Distribution and abundance of African waterfowl: examples from the African Waterfowl Census

Dodman, T. & Rose, P. 2000. Distribution and abundance of African waterfowl: examples from the African Waterfowl Census. Ostrich 71 (1 & 2): 235–243.

Wetlands International coordinates waterfowl counts in Africa. Counts from 1958–1990 were analysed in 1991, when the African Waterfowl Census (AfWC) was also launched. By 1996, 25 countries were participating. This preliminary appraisal of the AfWC shows that resulting data can be used to identify distribution and abundance patterns, although there are still significant gaps in AfWC coverage and focus. The degree to which AfwC data may be used to assess the conservation status of African waterfowl populations depends on a function of data quality, quantity and reliability. To enable this practical use of data, several priorities for future work are identified, based on the strengths and weaknesses of the current information: (1) simultaneous co-ordinated counts, (2) regular annual or biannual monitoring of the same sites, (3) development of priority list of sites for regular survey, (4) frequent monitoring of particularly important sites (e.g. every three months), (5) building waterbird surveys into broader programmes of ecological monitoring, (6) planning of special internationally coordinated surveys, (7) planning regular complete surveys in major wetlands, e.g. every five years, and (8) extending the AfWC to other taxa and broader surveys of wetland use by man. In Africa, 522 discrete waterbird populations have been identified. Over half the populations for which trends have been established are in decline. Results from a recent atlas of Anatidae are illustrated by the Fulvous Whistling-Duck Dendrocygnu bicolor, for which three discrete populations and 21 key sites are identified. Wetlands are the most important habitats for waterbirds. Many species (e.g. Grey Heron Ardea cinema) exploit a variety of wetland types and are geographically widespread; those with special habitat requirements (e.g. Blue-winged Goose Cyanochen cyanopterus) oh have restricted ranges. Hartlaub's Duck Pteronetta hartlaubi is one of the few waterbirds specific to the tropical forest biome. The movements of Abdim's Stork Ciconia abdimii in southern Africa show a clear response to rainfall.     

The current status of European wetland inventories and classifications

The status of wetland inventory and classification is considered for 44 European countries, as well as for the continent as a whole. Data and information were obtained from questionnaires compiled by the International Waterfowl and Wetland Research Bureau, the MedWet sub-project on inventory and monitoring, and the Ramsar Bureau. Nine European countries have national wetland inventories, and 32 have inventories of sites of international importance listed under the Ramsar Convention. There has been a trend in producing regional or continental inventories for wetlands that are important as waterfowl habitat. There is an urgent need to produce wetland inventories for all European countries. The Ramsar database takes into consideration hydrological and economic wetland values, as well as ecological ones. The Ramsar classification lists a total of 35 wetland types, and is sufficiently flexible that it could be used for classifying European wetlands at the national scale.     

­­Cross-taxon congruence in wetlands: Assessing the value of waterbirds as surrogates of macroinvertebrate biodiversity in Mediterranean Ramsar sites

Wetlands are among the most threatened habitats and the species they support among the most endangered taxa. Measuring and monitoring wetland biodiversity is vital for conservation, restoration and management, and often relies on the use of surrogate taxa. Waterbirds are commonly used as flagships of biodiversity and are the subject of major conservation initiatives. Therefore, it is important to assess the extent to which waterbirds indicate the general biodiversity of wetlands and serve as surrogates.We explore the relationships between community composition and species richness of waterbirds and aquatic macroinvertebrates in 36 Ramsar wetlands in southern Spain to assess if waterbirds are good surrogates for other taxonomic groups. Specifically, we aimed to (i) test the congruence of patterns of species composition and richness among waterbirds and aquatic macroinvertebrates; and (ii) investigate which environmental variables are associated with the biodiversity patterns of waterbirds and macroinvertebrates, with the purpose of identifying key factors explaining potential discordance in these patterns.We found a limited concordance between assemblage patterns of both taxonomic groups that may be related to their contrasting responses to environmental gradients. Assemblages of waterbirds appear to be more affected by climate variables and water surface area, whereas conductivity was the most important factor influencing macroinvertebrate communities. Furthermore, we found a negligible or inverse relationship in their patterns of richness, with wetlands with higher waterbird species richness showing significantly lower richness of Hemiptera and macroinvertebrate families, and no significant relationship with Coleoptera. In addition, GLM models showed that, in general, different environmental variables are related with the richness patterns of the different taxonomic groups.Given the importance of the Ramsar convention for the conservation of an international network of wetlands, our findings underline the limited potential of waterbirds as aquatic biodiversity indicators in Mediterranean wetlands, and the need for caution when using waterbirds as flagships. An integrative analysis of different biological communities, using datasets from different taxonomic groups, is a necessary precursor for successful conservation policies and monitoring. Our results illustrate the need to create a diversified and complete network of protected sites able to conserve multiple components of wetland biodiversity.     

