Role Of Waterbirds Research Articles

Accessing Waterbirds: A perspective into zooarchaeological assemblages and tax records in castles Kastelholm and Raseborg in the northern Baltic Sea

Waterbirds were important seasonal resources in the subsistence of prehistoric people in the Baltic area. However, a more detailed analysis of the importance of birds in the late medieval and early modern period is yet to be discussed. This paper aims to explore the economic value and role of waterbirds in the economy of the castles at Kastelholm and at Raseborg in the northern Baltic Sea area. The study is based on a comparison of written castle accounts from the mid-16th century and zooarchaeological assemblages recovered at the two sites. Despite easy access to water resources, the two castles had different economic interests and ways to obtain waterbirds, which is evident in the species representation of the zooarchaeological record. The accounts often refer only to waterbirds, or seabirds (sjöfåglar) in Swedish, but they were mostly considered as high-status foods as larger amounts of the birds were consumed at the castle bailiff's table. From Kastelhom, waterbirds were also transported to the castle of Stockholm, the King's residence, and therefore they had a wider market value than as a mere seasonal commodity at the castle. For Raseborg, waterbirds seem only to have been consumed in the castle and no export can be seen in the accounts. Prior to transportation, the waterbirds were processed for preservation, and not only for cooking purposes. The difference in the ecological setting and habitat for the waterbirds is reflected in both the accounts and zooarchaeological assemblages of the two administrative castles of the Swedish crown.

The role of waterbirds in the dispersal of freshwater cladocera and bryozoa in southern Africa

It has long been presumed that waterbirds disperse the propagules of aquatic organisms. However, it is only in recent years that this claim has been empirically explored and little is still known about waterbird-mediated dispersal in southern Africa. Aquatic invertebrates are thought to be well adapted to dispersal by waterbirds because of their ability to produce hardy resting eggs. We explored the capacity of waterbirds to disperse the eggs of both cladocera and bryozoans via endo- and ectozoochory. We examined 283 faecal samples and 394 feather brushings from six waterbird species and two wetland sites in South Africa for the presence of diapausing eggs. A total of 108 intact diaspores were recovered, with intact eggs present in 16% and 7% of the faecal samples and feather brushings, respectively. Our results indicate that southern African waterbirds do take up the resting eggs of aquatic invertebrates and that these eggs can survive intact through the gut or remain attached to the feathers. These results provide evidence that waterbirds may be important vectors for aquatic invertebrates in southern Africa and imply that waterbirds may play a vital role in maintaining connectivity between invertebrate populations in isolated wetland patches.

The role of waterbirds in the dispersal of aquatic alien and invasive species

AbstractAimTo review existing literature on the ability of waterbirds to spread aquatic alien and invasive species, and to assess the relevance of bird‐mediated dispersal for the conservation of freshwater ecosystems.LocationGlobal.MethodsLiterature Review.ResultsA systematic review of the literature revealed that quantitative studies investigating dispersal of alien organisms by waterbirds are rare (n = 14). Most studies citing waterbird dispersal rely on anecdotes or inferences from morphological dispersal syndromes. However, evidence from each stage of dispersal (i.e. emigration, transport and immigration) shows that waterbirds can carry alien plants and invertebrates internally and externally; transport them between water bodies at a variety of spatial scales; and deposit viable propagules in sites suited to aquatic invasive species.Main conclusionsOur review suggests that waterbirds can and do act as important dispersal vectors for freshwater invasive species. Further experimental and field based research on the numbers and viability of moved alien propagules, and the roles of different species in the bird community, is needed. Furthermore, consideration of the spatially explicit manner in which birds move is imperative to understanding invasive spread. Populations of alien aquatic species in seemingly isolated wetlands can no longer be considered contained if they are able to be spread through waterbird‐mediated dispersal, and containment measures must recognize such opportunities for further spread. Changing waterbird movement patterns, driven by climate and land use change, further add to the challenge of managing invasive species and offers an interesting opportunity for future research. The study of waterbird‐mediated dispersal of aquatic alien invasive species provides insights not only into species invasions, but more generally into movement ecology, population ecology and biogeography.

REVIEW: Perspectives on wastewater treatment wetlands and waterbird conservation

Summary 1. With the global loss of natural wetlands, waterbirds have become increasingly dependent on alternative and artificial habitats, but the use of such wetlands by waterbirds is typically opportunistic and little consideration has been given to the potential implications for water treatment or waterbird conservation objectives. 2. Wastewater treatment wetlands are currently of critical importance for certain waterbird species in some parts of the world, and we illustrate this with an example from south‐eastern Australia. Furthermore, we argue that their significance is likely to increase as they offer the most realistic means of treating wastewater in developing countries, where the demand for improved sanitation to lift people out of poverty is intense. 3. There is little scientific evidence to guide the construction of wastewater treatment wetlands with waterbird conservation in mind. 4. The use of wastewater by waterbirds poses health risks for both birds and humans and these risks must be better understood. 5. Synthesis and applications. Wastewater treatment wetlands are not a substitute for natural wetlands and reliance upon them should not compromise wetland conservation efforts. Nonetheless, they are a potentially valuable resource for waterbirds, and research should be directed towards deepening our understanding of their global distribution; food‐web dynamics; methods of deterring or excluding birds when bird or human health may be compromised; the effects of wastewater contaminants and pathogens on birds; and the role of waterbirds in human disease transmission.

