Waterfowl Breeding Research Articles

Livestock grazing in intermountain depressional wetlands: effects on breeding waterfowl

Livestock grazing is a prevalent land use in western North American intermountain wetlands, and physical and biotic changes related to grazing-related disturbance can potentially limit wetland habitat value for waterfowl. We evaluated breeding waterfowl use in 34 wetlands in relation to water retention, amount of wetlands on the landscape, and livestock grazing intensity. The study was conducted over 2 years in the southern intermountain region of British Columbia, Canada. For a subset of 17 wetlands, we measured aquatic invertebrate abundance over 1 year. Waterfowl breeding pairs and broods were classified into three functional groups: dabbling ducks, and two types of diving ducks, overwater and cavity nesters. We evaluated candidate models with variables considered singly and in combination using the Akaike Information Criterion. When selected, bare ground (an indicator of grazing intensity) and wetland density were negatively associated with breeding use while wetland fullness and invertebrate density were positively associated. Each factor was a significant predictor in at least one of the models, but unexpectedly, grazing intensity was the most consistent predictor of waterfowl wetland use (e.g., it was present in more ‘best models’ than wetland fullness). Grazing was associated with declines in the number of waterfowl pairs and broods, likely mediated through effects on wetland vegetation and aquatic macroinvertebrates. Models with site- and landscape-scale variables generally performed better than simpler models. Waterfowl breeding use of wetlands can be improved by reduced livestock grazing intensity adjacent to wetlands and by grazing later in the season. Wetland water retention is also an important constraint on waterfowl use of wetlands and may become more limiting with a shifting climate.

Monitoring and Material Simulation of Automatic-Cooling System for Waterfowl Incubator

In order to reduce the required manpower and biosecurity control risk for waterfowl breeding eggs, this study developed waterfowl automatic eggs cooling incubator which using the concept of pre-heating and pre-wetting type front control thermal system and add the automatic watering eggs cooling system, trolley egg rack, pneumatic eggs overturning system and monitoring system. The front control thermal system preheats and pre-wet the air to the required environment for hatching and import into incubator for the hatching test. The test results show that the hatching environment uniformity of automatic eggs cooling incubator developed by this study is better than the traditional incubator’s environment. The monitoring system can stable control the variation for three hatching parameters of temperature, humidity and carbon dioxide concentration. Besides the combination of automatic watering eggs cooling system for hatching process can significantly reduce the required manpower for watering eggs cooling and biosecurity control risk, the average hatching ratio is 82.06% that can satisfy the requirement of general professional goose breeding eggs incubator. The test using computational fluid dynamics simulation software (CFD) to simulate the variable turbulent wind speed. On the premise of using temperature as the respondence to conduct the optimization design of response surface methodology. The results shows that the incubator temperature standard deviation decreased from 0.26°C to 0.14°C when three turbulent wind speed changed from 4.25 m/s, 3.50 m/s and 4.63 m/s to 2 .00m/s, 5 .00m/s and 3.81 m/s. There is a further increase for the uniformity of the temperature field.

Environmental factors influence lesser scaup migration chronology and population monitoring

Identifying environmental metrics specific to lesser scaup (Aythya affinis; scaup) spring migration chronology may help inform development of conservation, management and population monitoring. Our objective was to determine how environmental conditions influence spring migration of lesser scaup to assess the effectiveness of the Waterfowl Breeding Population and Habitat Survey in accurately estimating scaup populations. We first compared peak timing of mallard (Anas platyrhynchos) and scaup migration from weekly ground surveys in North Dakota, USA because the Waterfowl Breeding Population and Habitat Survey is designed to capture annual mallard migration. As predicted, we detected that peak timing of scaup and mallard migrations differed in 25 of 36 years investigated (1980–2010). We marked scaup with satellite transmitters (n = 78; 7,403 locations) at Long Point, Lake Erie, Ontario, Canada; Pool 19 of the Mississippi River, Iowa and Illinois, USA; and Presque Isle Bay, Lake Erie, Pennsylvania, USA. We tested the assumption that our marked scaup were representative of the continental population using the traditional survey area by comparing timing of migration of marked birds and scaup counted in the North Dakota Game and Fish Department survey. We detected a strong positive correlation between marked scaup and the survey data, which indicated that marked scaup were representative of the population. We subsequently used our validated sample of marked scaup to investigate the effects of annual variation in temperature, precipitation, and ice cover on spring migration chronology in the traditional and eastern survey areas of the Waterfowl Breeding Population and Habitat Survey, 2005–2010. We evaluated competing environmental models to explain variation in timing and rate of scaup migration at large-scale and local levels. Spring migration of scaup occurred earlier and faster during springs with warmer temperatures and greater precipitation, variables known to influence energy budgets and wetland availability. Our results suggest that surveys designed to index abundance of breeding mallards is imprecise for estimating scaup abundance, and inaccurate at estimating breeding population size by survey stratum. © 2016 The Wildlife Society.

