The mitochondrial genome of Cygnus columbianus, the Whistling Swan.

The nucleotide sequence of the mitochondrial genome of the Whistling Swan, Cygnus columbianus, is reported. Many of the features common to avian mitochondrial genomes are present in C. columbianus and are described here. The gene order is the same as in Gallus gallus. The sequence of this mitochondrial genome allows relationships within the family Anatidae (swans, geese and ducks) to be reconsidered in the light of a large suite of mitochondrial characters. Protein-coding gene sequences of C. columbianus were concatenated to form a supergene, which was analyzed phylogenetically with similar constructs from previously published avian genomes. Relationships within Anatidae and between the Anatidae and the galliform birds were addressed. Three independent phylogenetic methods confirmed traditional classifications and the existence of the Galloanseres clade.     

Biogeographic models of gene flow in two waterfowl of the Australo‐Papuan tropics

There are many large, easy‐to‐observe anseriform birds (ducks, geese, and swans) in northern Australia and New Guinea and they often gather in large numbers. Yet, the structure of their populations and their regional movements are poorly understood. Lack of understanding of population structure limits our capacity to understand source‐sink dynamics relevant to their conservation or assess risks associated with avian‐borne pathogens, in particular, avian influenza for which waterfowl are the main reservoir species. We set out to assess present‐day genetic connectivity between populations of two widely distributed waterfowl in the Australo‐Papuan tropics, magpie goose Anseranas semipalmata (Latham, 1798) and wandering whistling‐duck Dendrocygna arcuata (Horsfield, 1824). Microsatellite data were obtained from 237 magpie geese and 64 wandering whistling‐duck. Samples were collected across northern Australia, and at one site each in New Guinea and Timor Leste. In the wandering whistling‐duck, genetic diversity was significantly apportioned by region and sampling location. For this species, the best model of population structure was New Guinea as the source population for all other populations. One remarkable result for this species was genetic separation of two flocks sampled contemporaneously on Cape York Peninsula only a few kilometers apart. In contrast, evidence for population structure was much weaker in the magpie goose, and Cape York as the source population provided the best fit to the observed structure. The fine scale genetic structure observed in wandering whistling‐duck and magpie goose is consistent with earlier suggestions that the west‐coast of Cape York Peninsula is a flyway for Australo‐Papuan anseriforms between Australia and New Guinea across Torres Strait.     

Phylogenetic relationships based on two mitochondrial genes and hybridization patterns in Anatidae

We produced DNA sequence data from two mitochondrial genes (cytochrome b and the NADH dehydrogenase subunit 2) to reconstruct the phylogenetic relationships among 121 species of the Anseriformes (waterfowls including ducks, geese, swans, the magpie goose and screamers). Phylogenetic analyses converged into a congruent topology and defined several well-supported clades. We calibrated a molecular clock and reconstructed ancestral biogeographical areas using Bayesian inference supporting an austral continental (Gondwanaland) origin of the waterfowls. Ducks, swans and geese might have diversified during the Miocene (23–5 Myr ago) reaching northern distributions in Holarctic and Afrotropical regions. The evolution of hybridization patterns in Anseriformes has been investigated using a cladistic analysis (morphology), which may underestimate or overestimate the phylogenetic divergence among species, or restricted only to ducks. Using a phylogenetic framework, genetic-based distances and a Bayesian time calibration, our data support the hypothesis based on immunological distances of slow rate of appearance of reproductive incompatibilities in waterfowls compared with other vertebrates and the view that these birds may be like frogs in having lost their interspecific hybridization potential more slowly than mammals.     

Agriculture and herbivorous waterfowl: a review of the scientific basis for improved management

