Microhabitat use and social structure in Linnet Carduelis cannabina and Corn Bunting Miliaria calandra at a winter roost in central Spain

Capsule Both species selected particular patches for roosting, and Linnets but not Corn Buntings showed a social structure with males occupying the preferred roosting positions.

Aims To evaluate microhabitat preferences of Linnet and Corn Bunting within a winter communal roost, and to examine roost structure according to sex, age and body size.

Methods We captured Linnets and Corn Buntings along a habitat gradient in a reed-bed in central Spain when they were coming to roost. Each bird was sexed, aged, and several body traits were measured. We also characterized the habitat patches where the birds were trapped and grouped patches according to their similarity.

Results Three groups of patches were defined according to reed structure. Linnets preferred patches with low density of high and thick shoots, while Corn Buntings preferably used patches with intermediate values for these variables. Interspecific competition for preferred positions was not evident. Male Linnets were proportionately more abundant in the preferred patches, and individuals in lower body condition, independent of sex, age or body size, occupied the non-preferred patches. Male Corn Buntings were less abundant, bigger in size, and showed better condition than females, although differences in body size and condition were not apparent among patches within the roost.

Conclusion Our results suggest that among-patch differences in structure and location within a reed-bed generate microhabitats that differ in quality for roosting passerines. This habitat heterogeneity in turn seems to be responsible for the social spatial structure observed in Linnets, in which females and individuals in poor physiological condition were displaced, possibly through competition, towards non-preferred positions. The relatively small body size of Linnets compared to Corn Buntings might explain Linnets' preference for patches that seem to provide more protection against harsh weather conditions.     

Factors determining the occupation of Marsh Harrier Circus aeruginosus breeding grounds in a Mediterranean environment

Capsule Wetland occupation by breeding Marsh Harriers is influenced by wetland and vegetation area, distance to other wetlands where conspecifics are present and also by the characteristics and conditions of the vegetation such as predominant species and its height at the start of the breeding period.

Aims To determine factors influencing the probability of wetland occupation by Marsh Harrier in relation to wetland dimensions, vegetation and hydric conditions, and to determine the effect of the predominant helophyte species in the wetlands and its physical characteristics.

Methods Three hundred and thirty-two wetlands were monitored during a breeding season in NW Spain, a Mediterranean area that hosts 10% of the total number of breeding pairs of Marsh Harriers in Spain. The probability of wetland occupation for breeding in terms of wetland size and proximity, vegetation characteristics, human disturbance and also hydrological variables, was analysed using logistic regression.

Results One hundred and sixty-five pairs were located in 131 wetlands. Variables affecting occupation include vegetation composition and characteristics, wetland dimensions and distance to other occupied wetlands. Wetlands with the highest probability of being occupied were larger, with greater areas of marsh vegetation, taller vegetation, rush and reed communities as the predominant species and which were closer to another wetland occupied by Marsh Harriers.

Conclusions The dimensions and predominant species of helophyte vegetation, and size and location determine the occupation of wetlands as breeding grounds by Marsh Harrier. Changes in the natural supply of water and nutrients due to the implementation of intensive irrigation farming are likely modifying flora in wetlands and affecting the distribution and population size of Marsh Harriers in this region of Spain.     

