Water bird communities in the Lower Zeeschelde: long-term changes near an expanding harbour

The Schelde estuary is an important wintering area and stop-over place for waders and waterfowl using the East Atlantic fly-way. The port of Antwerp is situated in the Lower Zeeschelde, the transition area between the brackish- and freshwater tidal part. Three intertidal areas in this zone (Groot Buitenschoor, Galgenschoor and Schor Ouden Doel) are protected under several international and national legislations. In this study long-term datasets (1982–1998) on water birds in these intertidal areas were analysed and attempts were made to assess the impact of two container terminals, constructed during the covered period. Overall abundance of water birds in the study area did not show any significant trends. Looking at individual areas, maxima and winter means on the Galgenschoor and Groot Buitenschoor were very variable but the peak seasons levelled out with time. On the Schor Ouden Doel, where hunting was banned, maximal numbers increased by a factor of four between 1985 and 1990, mainly due to an increase in Greylag Goose numbers. The trophic composition of the bird populations showed major shifts. Initially, species compositions in winter differed considerably between the three areas, but they became more similar during the study period. The results suggest that the area became more important as wintering and resting place for herbivores such as Greylag Goose and Wigeon while its function as feeding ground and stop-over site for migrating benthivorous birds became relatively less important, especially on the right bank. The water bird populations in the study area varied greatly with the geographic and regional trends for the different species and were influenced by winter severity but no direct proof of impacts from the container terminals could be established. Nearly every season the international 1 level was exceeded by one or more species, but the species of international importance changed with time. National and international protection measures are valuable but insufficient tools for the conservation of these estuarine habitats. A more comprehensive conservation strategy is proposed.     

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.     

Actual numbers and effects of recreational disturbance on the distribution and behaviour of Greylag Geese (Anser Anser) in the Neusiedler See – Seewinkel National Park Area

The Neusiedler See – Seewinkel National Park area is confronted with a remarkable increase in tourism and recreational activities during the last years. The “Koppel” area, situated on the eastern shore of the lake, is one of the most important breeding sites for Greylag Geese. Behaviour and distribution of the geese on the breeding site as well as touristic activities on the adjacent road leading along the Koppel were examined to investigate relations and interactions between the Greylag Goose population and tourism. Taking into account the excellent weather and breeding conditions in the year 2000 the results of the survey indicate a stable or even rising Greylag population, increasing numbers of visitors and high disturbance frequencies in the vicinity of the study area. The number of disturbances on the adjacent road seems to affect the suitability of the site in general, leading to a specific temporal and spatial distribution of the birds, whereas different disturbance qualities result in changes of the birds behaviour.     

Variation of the waterbird community relying to the Ichkeul National Park,Tunisia

For the period of 2001–2004, the detailed reaction of a waterbird community to dam building has been assessed in the Ichkeul National Park. Results showed that 71 species belonging to 8 orders were detected. Three herbivorous species were largely dominant: common coot (Fulica atra), common pochard (Aythya ferina), and Eurasian wigeon (Anas penelope). The three community parameters used in the analysis were: species richness, species abundance, and species diversity; which were significantly different between seasons. The wintering season was a key phase when the maximum values of these parameters were reached. This seasonal concentration of activity may be explained by migration. The upstream freshwater diversion was followed by a decrease in the annual abundance of the waterbird community due to the increasing salinity and the severe depletion of the swamp grass, Potamogeton (Potamogeton pectinatus). The total number of species was independent of the local conditions, and the annual variation was related to the number of uncommon species seen in each year.     

Geese and Red-knobbed Coot on the Kafue Flats in Zambia, 1970–1974

The occurrence, chronology of breeding and wing-moult, and feeding habits of the Pigmy Goose Nettapus auritus, Knob-billed Goose Sarkidiornis melanotos, Spur-winged Goose Plectropterus gambensis, Egyptian Goose Alopochen aegyptiaca and Red-knobbed Coot Fulica cristata on the Kafue Flats in Zambia are described based on observations made between October 1970 and January 1974 at Lochinvar National Park and, from the air, over the central section of the Flats. The Pigmy Goose, Knob-billed Goose, Egyptian Goose and Red-knobbed Coot fed largely by grazing. They were most abundant between March and June, occurring in greatest numbers at Lochinvar. Egyptian Geese occasionally nested on the flood-plain at Lochinvar between August and January, but there was no proof of the other species nesting there. Many Pigmy Geese and male Knob-billed Geese moulted on the lagoon at Lochinvar between March and June; small numbers of Egyptian Geese and Red-knobbed Coot also moulted in the Park, the former between February and May, the latter in June and July. The Spur-winged Goose fed mostly by grazing and grubbing. Numbers on the Flats were greatest between June and November when 60,000–90,000 moved downriver as the floods subsided. Many bred between January and March in the fringing zone and moulted on the floodplain between May and July. A hydroelectric scheme, completed in 1975, may benefit the Pigmy Goose and Red-knobbed Coot but harm the Spur-winged Goose.     