Swans, geese and some ducks (Anatidae) are obligate herbivores, many are important quarry species and all contribute to a variety of ecosystem services. Population growth and shifting ranges have led to increasing proximity to man and thus increasing conflicts. We review and synthesize the role of these birds as herbivores on agricultural land (cropland, rotational grassland and pasture) and other terrestrial habitats where conflict with human interests may occur. A bibliographic analysis of peer‐reviewed papers (N = 359) shows that publication activity peaked in 1991–2000 in North America and 2000–2010 in Europe, and has decreased since. Taxonomic and geographical biases are obvious in research to date: Snow Goose Chen caerulescens was the most studied species (N = 98), and Canada Branta canadensis, Barnacle B. leucopsis and Brent geese B. bernicla all featured in more than 40 studies; most studies originated in northwest Europe or North America, very few have been carried out in Asia and European Russia. On the basis of nutrient/energy budgets of herbivorous waterfowl, it is evident that dense single‐species crops (such as rotational grassland, early‐growth cereals and root crops) and spilled grain in agricultural landscapes offer elevated energetic and nutritional intake rates of food of higher quality compared to natural or semi‐natural vegetation. Hence, although affected by seasonal nutritional demands, proximity to roost, field size, disturbance levels, access to water, food depletion and snow cover, agricultural landscapes tend to offer superior foraging opportunities over natural habitats, creating potential conflict with agriculture. Herbivorous waterfowl select for high protein, soluble carbohydrate and water content, high digestibility as well as low fibre and phenolic compounds, but intake rates from grazing varied with goose body and bill morphology, creating species‐specific loci for conflict. Crop damage by trampling and puddling has not been demonstrated convincingly, nor do waterfowl faeces deter grazing stock, but where consumption of crops evidently reduces yields this causes conflict with farmers. Studies show that it is difficult and expensive to assess the precise impacts of waterfowl feeding on yield loss because of other sources of variation. However, less damage has been documented from winter grazing compared to spring grazing and yield loss after spring grazing on grassland appears more pronounced than losses on cereal fields. Although yield losses at national scales are trivial, individual farmers in areas of greatest waterfowl feeding concentrations suffer disproportionately, necessitating improved solutions to conflict. Accordingly, we review the efficacy of population management, disturbance, provision of alternative feeding areas, compensation and large‐scale stakeholder involvement and co‐management as options for resolving conflict based on the existing literature and present a framework of management advice for the future. We conclude with an assessment of the research needs for the immediate future to inform policy development, improve management of waterfowl populations and reduce conflict with agriculture.     

Seasonal variation in nutritional characteristics of the diet of greater white-fronted geese

We studied diet and habitat use of greater white-fronted geese (Anser albifrons) from autumn through spring on their primary staging and wintering areas in the Pacific Flyway, 1979–1982. There have been few previous studies of resource use and forage quality of wintering greater white-fronted geese in North America, and as a consequence there has been little empirical support for management practices pertaining to habitat conservation of this broadly distributed species. Observations of >2,500 flocks of geese and collections of foraging birds revealed seasonal and geographic variation in resource use reflective of changes in habitat availability, selection, and fluctuating physiological demands. Autumn migrants from Alaska arrived first in the Klamath Basin of California and southern Oregon, where they fed on barley, oats, wheat, and potatoes. Geese migrated from the Klamath Basin into the Central Valley of California in late autumn where they exploited agricultural crops rich in soluble carbohydrates, with geese in the Sacramento Valley feeding almost exclusively on rice and birds on the Sacramento–San Joaquin Delta primarily utilizing corn. White-fronted geese began their northward migration in late winter, and by early spring most had returned to the Klamath Basin where 37% of flocks were found in fields of new growth cultivated and wild grasses. Cereal grains and potatoes ingested by geese were low in protein (7–14%) and high in soluble nutrients (17–47% neutral detergent fiber [NDF]), whereas grasses were low in available energy (47–49% NDF) but high in protein (26–42%). Greater white-fronted geese are generalist herbivores and can exploit a variety of carbohydrate-rich cultivated crops, likely making these geese less susceptible to winter food shortages than prior to the agriculturalization of the North American landscape. However, agricultural landscapes can be extremely dynamic and may be less predictable in the long-term than the historic environments to which geese are adapted. Thus far greater white-fronted geese have proved resilient to changes in land cover in the Pacific Flyway and by altering their migration regime have even been able to adapt to changes in the availability of suitable forage crops. © 2010 The Wildlife Society.     

Experimental infections of waterfowl with Sphaeridiotrema globulus (Digenea)

Sphaeridiotrema globulus in experimentally infected mute swans (Cygnus olor), mallard ducks (Anas platyrhynchos) and Canada geese (Branta canadensis) induced ulcerative hemorrhagic enteritis. Sites of infection include the jejunum and ileum. The digeneans ulcerated the intestine. The inflammatory response was primarily lymphocytic with some eosinophils. Severe hemorrhage from damaged submucosal capillaries provided a blood meal for the parasite and caused anemia in the host. Extra-medullary hematopoiesis occurred in the liver, and an erythroid hyperplasia occurred in the bone marrow of infected birds. Infected birds exhibited muscular weakness and died from shock associated with severe blood loss. Mallards and Canada geese were less susceptible to fatal infection than the mute swan as evidenced by survivors in the higher dose groups.     