震旦鸦雀在镶嵌型芦苇收割生境中的巢址选择

大规模的芦苇收割会对在该生境中繁殖的鸟类产生严重影响。为降低芦苇收割对鸟类繁殖的负面影响,许多地区的湿地管理者逐渐采用了镶嵌型的芦苇收割方式。但是,这种新的芦苇管理方式对鸟类繁殖期生境选择的作用机理尚不清楚。震旦鸦雀是一种主要分布在我国东部、完全依赖芦苇生境而生存的珍稀鸟类,已被IUCN定为全球性近危物种。大规模的芦苇收割导致其适宜生境丧失,被认为是该物种面临的一个主要威胁。选择山东黄河三角洲国家级自然保护区为研究地区,采用AIC信息准则法,从巢址微生境、巢域斑块和全模型3个水平上对可能影响震旦鸦雀巢址选择的生境因子进行了逻辑斯蒂回归分析,并重点探讨芦苇镶嵌收割对其巢址选择的影响以及不同水平的相互效应。结果发现,震旦鸦雀的巢址选择受巢址微生境和巢域斑块尺度双重水平的影响,但巢址微生境因子的影响要大于巢域斑块因子。在巢址微生境水平上,影响震旦鸦雀巢址选择的因素有:1.5—2.5 m旧芦苇的密度、2.5 m以上新芦苇的密度、香蒲密度和巢的可见度;在巢域斑块水平上,影响因素包括芦苇生境类型、旧芦苇斑块面积的比例和植被盖度;在综合模型中,影响因素有1.5—2.5 m旧芦苇的密度、2.5 m以上新芦苇的密度、香蒲密度、巢的可见度和植被盖度。综上,震旦鸦雀倾向于在植被盖度较高、具有一定比例(18.3%)旧芦苇面积、1.5—2.5 m旧芦苇密度较高、可见度较低的生境斑块中筑巢。研究中,78.7%(n=141)的震旦鸦雀将巢筑在新旧芦苇混合的微生境中,其中36.9%的巢址附近旧芦苇的比例在一半以上;53.2%(n=111)的巢筑于新、旧两种芦苇茎秆之上,22.3%的巢的支撑芦苇中旧芦苇所占比例在一半以上。研究结果表明,旧芦苇在震旦鸦雀巢址选择和筑巢过程中发挥了重要作用。由于大范围的芦苇收割在微生境水平上可降低1.5—2.5 m旧芦苇的密度,在巢域斑块尺度上可降低旧芦苇斑块面积的比例,因此建议,在震旦鸦雀的繁殖地,未来的芦苇收割应采用镶嵌收割的形式,并至少应保留面积在20%以上的结构较好的旧芦苇斑块,以供震旦鸦雀选择巢址和繁衍后代。     

Willow Warbler Phylloscopus trochilus habitat in woods with different structure and management in southern England

Capsule Use of Light Detection and Ranging (LiDAR) data identified suitable Willow Warbler habitat based on mean vegetation height. This habitat model provided maps of distribution and occupation of suitable habitat.

Aims To identify habitat associations in woods with different vegetation structure and management systems during a period of low Willow Warbler populations.

Methods Locations of all Willow Warblers were mapped during the breeding season in three woods of contrasting management; recent low intervention, actively coppiced woodland and high forest with clear‐fells. Height profile models of each wood were derived from airborne LiDAR. The mean vegetation height at locations with Willow Warblers and a sample from the rest of the wood were used to produce models of optimum habitat and breadth of habitat occupied in each wood. The habitat model was then used to produce maps of suitable habitat.

Results The habitat models did not differ between woods, with highest probability of Willow Warbler occurrence in mean vegetation heights of 3.7–5.3 m. Habitat of heights 6–11 m appeared less suitable, being only partly occupied. Habitat maps showed that habitat of suitable height was only occupied when it occurred as large patches; smaller patches (mostly <0.5 ha) and edges along rides and fields were not used.

Conclusion The use of LiDAR derived measures of vegetation height identified areas of suitable habitat for Willow Warblers. Willow Warblers occupied areas of low mean vegetation height either as early successional or open canopy woodland in all woods. Height‐based habitat maps can identify areas of suitable habitat within larger expanses of heterogeneous woodland and are a potentially useful tool in assessing changes in extent of what are often temporary patches of habitat.     