Key sites for the conservation of waterbirds in Uganda

Arinaitwe, J., Byaruhanga, A. & Mafabi, P. 2000. Key sites for the conservation of waterbirds in Uganda. Ostrich 71 (1 &2): 102–105.

Uganda has a rich bird diversity with 1 008 species including 28 listed species (Collar et al. 1994) and 207 species of regional conservation concern (Bennun & Njoroge 1996). Over 240 species are waterfowl, of which nine are globally threatened, 45 are regionally threatened and five are considered to be of national conservation interest. This high waterbird diversity corresponds to a large wetland area covering about 10% of the land area of Uganda. However, only 6% of the wetlands fall under gazetted protected areas and only one site is recognised as of global importance under the terms of the Ramsar Convention. Three recent activities of JA, the National Wetlands Programme and East Africa Natural History Society (Uganda), have produced new information on distribution and abundance of waterbirds in Uganda. Concurrent with these activities, criteria for the identification of globally threatened species (Collar et al. 1994), species of regional conservation concern (Bennun & Njoroge 1996) and nationally important species (National Wetlands Programme, in press) have been developed. Also, criteria for selection of sites at the global (Ramsar and IBA), regional (IBA) and national (National Wetlands Programme) levels have become available. This paper reviews the advances in the knowledge of waterbirds in Uganda and applies the above criteria to highlight sites that are crucial for conservation at global, regional and national levels.     

Wetland Suitability and Connectivity for Trans-Saharan Migratory Waterbirds

To complete their life cycle waterbirds rely on patchily distributed and often ephemeral wetlands along their migration route in a vast unsuitable matrix. However, further loss and degradation of remaining wetland habitats might lead to a configuration and size of stopovers that is no longer sufficient to ensure long-term survival of waterbird populations. By identifying optimal conservation targets to maintain overall habitat availability en route, we can accommodate an as yet absent functional connectivity component in larger management frameworks for migratory waterbirds, such as the Ramsar Convention and the EU Natura 2000 Network. Using a graph-based habitat availability metric (Equivalent Connected Area) we determine the functional connectivity of wetland networks for seven migratory waterbirds with divergent habitat requirements. Analyses are performed at two spatial extents both spanning the Mediterranean Sea and centered around Greece (Balkan-Cyrenaica and Greece-Cyrenaica). We create species-specific suitable habitat maps and account for human disturbance by species-specific disturbance buffers, based on expert estimates of Flight Initiation Distances. At both spatial extents we quantitatively determine the habitat networks’ overall functional connectivity and identify wetland sites that are crucial for maintaining a well-connected network. We show that the wetland networks for both spatial extents are relatively well connected and identify several wetland sites in Greece and Libya as important for maintaining connectivity. The application of disturbance buffers results in wetland site-specific reduction of suitable habitat area (0.90–7.36%) and an overall decrease of the network’s connectivity (0.65–6.82%). In addition, we show that the habitat networks of a limited set of species can be combined into a single network which accounts for their autoecological requirements. We conclude that targeted management in few but specific wetland complexes could benefit migratory waterbird populations. Deterioration of these vital wetland sites in Greece and Libya will have disproportionate consequences to the waterbird populations they support.     

