Co-occurrence patterns of cavity-nesting birds in cottonwood-willow communities

Summary We studied the covariation of six species of cavity-nesting birds to determine the extent to which species' co-occurrence patterns were attributable to interspecific relations. We tested two null hypotheses: (1) inverse relations did not exist among potential competitors for nest trees or nest cavities, and (2) there were no positive relations among potential commensals for nest cavities. Statistical power analyses, and simple, partial, and multiple partial correlation and regression analyses provided little evidence of species-species or higher-order inverse or positive relations. Most of the variation in co-occurrence patterns was associated with stand characteristics. Collectively, an abundance of nest trees and nest cavities, differences among species in acceptable nest-tree and nest-cavity dimensions, and different periods of peak nesting activity appear to be responsible for the lack of negative relations among potential competitors. Positive relations among potential commensals were weak presumably because (1) secondary cavity nesters (SCNs) frequently used cavities that originated from wind-, lightning-, and/or disease-damaged limbs and were thus not dependent completely on primary cavity nesters for cavities, and (2) the lag time for cavity use by SCNs is often two or more seasons. Interspecific relations were apparently not major determinants of community structure during our investigation; assemblages of cavity nesters appeared instead to be influenced more by independent species-specific habitat responses.     

Climate change affects populations of northern birds in boreal protected areas

Human land-use effects on species populations are minimized in protected areas and population changes can thus be more directly linked with changes in climate. In this study, bird population changes in 96 protected areas in Finland were compared using quantitative bird census data, between two time slices, 1981-1999 and 2000-2009, with the mean time span being 14 years. Bird species were categorized by distribution pattern and migratory strategy. Our results showed that northern bird species had declined by 21 per cent and southern species increased by 29 per cent in boreal protected areas during the study period, alongside a clear rise (0.7-0.8 °C) in mean temperatures. Distribution pattern was the main factor, with migratory strategy interacting in explaining population changes in boreal birds. Migration strategy interacted with distribution pattern so that, among northern birds, densities of both migratory and resident species declined, whereas among southern birds they both increased. The observed decline of northern species and increase in southern species are in line with the predictions of range shifts of these species groups under a warming climate, and suggest that the population dynamics of birds are already changing in natural boreal habitats in association with changing climate.     

The distribution and biology of nomadic birds in the Karoo, South Africa

Dryland nomadic bird species, as a proportion of all bird species in a biome in southern Africa, are highest in the arid grassland and arid and semi-arid Karoo in South Africa. Nomadic birds, of which the most widespread species is the greybacked finchlark Eremopterix verticalis (Smith), are most frequently observed in the north-central and north western Nama Karoo. The species richness of nomadic species is inversely correlated with species richness of all bird species in the Karoo. Since the distribution of nomadic birds is in areas where rainfall is patchy, low (<250 mm per year) and aseasonal, this supports the idea that fewer species are able to cope with resources that are patchy in time and space, and that there has been selection for nomadism in the species that are able to use patchy environments. Species richness and abundance of nomadic birds is negatively correlated with rainfall amount but positively correlated with the coefficient of variation of the rainfall and with rainfall in autumn. The frequency of nomadic birds is inversely correlated with altitude range; nomadic species are most often recorded in structurally simple habitats (shrubland and grassland) on open plains. Most nomadic bird species in the Karoo are granivorous. Perennial desert grasses are important components of the habitat and diet of small nomadic granivores, and also provide nest sites and nest material. Nomadic birds can breed throughout the year, without a clearly defined ‘season’ in both the Succulent and Nama Karoo. Average clutch sizes do not differ significantly between resident and all nomadic species in the arid and semi-arid Karoo. Nomadism is an evolutionary stable strategy for individual species only when extremes in environmental conditions are frequent enough, and unpredictable enough, to maintain movements to high resource patches or to maintain dispersal away from low resource patches. If high rainfall years are too regular or infrequent, or peaks in fluctuations of resources in the environment too low, or rainfall patches are randomly distributed, nomadism would not be maintained as part of the individual behaviour pattern.     

