Red-crowned crane (Grus japonensis) prefers postharvest reed beds during winter period in Yancheng National Nature Reserve.
ABSTRACT: Reed beds represent an important habitat for the survival of birds by providing favorable foraging and reproduction conditions. Reed management, as a traditional agricultural activity, primarily includes water level control and vegetation removal by cutting. Red-crowned crane (Grus japonensis) is one of the most endangered cranes, and their population continues to decline due to habitat loss caused by artificial activities. A lack of research relating to how reed management affects crane habitat distribution patterns throughout the wintering period hinders our ability to offer conservation recommendations. In the present study, we explored the effect of reed management on the habitat distribution patterns and analyzed the food resources of red-crowned crane in the Yancheng National Nature Reserve (YNNR). According to the reed management activities in December, we divided the wintering period into two phases: the preharvest period and the postharvest period. Throughout the wintering period, the number of cranes recorded in the common seepweed (Suaeda glauca) tidal flats remained stable, but cranes were rarely recorded in the smooth cordgrass (Spartina alterniflora) tidal flats and aquaculture fish ponds. The number of cranes, however, showed a noticeable fluctuation in the reed beds during the two periods. Before the reed harvest, only a small proportion of cranes were recorded in the reed beds (relative abundance = 2.9%). However, more cranes (relative abundance = 61.0%) were recorded after the reed harvest. Water was introduced from adjacent rivers and fish ponds to submerge the cut reed beds. Changes in potential animal food resources (items and biomass) might be one of the vital reasons for the preference of cranes to the postharvest reed beds. Our results suggest that traditional reed management in the YNNR could benefit this flagship crane species that winters in the wetland system. However, as reed harvest has been forbidden in the core zone for conservation purposes since 2016, further research is needed to verify whether forbidding the harvest of reeds is reasonable.
Project description:The Endangered Red-crowned Crane (Grus japonensis) is one of the most culturally iconic and sought-after species by wildlife tourists. Here we investigate how the presence of tourists influence the vigilance behaviour of cranes foraging in Suaeda salsa salt marshes and S. salsa/Phragmites australis mosaic habitat in the Yellow River Delta, China. We found that both the frequency and duration of crane vigilance significantly increased in the presence of wildlife tourists. Increased frequency in crane vigilance only occurred in the much taller S. salsa/P. australis mosaic vegetation whereas the duration of vigilance showed no significant difference between the two habitats. Crane vigilance declined with increasing distance from wildlife tourists in the two habitats, with a minimum distance of disturbance triggering a high degree of vigilance by cranes identified at 300?m. The presence of wildlife tourists may represent a form of disturbance to foraging cranes but is habitat dependent. Taller P. australis vegetation serves primarily as a visual obstruction for cranes, causing them to increase the frequency of vigilance behaviour. Our findings have important implications for the conservation of the migratory red-crowned crane population that winters in the Yellow River Delta and can help inform visitor management.
Project description:Understanding the habitat use and spatial distribution of wildlife can help conservationists determine high-priority areas and enhance conservation efforts. We studied the wintering habitat use, preference, and utilization distribution of two crane species, that is, the black-necked crane (Grus nigricollis, Przevalski, 1876) and common crane (Grus grus, Linnaeus, 1758), in Huize National Natural Reserve, Yunnan-Guizhou Plateau, southwestern China. Line transects indicated that anthropogenic farmland habitat was highly utilized and was positively selected by both crane species (>90% of flocks observed for both species). Black-necked cranes preferred marshland in spring (February and March) but avoided grassland during the entire wintering period, whereas common cranes avoided both marshland and grassland throughout the entire period. The two cranes species had communal nightly roosting sites and separate daily foraging sites. Black-necked cranes were distributed within two km (1.89 ± 0.08 km) of the roosting site, covering an area of 283.84 ha, with the core distribution area encompassing less than 100 ha. In contrast, common cranes were distributed far from the roosting site (4.38 ± 0.11 km), covering an area of 558.73 ha, with the core distribution area encompassing 224.81 ha. Thus, interspecies competition may have influenced the habitat preference and spatial distribution divergence of these two phylogenetically related species. This study should help guide habitat management as well as functional zoning development and adjustment in the future. Based on our results, we recommend restoration of additional wetlands, retention of large areas of farmland, and protection of areas that cranes use most frequently.