Assessing the value of wetlands to waterbirds: exploring a population-based index at flyway and regional levels

Traditionally, species richness, species diversity, total count, biomass, energy consumption and the Ramsar ‘1% threshold’ have been used to assess the importance of wetlands for waterbirds. Designation of wetlands of international importance (Ramsar sites) based on waterbirds has focused on those species meeting the Ramsar 1% population threshold levels. These levels prioritise a subset of species as being important, with little or no consideration to the contributions of the remaining species’ populations. In this paper, we evaluate and further describe a quantitative method to assess wetland avifaunal importance. Termed the Waterbird Conservation Value (WCV), this index sums the ratio of each species’ abundance to its published 1% threshold across all species to give an overall measure of the ‘value’ of the waterbirds at a wetland. Large values indicate that large proportions of the total populations of waterbird species are present at the wetland. Indices can be evaluated at site and species levels. The WCV is a more nuanced approach, sensitive to actual species’ abundance rather than counts of ‘1% threshold’ species and considers all species in the assessment. The outputs of the WCV index are demonstrated and discussed using a case study from three regions within the East Atlantic flyway.     

Waterbird and wetland research and conservation in Ghana: a ten year perspective

Ntiamoa-Baidu, Y. & Gordon, C. 2000. Waterbird & wetland research and conservationin Ghana: a ten year perspective. Ostrich 71 (1 & 2): 95.

The study outlines the evolution of ecological research on waterbirds and wetland conservation initiatives in Ghana over a ten year period, 1986–1996. A survey of waterbird populations was initiated in the country in October 1985, through a collaborative effort between the Ghana Government, the Royal Society for the Protection of Birds (RSPB) UK and BirdLife International. These studies identified key wetland sites on the Ghana coast which have been regularly monitored up to today, thus providing the most comprehensive long-term data on waterbird populations within the West African sub-region. Over the ten year period the simple waterbird counting has led to comprehensive ecological research on waterbirds, the establishment of a national Bird Ringing Scheme and the development of a core of trained ornithologists in Ghana. In terms of conservation action, the data provided the justification for designation of the five most important coastal wetland sites as Ramsar sites and the establishment of the Ghana Coastal Wetlands Management Project (CWMP) to manage the sites. The management strategy adopted seeks not only to maintain the ecological integrity of the wetlands, but more importantly, to enhance the benefits derived from wetlands by local communities and improve the quality of life for the coastal people. Management actions are guided by a multi-disciplinary research on the coastal wetland ecosystem, which incorporates biological, physico-chemical and socio-economic dimensions. The large body of environmental data accumulated during the initial stages of the CWMP provide a solid base for the monitoring of the ecological character of the wetlands and the evaluation of management activities. The events in Ghana clearly demonstrate the value of a strong scientific data-base in our efforts to promote conservation of Africa's wetlands and wetland resources.     

Wetland conservation and sustainable use under global change: a tropical Australian case study using magpie geese

Imminent shifts in environmental parameters due to climatic change might have profound ramifications for wetlands listed under the Ramsar convention. Although the exact mechanisms by which global change will affect these systems are not known, models that simulate component drivers, particularly at a broad spatial scale, can nevertheless allow for more informed conservation decision making. Such general inference is particularly needed for wetlands across the tropics, where less knowledge and fewer resources are available to mitigate the impacts on important conservation sites. Here we develop a case study of wetland loss to sea level rise across tropical north Australia (including Ramsar‐listed sites), and link these to a metapopulation model for a keystone endemic waterbird, the magpie goose Anseranas semipalmata. We projected published models on sea level rise through to the year 2400, and found a non‐linear trajectory of inundation up to 20 m above present levels. Digital elevation models were used to simulate sea level rise and the spatially differentiated loss of wetland habitat used by geese. Range retraction was linked to decline in ecological carrying capacity, and we coupled wetland‐specific habitat loss projections to a spatially explicit demographic metapopulation model. Additionally, we included alternate harvest strategies based on present‐day estimates of indigenous and non‐indigenous offtake of geese, and examined the synergy between wetland loss and hunting on extinction risk. Our results suggest that Australia's once‐abundant and widespread magpie goose will be reduced to a fragmented population of just a few thousand individuals within the next 200–300 yr. Harvest could continue for some time, up to a “tipping point” at around 5% loss of current wetland habitat, after which the decline of geese is rapid. Given the inexorable nature of sea level rise, short‐ to medium‐term conservation of waterbirds across Ramsar wetlands must prepare for adaptive wetland management, such as through buffer‐placement, and ongoing monitoring of harvest.     

