Grus Vipio Research Articles

Shifting of the Migration Route of White-Naped Crane (Antigone vipio) Due to Wetland Loss in China

In the last 15 years, the west population of white-naped crane (Antigone vipio) decreased dramatically despite the enhanced conservation actions in both breeding and wintering areas. Recent studies highlighted the importance of protecting the integrity of movement connectivity for migratory birds. Widespread and rapid landcover changes may exceed the adaptive capacity of migrants, leading to the collapse of migratory networks. In this study, using satellite tracking data, we modeled and characterized the migration routes of the white-naped crane at three spatial levels (core area, migratory corridor, and migratory path) based on the utilization distribution for two eras (1990s and 2010s) spanning 20 years. Our analysis demonstrated that the white-naped crane shifted its migratory route, which is supported by other lines of evidences. The widespread loss of wetlands, especially within the stopover sites, might have caused this behavioral adaptation. Moreover, our analysis indicated that the long-term sustainability of the new route is untested and likely to be questionable. Therefore, directing conservation effects to the new route might be insufficient for the long-term wellbeing of this threatened crane and large-scale wetland restorations in Bohai Bay, a critical stopover site in the East Asian-Australasian flyway, are of the utmost importance to the conservation of this species.

Influences of submerged plant collapse on diet composition, breadth, and overlap among four crane species at Poyang Lake, China

BackgroundInterannual variation in resource abundance has become more unpredictable, and food shortages have increasingly occurred in the recent decades. However, compared to seasonal fluctuations in resource abundance, the influences of interannual variation in resource abundance on the dietary niches of consumers remain poorly understood. Poyang Lake, China, is a very important wintering ground for the globally endangered Siberian Crane (Leucogeranus leucogeranus), White-naped Crane (Grus vipio), and Hooded Crane (G. monacha), as well as the non-endangered Eurasian Crane (G. grus). Tubers of Vallisneria spp., the dominant submerged macrophytes at Poyang Lake, is an important food for cranes. Nevertheless, submerged macrophytes have experienced serious degradation recently. In this study, we used metabarcoding technology to explore the consequences of Vallisneria tuber collapse on the diet compositions, breadths, and overlaps of the four crane species based on fecal samples collected in winter 2017 (a year with tuber collapse) and winter 2018 (a year with high tuber abundance).ResultsCompared to previous studies, our study elucidates crane diets in an unprecedented level of detail. Vallisneria tubers was confirmed as an important food source of cranes. Surprisingly, the grassland plant Polygonum criopolitanum was also found to be an important food source in the feces of cranes. Agricultural fields were important foraging sites for Siberian Cranes, White-naped Cranes, and Hooded Cranes, providing foods that allowed them to survive in winters with natural food shortages. However, the three crane species preferred natural wetlands to agricultural fields when the abundance of natural foods was high. The abundance of Vallisneria tubers, and probably P. criopolitanum, greatly influenced the dietary compositions, breadths and overlap of cranes. During periods of preferred resource shortage, White-naped Cranes and Hooded Cranes widened their dietary niches, while Siberian Cranes maintained a stable niche width. The dietary niche overlap among crane species increased substantially under conditions of plentiful preferred food resources.ConclusionsOur study emphasizes the superior quality of natural wetlands compared to agricultural fields as foraging habitats for cranes. To provide safer and better foraging areas for cranes, it is urgent to restore the submerged plants at Poyang Lake. While high dietary niche overlap is often interpreted as intense interspecific competition, our study highlights the importance of taking food abundance into account.

