Wetland and Waterfowl research

Ecosystem services are ecosystem processes that directly or indirectly benefit human well-being.
There has been much recent literature identifying different services and the communities and species
that provide them. This is a vital first step towards management and maintenance of these services.
In this review, we specifically address the waterbirds, which play key functional roles in many
aquatic ecosystems, including as predators, herbivores and vectors of seeds, invertebrates and
nutrients, although these roles have often been overlooked. Waterbirds can maintain the diversity of
other organisms, control pests, be effective bioindicators of ecological conditions, and act as
sentinels of potential disease outbreaks. They also provide important provisioning (meat, feathers,
eggs, etc.) and cultural services to both indigenous and westernized societies. We identify key gaps
in the understanding of ecosystem services provided by waterbirds and areas for future research
required to clarify their functional role in ecosystems and the services they provide. We consider
how the economic value of these services could be calculated, giving some examples. Such valuation
will provide powerful arguments for waterbird conservation.

Legal regulation of human activities is a key mechanism for alleviating anthropogenic impacts on wildlife populations. Conservationists frequently request the regulation of toxic substances such as lead, which can be harmful to animals even at low levels of exposure. However, without assessments of the effectiveness of legislation, such regulations may be undermined or revoked and opportunities to make amendments to improve the legislation may be missed. Here we carried out a population-level study of the effectiveness of regulating the use of lead. We show that the increase in population size of a charismatic waterbird (the mute swan Cygnus olor) in Great Britain over 39 years was best explained by the regulation of lead fishing weights, rather than by changes in food supplies, habitat quality, or winter temperature. The proportion of individuals dying of lead poisoning dropped following regulation, from 0.34 to 0.06, suggesting that higher survival rates were the demographic driver of increased population size. Legal restriction therefore succeeded in alleviating, although not eliminating, the impact of poisoning on mute swans. Restrictions on the use of toxic substances, and their release into the environment, would provide an effective conservation mechanism for reducing negative effects of human activities on wildlife populations. At a time when many policy makers prefer to rely on voluntary actions or market forces to achieve change, our study highlights that legal regulations on human activities can be an effective means of alleviating anthropogenic impacts on wildlife.

Illegal killing of wildlife is a major conservation issue that, to be addressed effectively, requires insight into the drivers of human behaviour. Here we adapt an established socio-psychological model, the theory of planned behaviour, to explore reasons for hunting the Endangered Bewick's swan Cygnus columbianus bewickii in the European Russian Arctic, using responses from hunters to a questionnaire survey. Wider ecological, legal, recreational and economic motivations were also explored. Of 236 hunters who participated overall, 14% harboured intentions to hunt Bewick's swan. Behavioural intention was predicted by all components of the theory of planned behaviour, specifically: hunters' attitude towards the behaviour, perceived behavioural control (i.e. perceived capability of being able to perform the behaviour) and their subjective norms (perception of social expectations). The inclusion of attitude towards protective laws and descriptive norm (perception of whether other people perform the behaviour) increased the model's predictive power. Understanding attitudes towards protective laws can help guide the design of conservation measures that reduce non-compliance. We conclude that conservation interventions should target the sociopsychological conditions that influence hunters' attitudes, social norms and perceived behavioural control. These may include activities that build trust, encourage support for conservation, generate social pressure against poaching, use motivations to prompt change and strengthen peoples' confidence to act. This approach could be applied to inform the effective design, prioritization and targeting of interventions that improve compliance and reduce the illegal killing of wildlife.

