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

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.     

Genetic variation in the midcontinental population of sandhill cranes,Grus canadensis

Three subspecies of sandhill crane (Grus canadensis) are recognized in the Midcontinental population, the lesser (Grus c. canadensis), Canadian (G. c. rowani), and greater (G. c. tabida). Blood samples collected on the population's primary spring staging area in Nebraska, U.S.A., were used to resolve the genetic relationship among these subspecies. Phylogenetic analysis of 27 G. canadensis, by DNA sequencing of a 675 bp region of the mtDNA, supports the subspecies designations of G. c. canadensis and G. c. tabida. G. c. rowani individuals were intermediate with each of the other two subspecies. Genetic divergence ranged from 6.5 to 14.5% between G. c. canadensis and G. c. tabida, 0.5 to 6.6% within G. c. canadensis, and 0.1 to 6.0% within G. c. tabida. Sufficient DNA for analysis was obtained from shed feathers indicating a source of genetic material that does not require the capture or sacrifice of the birds. Other genetic markers and methods, including satellite telemetry, are required for obtaining detailed information on crane distributions as needed to establish effective management units for the MCP.     

Detection of parasitizing coccidia and determination of host crane species, sex and genotype by faecal DNA analysis

In Japan, the three main crane species are the endangered red-crowned crane (Grus japonensis) inhabiting Hokkaido, the northernmost island of Japan; the vulnerable hooded crane (Grus monacha); and the vulnerable white-naped crane (Grus vipio). Both the hooded and white-naped cranes migrate in winter to Izumi in Kyushu, the southern island of Japan. In this study, we investigated the cranes and their coccidian parasites, through a targeted molecular approach using faecal DNA to develop a noninvasive method for infectious disease research. To determine the origin of noninvasively collected faecal samples, host species were identified by sequencing a region of approximately 470 bp of the mitochondrial 16S ribosomal RNA gene in the faecal DNA. Furthermore, to avoid sample redundancy, individual determination was performed by fragment analysis using microsatellite and sex-linked markers. For microsatellite genotyping, previously reported markers and markers isolated in this study were examined, and seven loci for red-crowned cranes, eight for hooded cranes and six for white-naped cranes displayed polymorphisms. A low error rate was demonstrated by comparing microsatellite data generated from faecal DNA samples with that generated from feather DNA samples, indicating a high reliability. Polymerase chain reaction-based capillary electrophoresis (PCR-CE), employing genetic markers in the second internal transcribed spacer (ITS2) of nuclear ribosomal DNA, was employed to detect crane coccidia. The sensitivity of detection of PCR-CE using faecal DNA was inferior to that with traditional microscopy; however, our results suggest that PCR-CE can depict crane coccidia diversity with higher resolution and it is a useful tool to characterize community composition of coccidia in detail.     

Duet structure provides information about pair identity in the red-crowned crane (Grus japonensis)

We studied the acoustic features of the endangered red-crowned crane (Grus japonensis), and, specifically, whether or not the duets carry information about a mating pair identity. The population of this species in the wild is only approximately 2,000 individuals. In 2003–2006, we recorded 343 duets from eight captive and two wild pairs. All of the duets contained an introduction, an unordered alternation of pair mate calls, followed by the main part, representing the regular sequence of syllables, containing 1–2 male and 1–4 female calls per syllable. We subdivided the syllables into five types, by the number of male and female calls per syllable, and analyzed the occurrence of the different syllable types in the duets of the ten pairs. The analysis showed the sustainable pair-specific use of particular syllable types through the years. The discriminant analysis standard procedure, based on seven frequency and temporal parameters of male and female calls, showed 97.7% correct assignment to the pair, which is significantly higher than random values. The high pair specificity of the duet acoustic structures provides the basis for call-based censuses. This would enable the monitoring of the red-crowned crane mating pairs in their natural habitat.     

Obtaining an Interspecific Hybrid of Cranes by Artificial Insemination with Frozen–thawed Semen

Studies of artificial insemination of cranes and cryoconservation of their semen have been carried out in the nursery of rare species at the Oka Biosphere Reserve for many years. The criterion of successful cryoconservation of the semen is the obtaining of fertilized eggs after artificial insemination by the thawed semen. An experiment is described on artificial insemination of females of the white-naped crane Grus vipio by the frozen–thawed semen of the Siberian white crane G. leucogeranusafter one-year storage of semen in liquid nitrogen. As a result, an interspecific hybrid of cranes was obtained, which confirmed the possibility of producing a bank of cryoconserved crane semen. The use of the white-naped crane females was due to the absence of conspecific males and unavailability of Siberian white crane females. Problems of artificial insemination and cryoconservation of semen of rare crane species are discussed.     

Obtaining an Interspecific Hybrid of Cranes by Artificial Insemination with Frozen–thawed Semen

Studies of artificial insemination of cranes and cryoconservation of their semen have been carried out in the nursery of rare species at the Oka Biosphere Reserve for many years. The criterion of successful cryoconservation of the semen is the obtaining of fertilized eggs after artificial insemination by the thawed semen. An experiment is described on artificial insemination of females of the white-naped crane Grus vipio by the frozen–thawed semen of the Siberian white crane G. leucogeranus after one-year storage of semen in liquid nitrogen. As a result, an interspecific hybrid of cranes was obtained, which confirmed the possibility of producing a bank of cryoconserved crane semen. The use of the white-naped crane females was due to the absence of conspecific males and unavailability of Siberian white crane females. Problems of artificial insemination and cryoconservation of semen of rare crane species are discussed.     