不同水位下拟建鄱阳湖水利枢纽对食块茎鸟类栖息地适宜性的影响研究

鄱阳湖为亚洲最大的候鸟栖息地，近十余年发生了枯水期提前且延长及湖区生态环境日益恶化的问题，对于此问题江西政府提出了一种科学的工程措施--鄱阳湖水利枢纽（简称枢纽）。然而，枢纽对越冬候鸟栖息地的影响尚无定量研究。以鄱阳湖食块茎鸟类--白鹤（Grus leucogeranus）、白枕鹤（Grus vipio）和小天鹅（Cygnus columbianus）的栖息地为研究对象，利用3S技术结合生态学知识，在ArcGIS平台上搭建了食块茎鸟类栖息地适宜性评价模型，使用二维水动力模型联合适宜性评价模型，生成鄱阳湖在兴建枢纽前、后的食块茎鸟类栖息地适宜性分布图。选取工程调度时期水位相对稳定时段，以鄱阳湖无枢纽状态下星子水位为基础，探究鄱阳湖在不同水位时，有拟建枢纽和无拟建枢纽状态下食块茎鸟类的栖息地适宜性的变化，定量分析拟建枢纽对候鸟栖息地适宜性造成的影响。研究发现：枢纽的调度规则具有一定的科学性，水位调度方案对湖泊食块茎鸟类越冬初期栖息产生的影响较小，但会牺牲一部分越冬后期适合食块茎鸟类栖息的区域。拟建枢纽选址处至都昌站的食块茎鸟类栖息地适宜性受枢纽的负面影响最为显著，各级自然保护区之中，北部省级候鸟自然保护区受其负面影响最大，此保护区将减少18.01-39.80 km²适合食块茎鸟类栖息的面积。但是枢纽的运行能增加湖泊土壤水含量，使食块茎鸟类更易于觅食，且能增加喜食块茎鸟类的食物丰富度。本研究可为为今后鄱阳湖湖区水环境规划和水生态管理维护提供一定的科学参考。;Poyang Lake is the largest wintering habitat for migratory birds in Asia. In the last decade, the Lake has experienced early-occurring and prolonged dry season that has deteriorated the lake's ecological status. To tackle this issue, the Chinese government has proposed the construction of the Poyang Lake Hydraulic Project. However, there is no quantitative study on the impact of the Hydraulic Project on wintering migratory bird habitats. The habitats of the Tuber-eating Birds including Grus leucogeranus, Grus vipio, and Cygnus columbianus, etc. were studied. The 3S technology combined with ecological knowledge were used to build a suitability evaluation model for the habitat of the Tuber-eating Birds on the ArcGIS platform. Then, we used the suitability evaluation model combined with a two-dimensional hydrodynamic model to generate the habitat suitability map of the Tuber-eating Birds, with and without the presence/operation of the hydraulic project. During the hydraulic project dispatch period, the period of stable water level was selected. Based on the Xingzi water level without the hydraulic project, we explored the habitat suitability changes of Poyang Lake in different water levels, with and without the presence/operation of the hydraulic project. The impact of the hydraulic project on the suitability of the Tuber-eating Birds habitats was quantitatively studied. The results showed that the scheduling rule of the hydraulic project were scientific. The scheduling rule had little impact on the habitat of the Tuber-eating Birds in the early winter, but still sacrificed some of the areas suitable for the Tuber-eating Birds in the late winter. The region of hydraulic project to Duchang station was significantly negatively affected by the hydraulic project. In the nature reserves at all levels, the northern provincial migratory bird nature reserve was most significantly negatively affected, and the area will reduce the area of 18.01-39.80 km² suitable for the Tuber-eating Birds. However, the operation of the hydraulic project could increase the soil water content, making it easier for the Tuber-eating Birds to eat and increase the food richness. Our study can provide a scientific reference for the future water environment planning and ecological management of the Poyang Lake.

Онтогенез канадского журавля (Grus canadensis canadensis) в Северо-Западной Чукотке и реакции взрослых и птенцов на наблюдателя в сравнении с другими видами журавлей

Онтогенез канадского журавля (Grus canadensis canadensis) в Северо-Западной Чукотке и реакции взрослых и птенцов на наблюдателя в сравнении с другими видами журавлей

Avian Surveys in the Korean Inner Border Area, Gimpo, Republic of Korea.