Our understanding of how energy shapes animal behavioural decisions has been limited by the difficulty of measuring directly the energy gain and expenditure in free-living animals. Mechanistic models that simulate energy gain and expenditure from estimable parameters can overcome these limitations and hence could help scientists to gain a predictive understanding of animal behaviour. Such models could be used to test mechanistic explanations of observed patterns of resource use within a landscape, such as behavioural decisions to switch among food resources. Here, we developed mechanistic models of the instantaneous and daily rates of net energy gain for two species of migratory swans, the Bewick’s swan (Cygnus columbianus bewickii) and whooper swan (Cygnus cygnus), that feed on root and cereal crops within an agricultural landscape in eastern England. Field data show that both species shift from using predominantly root crops (e.g. sugar beet and potatoes) in early winter to using mostly cereals (e.g. wheat) in late winter. Our models correspondingly predicted that swans could achieve the greatest rates of net energy gain on root crops in early winter and on cereal crops in late winter. The change from root crops to cereal crops providing the greatest net rates of energy gain was predicted to occur at the same time as the birds’ switch from feeding predominantly on root crops to predominantly cereal crops (between December and January). We used Monte Carlo simulations to account for variance in model parameters on predictions of energy gain and profitability. A sensitivity analysis indicated that predictions of net energy gain were most sensitive to variance in the intake rate and food quantity parameters. The agreement between our model estimates of energy gain and the observed shifts in resource use observed among the overwintering swans suggests that maximising net rates of energy gain is an important resource selection strategy among overwintering birds. A mechanistic understanding of where and when birds will use food resources can inform the conservation management of key feeding areas for species of conservation concern, as well as the deployment of crop protection strategies.

1. Recent national and international policy initiatives have aimed to reduce the exposure of humans and wildlife to lead from ammunition. Despite restrictions, in the UK, lead ammunition remains the most widespread source of environmental lead contamination to which wildlife may be exposed.
2. The risks arising from the use of lead ammunition and the measures taken to mitigate these have prompted intense and sometimes acrimonious discussion between stakeholder groups, including those advancing the interests of shooting, wildlife conservation, public health and animal welfare.
3. However, relatively little is known of the perspectives of individual ammunition users, despite their role in adding lead to the environment and their pivotal place in any potential changes to practice. Using Q-methodology, we identified the perspectives of ammunition users in the UK on lead ammunition in an effort to bring forward evidence from these key stakeholders.
4. Views were characterised by two statistically and qualitatively distinct perspectives: (a) Open to change-comprised ammunition users that refuted the view that lead ammunition is not a major source of poisoning in wild birds, believed that solutions to reduce the risks of poisoning are needed, were happy to use non-lead alternatives and did not feel that the phasing out of lead shot would lead to the demise of shooting; and (b) Status quo-comprised ammunition users who did not regard lead poisoning as a major welfare problem for wild birds, were ambivalent about the need for solutions and felt that lead shot is better than steel at killing and not wounding an animal. They believed opposition to lead ammunition was driven more by a dislike of shooting than evidence of any harm.
5. Adherents to both perspectives agreed that lead is a toxic substance. There was consensus that involvement of stakeholders from all sides of the debate was desirable and that to be taken seriously by shooters, information about lead poisoning should come from the shooting community.

Understanding the effects of landscape change and environmental variability on ecological processes is important for evaluating resource management policies, such as the emulation of natural forest disturbances. We analyzed time-series of detection/nondetection data using hierarchical models in a Bayesian multi-model inference framework to decompose the dynamics of species distributions into responses to environmental variability, spatial variation in habitat conditions, and population dynamics and interspecific interactions, while correcting for observation errors and variation in sampling regimes. We modeled distribution dynamics of 14 waterbird species (broadly defined, including wetland and riparian species) using data from two different breeding bird surveys collected in the Boreal Shield ecozone within Ontario, Canada. Temporal variation in species occupancy (2000 – 2006) was primarily driven by climatic variability. Only two species showed evidence of consistent temporal trends in distribution: ring-necked duck (Aythya collaris) decreased and red-winged blackbird (Agelaius phoeniceus) increased. The models had good predictive ability on independent data over time (1997 – 1999). Spatial variation in species occupancy was strongly related to the distribution of specific land cover types and habitat disturbance: fire and forest harvesting influenced occupancy more than did roads, settlements or mines. Bioclimatic and habitat heterogeneity indices and geographic coordinates exerted negligible influence on most species distributions. Estimated habitat suitability indices had good predictive ability on spatially independent data (Hudson Bay Lowlands ecozone). Additionally, we detected effects of interspecific interactions. Species responses to fire and forest harvesting were similar for 13 of 14 species; thus, forest harvesting practices in Ontario generally appeared to emulate the effects of fire for waterbirds over time scales of 10-20 years. Extrapolating to all 84 waterbird species breeding on the Ontario shield, however, suggested that up to 30 species may instead have altered (short-term) distribution dynamics due to forestry practices. Hence, natural disturbances are critical components of the ecology of the boreal forest and forest practices which aim to approximate them may succeed in allowing the maintenance of the associated species, but improved monitoring and modeling of large-scale boreal forest bird distribution dynamics is necessary to resolve existing uncertainties, especially on less-common species.