Waterfowl populations are resilient to immediate and lagged impacts of wildfires in the boreal forest

Summary Wildfires are the principal disturbance in the boreal forest, and their size and frequency are increasing as the climate warms. Impacts of fires on boreal wildlife are largely unknown, especially for the tens of millions of waterfowl that breed in the region. This knowledge gap creates significant barriers to the integrative management of fires and waterfowl, leading to fire policies that largely disregard waterfowl. Waterfowl populations across the western boreal forest of North America have been monitored annually since 1955 by the Waterfowl Breeding Population and Habitat Survey (BPOP), widely considered the most extensive wildlife survey in the world. Using these data, we examined impacts of forest fires on abundance of two waterfowl guilds – dabblers and divers. We modelled waterfowl abundance in relation to fire extent (i.e. amount of survey transect burned) and time since fire, examining both immediate and lagged fire impacts. From 1955 to 2014, >1100 fires in the western boreal forest intersected BPOP survey transects, and many transects burned multiple times. Nonetheless, fires had no detectable impact on waterfowl abundance; annual transect counts of dabbler and diver pairs remained stable from the pre‐ to post‐fire period. The absence of fire impacts on waterfowl abundance extended from the years immediately following the fire to those more than a decade afterwards. Likewise, the amount of transect burned did not influence waterfowl abundance, with similar pair counts from the pre‐ to post‐fire period for small (1–20% burned), medium (21–60%) and large (>60%) burns. Policy implications. Waterfowl populations appear largely resilient to forest fires, providing initial evidence that current policies of limited fire suppression, which predominate throughout much of the boreal forest, have not been detrimental to waterfowl populations. Likewise, fire‐related management actions, such as prescribed burning or targeted suppression, seem to have limited impacts on waterfowl abundance and productivity. For waterfowl managers, our results suggest that adaptive models of waterfowl harvest, which annually guide hunting quotas, do not need to emphasize fires when integrating climate change effects.

Spring Migration Stopover Ecology of Avian Influenza Virus Shorebird Hosts at Delaware Bay.

Although low pathogenicity avian influenza viruses (LPAIV) are detected in shorebirds at Delaware Bay annually, little is known about affected species habitat preferences or the movement patterns that might influence virus transmission and spread. During the 5-wk spring migration stopover period during 2007-2008, we conducted a radiotelemetry study of often-infected ruddy turnstones (Arenaria interpres morinella; n = 60) and rarely infected sanderlings (Calidris alba; n = 20) to identify locations and habitats important to these species (during daytime and nighttime), determine the extent of overlap with other AIV reservoir species or poultry production areas, reveal possible movements of AIV around the Bay, and assess whether long-distance movement of AIV is likely after shorebird departure. Ruddy turnstones and sanderlings both fed on Bay beaches during the daytime. However, sanderlings used remote sandy points and islands during the nighttime while ruddy turnstones primarily used salt marsh harboring waterfowl and gull breeding colonies, suggesting that this environment supports AIV circulation. Shorebird locations were farther from agricultural land and poultry operations than were random locations, suggesting selection away from poultry. Further, there was no areal overlap between shorebird home ranges and poultry production areas. Only 37% (22/60) of ruddy turnstones crossed into Delaware from capture sites in New Jersey, suggesting partial site fidelity and AIV gene pool separation between the states. Ruddy turnstones departed en masse around June 1 when AIV prevalence was low or declining, suggesting that a limited number of birds could disperse AIV onto the breeding grounds. This study provides needed insight into AIV and migratory host ecology, and results can inform both domestic animal AIV prevention and shorebird conservation efforts.