广西西大明山冠斑犀鸟的繁殖生物学

作者于2014和2015年在广西西南部的西大明山自治区级自然保护区研究冠斑犀鸟(Anthracoceros albirostris)的繁殖生物学特征,以直接观察法或红外相机共观察5巢犀鸟,2014年2巢,2015年3巢。研究显示,西大明山的冠斑犀鸟在每年4月下旬至5月下旬开始营巢繁殖,雌鸟进入巢洞并在雄鸟协助下自封在其内,期间与幼鸟完全依靠雄鸟喂食。雄鸟带回巢的食物中,数量上有超过80%是果实。雌鸟在封巢期间完成换羽,并和幼鸟在7月中旬至8月中旬破巢而出,封巢时间为89 d和93 d(n=2),繁殖成功率为100%(n=4),平均出巢幼鸟为(2.3±0.5)只(2或3只,n=4)。营巢树与人工林/林下作物的平均距离为87 m(0～210 m,n=3),其中,两棵生长在当地人经常使用的山路旁。营巢树种分别为南酸枣(Choerospondias axillaris)及金叶树(Chrysophyllum lanceolatum),营巢树平均胸径为73.7 cm(72.0～75.0 cm,n=3),巢洞高度为7.8 m和9.0 m(n=2)。其中两棵营巢树在2014年和2015年的繁殖季均被重...     

New records of cestodes of New Zealand birds

Abstract

Ten species of cestodes are reported from aquatic birds in New Zealand. All are new records for the country.     

Breeding birds from reedbeds to alpine meadows

The main processes that determine the behaviour ofheavy metals in the Scheldt estuary are tidalhydrodynamics, sediment transport, and sorption ofheavy metals on suspended matter. The water qualitymodel WASP is applied to simulate the spatialdistribution of five heavy metals in the estuary,under average hydrodynamic and suspended sedimenttransport regimes. First, the hydrodynamical part ofthe model is constructed and the results are verifiedby comparison with measured water levels and flowvelocities. Secondly, a salt transport model is set upin order to evaluate the hydrodynamical dispersivemixing characteristics. Thirdly, a suspended sedimenttransport model is constructed and finally a transportmodel for heavy metals. The simulated distributions of the sorbedamounts of heavy metals, suspended sediment andsalinity in the estuary agree well with observations.The calculated profiles of dissolved and sorbedconcentrations of heavy metals in the water columnindicate an accumulation of heavy metals in the zoneof the turbidity maximum, while closer to the sea theconcentrations diminish due to mixing of the pollutedfluvial sediments with unpolluted marine sediments andbecause of sediment deposition in the estuary. It canbe concluded that only a small part of the heavymetals reaches the sea. This revised version was published online in July 2006 with corrections to the Cover Date.     

Nest predation and the species diversity of birds

In a recent series of papers, Thomas E. Martin has suggested that selective, density-dependent predation on nests may promote ecological diversification of birds and constrain the number of coexisting species in a community. In an experimental study, Martin has demonstrated density-dependent predation on artificial nests constructed and placed so as to mimic natural ones. Comparisons between habitats indicate that availability of suitable nest sites may influence community diversity more strongly than does diversity of foraging niches. Although his case is circumstantial at this point, Martin argues compellingly for considering predation more seriously in studies of community ecology. Indeed, many patterns attributed to competition for food resources may arise, instead, from the partitioning of predator-escape space.     

Mesozoic birds of China-a synoptic review

A synoptic review of the discoveries and studies of Chinese Mesozoic birds is provided in this paper.40Ar/39Ar dating of several bird-bearing deposits in the Jehol Group has established a geochronological framework for the study of the early avian radiation.Chinese Mesozoic birds had lasted for at least 11 Ma during about 131 Ma and 120 Ma (Barremian to Aptian)of the middle and late Early Cretaceous,respectively.In order to further evaluate the change of the avian diversity in the Jehol Biota,six new orders and families are erected based on known genera and species,which brings the total number of orders of Chinese Mesozoic birds to 15 and highlights a remarkable radiation ever since the first appearante of birds in the Late Jurassic.Chinese Early Cretaceous birds had experienced a significant differentiation in morphology,flight,diet and habitat.Further examination of the foot of Jeholornis suggests this bird might not have possessed a fully reversed hallux.However,the attachment of metatarsal Ⅰ to the medial side of metatarsal Ⅱ does not preclude trunk climbing,a pre-adaptation for well developed perching life of early birds.Arboreality had proved to be a key adaptation in the origin and early evolution of bird flight,and the adaptation to lakeshore environment had played an equally important role in the origin of omithurine birds and their near-modern flight skill.Many Chinese Early Cretaceous birds had preserved the direct evidence of their diet,showing that the most primitive birds were probably mainly insectivorous and that specialized herbivorous or carnivorous (e.g.,piscivorous)dietary adaptation had appeared only in later advanced forms.The only known Early Cretaceous bird embryo fossil has shown that precocial birds had occurred prior to altricial birds in avian history,and the size of the embryo and other analysis indicate it probably had a short incubation period.Leg feathers probably have a wide range of distribution in early birds,further suggesting that leg feathers had played a key role in the beginning stage of the flight of birds.Finally,the Early Cretaceous avian radiation can be better understood against the background of their unique ecosystem.The advantage of birds in the competitions with other vertebrate groups such as pterosaurs had probably not only resulted in the rapid differentiation and radiation of birds but also the worldwide spreading of pterosaurs and other vertebrates from East Asia in the Early Cretaceous.     