Lead poisoning in wild waterfowl in Japan

We collected 430 harvested ducks (Anas sp. and Aythya sp.) from nine prefectures in Japan between 1994 and 1997. Fifteen (4%) of 363 birds harvested during and after hunting seasons had one lead pellet each in the proventriculus and gizzard. In addition, 32 (34%) of 93 swans (Cygnus sp.) and two of 14 geese (Anser sp.) found dead from various wetlands had lesions consistent with lead poisoning. One to nine swans suspected of having toxicosis from ingestion of lead shot were found dead each year. Twenty-seven (84%) of the 32 lead-exposured swans were found in Hokkaido Prefecture. We concluded that lead poisoning is still a serious threat to waterfowl in Japan and that there is considerable need for environmental improvement concerning this problem.     

Large-scale patterns of summer and winter bird distribution in relation to farmland type in England and Wales

Over the last 30 yr, the loss of traditional crop rotations and the polarisation of pastoral and arable farming have led to a marked reduction in mixed agriculture in Britain at both the individual farm and the landscape scale. We assess the potential impact of this change on lowland farmland birds by examining the extent to which distributions (as shown by national atlases of summer and winter birds) of different species are associated with arable, pastoral or mixed‐farming landscape types. Relatively few species appeared as either widespread generalists, equally associated across the three broad farmland types, or specialists associated only with one landscape type. Most were associated with two farmland types but distributions showed seasonal differences. During the breeding season there was an approximate ratio of 2:2:1 of species associated with arable, mixed and pastoral landscapes. However, in winter, most species were at highest abundance in mixed farming landscapes. This coincided with a reduction in the number of species associated with pastoral landscapes relative to the breeding season, whereas the number of species associated with arable landscapes remained relatively stable. These patterns are likely to be related to foraging requirements; granivorous birds tended to be associated with arable habitats, which tend to be more seed‐rich, and invertebrate‐feeding species tended to be associated with mixed or pastoral ones, which may be more invertebrate‐rich. The relative importance of mixed landscapes in winter was attributed to seasonal changes in the distribution of some invertebrate feeders, particularly small insectivores (pipits, chats and wagtails), and some of those species considered to be widespread in summer. The results have two important implications for future research. First, most research on farmland birds has, to date, focused on species associated with arable farming during the breeding season. More research is required on species associated with agricultural grasslands, reflecting its importance for farmland birds in Britain, and on the winter ecology of farmland birds in general. These results also emphasise the importance of mixed habitats for farmland birds, particularly in winter, and suggest that further changes in agricultural practices causing reduction in habitat diversity will be detrimental for the farmland bird community. However, widespread benefits may be derived from small scale measures that increase habitat diversity within farmland, for example field margin management options within agri‐environment schemes and support for traditional farming practices in some Environmentally Sensitive Areas.     

The fine structure of granules in eosinophil leucocytes from aquatic and terrestrial birds

The ultrastructure of eosinophil granules from various aquatic and terrestrial birds has been described. Granules of three basic types were found. The first had a crystalline internum and was found only in the order Anseriformes, which included the black-necked screamer, ducks, geese and swans. The crystals occurred in three morphological forms. The second and least common granule examined contained a non-crystalline internum which was either homogeneous or composed of microfilaments or microtubules. The largest and most common group of birds had a homogenous granule with no internum shown. Homogeneous granules occurred less frequently than did those with interna.     

The fight against new types of influenza virus

In 1997, during an outbreak in chickens in Hong Kong the avian H5N1 influenza virus crossed the species barrier and infected 18 people, of which 6 cases were fatal. The virus also infected wild birds and continued to circulate and mutate in geese and ducks in southeastern China. Since this occurrence, new antigenic variants that are highly pathogenic for humans as well as wild, domestic, and exotic waterfowl continue to appear in Hong Kong. This virus is spreading across Asia, and is encroaching upon Europe and other continents. Wild birds are now considered as the main reservoir of H5N1 virus. Humans become infected with this H5N1 virus usually via close contact with infected birds or a highly contaminated environment. The very low transmissibility of this virus prevented further person-to-person dissemination in spite of the complete absence of immunity in the human population to H5N1 viruses. Viruses of the H5N1 subtype are characterized by an exceptionally high pathogenicity for humans. The cause of the viral virulence is not known so far; however, several virulence factors are considered. The unprecedented capability of H5N1 viruses to kill humans intensifies the concern about its pandemic potential with catastrophic consequences. The effectiveness of existing antivirals as well as vaccines for humans and birds are reviewed.     