Fish farming abandonment and pond use by ducks breeding in Sologne (Central France)

Fishpond complexes are important wetlands for waterfowl breeding in Europe. In France, extensive fish farming in several pond regions seems to be threatened by a massive abandonment of fish stocking and production due to low economic returns. This study investigated at pond level the consequences on duck breeding of the interruption of pond management by fish farmers in Sologne (Central France). We compared models (GLMs) with duck pair number or with the brood: pair ratio as dependent variables, including as explanatory variables an index of abundance in high or low littoral vegetation (descriptor of potential nesting cover), of willow Salix sp. stand development (descriptor of helophyte encroachment by wooden vegetation), physico-chemical characteristics of water and sediment, and a categorical variable for fish farming (ponds harvested every 1–3 years, not harvested for 4–10 years or for >10 years). Regular fish farming best explained: (1) high duck pair abundance and (2) high brood: pair ratios provided that water transparency was >40 cm. Our results seem to indicate that extensive fish farming, and therefore pond management by fish farmers, may contribute to enhance pond carrying capacity for breeding ducks.

Assessing spring direct mortality to avifauna from wind energy facilities in the Dakotas

The Northern Great Plains (NGP) contains much of the remaining temperate grasslands, an ecosystem that is one of the most converted and least protected in the world. Within the NGP, the Prairie Pothole Region (PPR) provides important habitat for >50% of North America's breeding waterfowl and many species of shorebirds, waterbirds, and grassland songbirds. This region also has high wind energy potential, but the effects of wind energy developments on migratory and resident bird and bat populations in the NGP remains understudied. This is troubling considering >2,200 wind turbines are actively generating power in the region and numerous wind energy projects have been proposed for development in the future. Our objectives were to estimate avian and bat fatality rates for wind turbines situated in cropland- and grassland-dominated landscapes, document species at high risk to direct mortality, and assess the influence of habitat variables on waterfowl mortality at 2 wind farms in the NGP. From 10 March to 7 June 2013–2014, we completed 2,398 searches around turbines for carcasses at the Tatanka Wind Farm (TAWF) and the Edgeley-Kulm Wind Farm (EKWF) in South Dakota and North Dakota. During spring, we found 92 turbine-related mortalities comprising 33 species and documented a greater diversity of species (n = 30) killed at TAWF (predominately grassland) than at EKWF (n = 9; predominately agricultural fields). After accounting for detection rates, we estimated spring mortality of 1.86 (SE = 0.22) deaths/megawatt (MW) at TAWF and 2.55 (SE = 0.51) deaths/MW at EKWF. Waterfowl spring (Mar–Jun) fatality rates were 0.79 (SE = 0.11) and 0.91 (SE = 0.10) deaths/MW at TAWF and EKWF, respectively. Our results suggest that future wind facility siting decisions consider avoiding grassland habitats and locate turbines in pre-existing fragmented and converted habitat outside of high densities of breeding waterfowl and major migration corridors. © 2016 The Wildlife Society.