Loss of boreal wetlands in Finland has negative consequences for waders, ducks and local socio-ecological systems. These changes result from over 70-years of human-made alterations to land and waterscapes. Climate change and associated extreme events are expected to be further drivers of negative change. In order to build resilience and seek answers to these challenges, a five-year monitoring of Linnunsuo, a 120-ha human-made wetland was conducted. Wood sandpiper (Tringa glareola) and Northern pintail (Anas acuta) were the indicator species. Analysis of co-management complemented the review. Results indicate that the creation of well-designed wetlands has the potential to increase resilience of these socio-ecological systems. They are cost-effective and can be replicated across the boreal region to address the need of habitat loss and climate impacts.

Range shifts and phenological change are two processes by which organisms respond to environmental warming. Understanding the mechanisms that drive these changes is key for optimal conservation and management. Here we study both processes in the migratory Bewick's swan (Cygnus columbianus bewickii) using different methods, analysing nearly 50 years of resighting data (1970-2017). In this period the wintering area of the Bewick's swans shifted eastwards ('short-stopping') at a rate of ~13 km/year, thereby shortening individual migration distance on an average by 353 km. Concurrently, the time spent at the wintering grounds has reduced ('short-staying') by ~38 days since 1989. We show that individuals are consistent in their migratory timing in winter, indicating that the frequency of individuals with different migratory schedules has changed over time (a generational shift). In contrast, for short-stopping we found evidence for both individual plasticity (individuals decrease their migration distances over their lifetime) and generational shift. Additional analysis of swan resightings with temperature data showed that, throughout the winter, Bewick's swans frequent areas where air temperatures are c. 5.5°C. These areas have also shifted eastwards over time, hinting that climate warming is a contributing factor behind the observed changes in the swans' distribution. The occurrence of winter short-stopping and short-staying suggests that this species is to some extent able to adjust to climate warming, but benefits or repercussions at other times of the annual cycle need to be assessed. Furthermore, these phenomena could lead to changes in abundance in certain areas, with resulting monitoring and conservation implications. Understanding the processes and driving mechanisms behind population changes therefore is important for population management , both locally and across the species range.

Abundant herbivores can damage plants and so cause conflict with conservation, agricultural, and fisheries interests. Management of herbivore populations is a potential tool to alleviate such conflicts but may raise concerns about the economic and ethical costs of implementation, especially if the herbivores are ‘charismatic’ and popular with the public. Thus it is critical to evaluate the probability of achieving the desired ecological outcomes before proceeding to a field trial. Here we assessed the potential for population control to resolve a conflict of non-breeding swans grazing in river catchments. We used a mathematical model to evaluate the consequences of three population management strategies; (a) reductions in reproductive success, (b) removal of individuals, and (c) reduced reproductive success and removal of individuals combined. This model gave accurate projections of historical changes in population size for the two rivers for which data were available. Our model projected that the River Frome swan population would increase by 54 %, from 257 to 397 individuals, over 17 years in the absence of population control. Removal of ≥ 60 % of non-breeding individuals each year was projected to reduce the catchment population below the level for which grazing conflicts have been previously reported. Reducing reproductive success, even to 0 eggs per nest, failed to achieve the population reduction required. High adult and juvenile survival probabilities (> 0.7) and immigration from outside of the catchment limited the effects of management on population size. Given the high, sustained effort required, population control does not represent an effective management option for preventing the grazing conflicts in river catchments. Our study highlights the need to evaluate the effects of different management techniques, both alone and in combination, prior to field trials. Population models, such as the one presented here, can provide a cost-effective and ethical means of such evaluations.