利用天然树洞繁殖的五种鸟的巢位特征及繁殖成功率

对吉林省左家自然保护区次生阔叶林中的大山雀 ( Parusmajor)、沼泽山雀 ( Paruspalustris)、普通跓( Sitta europacea)、白眉姬? ( Ficedula zanthopygia)和灰椋鸟 ( Sturnus cineraceus) 5种利用天然树洞繁殖的次级洞巢鸟进行了巢位选择和繁殖成功率研究。本研究中共发现 1 41巢。五种鸟对树洞类型的选择存在种间差异 ,普通跓不利用裂洞 ,沼泽山雀不利用啄洞 ,其它 3种鸟对 3种洞均有利用 ,但有一定的倾向性。对 5种鸟 9个巢位变量的比较中 ,只有洞口方向差异不显著 ( p >0 .0 5 ) ,其它 8个变量均差异显著 ( p<0 .0 5 ) ,该结果说明 5种次级洞巢鸟对巢位的选择具有其各自的需求。洞口横径、洞口纵径、洞处树直径、洞内径、巢距地高是巢位选择重要变量 ,它们决定不同种类对树洞的利用。巢损失多数出现在产卵之前和孵化阶段 ,44个繁殖失败的巢中有 35个在这两个阶段损失。大山雀的巢成功率最低 ,灰椋鸟的巢成功率最高。 5种鸟的孵化率都超过 90 %。人为破坏和动物捕食是繁殖失败的主要原因 ,占总数的 61 .4%。洞巢鸟巢位选择中的重要变量影响繁殖成功。普通跓繁殖是否成功受洞口横径和巢高影响 ,沼泽山雀受洞口纵径、树胸径和洞内径影响 ,大山雀受洞口横径、巢高和洞内径影响 ,灰椋鸟受洞内径和洞深影     

A habitat island approach to conserving birds in urban landscapes: case studies from southern and northern Europe

Wildlife conservation in urban habitats is increasingly important due to current urbanization trends. We review the different approaches to studying birds in urban landscapes, and point out the importance of the habitat island ecological theory as a research framework for the management and conservation of urban birds. Based on two comprehensive research projects conducted at urban parks in Spain (Madrid) and Finland (Oulu and Rovaniemi), several different issues related to bird conservation in cities are discussed, main findings of these projects are presented, and future research needs are suggested. Urban parks are important biodiversity hotspots in cities. Fragmentation conditions have the same deleterious effects to urban birds as in other fragmented landscapes. Park size accounts for species accumulation in urban parks; this pattern being highly nested. Urban parks of 10–35 ha would contain most of the species recorded in cities, but other indicators related to the probabilities of persistence of the target species should be obtained. Wooded streets can increase urban landscape connectivity by providing alternative habitat for feeding and nesting during the breeding season. Because increasing the size of parks is difficult in cities, enhancement of habitat diversity and resource availability for birds within parks (e.g. nest boxes, winter feeding tables, etc.) appears to be a straightforward way of increasing urban bird diversity. However, human disturbance (pedestrians) should be controlled since it can negatively influence many urban birds. We present a conceptual model for urban bird conservation, which includes three aspects (management, environmental education and research) and new alternatives to promote the involvement of different sectors of the society.     

The importance of Prespa National Park for breeding and wintering birds

The breeding avifauna of Prespa National Park is ofnational and international importance both due to itshigh richness and the internationally importantpopulations of rare species. The latter include theDalmatian (Pelecanus crispus) and Great White(Pelecanus onocrotalus) pelicans and the PygmyCormorant (Phalacrocorax pygmaeus). Populationsof national interest include Cormorant (Phalacrocorax carbo), Greylag Goose (Anseranser), Goosander (Mergus merganser), GreatWhite Egret (Egretta alba) and six otherspecies of ardeids. Among the 261 bird speciesobserved in the area of ca 250 km² since thelate 60s, 164 breed and 41 are very rarely observed.Passage migrants and winter visitors include 91species. Twelve breeding species became extinct in theNational Park during the last 25 years and others areendangered. Raptors and aquatic birds suffered moredue to habitat and land use alterations brought aboutby the construction of an irrigation scheme.Eighty-one species observed in the area are listed asin need of special protection in Annex I of the 79/409EEC Directive and 32 of them breed. Lake Mikri Prespais of virtually no importance for wintering waterfowlsince it is frozen every winter, but the Greek part ofLake Megali Prespa, which never freezes, concentratesamong other species the 20% and 35% respectively ofthe Great Crested Grebes and Tufted Ducks wintering inGreece.     