Combining waterfowl and breeding bird survey data to estimate wood duck breeding population size in the Atlantic Flyway

ABSTRACTWe combined data from the Atlantic Flyway Breeding Waterfowl Survey (AFBWS) and the North American Breeding Bird Survey (BBS) to estimate the number of wood ducks (Aix sponsa) in the United States portion of the Atlantic Flyway from 1993 to 2013. The AFBWS is a plot‐based survey that covers most of the northern and central portions of the Flyway; when analyzed with adjustments for survey time of day effects, these data can be used to estimate population size. The BBS provides an index of wood duck abundance along roadside routes. Although factors influencing change in BBS counts over time can be controlled in BBS analysis, BBS indices alone cannot be used to derive population size estimates. We used AFBWS data to scale BBS indices for Bird Conservation Regions (BCR), basing the scaling factors on the ratio of estimated AFBWS population sizes to regional BBS indices for portions of BCRs that were common to both surveys. We summed scaled BBS results for portions of the Flyway not covered by the AFBWS with AFBWS population estimates to estimate a mean yearly total of 1,295,875 (mean 95% CI: 1,013,940–1,727,922) wood ducks. Scaling factors varied among BCRs from 16.7 to 148.0; the mean scaling factor was 68.9 (mean 95% CI: 53.5–90.9). Flyway‐wide, population estimates from the combined analysis were consistent with alternative estimates derived from harvest data, and also provide population estimates within states and BCRs. We recommend their use in harvest and habitat management within the Atlantic Flyway. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Where does environmental stochasticity most influence population dynamics? An assessment along a regional core‐periphery gradient for prairie breeding ducks

AbstractAimGeographical disparities in the effect of the environment on population dynamics have been shown to follow a core‐periphery gradient when peripheral populations are less abundant and occur in marginal habitat. Whether the gradient in environmental influence occurs in the absence of a gradient in abundance is not known. We tested whether duck populations on the periphery of their main breeding region were more strongly affected by environmental stochasticity and less abundant than at the core.LocationThe Prairie Pothole Region of central United States and CanadaMethodsWe used the North American Waterfowl Breeding Population and Habitat Survey to model the dynamics of 10 duck species at 1059 sites spanning 1961–2012. We used the North American Breeding Bird Survey to measure abundance at the same sites, averaged over the same time span. We used structural equation models to characterize relationships among a site's distance from the regional centre, a site's abundance, and the degree to which a site's ducks were affected by environmental stochasticity.ResultsEnvironmental stochasticity never strongly contributed to population dynamics in the region's core. However, we did not find a linear increase in environmental stochasticity with increasing distance from the core. For seven species, we found that environmental stochasticty was stronger in sites of lower abundance. For only two species did average abundance decline from the region's core to periphery.Main conclusionsVariability in the magnitude of environmental stochasticity follows coarse spatial differences in wetland productivity. Yet, among peripheral sites, the contribution of the environment to population dynamics varies, possibly reflecting the importance of the local environment and dispersal.

Building the foundation for international conservation planning for breeding ducks across the U.S. and Canadian border.

We used publically available data on duck breeding distribution and recently compiled geospatial data on upland habitat and environmental conditions to develop a spatially explicit model of breeding duck populations across the entire Prairie Pothole Region (PPR). Our spatial population models were able to identify key areas for duck conservation across the PPR and predict between 62.1 – 79.1% (68.4% avg.) of the variation in duck counts by year from 2002 – 2010. The median difference in observed vs. predicted duck counts at a transect segment level was 4.6 ducks. Our models are the first seamless spatially explicit models of waterfowl abundance across the entire PPR and represent an initial step toward joint conservation planning between Prairie Pothole and Prairie Habitat Joint Ventures. Our work demonstrates that when spatial and temporal variation for highly mobile birds is incorporated into conservation planning it will likely increase the habitat area required to support defined population goals. A major goal of the current North American Waterfowl Management Plan and subsequent action plan is the linking of harvest and habitat management. We contend incorporation of spatial aspects will increase the likelihood of coherent joint harvest and habitat management decisions. Our results show at a minimum, it is possible to produce spatially explicit waterfowl abundance models that when summed across survey strata will produce similar strata level population estimates as the design-based Waterfowl Breeding Pair and Habitat Survey (r2 = 0.977). This is important because these design-based population estimates are currently used to set duck harvest regulations and to set duck population and habitat goals for the North American Waterfowl Management Plan. We hope this effort generates discussion on the important linkages between spatial and temporal variation in population size, and distribution relative to habitat quantity and quality when linking habitat and population goals across this important region.