BackgroundBirds are useful environmental indicators as their presence reflects the health of the food web. Bird occurrence, rarity and abundance are reliable indicators of ecosystem health. Monitoring of avian populations in the Republic of Korea (ROK) is a primary requirement due to plummeting populations and the risks to threatened species. The Ministry of Environment of ROK started conducting winter bird censuses in 1999, including inland areas and coast areas, such as Cheorwon, Yeoncheon, Junam Reservoir and Han River. Cheolwon, Yeoncheon and some extent islands in the West Sea have been survey extensively due to iconic bird species, such as White-naped Crane (Grus vipio) or Red-Crowned Crane (Grus japonensis) wintering there. However, the winter bird census has not covered Yu Islet, Han River Estuary. Yu Islet is located within the Han River Estuary, a protected wetland in the Neutral Zone between the two Koreas and north of Gimpo in the ROK. The Islet currently supports a large, mixed breeding colony of waterbirds, such as one of the nation’s largest concentration of breeding Great Cormorants (Phalacrocorax carbo) and smaller numbers of breeding Black-faced Spoonbill (Platalea minor), Grey Heron (Ardea cinereal), Great Egret (Ardea alba) and Intermediate Egret (Ardea intermedia). Access to the area has long been restricted for military reasons, but recently, regular survey activity is possible supported by Gimpo City and the military base in Gimpo from November 2018.New informationHere, we provide data demonstrating that Yu Islet is important for breeding for waterbirds; and that the northern Gimpo part of Han River Estuary is also internationally important for waterbirds during the migratory bird season, as defined by the Ramsar Convention (Ramsar 1971, RRC-EA 2017). In particular, four waterbird species were found during the survey in the Main Survey Area: Swan Goose (Anser cygnoides), Taiga Bean Goose (Anser fabalis), Tundra Bean Goose (Anser serrirostris) and Greater White-fronted Goose (Anser frontalis). Once considered widespread in East Asia and abundant, the world population of Swan Goose is now estimated at only 60,000 - 78,000 individuals (Wetlands International 2020) and the species is assessed by BirdLife International as globally Vulnerable (BirdLife International 2020). The 1,010 Swan Goose (Anser cygnoides) counted on the vegetated mudflats at Jogang-Ri in the Main Survey Area on 27 November 2018 represents more than 1% of the total world population of this species. Notably, it is also the highest count of this species in the ROK for at least a decade. The count confirms the continuing international importance of the Han River Estuary for the survival of the Swan Goose. The number counted in November had fallen to 250 by 28 December 2018; and none was recorded in the Main Survey Area in January or February 2019. Although searched for in March, none was noted during the northward migration either. The surveys also found small numbers of nationally-scarce Grey-capped Pygmy Woodpecker (Yungipicus canicapillus) in several areas of woodland surrounded by the Han River Estuary. By selecting the most species-rich count within a given month in each of the two survey sectors, the number of species we recorded ranged from a minimum 29 in January to a maximum of 65 in April 2019. Based on the species recorded, the survey area is clearly important for avian conservation. Its importance derives from the combination of the extensive areas of high-quality wetland and its geographic location within one of the Korea Peninsula’s largest and most important remaining wetland ecosystems, the Han River Estuary. Our surveys resulted in the detection of a substantial number of bird species, especially in March and April when forest-breeding birds are more obviously vocal. The survey result is provided in the supplementary material (Suppl. material 1).

Identifying high-priority conservation areas for endangered waterbirds using a flagship species in the Korean DMZ

The Hangang River and Imjingang River estuaries in Korea are part of the main transit route for many migratory birds that use the East Asia-Pacific flyway. Despite the global importance of this area as a seasonal bird stopover site and resting area, conservation areas have not been established in this area based on ecological properties. This study aimed to examine the umbrella effect of the white-naped crane (Antigone vipio), which is one of the best-known flagship species in East Asia, and to determine the effectiveness of establishing a conservation plan in the western DMZ based on the distribution of white-naped cranes. Species distribution modeling was performed for the white-naped crane; other threatened waterbirds wintering in the western DMZ; Group 1, including species with ecological traits similar to those of the white-naped crane; and Group 2, including species with ecological traits different from those of the white-naped crane. The modeling was based on field survey data from a citizen science project, and a systematic conservation planning approach was adopted for each species group. The results showed no significant differences between the plan for the target species and the plans for the other species groups, indicating that protecting white-naped cranes habitat can also protect the habitat of other threatened waterbirds.