Victims and Vectors: Highly Pathogenic Avian Influenza H5N1 and the Ecology of Wild Birds

The emergence of highly pathogenic avian influenza (HPAI) viruses has raised concerns about the role of wild birds in the spread and persistence of the disease. In 2005, an outbreak of the highly pathogenic subtype H5N1 killed more than 6,000 wild waterbirds at Qinghai Lake, China. Outbreaks have continued to periodically occur in wild birds at Qinghai Lake and elsewhere in Central China and Mongolia. This region has few poultry but is a major migration and breeding area for waterbirds in the Central Asian Flyway, although relatively little is known about migratory movements of different species and connectivity of their wetland habitats. The scientific debate has focused on the role of waterbirds in the epidemiology, maintenance and spread of HPAI H5N1: to what extent are they victims affected by the disease, or vectors that have a role in disease transmission? In this review, we summarise the current knowledge of wild bird involvement in the ecology of HPAI H5N1. Specifically, we present details on: (1) origin of HPAI H5N1; (2) waterbirds as LPAI reservoirs and evolution into HPAI; (3) the role of waterbirds in virus spread and persistence; (4) key biogeographic regions of outbreak; and (5) applying an ecological research perspective to studying AIVs in wild waterbirds and their ecosystems.

High dispersal capacity of a broad spectrum of aquatic invertebrates via waterbirds

Speculation about the role of waterbirds in the dispersal of aquatic invertebrates pre-dates Darwin. However, there is a critical shortage of field studies quantifying such dispersal. We quantified the viability of aquatic invertebrates in the faeces of different waterfowl species collected in the field at different times during winter. Faeces were collected from four duck species (Northern Pintail Anas acuta, Mallard A. platyrhynchos, Shoveler A. clypeata, Eurasian Teal A. crecca) and Eurasian Coot Fulica atra in November 2004 and January 2005. We also collected soil samples from resting sites as an indicator of what may be transported on birds’ feet and plumage. Faecal and soil samples were incubated using two treatments (0.4 and 4.0 mS cm-1) to quantify the potential for dispersal between aquatic habitats of different salinities. We found that viable Nematoda, Rotifera, Copepoda, Ostracoda, Insecta (Tipulidae), and Daphnia and Moina cladocerans were transported internally by birds in the wild. We also found evidence that nematodes, rotifers, ostracods, copepods, tipulids, chironomids and hemipterans can be dispersed on birds’ feet and feathers. The overall incidence of hatching from all samples was higher in January (59.4%) than in November (11.5%). With the exception of bdelloid rotifers, we found no evidence that the potential for dispersal between two habitats would be impeded by salinity in the range tested. Our data suggest that the taxonomic range of dispersed invertebrates and the frequency of their dispersal via waterfowl has previously been underestimated.

The role of herbivorous water birds in aquatic systems through interactions with aquatic macrophytes, with special reference to the Bewick’s Swan – Fennel Pondweed system

The role of aquatic macrophytes in stimulating biodiversity and maintaining clear waters is currently undisputed. The management of (eutrophic) shallow waters is therefore often directed at (re-)establishing macrophyte domination. In contrast, the role of water birds has long been considered of minor importance for the functioning of fresh water ecosystems. Indeed, in terms of biomass and production, water birds constitute only a minor part of these systems. However, water birds may graze heavily on water plants under certain circumstances, and the question arises whether herbivorous water birds have an important indirect effect on shallow fresh water systems. Mainly illustrated with the interaction between Bewick’s Swans and Fennel Pondweed, we present data on the role that water plants may play in the life of water birds and how water birds may impact water plants’ fitness in terms of survival, production, dispersal and competitive ability. It appears that water plants may be crucial for water birds during periods of high-energy requirements, such as migration. Despite the plants’ costs associated with water bird grazing, the interaction between water birds and water plants varies in nature from an apparent predator–prey relationship to a mutually beneficial interaction depending on the context and the perspective. For the case of the Bewick’s Swan–Fennel Pondweed interaction, regular bird grazing is sustainable and may actually favour the plant’s dispersal. Thus, Bewick’s Swans themselves may in fact play a crucial role in establishing and maintaining the Fennel Pondweed rich staging sites between the swans’ wintering and breeding grounds, which are vital for the swans’ successful migration.