Habitat use by three Acrocephalus warblers in an intensively used farmland area: the influence of breeding patch and its surroundings

Habitat use by the sedge warbler Acrocephalus schoenobaenus, reed warbler A. scirpaceus and marsh warbler A. palustris was studied during 1998–2000 in an intensively cultivated agricultural landscape in western Poland. The birds occupied mid-field marsh patches (0.05–9.84 ha) and drainage ditches. Using logistic regression models, habitat preferences for particular patch type, characteristics of breeding patch vegetation and surrounding crop type were investigated. All habitat measurements were done within 50-m radius circles around breeding territory centers. The most important factors that influenced species distributions were the proportions of particular habitats within patch area and the type of surrounding crops. Sedge and reed warblers preferred areas with a high proportion of reeds and meadows. Marsh warblers avoided emergents other than reeds, and favored herbaceous vegetation and bushes. Open water areas positively affected reed warbler distribution. Crop type had a significant influence on within-year territory distribution and changes in between-year occupation pattern. In general, birds preferred to settle near fields of oil seed rape, while root crops and spring cereals were avoided. Breeding patch type and structure of reedbeds had relatively little influence on the distribution of breeding territories. The results obtained show that the surrounding landscape may significantly influence habitat use of species breeding in habitat islands in farmland. Depending on their structure and food resources, crops might have different value to the birds.     

Nest-site selection and predation in Savi's Warblers Locustella luscinioides

Capsule Savi's Warblers preferred sites dominated by high and dense Juncus and Rubus with thick litter, and avoided pure reeds; predation was higher in sites with less litter.

Aim To describe nest-site selection and identify which habitat and nest features influence predation risk.

Methods Comparisons were made between habitat characteristics measured at nest-sites and random points, and between predated and successful nests.

Results Total vegetation cover, litter thickness, habitat type, undergrowth height and undergrowth cover, which were higher or denser at nest-sites, were the most important variables influencing the distribution of Savi's Warbler nests. Nests were most often predated in sites with low litter thickness.

Conclusion Savi's Warblers are dependent on the presence of dense low vegetation and litter for nesting, which should be maintained close to or within reed-beds for their benefit.     

Factors influencing patch occupancy and within‐patch habitat use in an apparently stable population of Willow Tits Poecile montanus kleinschmidti in Britain

Capsule Birds selected younger woodland patches with fewer conifers and higher soil moisture content; within these patches, they selected areas with higher vegetation cover at 2–4 m, and less bracken.

Aims For an apparently stable population, to investigate habitat differences between occupied and unoccupied woodland patches and habitat selection within occupied woodlands.

Methods We surveyed woodland patches for breeding Willow Tits in April 2006 in an area with an apparently stable population. Habitat was measured at points spread throughout each woodland patch and at points where Willow Tits were located. We compared habitat between occupied and unoccupied sites. In addition, within occupied sites, we examined habitat differences between Willow Tit locations and the points spread throughout the wood.

Results We surveyed 65 woodland patches, of which 29 were occupied. Willow Tits were more likely to be found in deciduous woodland that was younger and had higher levels of soil moisture. Probability of occupancy fell from 60% for woods aged 20–25 years to only around 15–30% for woods aged over 80 years. Within occupied woods, Willow Tits were more likely to be found in areas with more vegetation cover at the 2–4 m level and in areas with less bracken.

Conclusions Habitat management for Willow Tits should involve provision of young woodland patches with moist soils. Changes to the age structure and/or the soil moisture content of woods may be implicated in the dramatic decline of Willow Tits in Britain.     

Modelling the nesting-habitat of the Cinereous Vulture Aegypius monachus on a fine scale for conservation purposes

Capsule Nests of Cinereous Vultures were found to be located farther from roads, villages and the edge of large vegetation patches. They preferred large vegetation patches containing extensive Cork Oak cover on steeper slopes and with lower solar radiation. Less than 8% of the study area was predicted to be suitable for nesting.

Aims To generate a predictive habitat suitability map for the Cinereous Vulture's nesting-habitat on a fine scale for conservation applications within its breeding range.

Methods Habitat features of 43 nest-locations and random points were compared in order to identify nest-habitat selected in the region of the Hornachuelos Natural Park (Spain). A logistic regression approach was used to create habitat models.

Results Compared with random points, nests were found to be located farther from roads, villages and patch edges, and in large vegetation patches containing extensive Cork Oak cover on steeper slopes with lower solar radiation. The predictive map revealed that less than 8% of the study area had a greater probability of occupancy than 0.8.