Long-term changes in numbers of geese stopping over and wintering in south-western Poland

South-western Poland belongs to the key staging areas for geese in Europe, supporting some 100000 birds in recent years. We compared goose counts conducted in the 1970s, 1990s and during 2009–2011 in this region, and linked the findings to the recent assessments of trends in the flyway-populations. Numbers increased several dozen times between the first two counts and have stabilized to the present. More than 14% of the flyway Tundra Bean Goose (Anser fabalis rossicus) stopped over in SW Poland on passage. Smaller numbers of White-fronted Goose (A. albifrons), Greylag Goose (A. anser), and four other rarer species, have all increased since the 1970s. The likely factors responsible for these changes are mild weather conditions, increased availability of large water bodies and shifts in winter ranges of particular species. Temporal mismatch between SW Poland and the total flyways in Bean and White-fronted Geese was recorded when we compared the long-term and the short-term population trends. Increasing reports of other species in SW Poland match the general tendencies in Europe. These data document that regional trends are not a simple reflection of those in flyways as a whole. To understand changes in goose populations a re-established international count network is desired.     

Observations on the Breeding Kittiwake

The drought conditions prevailing in the Marismas of the Guadalquivir (SW Spain) during the winter 1982–83 caused a large proportion of the wintering Greylag Goose population to use the same flooded areas throughout the winter at very high densities. Results indicate that Greylags prefer small Scirpus rhizomes to large ones, the geese taking an increasing amount of larger rhizomes as smaller rhizomes are depleted. A combination of factors (abundance, extraction and handling times, nutritive quality) could make smaller rhizomes more profitable food for Greylags than larger rhizomes. The large concentrations of birds in some areas probably determined the depletion of preferred resources and this could have led some geese to steal food from conspecifics; some aspects of this behaviour are discussed.     

Central European Greylag Geese Anser anser show a shortening of migration distance and earlier spring arrival over 60 years

Global climate change can cause pronounced changes in species? migratory behaviour. Numerous recent studies have demonstrated climate‐driven changes in migration distance and spring arrival date in waterbirds, but detailed studies based on long‐term records of individual recapture or re‐sighting events are scarce. Using re‐sighting data from 430 marked individuals spanning a 60‐year period (winters 1956/1957 to 2015/2016), we assessed patterns in migration distance and spring arrival date, wintering‐site fidelity and survival in the increasing central European breeding population of Greylag Geese Anser anser. We demonstrate a long‐term decrease in migration distance, changes in the wintering range caused by winter partial short‐stopping, and the earlier arrival of geese on their breeding grounds. Greylag Geese marked on central Europe moulting grounds have not been recorded wintering in Spain since 1986 or in Tunisia and Algeria since 2004. The migration distance and spring arrival of geese indicated an effect of temperature at the breeding site and values of the NAO index. Greylag Geese migrate shorter distances and arrive earlier in milder winters. We suggest that shifts in the migratory behaviour of Central European Greylag Geese are individual temperature‐dependent decisions to take advantage of wintering grounds becoming more favourable closer to their breeding grounds, allowing birds to acquire breeding territories earlier.     

Breeding habitat preferences of the turtledove (<Emphasis Type="Italic">Streptopelia turtur</Emphasis>) in the Dadia-Soufli National Park and its implications for management

Forested areas provide important breeding habitats for the turtledove (Streptopelia turtur) in Dadia-Lefkimi-Soufli National Park, Northeastern Greece. We censused the birds in two forested habitat types using the point-count technique at 60 sites during the breeding season (from mid-April to mid-June) in 2001 and 2002. We sampled vegetation structure at the same sites by measuring horizontal (tree species and density in different size classes) and vertical (percentage canopy closure in dominant, intermediate, suppressed and shrub layer) characteristics within 0.04 ha circular plots centred on the established points. Univariate and multivariate statistical techniques were employed to examine the response of the turtledove′s presence to habitat differences between used and unused sites. The results of this study indicate that habitat structure influence the presence of the turtledove during the breeding season. Middle-aged forest stands particularly those dominated by pine trees with low percentage cover in understory are likely to be beneficial to breeding the turtledove population. A combination of multipurpose forestry operations allowing development of managed woodland in mosaics with other habitat types could provide high-quality habitats for a wide range of wildlife species including game and non-game species in the area. Silvicultural methods of maintaining appropriate breeding habitat for turtledove in Dadia-Lefkimi-Soufli National Park (DLS NP), which are in conflict with commercial forestry, are discussed.     