Temporal variation in pond use and breeding success for ducks in French fishpond regions: on possible consequences of a decline in fish farming

Fish farming abandonment or extensification may theoretically lead to contrasting consequences for waterfowl breeding in fishpond complexes. We investigated the variation of four indices of duck density or breeding success in pond samples of three main French fishpond areas: Dombes, Forez and Brenne, along with recent changes in fish farming management. In Forez, where fish stocking has been frequently interrupted or fish biomass in ponds has substantially decreased during the two last decades, duck pair density strongly increased in the same time interval, but Mallard Anas platyrhynchos brood size decreased. In Brenne, no fish farming abandonment was observed but pond fertilization with organic manure or mineral nitrogen became less frequently implemented during the 2000s. The duck brood: pair ratio decreased meanwhile, indicating either a lower nesting success or higher losses before or immediately after hatching. In Dombes, lower fish stock densities since the 1990s did not reverse a negative trend in duck populations which started in the early 1980s. Our results suggest that fish biomass density in fishponds might be a limiting factor for breeding waterfowl, but a decrease in the nutrient level, for example with lower fertilizer inputs, may negatively affect duck reproductive success.

Hierarchical model analysis of the Atlantic Flyway Breeding Waterfowl Survey

We used log-linear hierarchical models to analyze data from the Atlantic Flyway Breeding Waterfowl Survey. The survey has been conducted by state biologists each year since 1989 in the northeastern United States from Virginia north to New Hampshire and Vermont. Although yearly population estimates from the survey are used by the United States Fish and Wildlife Service for estimating regional waterfowl population status for mallards (Anas platyrhynchos), black ducks (Anas rubripes), wood ducks (Aix sponsa), and Canada geese (Branta canadensis), they are not routinely adjusted to control for time of day effects and other survey design issues. The hierarchical model analysis permits estimation of year effects and population change while accommodating the repeated sampling of plots and controlling for time of day effects in counting. We compared population estimates from the current stratified random sample analysis to population estimates from hierarchical models with alternative model structures that describe year to year changes as random year effects, a trend with random year effects, or year effects modeled as 1-year differences. Patterns of population change from the hierarchical model results generally were similar to the patterns described by stratified random sample estimates, but significant visibility differences occurred between twilight to midday counts in all species. Controlling for the effects of time of day resulted in larger population estimates for all species in the hierarchical model analysis relative to the stratified random sample analysis. The hierarchical models also provided a convenient means of estimating population trend as derived statistics from the analysis. We detected significant declines in mallard and American black ducks and significant increases in wood ducks and Canada geese, a trend that had not been significant for 3 of these 4 species in the prior analysis. We recommend using hierarchical models for analysis of the Atlantic Flyway Breeding Waterfowl Survey. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

Criteria for determining breeding‐pair status of male mallards captured in decoy traps

ABSTRACTMethods for accurately determining pair status of male ducks during the breeding season are necessary for further understanding the roles of paired and unpaired males in waterfowl breeding populations. Previous studies assigned pair status based on behavioral observations of randomly captured and marked birds, but this method limits control over sample sizes of paired and unpaired individuals. We evaluated 8 criteria for determining breeding‐pair status (i.e., paired, unpaired) of male mallards (Anas platyrhynchos) based on scenarios of capture in decoy traps during late March–early April in Prairie‐Parkland Canada and central New York, USA. Of the 51 males we classified as paired across 3 study sites and years, we confirmed from repeated visual observations that 46 (90%) were indeed paired. All 36 males classified as unpaired were subsequently confirmed to be unpaired. The predicted overall probability of correctly assigning pair status to captured males was 93.7% (95% CI = 86.8–97.3%). These criteria provide an effective yet simple technique to identify pair status of male mallards captured in decoy traps and should enable more efficient use of time and logistical resources in studies requiring samples of paired and unpaired male ducks. © 2014 The Wildlife Society.

