle and lower reaches of Yangtze River region, and the key area was at Poyang Lake. A large area of shallow lakes provided potentially suitable habitat for Hooded Crane. The potential impact of The Three Gorges and possible Poyang Lake Hydro Project is a threat for wintering grounds of Hooded Cranes.3) The wintering Hooded Crane preferred to forage at farmland with high-energy food, and the natural habitat was secondary foraging site and main resting site. Human interference was the main factor to affect foraging strategy of Hooded Crane.Foraging habitat utilization and strategy are decided by food resources of wintering Hooded Crane at the middle and lower reaches of Yangtze River region. When human activities are low at dawn and dusk, the Cranes choose to feed rice and beans at artificial feeding habitat; they also fed on roots of Potentilla limprichtii J. Krause and Polygonum criopolitanum Hanceat at natural habitats. In artificial habitats, the time budget of foraging behavior was significantly higher than that at the natural habitat (p<0.01,p<0.05). For vigilance behavior time, natural habitats were significantly higher than that at artificial habitats (p<0.01); But for vigilance times, artificial habitats was significantly higher (Z=-4.772,p<0.01). With respect to the food at natural habitats, rice and beans can provide higher energy, and be easy to obtain. So foraging strategy of wintering Hooded Crane in China is consistent with the Optimal Foraging Theory in theory.In summary, food and security were the main limiting factors for nest selection of Hooded Crane in Lesser Khangan region, China. The farmland and wetland in Songnen Plain and middle and lower reaches of Yangtze River were the potential suitable distribution of stopover and wintering area. Even faced on human interference, farmland was still preferential foraging site for wintering Hooded Crane in China. This is the first study of foraging strategies for Hooded Crane among different wintering habitats in China, and also the first time to integrate habitats on migration route of Hooded Crane as a whole to study about habitat selection and suitability evaluation. It systematically provides habitat information of Hooded Crane, and also provides a new perspective for the study and protection of other migratory birds. We think the key to protect this species is keeping touch between different habitats on migratory route.This paper showed the relatively comprehensive habitat study on migratory route of Hooded Crane in China. Due to time constraints, partial researchers need to develop or fill the void. On the basis of this study, follow-up studies can be carried out in these areas:the suitable evaluation of breeding grounds in our country even Siberia of Hooded Crane; The information of migration and breed is less to know about wintering Cranes in our country, so using stable isotope and satellite tracking to study the migratory and breeding situation of wintering Hooded Crane in China is needed; According to the long-time effection of Three Gorges Dam on lower lakes, the researches can foucus on the distributional simulation scenarios of Hooded Crane under possibly future change. Combining these studies, there will be more comprehensive understanding of Hooded Crane in our country which plays a crucial role in protecting and managing the species and their habitat.