Conclusions Most habitats in the study area are unsuitable for nesting suggesting that conservation of the best suitable areas is important. The fine-scale predictive map approach may be valuable in designating conservation priority areas.     

The effects of reed canary grass (<Emphasis Type="Italic">Phalaris arundinacea</Emphasis> L.) on wetland habitat and arthropod community composition in an urban freshwater wetland

Reed canary grass (Phalaris arundinacea L.) is an aggressive invader that dominates wetlands throughout the US. We examined the effects of reed canary grass on wetland habitat, both vegetation canopy architecture and soil environment, and its impacts the arthropod community in an urban wetland in Portland, OR, USA. Reed canary grass dominance resulted in reduced vegetation canopy complexity through reductions in native vegetation diversity and canopy height. In addition, reed canary grass dominance significantly changed the wetland soil environment, decreasing soil organic content and increasing soil moisture. The arthropod community responded to these habitat changes, being distinct between plots dominated by reed canary grass and those dominated by native vegetation. In addition, diversity measures were significantly lower in plots dominated by reed canary grass. Variables describing both vegetation canopy complexity and soil environment were more important predictors than relative abundance of reed canary grass in multiple regression models developed for dominant arthropod taxa and community metrics. Our results suggest that the mechanism by which reed canary grass affects the wetland arthropod community is primarily indirect, through habitat changes, rather than by directly altering its food source.     

Nest predation in Reed Buntings Emberiza schoeniclus: an experimental study

Predation is a major cause of nest failure in many bird species. High levels of nest loss may be a consequence of habitat fragmentation, leading to increased amounts of edge habitat. Yet the evidence for generally high nest predation rates along edges in fragmented landscapes is ambiguous. Using real nests of Reed Buntings Emberiza schoeniclus in which artificial Reed Bunting and real Japanese Quail Coturnix japonica eggs were placed, we experimentally tested for edge effects on nest predation in highly fragmented reed Phragmites sp. habitats in the Swiss lowlands. We also examined seasonal patterns of predation and the impacts of nest visits by observers. We found evidence for an edge effect at the water-sided reed edge, with nests located closer to the water being more likely to be predated than those further away. Predation probability increased from early to late season, suggesting that nest predation may be density dependent. Probability of nest predation was only weakly influenced by whether or not a nest was visited. Our results suggest that the intensive reed management currently applied in Swiss nature reserves may result in unnaturally high levels of nest losses in the Reed Bunting, because reed bands are not wide enough to allow nest placement at a safe distance from reed edges.     

An inter-regional approach to intraspecific variation in habitat association: Rock Buntings Emberiza cia as a case study

The habitat association approach has been increasingly used in ecology to resolve problems in wildlife conservation and management. One problem related to habitat association studies is that they are restricted to small geographical areas within a species' range, and thus they are applicable to only a limited set of environmental conditions utilized by the species. In addition, very few studies address why the preference for specific habitat components may be adaptive for the species in question. The objective of this study was to examine how consideration of populations of a species from two dramatically different environments affects the results of habitat association modelling for a ground-nesting passerine, the Rock Bunting Emberiza cia . At a regional scale, a trend to defending breeding habitat patches with relatively higher stone cover was confined to birds from a temperate region in Slovakia. In contrast, in a semi-arid region in southeastern Spain, Rock Buntings preferred to use breeding habitat patches that had relatively higher grass cover. Combining data from both regions, breeding Rock Buntings showed a general pattern of using habitat patches close to hedges, with low bush cover, high ditch density and a steep slope. Whereas regional habitat association models appear to be sensitive to the particularities of the breeding environment, our study suggests that Rock Bunting breeding habitat association is constrained by the adults' tactics to protect themselves against predators. Although the birds prefer to nest in patches of low vegetation, the better to see nearby predators, these patches are ideally close to taller vegetation that can be used to provide cover when evading predators, and they are also of a rugged profile that helps the birds to approach and leave the nest stealthily.     