Brent Geese Branta bernicla and Zostera; factors affecting the exploitation of a seasonally declining food resource

Brent Geese Branta bernicla wintering at Lindisfarne, northeastern England, fed almost exclusively on intertidal habitats. Their main food supply was two species of Eelgrass Zostera noltii and Zostera angustifolia. Although abundant when the birds arrived in September, this Zostera was rapidly depleted during the period October-December. Brent Goose food intake rate declined with the decreasing food supply, and the birds responded by extending the time that they spent feeding. When it was no longer possible to extend the time spent feeding (i.e. they were feeding for all of the time that the food supply was available to them), they moved away from the site. The geese fed extensively at night in order to achieve their daily feeding requirements, especially later in the season. Conversion of daily food intake to energetic intake suggested that there may have been an energetic trigger acting: the geese left the site when they were unable to satisfy their basic energy demand. No evidence was found for direct interference competition between Brent Geese and the other grazer in the system, Wigeon Anas penelope: the two species showed no spatial segregation in their feeding areas at the scale investigated nor any temporal avoidance of each other.     

Reactions of the herb and moss layer,tree saplings and the shrub layer to tree deaths in forests of the Wielkopolska National Park (Western Poland)

This study examines the impact of canopy and canopy gaps on the development of lower forest layers in five protected phytocoenoses of oak-hornbeam habitats (natural and regeneration stands) and oak-pine habitats in the Wielkopolska National Park (WPN). In the studied forests the most common form of dead trees are those which are uprooted (45–59%), while the most frequently dying tree is pine (40–88%). The total area of gaps in relation to the studied forest area ranges from 329 to 2356 m²/ha.     

Noninvasive genetic monitoring of tiger (Panthera tigris tigris) population of Orang National Park in the Brahmaputra floodplain, Assam, India

The Brahmaputra Valley of Assam, India, is one of the prime habitats for the endangered Royal Bengal tiger Panthera tigris tigris. With dwindling global population, estimation of the minimum number of tigers has always been a curiosity to wildlife researchers as well as to protected area managers. In the present study, DNA-based techniques were used for identifying individual tigers present in Orang National Park of Assam, from 57 faecal samples collected during February 2009. Orang National Park stands as an island of a single forest patch along the north bank of river Brahmaputra. The present study confirms the presence of 17 individual tigers in Orang National Park, with five male and 12 female. DNA-based capture–recapture analysis yielded minimum range estimate of 18 and 19 individuals, with possible overestimates of population size following two models of capture probability in CAPWIRE. The results of our genetic counting of tigers are compared with the estimates of 19 tigers based on pugmark analysis by the state Forest Department in 2000 and an independent capture–recapture estimate of 14 (±3.6) individuals based on photographic identity study in 2009. Looking at high mortality of tigers in the area, with 19 reported deaths during 2000 to 2009, our results indicate high individual turnover in the area. This study shows that Orang National Park harbours a healthy breeding population of tigers. However, the possibility of a source-sink dynamics operating in the landscape could not be ruled out, with possible immigration from nearby Kaziranga National Park on the south bank of Brahmaputra, which has the highest reported density of the species in the world.     

Can horse riding induce the introduction and establishment of alien plant species through endozoochory and gap creation?

The risk of spreading of alien species to protected forest habitats through recreational horse-back riding was experimentally investigated at Oulanka National Park, north-eastern Finland during 2002–2005. Levels of disturbance, horse manure and seed rain of dwarf shrubs were manipulated in genuine boreal forest habitat. Specifically we asked (i) whether the seeds of alien species can be dispersed to natural forests by horse manure and (ii) whether disturbance in soils and vegetation increases the density of alien species and decrease the density of native species. Manure addition introduced seeds of graminoid and forb species, which were absent elsewhere in the study area. Establishment of the alien species was further enhanced by the disturbance treatment. Germination of natural shrub species was enhanced by disturbance treatment, whereas manure addition had little impact on the native shrubs. The results indicate that alien species may be introduced to natural forests through recreational horse riding, if horses are fed by hay that contains germinable seeds. Soil disturbance enhances the germination of seeds. In practice, the risk of alien species to the biodiversity of natural forests may be relatively small due to the lack of continuous disturbance in these habitats. Instead, the greatest risk is caused by the possibility of alien species to spread via trails to neighbouring, extremely sensitive open habitats.     