Environmental and chemical characteristics of the Zeya-Bureya plain small river Filinovka

The article discusses the results of hydrochemical study of water of the small Filinovka River, the left-bank tributary of the Amur River, flowing along the south of the Zeya-Bureya Plain. Water is characterized by high oxygen content. The content of nitrogen and phosphorus compounds in water undergoes seasonal dynamics. The water of the small Filinovka River is characterized by a high content of iron and manganese, which are caused by the natural factor. The content of zinc and copper in water is higher than the fisheries standard. Macrophytes Najas marina and Ceratophyllum oryzetorum and feathers of birds Grus monacha and Grus vipio contain a high concentration of lead and cadmium. The results of studying the hydrochemical parameters of the water ecosystem of a small river flowing along the south of the Zeya-Bureya plain are the basis for studying the agricultural load on small rivers.

Pathogenicity of H5 highly pathogenic avian influenza virus in rooks (Corvus frugilegus)

ABSTRACTRooks (Corvus frugilegus) are considered migratory crows in Japan. Some rooks share a wintering site in the Izumi plain in Kagoshima Prefecture with hooded cranes (Grus monacha) and white-necked cranes (Grus vipio), which are designated as “endangered” in the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Highly pathogenic avian influenza (HPAI), caused by H5 subtype viruses, has recently been reported in these crane species in Japan, in conjunction with a massive decrease in their population. In the present study, the pathogenicity of HPAI virus was assessed in rooks to evaluate the likelihood that they are a source of infections in other bird species. One of four rooks intranasally inoculated with A/mandarin duck/Miyazaki/22M807-1/2011 (H5N1) died at 10 days post-inoculation (d.p.i.). The other three rooks exhibited seroconversion but no clinical signs. All the rooks had shed virus by the oral route at <103 50% egg infectious dose/ml until 7 d.p.i. Virus was also recovered from multiple tissues of the rook that succumbed to the infection. These results suggest that rooks are susceptible to infection with H5 HPAI viruses, leading to prolonged viral shedding. The rooks shed the virus at low titres however, indicating that they are likely to function as transmission vectors in wintering bird flocks. The rooks exhibited clear antibody responses against the H5 HPAI virus, and thus serological surveillance of them in the field should be helpful for assessing viral pervasion into the habitats of crane species.

Luan River upper reaches: The important stopover site of the white-naped crane (&lt;i&gt;Grus vipio&lt;/i&gt;) western population

Luan River upper reaches: The important stopover site of the white-naped crane (&lt;i&gt;Grus vipio&lt;/i&gt;) western population

Potential habitat and priority protection area of cranes with climate change in the Great Xing'an Mountains, China

To clarify the impacts of climate change on the potential distribution of six crane species in the Great Xing'an Mountains region, and promote the effective protection of these species, we selected key environmental variables such as climate, topography, and vegetation type based on Pearson correlation and Jackknife analysis, and modeled the potential distribution of six crane species in the Great Xing'an Mountains using MaxEnt with the current and the future climate change scenarios (RCP4.5 and RCP8.5). We identified the priority protection areas (PPAs) and the target PPAs by zonation and ArcGIS. The results showed that with the current climate condition, the sui-table habitats of these species were mainly distributed in the central and the northwest part of the Great Xing'an Mountains. With RCP4.5 and RCP8.5 scenarios, the suitable habitats of Grus monacha, Grus japonensis, Grus vipio, Grus grus and Anthropoides virgo would decrease, while that of Grus leucogeranus would expand by 5.4%-6.3%. With current and the future climate change scenarios, the PPAs of these species were mainly distributed in the northwest, southeast and west-central parts of the Great Xing'an Mountains. The protect rate could reach about 20.1%-23.8% of the target PPAs conserved by protected areas (PAs). The protection gaps were mainly distributed in the west of Mohe County, the north-central of Ergun, the central and east of Genhe, the northeast of Yakeshi, and the south of Oroqen Autonomous Banner. We proposed to expand PAs to provide a strong guarantee for the effective protection of cranes species.