Project description:For migratory birds that specialize on particular benthic macroinvertebrate species, the timing of migration is critical since prey availability may be temporally limited and a function of local ambient temperature. Hence, variation in local ambient temperature can influence the diet composition of migrant birds, and, consequently, they may be constrained by which stopover and wintering sites they are able to utilize during periods of colder temperatures. Here, we use fecal analysis, observer-based population counts, digital video recordings, and temperature data to test five predictions regarding the influence of local ambient temperature on the activity and availability of mudflat crabs-a key prey resource at three staging/wintering sites in eastern China, for migratory Red-crowned cranes (Grus japonensis) and how this subsequently influences crane diet and use of wetland sites. Pearson's correlations and generalized linear models revealed that mudflat crabs became significantly more surface active with increasing burrow ambient temperature. Piecewise regression analysis revealed that crab surface activity was largely limited to a burrow ambient temperature threshold between 12 and 13? after which activity significantly increased. Crab activity declining temporally during the crane's autumn migration period but increased during spring migration. Crabs accounted for a significant proportion of crane diet at two of three sites; however, the frequency of crab remains was significantly different between sites, and between autumn and spring migration. Analyses of crane count data revealed a degree of congruence between the migration timing of Red-crowned cranes with periods of warmer ambient temperature, and a significant, positive correlation between the percentage of crab remains in crane feces and site ambient temperature. Collectively, our data suggest that temperature-related mudflat crab activity may provide an important time window for migratory Red-crowned cranes to utilize critical stopover sites and the crabs' food resources.
Project description:The red-crowned crane is one of the rarest crane species, and its population is decreasing due to loss of habitat, poisoning, and infections. Using a viral metagenomics approach, we analyzed the virome of feces from wild and captive red-crowned cranes, which were pooled separately. Vertebrate viruses belonging to the families Picornaviridae, Parvoviridae, Circoviridae, and Caliciviridae were detected. Among the members of the family Picornaviridae, we found three that appear to represent new genera. Six nearly complete genomes from members of the family Parvoviridae were also obtained, including four new members of the proposed genus "Chapparvovirus", and two members of the genus Aveparvovirus. Six small circular DNA genomes were also characterized. One nearly complete genome showing a low level of sequence identity to caliciviruses was also characterized. Numerous viruses believed to infect insects, plants, and crustaceans were also identified, which were probably derived from the diet of red-crowned cranes. This study increases our understanding of the enteric virome of red-crowned cranes and provides a baseline for comparison to those of other birds or following disease outbreaks.
Project description:Three species of cranes are distributed widely throughout southern Africa, but little is known about how they respond to the changes in land-use that have occurred in this region. This study assessed habitat preference of the two crane species across land-use categories of the self contained small scale commercial farms of 30 to 40 ha per household (A1), large scale commercial agriculture farms of > 50 ha per household (A2) and Old Resettlement, farms of < 5 ha per household with communal grazing land in Driefontein Grasslands Important Bird Area (IBA), Zimbabwe. The study further explored how selected explanatory (environmental) habitat variables influence crane species abundance. Crane bird counts and data on influencing environmental variables were collected between June and August 2012. Our results show that varying land-use categories had an influence on the abundance and distribution of the Wattled Crane (Bugeranus carunculatus) and the Grey Crowned Crane (Belearica regulorum) across Driefontein Grasslands IBA. The Wattled Crane was widely distributed in the relatively undisturbed A2 farms while the Grey Crowned Crane was associated with the more disturbed land of A1 farms, Old Resettlement and its communal grazing land. Cyperus esculentus and percent (%) bare ground were strong environmental variables best explaining the observed patterns in Wattled Crane abundance across land-use categories. The pattern in Grey Crowned Crane abundance was best explained by soil penetrability, moisture and grass height variables. A holistic sustainable land-use management that takes into account conservation of essential habitats in Driefontein Grasslands IBA is desirable for crane populations and other wetland dependent species that include water birds.
Project description:The red-crowned crane (Grus japonensis) is an endangered species listed by International Union for Conservation of Nature (IUCN) HARRIS J (2013). The largest population of this species is distributed mainly in China and Russia, which is called continental population SU L (2012)-Curt D (1996). This population is migratory, which migrates from its breeding range located in Northeast China and Southern Russia, to the wintering range in the south of China to spend the winter every year. The breeding range of this species is critical for red-crowned crane to survive and maintain its population. Previous studies showed the negative effects of habitat loss and degradation on the breeding area of red-crowned crane Ma Z (1998), Claire M (2019). Climate change may also threat the survival of this endangered species. Previous studies investigated the impacts of climate change on the breeding range or wintering range in China Wu (2012), . However, no study was conducted to assess the potential impacts of climate change on the whole breeding range of this species. Here, we used bioclimatic niche modeling to predict the potential breeding range of red-crowned crane under current climate conditions and project onto future climate change scenarios. Our results show that the breeding range of the continental population of red-crowned crane will shift northward over this century and lose almost all of its current actual breeding range. The climate change will also change the country owning the largest portion of breeding range from China to Russia, suggesting that Russia should take more responsibility to preserve this endangered species in the future.