Optimal water depth management on river-fed National Wildlife Refuges in a changing climate

The prairie pothole region (PPR) in the north-central United States and south-central Canada constitutes the most important waterfowl breeding area in North America. Projected long-term changes in precipitation and temperature may alter the drivers of waterfowl abundance: wetland availability and emergent vegetation cover. Previous studies have focused on isolated wetland dynamics, but the implications of changing precipitation on managed, river-fed wetlands have not been addressed. Using a structured decision making (SDM) approach, we derived optimal water management actions for 20 years at four river-fed National Wildlife Refuges (NWRs) in North and South Dakota under contrasting increasing/decreasing (+/−0.4 %/year) inflow scenarios derived from empirical trends. Refuge pool depth is manipulated by control structures. Optimal management involves setting control structure heights that have the highest probability of providing a desired mix of waterfowl habitat, given refuge capacities and inflows. We found optimal seasonal control structure heights for each refuge were essentially the same under increasing and decreasing inflow trends of 0.4 %/year over the next 20 years. Results suggest managed pools in the NWRs receive large inflows relative to their capacities. Hence, water availability does not constrain management; pool bathymetry and management tactics can be greater constraints on attaining management objectives than climate-mediated inflow. We present time-dependent optimal seasonal control structure heights for each refuge, which are resilient to the non-stationary precipitation scenarios we examined. Managers can use this information to provide a desired mixture of wildlife habitats, and to re-assess management objectives in reserves where pool bathymetry prevents attaining the currently stated objectives.

Surveying populations of breeding grebes in prairie parkland Canada: Estimation problems and conservation applications

ABSTRACTAnnual ground surveys of mid‐continent waterfowl may provide a monitoring framework for other wetland‐associated species. We used a repeated‐counts method to estimate detection probabilities of adult horned (Podiceps auritus) and pied‐billed (Podylimbus podiceps) grebes on the Waterfowl Breeding Population and Habitat Survey (WBPHS) ground component conducted annually each May in the prairie and parkland ecoregions of Canada. Detection probabilities ( ± SE) were higher, more precise, and more consistent through time for horned grebes (0.52 ± 0.06 and 0.44 ± 0.05 in 2010 and 2011, respectively) than for pied‐billed grebes (0.25 ± 0.08 and 0.11 ± 0.05 in 2010 and 2011, respectively). Our results suggest that the ground component of the WBPHS could be used to monitor horned grebes in these ecoregions. Although an active call‐broadcast component would be valuable for obtaining unbiased abundance estimates for horned grebes, such a component would be critical for monitoring pied‐billed grebes. © 2013 The Wildlife Society.

СТІЙКІСТЬ СТРУКТУРИ ВИДОВОГО РІЗНОМАНІТТЯ ОСТРІВНИХ УГРУПОВАНЬ ПТАХІВ

<p>Suggested approach is based on estimation of biodiversity stability that includes quality changes of diversity and number dynamics of bird species in the communities. We took the data from some model islands of Central, Eastern, and Western Sivash; Obitochniy Bay and Molochniy Estuary (Azov Sea basin). We used parameters from island bird communities of colonial breeding waterfowl. The results of analysis suggested that biodiversity stability correlated with biodiversity indices and species evenness index.</p> <p><em>Key words: species diversity, stability, birds, communities.</em></p> <p><strong> </strong></p>

GEESE FATTY ACID COMPOSITION OF BRAIN AND HEART LIPIDS IN HYPO-AND HYPEROXIA

Suggested approach is based on estimation of biodiversity stability that includes quality changes of diversity and number dynamics of bird species in the communities. We took the data from some model islands of Central, Eastern, and Western Sivash; Obitochniy Bay and Molochniy Estuary (Azov Sea basin). We used parameters from island bird communities of colonial breeding waterfowl. The results of analysis suggested that biodiversity stability correlated with biodiversity indices and species evenness index.