芦苇收割对震旦鸦雀觅食活动的影响

芦苇(Phragmites australis)湿地具有重要的社会经济价值和特殊的自然保育意义,芦苇收割是芦苇湿地管理的主要手段,往往对栖息于芦苇湿地中的动物群落产生影响,尤其对专食芦苇昆虫的鸟类影响较大。2007年1～4月,在长江口崇明岛崇西湿地科学实验站研究基地芦苇收割前后通过样方法研究了芦苇收割对震旦鸦雀(Paradoxornis heudei)觅食的影响。研究表明,芦苇收割显著减少了震旦鸦雀潜在食物资源,改变了震旦鸦雀觅食分布并使震旦鸦雀提前转移到新生芦苇枝上取食,芦苇收割后残留老芦苇枝对震旦鸦雀取食具有重要影响。芦苇收割时保留一定的斑块状和条带状老芦苇有利于震旦鸦雀利用新芦苇枝上潜在食物资源,可以在一定程度上缓解芦苇收割引起的震旦鸦雀食物短缺。     

Patterns of change in reed cover and distribution in a seasonal riverine wetland in South Africa

Phragmites mauritianus is the dominant herbaceous species colonizing riverine habitats in the Kruger National Park, South Africa. These perennial systems are characterized by high annual and seasonal flow variability and a complex mosaic of patches of reeds, sand, water, rock and other vegetation. Patterns of increase and decrease in reed cover in the Letaba River were determined from aerial photographs covering a 54-year period. An initial period of reed expansion (1942–1965) was followed by a period of reed loss (1965–1977) and subsequent gradual re-establishment (1977–1996). A spatially explicit analysis of changes in reed distribution over an 8-year period (1988–1996) showed that patches of reed vegetation are, in the short term, highly dynamic elements within the river landscape. Analyzing short-term, small-scale change provides information which is not obtainable from long-term, large-scale studies. We propose that causes of reed expansion or decline cannot be determined without an understanding of both long- and short-term patterns of change.     

Habitat associations of Wood Warblers Phylloscopus sibilatrix breeding in Welsh oakwoods

Capsule Territory locations, density and the change in numbers over 20 years were associated with characteristics of the canopy, understorey structure and field-layer vegetation cover.

Aims To identify habitat characteristics associated with territory locations and density of Wood Warblers Phylloscopus sibilatrix in Welsh oakwoods in 2009–2011, and the change in abundance between 1982–1984 and 2003–2004.

Methods In 2009–2011, habitat characteristics were compared between 106 territories and 226 unoccupied points in 19 woods. Mean wood-scale habitat values were related to density in 27 woodland blocks. The change in Wood Warbler numbers between 1982–1984 and 2003–2004 was related to initial habitat quality in the 1980s and the change in habitat characteristics between the two time periods.

Results The location of territories in 2009–2011 was positively associated with canopy height, and with intermediate values of slope steepness, field-layer vegetation cover, canopy cover, the proportion of Oak Quercus in the tree community and subcanopy cover. Density was positively associated with slope, subcanopy cover at 0.5–2 m height and a landscape dominated by coniferous plantation and moorland; and with intermediate values of the proportion of oaks in the tree community. Wood Warblers declined by 24.4% in the two Welsh regions between 1982–1984 and 2003–2004, and trends were positively associated with the initial cover of Bramble and, in Gwynedd only, canopy cover.

Conclusions Wood Warblers were associated with a number of structural habitat variables, which could be related to the past management of the study woods. Management should be targeted at restoring habitat quality for Wood Warblers through the introduction of a moderate grazing regime.     

Effect of cereal harvesting method on a recent population decline of Corn Buntings Emberiza calandra on the Western Isles of Scotland

Capsule Population decline since 1995 is associated with the harvesting of cereals as arable silage.

Aim To survey Corn Bunting populations on the Western Isles and test whether population changes since 1995 are associated with change in cereal harvesting methods.