Project description:Wetlands are disappearing or degrading at an unprecedented rate due to the increase in human encroachment and disturbance, eventually leading to habitat loss for waterbirds, which is the primary cause of the decline in the Hooded Crane (Grus monacha) population. The Hooded Cranes have to constantly adjust their foraging strategies to survive to cope with this situation. In order to study how cranes respond to food resources in mosaic habitat, we surveyed a total of 420 food quadrats and 736 behavioral samples from three habitats during three wintering periods in Shengjin Lake and Caizi Lake. We measured temporal and between-habitat differences in foraging time budget, foraging frequency, and foraging success rate. Akaike's information criterion was selected between the models of food abundance and availability. The results indicated that the wintering cranes spent the majority of their time (66.55%) foraging and shifted their foraging behaviors based upon food abundance and availability in different habitats. Our analyses also indicated that cranes were willing to forage more food with poor sediment penetrability in sub-optimal habitats. Foraging time budget was based on the food depth, and the foraging frequency and foraging success rate were based on food abundance. Cranes adopted flexible foraging strategies in response to the alternative food resources in mosaic wetland habitats, as it could mitigate the negative impacts of habitat loss and facilitate survival.
Project description:Numerous studies have addressed antipredatory benefits of mixed-species flocks of foragers, but studies on individual's vigilance as a function of group size are limited. In the Cheolwon area of the Korean Demilitarized Zone, vigilance of the subordinate White-naped cranes (Grus vipio) in 11 groups composed of conspecifics and the dominant Red-crowned cranes (Grus japonensis) was examined. Vigilance correlated negatively with group size due to negative correlation with the number of conspecifics, but not the dominant heterospecifics. This is consistent with the hypothesis that a decrease in vigilance in larger groups is due to antipredatory benefits from increased predator detection in larger groups (associated with the presence of a larger number of conspecifics). This suggested that the mechanism leads to canceling out of the otherwise expected antipredatory benefits to the subordinate species from the increased predator detection by larger group size (associated with larger number of dominants). This is one of only a few behavioral studies of these endangered crane species in the relatively inaccessible wintering area of international importance in the areas of high conservation value.
Project description:The Flow-Sediment-Mechanical approach is one of two management strategies presented in the Platte River Recovery Implementation Program's (Program) Adaptive Management Plan to create and maintain suitable riverine habitat (?200 m wide unobstructed channels) for whooping cranes (Grus americana). The Program's Flow-Sediment-Mechanical management strategy consists of sediment augmentation, mechanical vegetation clearing and channel widening, channel consolidation, and short duration high flow releases of 142-227 m3/s for three to five days in two out of three years in order to increase the unvegetated width of the main channel and, by extension, create and maintain suitable habitat for whooping crane use. We examined the influence of a range of hydrologic and physical metrics on total unvegetated channel width (TUCW) and maximum unobstructed channel width (MUOCW) during the period of 2007-2015 and applied those findings to assess the performance of the Flow-Sediment-Mechanical management strategy for creating and maintaining whooping crane roosting habitat. Our investigation highlights uncertainties that are introduced when exploring the relationship between physical process drivers and species habitat metrics. We identified a strong positive relationship between peak flows and TUCW and MUOCW within the Associated Habitat Reach of the central Platte River. However, the peak discharge magnitude and duration needed to create highly favorable whooping crane roosting habitat within our study area are much greater than short duration high flow releases, as currently envisioned. We also found disking in combination with herbicide application to vegetated portions of the channel are effective for creating and maintaining highly favorable unobstructed channel widths for whooping cranes in all but the very driest years. As such, resource managers could prioritize the treatment of mid-channel islands that are vegetated to increase the suitability of roosting habitat for whooping cranes.
Project description:Habitat loss is one of the key factors underlying the decline of many waterbird species, including Siberian Crane (Grus leucogeranus), a threatened species worldwide. Wetlands are the primary stopover for many waterbirds and restoration of these wetlands involves both hydrological restoration and water resource management. To protect the stopover sites of Siberian Cranes, we collected Siberian Crane stopover numbers, meteorological and hydrological data, and remote sensing data from 2008 to 2011 in Momoge National Nature Reserve, one of the largest wetlands in northeastern China. A model was developed to estimate the suitability of Siberian Crane stopover sites. According to our results, the most suitable daily water level for Siberian Cranes between 2008 and 2012 occurred in the spring of 2008 and in the Scirpus planiculmis growing season and autumn of 2010. We suggest a season-dependent water management strategy in order to provide suitable conditions at Siberian Crane stopover sites.