1. Frugivory is widely recognized as vital for the dispersal of many plants. Moreover, plant species and their frugivorous dispersers form seed-dispersal assemblages whose structure has important implications for the persistence and stability of the community. However, dispersal interactions between plants and non-frugivorous animal groups such as waterbirds remain largely understudied. 2. We aimed to characterize the structure of waterbird seed-dispersal networks, assess if this structure is similar to that of networks formed between frugivorous birds and fleshy-fruited plants, and identify bird or plant functional traits important for the maintenance of network structure. 3. We used network analyses and data from four community-level studies on water-bird gut contents, including 12 bird and 88 plant species. We compared the network structure of waterbirds to those from previous studies of frugivorous birds. We also related the contribution of each species to the network structure with functional traits (e.g. size, habitat requirements, diet). 4. Waterbird seed-dispersal networks are similarly nested (i.e. specialists interact with a subset of those species that interact with generalists) but less modular (i.e. fewer semi-independent groups of highly interacting species) than those of frugi-vores. Dabbling ducks, diving ducks and rallids did not separate into modules. The contribution of bird or plant species to network structure was not related to any functional trait. 5. Seed-dispersal networks of waterbirds share some organizational patterns with those of frugivores, but the underlying processes are not related to functional traits. This is probably related to fundamental differences between waterbirds and frugivores in how seeds are ingested. Differences in the functional role of waterbirds for seed dispersal are likely driven by other processes such as differences in population size, movement, ecology or gut processing of seeds. K E Y W O R D S diet, endozoochory, functional traits, modularity, nestedness, wetlands

Killing protected species mistaken for morphologically similar quarry species, or species with weaker protection, can hinder their conservation. Despite policy aims to reduce threats from illegal killing, information is lacking on susceptible species, conservation impacts and the identification accuracy of hunters. We examined the ability of hunters (n = 232) in Arctic Russia to identify the endangered Northwest European Bewick's swan Cygnus columbianus bewickii using photographs. Only 14% (n = 33) identified this species correctly and distinguished it from sympatric and congeneric whooper swans C. cygnus and mute swans C. olor, with 15% of individuals admitting to accidentally hunting a Bewick's swan in the previous 3 years. We conclude that there is a risk of Bewick's swans being shot accidentally when mistaken for similar species with less legal protection. Improving hunters' skills in discerning protected from legitimate quarry species is likely to be an effective tool for conservation of morphologically similar species.

The effects of glyphosate herbicide-induced changes in wetland emergent vegetation (largely cattails, Typha spp.) on densities of ducks (Anatinae) were assessed in northeastern North Dakota. In 1990 and 1991, 17 cattail-dominated wetlands were randomly assigned to 0% (reference wetlands), 50%, 70%, or 90% areal spray coverages with glyphosate herbicide. Densities of green-winged teal (Anas crecca), blue-winged teal (Anas discors), gadwalls (Anas strepera), and ruddy ducks (Oxyura jamaicensis) were similar among treatments during both post-treatment years (P ? 0.1). One year post-treatment, mallard (Anas platyrhynchos)
and northern pintail (Anas acuta) abundances did not differ among treatments (P? 0.1), whereas two years post-treatment their abundances were greater in the sprayed wetlands than in the reference wetlands (P s 0.1). Densities of northern shovelers (Anas clypeata) and redheads (Aythya americana) differed among
treatments in both post-treatment years, with the 50% sprayed wetlands harboring more ducks than did the other three treatments. Percent coverage and hectares of open water were positively correlated with numbers of diving ducks (Aythyini and Oxyurini) (P s 0.1 ). Dabbling duck (Anatini and Cairinini) numbers correlated positively with hectares of open water and dead vegetation, whereas their numbers were negatively correlated
with percent coverage of live vegetation (P s 0.1 ). Results of this study suggest that numbers of ducks were positively influenced by creating a mosaic of open water, live vegetation, and dead vegetation with glyphosate herbicide.