The Taolimiao-Alashan Nur:its Wetland Bird Community and the Wetland Habitat Assessment

1IntroductionStudiesonbirdsinOrdoswereinitiatedintheprojectofinvestigationontheavifaunaofInnerMongoliaAutonomousRegion.On29thApril1987,skinsofapairofgullswerecol-lectedatasmalllakenotfarfromthe'Ikolimiao-AlashanNur,towhichitwaslateron,bykindhelpofDr.MartinWilliams,identifiedastheRelictGull(Larusrelictus)(Duffetal.[991).InMayof1990,alargebreedingcolonyoftheRelictGullwasfoundattheT-ANut,thenregularfieldobservationsonthegullandonotherwetlandbirdsaroundthelakewerehencestartedand,during199…     

Diversity of waterbirds wintering in Douz wetlands (south Tunisia): factors affecting wetland occupancy and species richness

Understanding the environmental factors shaping wetland attractiveness for waterbirds is an important question in wetland ecology and for conservation purposes. However, detailed data from numerous North African wetlands, notably those situated in inland areas, are still lacking. Thus, the aim of this study was to identify the factors influencing wetland use by waterbirds wintering in one of such poorly known habitat systems, namely the Saharan wetland complex of Douz, in south-western Tunisia. Thirty-four waterbird species (20 wading birds and 14 waterfowl species) were found to winter in this area. Using discriminant function analyses, we found that wetland size was the unique variable discriminating between occupied and unoccupied sites for total waterbirds and wading birds, while waterfowl distribution was related to both wetland size and water depth. Wetland size also provided the strongest predictor of species richness of wading birds, waterfowl and total waterbirds. Overall, our findings highlight the importance of wetland size as a key factor determining the attractiveness of wetlands for waterbirds wintering in the Saharan wetland complex of Douz. The possible explanations of this wetland size effect are discussed.     

鄂尔多斯桃力庙-阿拉善湾海子湿地鸟类群落研究与湿地生境评估

近年来的野外工作结果表明,桃力庙 － 阿拉善湾海子(以下简称桃 － 阿海子)对于遗鸥鄂尔多斯种群的生存具有特别重要的意义,出现于那里的湿地鸟类集中地反映了鄂尔多斯荒漠型湿地鸟类群落的特点;鉴于我国于1992年7月已成为《具国际重要意义特别是作为水禽栖息地的湿地公约》(简称《拉姆萨公约》)的缔约国,本项研究比照《公约》所推荐的评判标准对桃 阿海子作了评估,提出该地点依据《公约》标准应被列入《国际重要湿地名录》。     

Wetland mitigation and compensation: Canadian experience

Since Canada’s accession to the Ramsar Convention on Wetlands in 1981, the nation’s commitment to wetland conservation and management has increased significantly. This includes the adoption of one of the World’s first national wetland conservation policies by the Government of Canada, and the adoption of complementary policy and legislative initiatives by most of the 13 provincial and territorial jurisdictions. Numerous habitat ‘no net loss’ and environmental assessment policies, regulations and guidelines for incorporating mitigation processes into development decisions affecting wetland resources are used throughout Canada. The governments of Canada and six provinces have so far adopted wetland mitigation measures. These are in addition to comprehensive wetland fish and wildlife habitat initiatives, such as the species and habitat joint ventures delivered in Canada through the North American Waterfowl Management Plan by all jurisdictions and numerous non-government partners. This paper examines the current policies, regulations and programs, as well as past implementation experience with wetland mitigation and compensation in Canada.     