Spatial, temporal, and species variation in prevalence of influenza A viruses in wild migratory birds

Although extensive data exist on avian influenza in wild birds in North America, limited information is available from elsewhere, including Europe. Here, molecular diagnostic tools were employed for high-throughput surveillance of migratory birds, as an alternative to classical labor-intensive methods of virus isolation in eggs. This study included 36,809 samples from 323 bird species belonging to 18 orders, of which only 25 species of three orders were positive for influenza A virus. Information on species, locations, and timing is provided for all samples tested. Seven previously unknown host species for avian influenza virus were identified: barnacle goose, bean goose, brent goose, pink-footed goose, bewick's swan, common gull, and guillemot. Dabbling ducks were more frequently infected than other ducks and Anseriformes; this distinction was probably related to bird behavior rather than population sizes. Waders did not appear to play a role in the epidemiology of avian influenza in Europe, in contrast to the Americas. The high virus prevalence in ducks in Europe in spring as compared with North America could explain the differences in virus-host ecology between these continents. Most influenza A virus subtypes were detected in ducks, but H13 and H16 subtypes were detected primarily in gulls. Viruses of subtype H6 were more promiscuous in host range than other subtypes. Temporal and spatial variation in influenza virus prevalence in wild birds was observed, with influenza A virus prevalence varying by sampling location; this is probably related to migration patterns from northeast to southwest and a higher prevalence farther north along the flyways. We discuss the ecology and epidemiology of avian influenza A virus in wild birds in relation to host ecology and compare our results with published studies. These data are useful for designing new surveillance programs and are particularly relevant due to increased interest in avian influenza in wild birds.     

Overcompensation and grazing optimisation in a swan–pondweed system?

1. The general notion is that negative effects of vertebrate herbivores on water plants, which play a key role in freshwaters, prevail, and that positive feedbacks of herbivores on plants are insignificant. 2. The most likely systems to find such positive feedbacks are those in which herbivores exert strong feeding pressures on plants during part of the year. Previous theoretical work has suggested that compensatory production occurs when migratory Bewick's swans forage on tubers of fennel pondweed. As a corollary, the swans can exploit the tubers down to a level that maximises their tuber yield. 3. In order to test these hypotheses, I measured pondweed tuber biomass on three occasions per year (just before and after foraging, and just before tuber sprouting) in three consecutive years. The 17 sampling sites in the Lauwersmeer (the Netherlands) were classified according to their silt content and water depth. Within four silt‐depth classes, I predicted for each year tuber biomass production and, from that, the optimum foraging threshold that would result in the maximum tuber biomass yield. 4. Water depth did not affect tuber production, and silt content only did in one of the 3 years. In accordance with overcompensation predictions, tuber production was higher at plots with moderate foraging pressures than at plots with little or no grazing. However, the winter and summer conditions following the swan foraging had large unpredictable effects on tuber mortality and production. 5. These results indicate that overcompensation by fennel pondweed occurs and that Bewick's swans are generally able to profit from it, albeit without fine‐tuning of the foraging threshold to the yield.     

Effects of agricultural change on abundance, fitness components and distribution of two arctic-nesting goose populations