Assessments of the sex ratio among Common Pochard Aythya ferina flocks were undertaken in countries across Europe and into North Africa in January 2016, for comparison with results from surveys carried out over the same area in January 1989 and January 1990. The mean (± 95% CI) proportions of males in the population were estimated as 0.617 (0.614–0.620) in 1989–1990 and 0.707 (0.705–0.710) in 2016; this difference between surveys was found to be highly significant. Whilst male bias increased with latitude in both surveys, this relationship was weaker in 2016 as the increases in male bias between 1989–1990 and 2016 were greater in countries further south. Given that the sex ratio of Pochard broods is approximately 1:1 at hatching, the strong male bias observed among adult birds is indicative of lower survival of females compared with males. The results of this study suggest that factors adversely affecting female survival rate (relative to that of males) may partly explain the decline in overall Common Pochard abundance. Given the widespread and ongoing decline of this species throughout most of Europe and North Africa, further information on possible demographic drivers of change is urgently required.

Background: Our understanding of any impacts of swans on other waterbirds (including other swans), and potential effects on waterbird community structure, remain limited by a paucity of fundamental behavioural and ecological data, including which species swans interact aggressively with and how frequently such interactions occur. Methods: Behavioural observations of aggression by swans and other waterbirds in winters 2018/2019 and 2019/2020, were carried out via live-streaming webcams at two wintering sites in the UK. All occurrence sampling was used to identify all aggressive interactions between conspecific or heterospecifics individuals, whilst focal observations were used to record the total time spent by swans on aggressive interactions with other swans. Binomial tests were then used to assess whether the proportion of intraspecific aggressive interactions of each species differed from 0.5 (which would indicate equal numbers of intraspecific and interspecific interactions). Zero-inflated generalized linear mixed effects models (ZIGLMMs) were used to assess between-individual variation in the total time spent by swans on aggressive interactions with other swans. Results: All three swan species were most frequently aggressive towards, and received most aggression from, their conspecifics. Our 10-min focal observations showed that Whooper (Cygnus cygnus) and Bewick's Swans (C. columbi-anus bewickii) spent 13.8 ± 4.7 s (means ± 95% CI) and 1.4 ± 0.3 s, respectively, on aggression with other swans. These durations were equivalent to 2.3% and 0.2% of the Whooper and Bewick's Swan time-activity budgets, respectively. Model selection indicated that the time spent in aggressive interactions with other swans was best-explained by the number of other swans present for Whooper Swans, and an interactive effect of time of day and winter of observation for Bewick's Swans. However, the relationship between swan numbers and Whooper Swan aggression times was not strong (R 2 = 19.3%). Conclusions: Whilst swans do exhibit some aggression towards smaller waterbirds, the majority of aggression by swans is directed towards other swans. Aggression focused on conspecifics likely reflects greater overlap in resource use, and hence higher potential for competition, between individuals of the same species. Our study provides an example of how questions relating to avian behaviour can be addressed using methods of remote data collection such as live-streaming webcams.

The eighth international census of Whooper Swans Cygnus cygnus wintering in Britain, Ireland and Iceland (also including the Isle of Man and the Channel Islands) took place in January 2020, to update the estimates of the size, midwinter distribution, habitat use and breeding success of the Icelandic Whooper Swan population. The total of 43,255 swans counted represented a 27.2% increase in numbers since the previous census in 2015. Overall, 36.8% of the population (15,927 birds) was recorded in England, 33.4% (14,467) in the Republic of Ireland, 11.7% (5,052) in Scotland, 10.7% (4,644) in Northern Ireland and 6.8% (2,923) in Iceland, with < 1% (242) in Wales, the Isle of Man and the Channel Islands combined. Despite numbers increasing in both the Republic of Ireland and Northern Ireland since 2015, the proportion of the total population in the Republic of Ireland was significantly lower in 2020 and no significant difference was detected for Northern Ireland, whereas proportions in England and Scotland were significantly higher in 2020 and lower in Iceland. Breeding success was not associated with temperatures on either the breeding or wintering grounds. It also showed no clear trend over time, suggesting that increased survival may be the demographic driver of the population growth.