Methods Twelve areas of machair on the Uists and Benbecula were re-surveyed in 2002, after previous surveys in 1983 and 1995. These and other areas of suitable habitat on these islands, plus Berneray, Baleshare, Vallay, Barra and Vatersay, were surveyed in 2003–05 to provide a breeding population estimate for the Western Isles. Cereal strips in the 12 core survey areas were mapped in 2002 and the timing and method of harvesting of each was recorded. Cattle-feeding stands in 24 crofting townships were visited in March 2003 to record the type of fodder available, measure grain abundance and ripeness in fodder samples, and record foraging Corn Buntings. Experimental trials tested whether Corn Buntings selected fodder with riper grain.

Results The Western Isles Corn Bunting population was estimated at 117 occupied territories in 2005, a decline of 17% since 2002/03, and of at least 62% since 1995. Population decline was greater in areas with higher proportions of the cereal area harvested as arable silage. Arable silage contained fewer and less-ripe grains than traditionally harvested cereal, and was less likely to attract feeding Corn Buntings. Corn Buntings preferred to feed on silage containing riper grain.

Conclusions The remaining Corn Bunting population of the Western Isles is declining rapidly, probably because of reduction in winter grain supply caused by change from traditional reaper-binder harvesting and stacking of fully ripe cereals to harvesting the crop as unripe or partially ripe arable silage. Management change to restore a supply of ripe grain over winter is likely to be essential if this population decline is to be halted and reversed.     

Effects of variation in breeding habitat on Ring Ouzel Turdus torquatus productivity and chick condition

Capsule Territory habitat influenced clutch size and within-brood variability of chick condition in Ring Ouzel Turdus torquatus.

Aims To assess the relationship of Ring Ouzel productivity and chick condition with territory habitat, in order to improve understanding of the importance of breeding habitat for population change.

Methods Productivity and chick condition were recorded for Ring Ouzel pairs in a small area of upland Scotland and these were related to vegetation and physical characteristics for all breeding territories using General Linear Models.

Results We found that clutch size and variability of chick condition varied with Ring Ouzel breeding habitat.

Clutch size was related to variation in territory habitat, broadly increasing with territory grass, sedge and rush cover. The best-supported models for within-brood variability of chick condition included fledgling number and territory habitat, with chick condition broadly becoming more variable with territory bracken cover. Relationships between breeding habitat and brood size, fledgling number or mean chick condition were not supported by the data, although statistical power was low.

Conclusion Breeding habitat may be a driver of demographic rates of Ring Ouzel, with the effects of poor habitat being passed on indirectly through chick condition. The population-level importance of these effects is unclear, but this study highlights a possible link between recent observed habitat changes and first-year survival, the demographic parameter contributing most to variation in population growth rate in UK Ring Ouzels.     

上海崇明东滩震旦鸦雀冬季种群栖息地的生境选择

2008年11月-2009年3月,在崇明东滩对震旦鸦雀(Paradoxornis heudei)种群生态进行调查研究,并对震旦鸦雀种群和生境因子的相关性进行分析。运用单因素方差对互花米草(Spartina alterniflora)入侵和芦苇(Phragmites australis)收割造成的芦苇滩涂变化进行分析,并运用多元回归的方法对震旦鸦雀种群的密度和分布以及相关环境因子进行生境选择分析。结果表明,崇明东滩震旦鸦雀种群的密度为(5.08±3.11)只/hm2;震旦鸦雀种群的密度和芦苇直径呈极显著正相关,震旦鸦雀种群的分布和芦苇的高度、密度呈极显著正相关,和食物资源量呈显著正相关;互花米草和震旦鸦雀种群的密度和分布呈显著负相关;互花米草入侵和芦苇收割降低了震旦鸦雀越冬期的栖息地质量,保留一部分生长质量较好的芦苇可以缓解震旦鸦雀冬季种群的生存压力。     

The breeding ecology of Reed Buntings Emberiza schoeniclus in farmland and wetland habitats in lowland England