Intensification of agriculture since the 1950s has enhanced the availability, competitive ability, crude protein content, digestibility and extended growing seasons of forage grasses. Spilled cereal grain also provides a rich food source in autumn and in winter. Long‐distance migratory herbivorous geese have rapidly exploited these feeding opportunities and most species have shown expansions in range and population size in the last 50 years. Results of long‐term studies are presented from two Arctic‐breeding populations, the Svalbard pink‐footed goose and the Greenland white‐fronted goose (GWFG). GWFGs have shown major habitat shifts since the 1950s from winter use of plant storage organs in natural wetlands to feeding on intensively managed farmland. Declines in local density on, and abandonment of, unmodified traditional wintering habitat and increased reproductive success among those birds wintering on farmland suggest that density‐dependent processes were not the cause of the shift in this winter‐site‐faithful population. Based on enhanced nutrient and energy intake rates, we argue that observed shifts in both species from traditionally used natural habitats to intensively managed farmland on spring staging and wintering areas have not necessarily been the result of habitat destruction. Increased food intake rates and potential demographic benefits resulting from shifts to highly profitable foraging opportunities on increasingly intensively managed farmland, more likely explain increases in goose numbers in these populations. The geographically exploratory behaviour of subdominant individuals enables the discovery and exploitation of new winter feeding opportunities and hence range expansion. Recent destruction of traditional habitats and declines in farming at northern latitudes present fresh challenges to the well being of both populations. More urgently, Canada geese colonizing breeding and moulting habitats of white‐fronted geese in Greenland are further affecting their reproductive output.     

Incidence of embedded shotgun pellets and inferred hunting kill amongst Russian/Baltic barnacle geese Branta leucopsis

X-rays of wild caught barnacle geese from the Russian/Baltic population were taken in Denmark in the springs of 2009 and 2011 to determine the incidence of embedded shotgun pellets and to estimate the annual hunting kill. On average, 13 % of adult geese (n?=?212) and 6 % of first year geese (n?=?35) examined contained pellets in their tissue. Assuming that these birds represented a random sample, extrapolation to the entire population of c. 770,000 individuals indicates that 96,000 barnacle geese carry embedded pellets. Based on the assumption that the ratio between the number of birds with embedded shot and the total number of birds harvested per season is similar to that found in pink-footed geese Anser brachyrhynchus (recorded as 3.6:1 during 1990–1996 and 1.7:1 during 2009–2011), the annual kill of barnacle geese was estimated at 26,300–58,300 birds. The Russian/Baltic barnacle geese are protected from hunting on their winter quarters (The Netherlands, Germany and Denmark), but are quarry in Russia and are shot under license to protect agricultural crops in Estonia, Germany, Sweden and Denmark (amounting to a total of c. 1,800–3,000 geese shots per year). Barnacle geese are known to be shot illegally (accidentally and deliberately) along the migration route, but in the absence of Russian bag statistics, the contribution of illegal hunting to the overall harvest cannot be substantiated. Although the population is currently increasing at an annual rate of 8 %, the indirectly estimated hunting pressure (3–7 %) is not insubstantial and should be taken into account in future population management models.     

Large-scale land use change may explain bird species declines in semi-natural areas: the case of Black Grouse population collapse in Lower Saxony, Germany

Farmland birds in Central Europe have been heavily declining in past decades. Among them are many ground-nesting species, adapted to semi-natural but secondary habitats. A vivid example is the Black Grouse (Tetrao tetrix) in the lowlands of north-western Germany, the Netherlands and Denmark, where the species′ populations experienced dramatic declines between the 1950s and 1970s. One explanation for these ubiquitous population declines might be large-scale changes in agricultural land use and land cover. We investigated several agricultural indices at three hierarchic administrative scales in parts of the federal state Lower Saxony, Germany, and related changes in these indicators with the Black Grouse declines. Land cover proportions remained relatively stable whereas indices of agricultural intensification heavily increased from 1952 to 1973. Multiple regression showed that change in farmland area was the best predictor of the trends across scales. Correlates of Black Grouse abundance were moor at the medium scale and pasture cover and fallow land at the smallest scale. Our results support the hypothesis that Black Grouse population dynamics in the lowlands of Central Europe were affected by land use changes. They show that Black Grouse populations in Central Europe were dependent upon extensive farming and may provide additional explanation where underlying factors on the habitat scale cannot fully explain the declines.     