Surveillance of antibiotic resistance in Escherichia coli isolated from wild cranes on the Izumi plain in Kagoshima prefecture, Japan.

The prevalence of antibiotic resistance in 376 Escherichia coli (E. coli) isolates from fecal samples of Hooded and White-naped cranes was investigated on the Izumi plain in Kagoshima prefecture, Japan, during winter 2016 and 2017. Resistance to oxytetracycline, ampicillin, and nalidixic acid were observed in 10.9%, 3.1–4.4%, and 2.1–7.7% of isolates, respectively. Since the previous surveillance in 2007, isolation rates of antibiotic-resistant E. coli recovered from wild cranes have remained at significantly low levels compared with those in Japanese livestock. Our results indicate that surveillance of antibiotic-resistant E. coli from wild cranes wintering in the Izumi plain could be a useful strategy to indicate natural environmental pollution by antibiotic-resistant bacteria in the environment.

Vigilance responding to number of conspecifics among mixed groups of cranes in demilitarized zone

ABSTRACTNumerous 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.

Cryopreservation effects on sperm function and fertility in two threatened crane species

The capacity to cryopreserve semen from captive cranes facilitates production of offspring from behaviorally incompatible or geographically separated pairs, and allows for long-term preservation of valuable genetic materials. The present study sought to develop effective cryopreservation protocols for whooping (Grus americana) and white-naped (Grus vipio) cranes, through examining the influences of two permeating (DMA and Me2SO) and one non-permeating (sucrose) cryoprotectants, as well as vitamin E on post-thaw sperm survival. In Study 1, ejaculates (whooping: n = 10, white-naped: n = 8) were collected and cryopreserved in one of six cryo-diluents (crane extender with: DMA; DMA+0.1M sucrose; Me2SO; Me2SO+0.1M sucrose; 0.1M sucrose; 0.2M sucrose) using a two-step cooling method. Frozen samples were thawed and assessed for overall motility, motion characteristics, membrane integrity, morphology, and ability to bind to the inner perivitelline membrane (IPVM). In Study 2, whooping crane ejaculates (n = 17) were frozen in crane extender containing Me2SO alone or with vitamin E (5 μg/mL or 10 μg/mL). Frozen samples were thawed and assessed as in Study 1, except the binding assay. White-naped crane sperm were more tolerant to cryopreservation than whooping crane (15% vs 6% post-thawed motility). In both species, sperm cryopreserved in medium containing Me2SO alone displayed higher post thaw survival and ability to bind to IPVM than the other cryodiluent treatments. Vitamin E supplementation exerted no benefits to post thaw motility or membrane integrity. The findings demonstrated that there was species specificity in the susceptibility to cryopreservation. Nevertheless, Me2SO was a preferred cryoprotectant for sperm from both whooping and white-naped cranes.

Genetic characterization of low-pathogenic avian influenza viruses isolated on the Izumi plain in Japan: possible association of dynamic movements of wild birds with AIV evolution.

The Izumi plain in Kagoshima Prefecture, Japan, is an overwintering site of endangered cranes (hooded cranes and white-naped cranes) and of many other migratory birds (including wild ducks) that are considered carriers of avian influenza viruses (AIVs). To assess the risks of a highly pathogenic avian influenza outbreak in the crane populations, we tested various environmental samples for AIVs in this area. In the 2014-2015 winter season, we isolated one AIV of the H6N2 subtype from the cranes' roost water and two AIVs of the H11N9 subtype from a crane fecal sample and a cloacal swab of a dead spot-billed duck. Genetic analysis of these AIV isolates indicated that our H6N2 isolate is genetically close to AIVs isolated from wild birds in Southeast Asian countries, except that the PB1 and NS genes belong to the North American virus lineage. All genes of the two H11N9 isolates are related to AIVs belonging to the Eurasian virus lineage. Notably, in our phylogenetic trees, H11 HA and N9 NA genes showing high sequence similarity to the corresponding genes of isolates from wild birds in South Africa and Spain, respectively, did not cluster in the major groups with recent wild-bird isolates from East Asia. These results suggest that AIVs with viral gene segments derived from various locations and bird species have been brought to the Izumi plain. These findings imply a possible association of dynamic movements of wild birds with AIV evolution.