Relationships between grazing and waterfowl production in the Canadian prairies

AbstractThe survival of waterfowl nests is positively correlated with the amount of grassland on the landscape, and population growth rates of some waterfowl species (e.g., mallards [Anas platyrhynchos]) are sensitive to nest survival rates. Thus, the effect of actions that alter grassland vegetation physiognomy, such as grazing, on waterfowl production is of interest to waterfowl habitat managers. Additionally, grasslands contribute other ecological goods (e.g., forage for livestock and wildlife) and services (e.g., photosynthesis, carbon sequestration), which can be influenced by grazing practices. We address key uncertainties about the linkages between grazing, vegetation physiognomy, and the survival and density of duck nests at study‐site, field, and nest‐site spatial scales. Using data from 2,554 duck nests found in 434 grazed or idled fields (median field size = 48.0 ha) in the Canadian Prairie Pothole Region between 2002 and 2009, we found that vegetation physiognomy affected nest survival at both the field and nest‐site scales, such that nest survival increased with nest‐site vegetation density and late‐season field vegetation density. Nest survival also responded to early‐season within‐field variation in vegetation height in a quadratic manner, such that survival was greatest in fields with moderate variation in vegetation height. Nest survival was negatively related to the intensity of grazing and to the amount of cropland in the surrounding landscape. Both the abundance of wetlands and the average vegetation height in the field had a positive influence on nest density. Fields idled during the breeding season had greater densities of nests than fields grazed either early or late in the breeding season. Leaving lands idled may be the most effective way to increase both waterfowl nest survival and nest density. When management of upland vegetation is required, we recommend grazing at moderate stocking rates (between 2 and 2.5 animal unit months [AUM]/ha) after the waterfowl breeding season is complete and monitoring vegetative characteristics to ensure they remain suitable to attract nesting waterfowl (e.g., leaving vegetation height >28 cm). Where grazing must be carried out during the breeding season, low to moderate stocking rates should be encouraged as these rates appear to have the least negative impact on both waterfowl nest survival and nest density. These stocking rates also will maintain rangeland in good condition to the long‐term benefit of producers. © 2013 The Wildlife Society.

Dix années de suivi des anatidés nicheurs sur le lac de Sidi Boughaba (Nord-ouest Marocain) : Situation, tendances d’évolution et perspectives de recherche

Ten-year survey of breeding Anatidae of Lake Sidi Boughaba (North-western Marocco) : status, tendencies of change and avenues for future research. A ten years survey of duck species was carried out in the Ramsar site and Important Bird Area (IBA) of Sidi Boughaba. No such survey has ever been conducted before in Morocco to study the change in number of breeding duck species in the country. Overall results have shown the appearance of new breeding species in the site : Red-crested Pochard (Netta rufina), Common Pochard (Aythya ferina) and White-Headed Duck (Oxyura leucocephala). Other species have become more regular like Gadwall (Anas strepera) and Ferruginous Duck (Aythya nyroca) while the vulnerable Marbled Teal (Marmaronetta angustirostris) and the Mallard (Anas platyrhynchos) continue to breed in this wetland with numbers that remain stable though the numbers of females with ducklings are decreasing in these two species. The number of breeding ducks species in this wetland is the highest in Morocco and in the Maghreb. The overall results showed that the numbers of Gadwall, Red-crested Pochard, Common Pochard and Ferruginous Duck are markedly increasing following the same expansion patterns at both regional and Mediterranean levels. The initiation of similar researches on other wetlands is essential to assess the abundance of duck populations and indicate trends of this breeding waterfowl group at larger scales.

Changes in numbers and distribution of breeding waterfowl in the Swedish mountain chain between 1972–1975 and 2009

During 1972–1975, the breeding waterfowl populations of the northern parts of Fennoscandia (south to 65° N in Sweden) were surveyed for the first time. In 2009, a new survey was undertaken in the Swedish part of the mountain chain. Censuses were performed from the air in transects of 5×5 km squares and in special areas. The distribution of the different species was largely similar between the two periods but there were a number of differences on the regional level. Most species had more or less the same population sizes but there were some variation in the different parts of the mountains. Three species showed clear increases between the periods. Cygnus cygnus had the same increase in the mountain chain as in the rest of the country. Melanitta nigra was about four times as common in 2009 compared to the 1970s and Mergus merganser also had higher counts in 2009. Melanitta fusca decreased markedly in the mountain chain as along the coasts.