We studied the nesting and feeding ecology of Reed Buntings Emberiza schoeniclus breeding on farmland and wetland habitats along the Trent Valley in Nottinghamshire, England. Rank and emergent vegetation accounted for most nests and most foraging by provisioning adults. Caterpillars and spiders accounted for 70% of chick invertebrate prey and all broods were fed cereal grain or other vegetable matter. Variation in the abundance of key invertebrate prey across habitats accounted for the foraging preferences of adult buntings. Depredation was the main cause of nest failure, and survival of nests at the egg stage was positively related to the extent of nest concealment. A measure of total brood biomass was positively related to the abundance of key invertebrate prey within 100 m of nests. Rank and emergent vegetation provided Reed Buntings with greater nest concealment and a richer source of invertebrate prey than agricultural habitats such as set-aside, cereals and oilseed rape. The provision of rank and emergent vegetation on farmland is likely to increase the nesting opportunities and productivity of Reed Buntings in agricultural landscapes.     

Nesting habitat and nest features of Water Rails Rallus aquaticus and Little Crakes Zapornia parva on large wetlands

ABSTRACT

Capsule: In large and medium wetlands with extended reed beds Phragmites and cattail Typha dominated areas, Water Rails Rallus aquaticus and Little Crakes Zapornia parva show higher differences in nesting sites in contrast with other populations from small and fragmented wetlands, where the ranges of values for environmental variables at nesting sites overlap greatly.

Aims: To investigate the nesting sites and nesting habitats of both species to a fine scale, on medium and large wetlands, to evaluate the potential overlapping of nesting habitat and to compare data with those obtained in small wetlands.

Methods: In the study area, the Fize? Basin, Romania, 17 wetlands, ponds and reed beds ranging from 11.78 to 252.68 ha were investigated. The species were present on 4 wetlands, which were subsequently surveyed for nests. Between April and August 2010–2012, a total of 83 Water Rail and 46 Little Crake nests were found, measured and analysed in terms of nesting habitat and nest features.

Results: Principal component analyses suggest no overlap in nest site selection and a partial overlap in the nest features. An analysis of similarity confirmed significant nest structural differences. A discriminant function analysis highlights the main factors dividing the nest features of both species being: water depth and distance between the nest and a water surface. Little Crakes build their nests in cattail Typha sloped clumps, while Water Rails build their nests near reed Phragmites strains.

Conclusion: In large and medium wetlands, Water Rails nest deep in the reed bed rather than in other types of habitats, contrary to what has been reported for small ponds areas. Little Crakes nest in cattail independently of the size of the wetland where they occur.     

Song in two cryptic species: comparative analysis of Large-billed Reed Warblers Acrocephalus orinus and Blyth’s Reed Warblers Acrocephalus dumetorum

Capsule: Songs of Large-billed Reed Warblers Acrocephalus orinus and Blyth’s Reed Warblers Acrocephalus dumetorum differed in quantitative parameters. Blyth’s Reed Warbler used different modes of singing on breeding grounds and migration stopovers.

Aims: To compare the songs of two cryptic species of reed warblers. To compare Blyth’s Reed Warbler songs in different parts of the breeding range and on migration stopovers in central Asia. To investigate the status of Blyth’s Reed Warblers in central Asia.

Methods: We analysed song recordings of individual singing males and conducted field observations of singing behaviour at migration stopover and breeding sites. The status of Blyth’s Reed Warblers in central Asia was reviewed from the historical Russian literature and other sources.

Results: We found differences between six out of eight variables in songs of Large-billed and Blyth’s Reed Warblers on breeding sites. Blyth’s Reed Warbler songs recorded on migration stopovers showed differences in five variables from Large-billed Reed Warblers and in six variables from breeding Blyth’s Reed Warblers. On migration stopovers, Blyth’s Reed Warblers sang actively but did not stay more than 1–2 days. The evidence suggests that Blyth’s Reed Warbler does not breed in central Asia.

Conclusion: Songs of Large-billed and Blyth’s Reed Warblers could be distinguished by quantitative analysis. Blyth’s Reed Warblers used different modes of singing on breeding sites and migration stopovers. We believe vocalizations of Blyth’s Reed Warblers on migration to be plastic song.