Characterization of gizzards and grits of wild cranes found dead at Izumi Plain in Japan.

We analyzed the gizzards, and grits retained in the gizzards of 41 cranes that migrated to the Izumi Plain during the winter of 2015/2016 and died there, either due to accident or disease. These included 31 Hooded Cranes (Grus monacha) and 10 White-naped Cranes (G. vipio). We determined body weight, gizzard weight, total grit weight and number per gizzard, and size, shape, and surface roundness of the grits. Average gizzard weights were 92.4 g for Hooded Cranes and 97.1 g for White-naped Cranes, and gizzard weight positively correlated with body weight in both species. Average total grit weights per gizzard were 19.7 g in Hooded Cranes and 25.7 g in White-naped Cranes, and were significantly higher in the latter. Average percentages of body weight to grit weight were 0.8% in Hooded Cranes and 0.5% in White-naped Cranes. Average grit number per gizzard was 693.5 in Hooded Cranes and 924.2 in White-naped Cranes, and were significantly higher in the latter. The average grit size was 2.8 mm in both species. No differences were found in the shape and surface roundness of grits between the two species. To the best of our knowledge, this is the first study on the grits retained in the gizzards of Hooded and White-naped Cranes.

Distribution and Long-Term Population Trends of Wintering Waterbirds in Poyang Lake, China

Although total wintering waterbirds have increased in Poyang Lake, some groups or species might have declined. Identifying declining groups and species will help to optimize conservation strategies. In addition, knowledge of waterbird distribution is required to identify priority areas for protection. In this study, we aimed to explore long-term population trends of waterbird groups and species and to investigate waterbird distribution in Poyang Lake by integrating survey data from 1996/1997 to 2014/2015. Poyang Lake Nature Reserve, Duchang and Nanji Wetland Nature Reserve had high waterbird richness and abundance and high proportion of IUCN endangered species, thus they are important areas for waterbird protection. An important limitation to waterbird protection in the three areas is lack of management rights of most sub-lakes. Most waterbird groups in Poyang Lake have grown, but ducks have declined. Hunting and the decline of aquatic vegetation might be driving the duck declines. In addition, White-naped Crane (Grus vipio), Spot-billed Duck (Anas poecilorhyncha) and Northern Lapwing (Vanellus vanellus) have declined. While we believe the data presented here indicate general trends in groups and species, the analyses suffered from variation in methods used in different surveys. We advocate long-term waterbird monitoring using standardized methods to better understand waterbirds’ population dynamics.

Increased Populations of Endangered Cranes After Amur River Flood

Abstract. Dam construction on the Zeya River, which is an important tributary of the Amur River in Far East Russia, has caused significant declines in water levels and frequency of floods in the adjacent floodplains since 1980. However, an extreme flood event occurred in 2013. Populations of six crane species were monitored before and after these drastic water level changes at Muraviovka Park in Far East Russia, an important breeding and stop-over site. Individuals were counted by territory mapping during the breeding season (2000–2015) and by roosting site counts during autumn migration (2006–2015). The objective of this study was to evaluate whether changes in water levels had a significant impact on local and migratory crane populations. We found a positive effect of flooding on numbers of breeding Red-crowned Cranes (Grus japonensis) and White-naped Cranes (Antigone vipio), as well as on numbers of roosting Hooded Cranes (Grus monacha) in autumn. Siberian Cranes (Leucogeranus leucogeranus) were only o...