Given their popularity with researchers and public alike, together with their well-documented importance in aquatic and terrestrial ecosystems, fundamental and applied research on swans continues to develop in the 21st century. The 6th International Swan Symposium (6th ISS), was held at the Estonian University of Life Sciences in Tartu, Estonia, in October 2018. The symposium brought together 101 delegates from 17 countries, with presentations on a range of topics on Cygnus and Coscoroba species, including monitoring, habitat and resource use, demography, movements and migration, and threats and conservation. The proceedings of the 6th ISS in this special issue of Wildfowl include select papers on swan research presented at the 6th ISS, covering a wide range of species, systems and issues. This paper presents a synthesis of the 6th ISS and an overview of current trends and future directions in swan research. Despite progress on many topics, southern hemisphere swan species continue to receive less attention than their northern hemisphere counterparts, whilst facing many of the same pressures. It is clear that, given the challenges facing swan researchers in the twenty-first century, international cooperation will continue to be vital. Swans are highly mobile animals and many populations undertake migrations spanning thousands of kilometres, and crucially do not recognise human geographic and political borders. Such international collaborations will be particularly important in coordinating future monitoring and conservation activities. The IUCN-SSC/Wetlands International Swan Specialist Group (SSG) will continue to facilitate international collaborations and communication among the global network of swan researchers, through its activities, website and annual newsletter. Given the substantial challenges and knowledge gaps documented here, there is no doubt that swan researchers will continue to benefit from regular symposia to share information and develop collaborations towards understanding and addressing emerging conservation issues. As such, we recommend holding International Swan Symposia every 4–5 years.

The data on the distribution and numbers of waterfowl and waterbirds on 17 sample plots in river flood-plains in Kharkiv region, North-eastern Ukraine is discussed. The most abundant were 5 species: Mallard (Anas platyrhynchos), Garganey (Anas querquedula), Moorhen (Gallinula chloropus), Coot (Fulica atra), and Common Snipe (Gallinago gallinago).

The effects of human-induced changes in wetland habitat on
birds, particularly ducks (Anatidae), must often be assessed during one visit because of limited resources. Thus, selection of count methodology is critical for an accurate assessment of treatment effects. Using the point-count and wade-flush census techniques, we conducted duck counts on 17 wetlands in
North Dakota in June 1992 and 1993. Densities of dabbling ducks, diving ducks, and all ducks combined did not differ between point-count and wade-flush methods (P > 0.05). Densities of ducks detected with point-counts were positively correlated with percent open water (P < 0.05); whereas, densities of ducks detected by wade-flush counts were independent of percent open water (P > 0.05). Additional research on various census methods is needed
to assess their cost-effectiveness for detecting the diversity and abundance of wetland-dwelling birds.

Les zones humides assurent plusieurs fonctions qui fournissent des avantages ecologiques et economiques considerables. Elles sont classees comme etant les ecosystemes les plus productifs du monde abritant les plus riches biodiversites. Outre les connaissances generales de l'ecosysteme de zone humide, cet ouvrage propose egalement le premier inventaire cartographie de 55 zones humides du Bas-Sahara algerien. L'ensemble de ces sites est classe suivant les criteres de la convention Ramsar avec proposition d'une typologie specifique pour les zones humides du Sahara. Le Lac Ayata faisant partie de la Vallee d'Oued Righ, pris comme exemple type, a fait egalement l'objet d'une etude bioecologique poussee portant sur la diversite des peuplements floristiques et faunistiques avec analyses de leurs dynamiques spatiotemporelles. Cette approche qui vise a connaitre et a mettre en valeur les ressources biologiques des zones humides dans une region ou l'eau est consideree comme denree rare, constitue un outil de travail tant pour les scientifiques que pour les amenagistes et gestionnaires soucieux d'une utilisation durable du patrimoine naturel des zones humides du Sahara.