Ornithological importance of coastal wetlands in Guinea

Fode, L.C. 2000. Omithological importance of coastal wetlands in Guinea. Ostrich 71 (1 & 2): 343.

For a number of years, the Guinean government has given high priority to nature conservation. Currently the conservation and wise use of natural resources are important issues of the country's developmental policy. The country has a rainy season of seven months (May-November), and heavy rainfall in the coastal area, an average of 2 000–4 000 mm/yr. Coastal wetlands cover a large area: 700 km² mud flats, 600 km² mangroves, 780 km² rice fields and several hundred km² freshwater swamp. Large numbers of waterbirds can be found in the Guinean coastal wetlands, and also in Senegal, Sierra Leone, Liberia, Cöte d'Ivoire, Guinea-Bissau, and Gambia. These countries share the same natural resources with Republic of Guinea, especially during the European winter, when, in addition to the Afrotropical species, there are many palearctic migrants. Over half a million waterbirds winter in the area, of which the palearctic waders, with 430 000, form the major part. Additionally, there are considerable numbers of flamingos, herons, egrets, and terns. The numbers of waterbirds during the European summer amount to 20% of those in winter, of the palearctic waders alone to 10%. In both seasons by far the largest number of waterbirds can be found on the mudflats. Various breeding waterbirds can be found on a few islands (> 3 000 pairs of brown booby, Sula leucogaster on the Isle of Alcatraz), and in the mangroves, rice fields and freshwater swamps. There are considerable breeding numbers of African Darter Anhinga rufa, Green-backed heron Buroroides striatus, White-necked stork Ciconia espiscopus and Caspian Tem Sterna caspia—breeding occurs mainly in the rainy season, except for the island, where most breeding takes place in the dry season. The Guinean coastal wetlands meet also the various criteria developed under the terms of the Ramsar Convention to identify wetlands of international importance. They easily meet the criterion of “regularly supporting 20 000 waterfowl” by the mere occurrence of large numbers during this period. The Guinean coastline, which has a length of 300 km, covers about a quarter of the West African mangrove coast between mid-Senegal and Sierra Leone. Although part of the mangroves have disappeared because of tree cutting and land reclamation for rice cultivation, these tidal forests still form a main part of the Guinean coast. Nearly all the well-developed large scale mangrove areas lie north of Conakry. According to some observations these are the three major threats to the coastal wetlands of Guinea: destruction of the mangrove habitats, hunting, disturbance of breeding sites, the latter being predominantly human disturbance of breeding bird colonies. Especially important is the destruction of parts of the mangrove zones by wood cutting and land reclamation in favour of rice cultivation. The Ninth Pan-African Ornithological Congress should be an opportunity to recommend the execution of appropriate national regional training programmes for concerned African countries. That programme will help to have solid specialists able to present adapted ornithological policies in the interested countries of Africa. The congress should also organise an official regional institution through which periodical contacts of specialists and quthorities can be made at local and international level. The congress must have some international development co-operation in ornithological fields in Africa. The congress may recommend development co-operation policy with Ramsar Convention Office, Wetlands International, WWF, IUCN, and any other concerned institutions.     