Pre-migratory congregations of Red-crowned (Grus japonensis), White-naped (G. vipio) and Hooded (G. monacha) cranes in the Muraviovka Park for Sustainable Land Use in 1992

The autumn pre-migratory concentrations of Red-crowned, White-naped and Hooded Cranes were studied in the Muraviovka Park for Sustainable Land Use and Environmentla Education (Tambov District, Amur Region, Russian Federation) during 23.08–29.09.1992. We counted 292 Hooded Cranes, 34 White-naped Cranes, and 17 Red-crowned Cranes during the study period. We also marked specific differences in the behaviour of the birds connected with their readiness for migration. The Hooded Cranes showed the greatest readiness for migration. We observed mutual flights, overnight stays, and feeding of adult birds and family groups in their flocks. This was not the same in the flocks of White-naped Cranes. However, the average number of birds in the flocks of White-naped Cranes had increased by the end of our observations due to new families joining the general flock. The family parties of the Red-crowned Crane and adult birds without young individuals stayed apart from each other and from other crane species during the whole observation period. We registered the autumn departure of Hooded Cranes in late September, the migratory departure of White-naped Cranes in the middle of October, and the Red-crowned Cranes left the area in the first half of November. The breeding period for all crane species starts at the same time: the third decade of April – the beginning of May. The young of the studied crane species differ significantly in the period of time before fledging: Hooded Cranes – 55–60 days, White-naped Cranes – 65–70 days, and Red-crowned Cranes – 70–75 days because of their specific differences in the ratio of size to weight (1 : 1.3 : 1.7). Thus, the time difference between the Hooded and Red-crowned Cranes is about 2–3 weeks. We suggest that this is the main reason that determines the differences between these species in the timing of the the start of autumn migration.

Activity Patterns of four Cranes in Poyang Lake, China: Indication of Habitat Naturalness

Poyang Lake is one of the most important wintering habitats for cranes in China, and thousands of cranes including Siberian Crane (leucogeranus leucogeranus), White-naped Crane (Grus vipio), Hooded Crane (G. monacha) and Common Crane (G. grus) winter here annually. Despite their different conservation status, the four cranes have substantial ecological niche overlap and often form mixed flocks in their wintering grounds. To understand the persistence and coexistence of the species, we used time-budgeting to investigate how these sympatric cranes allocate time to their activities. Our results indicate that the cranes had more foraging time and less vigilance time at Poyang Lake than at other wintering sites. Also, the four cranes displayed significantly different activity patterns in the shared habitat. Compared with the smaller sized Common Cranes and Hooded Cranes, the larger sized Siberian Cranes and White-naped Cranes tended to be more relaxed, suggesting foraging ability decides the crane community structure as evidenced in many ecosystems. Our results suggested that Poyang Lake is crucial for the cranes conservation, which needs a transregional even global management strategy.

Why choose Random Forest to predict rare species distribution with few samples in large undersampled areas? Three Asian crane species models provide supporting evidence.

Species distribution models (SDMs) have become an essential tool in ecology, biogeography, evolution and, more recently, in conservation biology. How to generalize species distributions in large undersampled areas, especially with few samples, is a fundamental issue of SDMs. In order to explore this issue, we used the best available presence records for the Hooded Crane (Grus monacha, n = 33), White-naped Crane (Grus vipio, n = 40), and Black-necked Crane (Grus nigricollis, n = 75) in China as three case studies, employing four powerful and commonly used machine learning algorithms to map the breeding distributions of the three species: TreeNet (Stochastic Gradient Boosting, Boosted Regression Tree Model), Random Forest, CART (Classification and Regression Tree) and Maxent (Maximum Entropy Models). In addition, we developed an ensemble forecast by averaging predicted probability of the above four models results. Commonly used model performance metrics (Area under ROC (AUC) and true skill statistic (TSS)) were employed to evaluate model accuracy. The latest satellite tracking data and compiled literature data were used as two independent testing datasets to confront model predictions. We found Random Forest demonstrated the best performance for the most assessment method, provided a better model fit to the testing data, and achieved better species range maps for each crane species in undersampled areas. Random Forest has been generally available for more than 20 years and has been known to perform extremely well in ecological predictions. However, while increasingly on the rise, its potential is still widely underused in conservation, (spatial) ecological applications and for inference. Our results show that it informs ecological and biogeographical theories as well as being suitable for conservation applications, specifically when the study area is undersampled. This method helps to save model-selection time and effort, and allows robust and rapid assessments and decisions for efficient conservation.