河南大学校园鸟类初步调查

截至2010年12月,为期2年的河南大学校园鸟类调查共记录到鸟类44种,隶属11目、25科;其中雀形目鸟类28种,留鸟20种,夏候鸟18种,冬候鸟和旅鸟各3种,分别占总数的63.6%、45.5%、40.9%、6.8%和6.8%;区系分析表明东洋种9种,古北种16种,广布种19种,分别占总数的20.5%、36.4%和43.2%。整体表现出南北混杂,古北种鸟类较东洋种比例大,广布种鸟类较多的特点。在调查基础上,提出了一些校园鸟类保护的建议。     

The relative timing of the origin of flight and endothermy: evidence from the comparative biology of birds and mammals.

Evidence from the comparative biology of living birds and mammals is used to address the question ‘which came first, flight or endothermy?’. Birds and mammals have evolved different solutions to the problems of high energy flow demanded by endothermy. The heavy apparatus needed for processing food to allow the rapid assimilation of energy is housed in the head of mammals, but low down in the bird's body. The primitive inefficient tidal-flow system of ventilation is simply enlarged in mammals, but is replaced in birds by a lighter uni-flow system through air sacs and parabronchi. Birds avoid the weight problems associated with the mammalian systems of viviparity and lactation by nourishing their young with large quantities of yolk within the egg and an unprocessed diet after hatching. The apparent adaptedness for flight of the avian systems suggests that in the animals ancestral to birds the adaptations for high energy flow were constrained from the start by the need for aerodynamic stability, i.e. flight was initiated before endothermy. The implications of this conclusion for the origin of flight and feathers are discussed.     

Population biology of the crustose red alga Lithophyllum incrustans Phil. Three populations on the east coast of Britain

The distribution of the crustose red alga Lithophyllum incrustans in the British Isles is described. Three populations are analysed demographically, two having age class distributions corresponding to a type III survivorship curve characteristic of populations in which the greatest mortality occurs in the youngest age classes. The more southern of these two populations has a longer generation time (14.2 years) than the more northern (8.5 years). The third and most southern population has an age class distribution dominated by the 6- and 7-year-old categories. There were few sexual thalli (around 3^o,) but they appeared to put more effort into reproduction than the asexual thalli.     

Comparisons of urban and rural bioclimatological conditions in the case of a Central-European city

This paper examines the influence of a medium-sized city (Szeged, Hungary) on the bioclimatological conditions of human beings. With the help of suitable indices for the available data set, differences in the annual and diurnal variation of human bioclimatic characteristics between an urban and rural environment are evaluated over a 3-year period. These indices are the thermohygrometric index (THI, defined by air temperature and relative humidity), the relative strain index (RSI, defined by air temperature and vapour pressure) and the number of ”beergarden days” (defined by air temperature at 2100 hours). In urban and rural areas, ”hot” THI conditions characterize 6% and 1% of the year, ”comfortable” conditions 30% and 20%, ”cool” conditions 10% and 12%, and ”cold” conditions 54% and 66% respectively. Over longer periods (e.g. one, month) RSI remains below the threshold value for strong heat stress in the city. The monthly frequencies of beergarden days show that these days appears from May until October and the city has almost twice as many pleasant evenings as the rural areas. Consequently, the city favourably modifies the main climatological elements within the general climate of its region; periods likely to be comfortable are therefore found more frequently in the city than in rural areas. Received: 24 November 1998 / Revised: 14 June 1999 / Accepted: 4 August 1999     

Species richness and endemism of birds in Bioko

The status of 50 taxonomically unique bird taxa found in Bioko is described. A complete updated species list for birds in Bioko is also given. Notes on habitat occupied and altitudinal distribution of each species as well as information on their general abundance is also included. Species distributions may have been affected by habitat modifications brought about by humans but most taxonomically unique forms are found in the montane areas. Comparisons are made with the neighbouring Mount Cameroon area.