Characterisation of 14 blue crane <Emphasis Type="Italic">Grus paradisea</Emphasis> (Gruidae,AVES) microsatellite loci for use in detecting illegal trade

Forty-two unique microsatellite loci were isolated from an unenriched and a tetranucleotide-enriched blue crane (Grus paradisea) genomic library. Fourteen polymorphic loci were characterised in 20 unrelated wild blue crane individuals from the Karoo region, South Africa, and displayed 4–27 alleles with observed heterozygosities ranging between 0.50 and 0.95. All 14 loci were also polymorphic in the grey-crowned crane (Balearica regulorum) and the wattled crane (Grus carunculatus). These markers are aimed at assisting the identification of illegal trade in the blue crane but have wider population and conservation applications for most, if not all, crane species.     

Decision analysis for conservation breeding: Maximizing production for reintroduction of whooping cranes

Captive breeding is key to management of severely endangered species, but maximizing captive production can be challenging because of poor knowledge of species breeding biology and the complexity of evaluating different management options. In the face of uncertainty and complexity, decision-analytic approaches can be used to identify optimal management options for maximizing captive production. Building decision-analytic models requires iterations of model conception, data analysis, model building and evaluation, identification of remaining uncertainty, further research and monitoring to reduce uncertainty, and integration of new data into the model. We initiated such a process to maximize captive production of the whooping crane (Grus americana), the world's most endangered crane, which is managed through captive breeding and reintroduction. We collected 15 years of captive breeding data from 3 institutions and used Bayesian analysis and model selection to identify predictors of whooping crane hatching success. The strongest predictor, and that with clear management relevance, was incubation environment. The incubation period of whooping crane eggs is split across two environments: crane nests and artificial incubators. Although artificial incubators are useful for allowing breeding pairs to produce multiple clutches, our results indicate that crane incubation is most effective at promoting hatching success. Hatching probability increased the longer an egg spent in a crane nest, from 40% hatching probability for eggs receiving 1 day of crane incubation to 95% for those receiving 30 days (time incubated in each environment varied independently of total incubation period). Because birds will lay fewer eggs when they are incubating longer, a tradeoff exists between the number of clutches produced and egg hatching probability. We developed a decision-analytic model that estimated 16 to be the optimal number of days of crane incubation needed to maximize the number of offspring produced. These results show that using decision-analytic tools to account for uncertainty in captive breeding can improve the rate at which such programs contribute to wildlife reintroductions. © 2011 The Wildlife Society.     

黑龙江扎龙自然保护区白枕鹤巢址选择特征

为了探讨白枕鹤Grusvipio的巢址选择特征,2007～2009年的4～5月,在黑龙江省扎龙自然保护区采用定点观察法、样方调查法、因子调查法和因子分析及显著性检验等,对白枕鹤的营巢生境类型和营巢生境特征进行了调查。结果表明,白枕鹤对营巢生境类型的要求比较单一,仅选择芦苇沼泽;巢址生境特征具有明显的偏好,即(1)距干扰区的距离多在1.5km以上(86.36%),(2)巢周的水深多小于16cm(95.45%),(3)巢周明水面面积多小于200m2(90.90%),(4)巢距火烧地的距离以1.0～2.5km居多(63.64%),(5)剩余苇丛面积多小于200m2(86.37%)、距剩余苇丛距离多大于30m(81.82%)、剩余苇丛密度多小于500株/m2(77.27%)、剩余苇丛高度以大于1.5m的居多(72.73%)。进一步分析表明,白枕鹤对营巢生境特征的要求具有普遍性和特殊性,表现出一定的适应能力,火烧地、剩余苇丛、干扰区和水是其营巢的主要环境特征。     

基于MAXENT模型的丹顶鹤营巢生境适宜性分析——以扎龙保护区为例

明确物种繁殖栖息地的潜在分布对于受胁物种的保护与科学管理具有十分重要的意义。扎龙保护区是国际濒危物种丹顶鹤西部迁徙种群的主要繁殖地之一,近年来繁殖种群数量波动较大。通过GIS空间技术平台,利用MAXENT模型,结合2012—2013年丹顶鹤(Grus japonensis)营巢分布点和环境特征变量,对扎龙保护区丹顶鹤营巢生境的适宜性进行了分析。结果表明:模型的评价效果达到优秀水平(训练集AUC=0.901);绿度(34.9%)、距道路距离(17.1%)、土壤湿度(16.3%)、海拔(15.7%)是丹顶鹤营巢生境的主要环境特征变量;核心区中部和南部是丹顶鹤主要的适宜营巢分布区,缓冲区和实验区有少量的适宜营巢区分布,丹顶鹤适宜营巢生境面积为35857.35hm~2,占保护区总面积的17.07%。建议在重点管理核心区的同时,对缓冲区和实验区的小面积芦苇沼泽给予更多关注。