Trends in the use of a small coastal lagoon by waterbirds: Muni Lagoon (Ghana)

This paper presents data from a twelve-year (1986–98) monitoring of waterbird populations at Muni Lagoon, and discusses the ornithological importance of the lagoon and trends in the use of the site by waterbirds. The small brackish lagoon forms part of the Muni-Pomadze Ramsar site situated on the Ghana coast. A total of 48 species of waterbirds were recorded at the site comprising of 29 species of waders, eight species of terns, two species of gulls, seven species of herons and egrets, one species each of duck and cormorant. The most abundant waterbirds species recorded on the site were the Curlew Sandpiper, Ringed Plover, Greenshank, Black-winged Stilt, Common Tern, Black Tern, Royal Tern and the Sandwich Tern. Three species of waders, Black-winged Stilt, Pratincole and Little Tern were observed to breed at the site. The highest numbers of waterbirds occurred on the site in the period September to March. The site remains an internationally important wetland site by virtue of supporting internationally important numbers of four species of terns: Royal Tern, Sandwich Tern, Common Tern and Black Tern. The value of Muni lies more in its use as a feeding/staging site for migrating waders that spend the non-breeding season in Ghana or pass through to winter further south, and as a roosting site for terns which feed mainly at sea. The use of the site by waterbirds has increased by some 400% between 1986 and 1998. This is attributed to improved prey availability resulting from the opening of the lagoon into the sea during the 1994 floods, and reduced disturbance of feeding and roosting birds. This would imply that the value of the site as waterbird habitat could improve considerably with appropriate habitat management interventions and continued protection.     

A geomorphic approach to global classification for natural inland wetlands and rationalization of the system used by the Ramsar Convention – a discussion

Globally, the most widely used wetland classification is that adopted by the contracting parties of the Ramsar Convention, which is the Convention on Wetlands of International Importance especially as Waterfowl Habitat. A review of the Inland Wetland component of this system shows that mixed criteria are used to separate the wetlands, and that not all natural inland wetlands have been addressed. A classification system using landform and hydro-period, which results in 13 primary geomorphically non-emergent types for natural wetlands, is proposed to describe the full variety of wetlands at a primary level around the globe, and is suggested to be incorporated as the first-tier of the Ramsar classification.The proposed classification has been designed so wetlands can be described, classified and compared systematically. This paper attempts to reconcile the Ramsar Classification system with the proposed approach. The intention in this paper is not to displace the Ramsar Classification, but rather to indicate its inherent underlying geomorphic structure, and hence re-order its hierarchical framework. This adjustment to the existing classification system would highlight underlying similarities between wetlands so that global comparisons can be more readily made. It also has considerable advantages for a staged, systematic discrimination and classification of the vast array of differing wetlands globally.The use of geomorphic and hydrologic elements as the primary and secondary divisions with the more commonly used Ramsar Classification terms as a tertiary division, provides a logical structure to compare and contrast wetlands globally.     

Reduction of avian diversity in created versus natural and restored wetlands

Natural wetland ecosystems continue to suffer widespread destruction and degradation. Many recent studies argue that artificial or restored wetlands compensate for wetland loss and are valuable for waterbird conservation. However, detailed comparisons of the value of natural, artificial and restored wetlands are lacking. Our aim was to assess if the restoration or creation of wetlands can fully compensate for the loss of natural wetlands for waterbirds. We compared the waterbird communities in a set of 20 natural, restored and artificial wetlands, all of which are considered important for waterbirds and are located within the same protected area (Doñana Natural Space, south‐west Spain). We used different measures of diversity, including phylogenetic relatedness, and the proportion of threatened species at national, European and international levels. We found that artificial wetlands have consistently lower value than restored and natural wetlands, with little difference between the latter two. Natural wetlands are essential for conserving diversity across the tree of life and for threatened species, but restored wetlands can be of similar value and can assure maintenance of key ecological processes. Thus, when economic costs per unit area are similar, resources for wetland conservation are better invested in restoration projects than in wetland creation, and caution is required when suggesting that artificial wetlands compensate for the loss of natural wetlands.     