Habitat use and dispersal characteristic by <Emphasis Type="Italic">Stethophyma grossum</Emphasis>: the role of habitat isolation and stable habitat conditions towards low dispersal

Species in a highly fragmented environment, such as the intensively used agricultural landscapes of Europe, are expected to be in danger of extinction. We hypothesize according to Kisdi’s theory (Am Nat 159:579–596, 2002) that species in fragmented landscapes with isolated habitats in general tend to possess low dispersal. In order to verify this hypothesis we studied the movement patterns of Stethophyma grossum, a hygrophilous species of wetlands, by mark–release–recapture techniques in a landscape with scattered suitable habitats over 3 years. The study focused on the major population in this landscape (site #1) as dispersal behaviour was assumed to be greatest. Actually, marked individuals of S. grossum were never found in any further suitable habitats in close vicinity to site #1. Despite that the peatland meadow of study site #1 was all over covered with homogenous vegetation only 6% (1.8 ha) of the whole area (30 ha) were occupied by S. grossum. The mean recapture rate over 3 years amounted to 39% with no significant differences between males and females. Both covered little distances within their mean range size of 1.8 ha; the median distances were 36.91 m for males and 26.65 m for females. We confirm the hypothesis that sub-populations of species in longstanding naturally isolated habitats, which habitat conditions have been stable; evolved low dispersal with little movements which are routine movements to find mating partners or food.     

Rise in human activities on the mudflats and Brent Geese (Branta bernicla) wintering distribution in relation to Zostera spp. beds: a 30-year study

Human activities may restrict access of wintering birds to their food resources, but habitat destruction and fragmentation may interact with disturbance to reduce carrying capacity. We analysed the abundance and distribution of wintering Brent Geese (Branta bernicla) in a major French wintering site from 1970 to 2000, when they experienced increases in human foreshore activities. We used mixed-effects models to test whether spatial extent of two Zostera species, Z. noltii and Z. marina, influenced the distribution of Brent Geese. The number of geese increased significantly with the area of both Zostera species beds. However, the relationship changed in the period after the increase in human activities. More specifically, fragmentation of the most accessible food resource, Z. noltii, negatively affected Brent Goose distribution. This fragmentation was in turn increased by human activities and reduced by the protection of Z. noltii (by banning human access). This implies that direct disturbance, although not excluded, might not have been the major cause of changes in Brent Goose distribution, but rather the effects of human activities on food resources. Thus, our results show that establishment of resource protection areas are efficient as conservation measures, and they underline the need for studies of impacts of human activities on resources, in addition to disturbance effects.     

极端洪水作用下升金湖消落带生境变化对越冬水鸟群落结构的影响

水鸟是湿地生境质量的重要指示性动物类群,可敏感地反映湿地环境变化。浅水通江湖泊消落带具有复杂多样的生境和丰富的食物资源,是水鸟特别是越冬水鸟的重要聚集区,其食物资源的丰富度和可获得性受水文节律影响。在极端洪水作用下,消落带生境变化对越冬水鸟群落结构及其多样性的影响是一个值得关注的水鸟及湿地生态学问题。选择了具有典型消落带生境的升金湖作为研究区域,对2019年(正常水位)和2020年(异常水位)两个越冬季水鸟的数量、种类进行调查统计,分析了消落带的生境变化情况对越冬水鸟群落结构的影响。2019年越冬期,记录到水鸟(50984.20±9595.71)只(n=5),隶属7目13科51种;2020年越冬期,记录到水鸟(27923.00±13808.47)只(n=5),隶属7目12科53种。整个越冬季消落带的水鸟种类略增但数量减少,2019年游禽中的优势种为豆雁,2020年游禽中的优势种增加为豆雁和斑嘴鸭,但涉禽中的优势种由白琵鹭、反嘴鹬、凤头麦鸡转变为苍鹭、大白鹭和反嘴鹬。洪水导致的草滩-水域混合区生境面积减小使湿生植物退化,可能是导致以豆雁为主的食苔草水鸟数量大幅度减少的重要原因;因湖水延迟...     