Planning for the recovery of Lake Toolibin,Western Australia

Lake Toolibin, an intermittently flooded freshwater wetland in the southwest of Western Australia, is threatened by salinization due to extensive clearing within its catchment. The lake is a Wetland of International Importance under the Ramsar Convention because of the extensive stands of trees on the lake bed and its significance as a waterbird breeding site. Past research and monitoring have identified the causes of wetland vegetation and water quality decline and this information has been used to design a Recovery Plan for the lake. The plan is currently in the early stages of implementation and includes both short-term engineering measures to reduce salinity within the lake and long-term rehabilitation measures within the catchment. Community involvement in the recovery process is an integral part of the plan and ensures that recovery of the lake remains as the focus for ongoing catchment rehabilitation.     

Areas of high diversity for the world’s inland-breeding waterbirds

Waterbirds are a globally-distributed, species-rich group of birds that are critically dependent upon wetland habitats. They can be used as ecosystem sentinels for wetlands, which as well as providing ecosystem services and functions essential to humans, are important habitats for a wide range of plant and animal taxa. Here we carry out the first global analysis of inland-breeding waterbird distributions using data from 471 waterbird species in 28 families to identify global areas of high waterbird diversity. First we identify the primary area of high diversity for all inland-breeding waterbird species to be in Eastern Africa. For globally threatened inland-breeding waterbirds, the area of highest diversity is in Eastern China. Second, we show that the current network of protected areas provides poor coverage for threatened waterbirds in Eastern and Central Asia, and Northern India. In contrast, there is a higher protected area coverage in most of Europe and Brazil. Targeting the specific areas that have the highest numbers of species and the poorest coverage of protected areas is vital for both waterbird and wetland conservation.     

Biotic wetland connectivity—supporting a new approach for wetland policy

Wetlands are key habitats connected physically and socially with processes occurring over a much wider territory. The biotic connection through dispersal mechanisms among wetlands is of primary importance to wetland management and policies. However, traditional wetland conservation approaches are based on the preservation of isolated sites considered to be of special importance (typically owing to their importance for concentrations of migratory waterbirds). Research linking local species richness and bird migration suggests that the effect of wetland loss on regional diversity might be much larger than what would be expected from direct habitat loss. Since the biotic connection among wetlands serviced by waterbirds appears to be more efficient within a limited range, the distribution of wetlands in space is a key aspect determining wetland connectedness even in the absence of direct hydrologic links. Protected areas should thus be defined with regard to waterfowl movements and waterbird migration as functional processes contributing to aquatic species migration and local species richness. This calls for a regional approach to wetland management within a continental context. This paper aims at defining an operational view of the dispersion function of wetlands and its implication for conservation policies. For this purpose, we examined the conservation policies of the Ramsar Convention (the international treaty that protects wetlands) and the European Union (as an example of relevant continental level policy-making) from the viewpoint of bird-mediated dispersal of aquatic organisms. We propose nine specific avenues for the inclusion of bird-mediated dispersal in the policy documents examined. Non-governmental organisations and other organisations working in waterbird conservation should also recognise the importance of their policies for aquatic biodiversity at broader levels and avoid compartmentalising their conservation activities.     

How can Habitat Selection Affect the use of a Wetland Complex by Waterbirds?

The factors regulating the distribution of dabbling and diving waterbirds were studied, taking into account habitat selection by the species in a wetland complex of 26 ponds in south-eastern Spain. Such information can be used to management and conservation of wetland threatened bird species. Direct counts and feeding-microhabitat surveys of waterbirds were conducted. The feeding-niche width and the feeding-microhabitat use, as a function of the horizontal spatial gradient in the ponds, were related to the mean size of ponds used for each species. While the more generalist birds, which usually feed close to the shore, probably had available resources in small ponds, specialists that also frequently selected central zones of the pond had proportionally more limited feeding space and, therefore, less resource availability in small ponds. The differences in habitat selection of the different species appeared to encourage their hierarchical disappearance from the wetland complex at the same rate as the ponds diminished in size (‘nested’ pattern). The results support the conservation, restoration or creation of, at least, ponds of greater size in order to preserve extensive open-water zones in the wetlands and maintain the greatest number of specialist, threatened, and area-dependent species, such as the globally endangered White-headed Duck (Oxyura leucocephala).