Habitat use of urban Tree Sparrows in the process of urbanization: Beijing as a case study

The Tree Sparrow (Passer montanus) is a dominant species in urban bird communities. With the development of urbanization, the habitats and sources of food for Tree Sparrows are decreasing. Can the urban Tree Sparrow adapt to changes in the urban environment? To answer this question, we studied the habitat use of Tree Sparrows in eight types of urban areas in Beijing. The results show that the number of both breeding and wintering Tree Sparrows decreased with increasing urbanization. The habitat use of Tree Sparrows, analyzed using stepwise discriminant analysis, was positively correlated with the number of brick bungalows, coniferous and broad-leaved trees and air conditioners. It was negatively correlated with the area of high buildings and hardened roads, pedestrian and automobile flux. This indicates that the Tree Sparrow had not adapted to rapid urbanization even though it is a generally adaptable species. Urban planning should take birds such as the Tree Sparrow into consideration. __________ Translated from Biodiversity Science, 2006, 14(5): 372–381 [译自:生物多样性]     

Migration, wintering and breeding of a lesser spotted eagle ( Aquila pomarina) from Slovakia tracked by satellite

In northern Slovakia an adult male Lesser Spotted Eagle (Aquila pomarina) occupied the same nest site for 11 years running (1992–2002), where it was ringed and fitted with two satellite transmitters. In six of these years it successfully reared a young. In 1994 and 2000–2002 its behaviour during migration could be followed in detail by means of satellite telemetry. The eagle took the known route for this species to South Africa. In 2001, it spent 43% of the year at its breeding site, 33% in its winter quarters, the remaining 24% being spent on migration. In three cases the autumn migration took 40, 48 and 61 days respectively. In two cases the spring migration took 49 days. All five recorded autumn and spring migrations averaged a daily flight distance of 178 km. In spring the daily flight distance was in general slightly greater than in autumn. The longest was recorded from 30 March to 2 April 2001, between Uganda and the Red Sea, during which the bird covered a total of 1,650 km, averaging 412 km per day. In 2001, the spring migration from the wintering grounds was 2 weeks later than in 2002. The wintering grounds, where in 2 years the bird spent around 3.5 months, covering at least 1,666 and 2,269 km, respectively, comprised a large part of Zimbabwe together with the Kruger National Park in South Africa and neighbouring parts of Mozambique. The annual journeys flown, including movements around the wintering grounds, amounted in 2000-2001 to at least 20,396 km and in 2001-2002 to 19,041 km. Except during its crossing of the Sahara, the eagle must have taken food on nearly all its days of migration.     

Habitat specificity and diversity of tree species in an African wet tropical forest

Niche differentiation with respect to habitat has been hypothesized to shape patterns of diversity and species distributions in plant communities. African forests have been reported to be relatively less diverse compared to highly diversed regions of the Amazonian or Southeast Asian forests, and might be expected to have less niche differentiation. We examined patterns of structural and floristic differences among five topographically defined habitats for 494 species with stems ≥1 cm dbh in a 50-ha plot in Korup National Park, Cameroon. In addition, we tested for species–habitat associations for 272 species (with more than 50 individuals in the plot) using Torus translation randomization tests. Tree density and basal area were lowest in areas with negative convexity, which contained streams or were inundated during rainy periods and highest in moist well-drained habitats. Species composition and diversity varied along the topographical gradient from low flat to ridge top habitats. The low depression and low flat habitats were characterized by high diversity and similar species composition, relative to slopes, high gullies and ridge tops. Sixty-three percent of the species evaluated showed significant positive associations with at least one of the five habitat types. The majority of associations were with low depressions (75 species) and the fewest with ridge tops (8 species). The large number of species–habitat associations and the pronounced contrast between low (valley) and elevated (ridgetop) habitats in the Korup plot shows that niche differentiation with respect to edaphic variables (e.g., soil moisture, nutrients) contributes to local scale tree species distributions and to the maintenance of diversity in African forests.     

甘肃黑河内陆河湿地自然保护区候鸟多样性

甘肃黑河为我国第二大内陆河,位于其中游的黑河湿地自然保护区为内陆河流湿地生态系统自然保护区。2008年分季节采用样线法和样点法调查该保护区湿地、农田村庄、人工林和荒漠4种生境的鸟类种类和数量。调查共记录保护区分布的鸟类17目35科116种,其中夏候鸟73种(占鸟类种类的62.93%),迁徙过路鸟20种(占17.24%),留鸟17种(占14.66%),冬候鸟6种(占5.17%)。其中,属于《湿地公约》的水禽56种。在湿地生境共记录鸟类70种,占保护区鸟类种数的60.34%,其中繁殖期在湿地生境栖息的鸟类有50种,绝大部分为夏候鸟(47种),留鸟只有3种;迁徙季节分布有44种鸟类,其中迁徙过路鸟(只在迁徙季节见到)有17种,占迁徙季节鸟类种类数的38.64%。村庄农田、人工林以及荒漠生境中,繁殖期和迁飞期共记录鸟类57种,夏候鸟有33种,留鸟有17种,迁徙过路鸟只有3种。甘肃张掖黑河湿地保护区是众多水禽在我国西北地区的重要繁殖地和迁徙停歇地,是我国候鸟迁徙西部路线上的关键区域。