若尔盖湿地水鸟资源季节变化

若尔盖湿地位于青藏高原东缘,是我国最大的高寒泥炭湿地之一。2010年从3月至12月,对若尔盖湿地水鸟种类、数量和分布进行了较为系统的调查。共记录到48种26 050只水鸟,隶属于6目12科,其中雁鸭类水鸟最多,共统计到21 408只,占水鸟总数的82.2%。3月和10月是若尔盖湿地水鸟数量的高峰期;11月是低谷期,主要是由于水鸟的迁离和越冬水鸟尚未到达的缘故。尕海是若尔盖湿地的重要组成部分,全年物种数和水鸟数量占了整个若尔盖湿地较大的比例。卫星跟踪的结果表明,青海湖斑头雁(Anser indicus)在若尔盖湿地与云南和贵州的越冬水鸟汇合,因此加强若尔盖湿地禽流感的防控是非常重要的。     

Avian cholera exposure and carriers in greater white-fronted geese breeding in Alaska, USA

We conducted a 3-yr study (2001-03) on greater white-fronted geese (Anser albifrons frontalis) breeding in Alaska, USA, to determine the exposure of this population to Pasteurella multocida and the potential role of these birds as disease carriers. We tested sera from nearly 600 adult geese for antibodies to P. multocida serotype 1. We found a low prevalence (<5%) of positive antibodies in adult geese, and based on the short duration of detectable antibodies, these findings indicate recent infection with P. multocida. Prevalence was similar to serologic results from both breeding and wintering lesser snow geese. We also collected oral (n=1,035), nasal (n=102), and cloacal (n=90) swab samples to determine the presence of avian cholera carriers in this population. We were unable to isolate P. multocida serotype 1 from any of the birds sampled. Based on comparison with other waterfowl species, we concluded that these geese may be exposed to avian cholera during the winter or spring migration but are unlikely to play a significant role as carriers of the bacterium causing avian cholera.     

Effects of seasonality,isolation and patch quality for habitat selection processes by mute swans Cygnus olor in a fishpond landscape

Foragers in patchy environments do not only select sites for single patch characteristics, but also have to consider the local environment of such patches. We studied habitat selection by mute swans Cygnus olor in a wide and heterogeneous fishpond region (the Dombes, eastern France). In this study, we considered fishpond isolation, resource quality within fishponds and breeding status of mute swans during both summer and winter. Mute swans did not select aquatic habitat randomly within the landscape. During summer, the population spread preferentially on medium to large fishponds, in subregions with numerous or closely related waterbodies, without generating a clumped distribution of birds. In addition to a positive effect of local fishpond number (2 km radius), breeding birds also responded positively to fishpond size. Non‐breeders selected fishponds mainly according to their size. Intraspecific territoriality did not appear to limit the presence of non‐breeders (i.e. moulting flocks), since both breeders and non‐breeders could coexist on the larger fishponds. During winter, mute swans used medium to large reflooded fishponds after summer drainage. The surrounding aquatic environment of fishponds played a minor role in determining flocking, compared to actual patch quality. Flocking occurred on large fishponds that had reflooded after having dried the summer before, whatever the agricultural cultivation practiced in the summer following drainage. The results suggest that geographical aspects should be taken into account when considering the potential impact of this expanding species within such ecosystems, and also in more general management policies dealing with aquatic habitats for waterbird populations.     

Exceptional avian herbivores: multiple transitions toward herbivory in the bird order Anseriformes and its correlation with body mass

Herbivory is rare among birds and is usually thought to have evolved predominately among large, flightless birds due to energetic constraints or an association with increased body mass. Nearly all members of the bird order Anseriformes, which includes ducks, geese, and swans, are flighted and many are predominately herbivorous. However, it is unknown whether herbivory represents a derived state for the order and how many times a predominately herbivorous diet may have evolved. Compiling data from over 200 published diet studies to create a continuous character for herbivory, models of trait evolution support at least five independent transitions toward a predominately herbivorous diet in Anseriformes. Although a nonphylogenetic correlation test recovers a significant positive correlation between herbivory and body mass, this correlation is not significant when accounting for phylogeny. These results indicate a lack of support for the hypothesis that a larger body mass confers an advantage in the digestion of low‐quality diets but does not exclude the possibility that shifts to a more abundant food source have driven shifts toward herbivory in other bird lineages. The exceptional number of transitions toward a more herbivorous diet in Anseriformes and lack of correlation with body mass prompts a reinterpretation of the relatively infrequent origination of herbivory among flighted birds.     

Foraging ecology, fluctuating food availability and energetics of wintering brent geese

Changing energy requirements and dramatic shifts in food availability are major factors driving behaviour and distribution of herbivores. We investigate this in wintering East Canadian High Arctic light-bellied brent geese Branta bernicla hrota in Northern Ireland. They followed a sequential pattern of habitat use, feeding on intertidal Zostera spp. in autumn and early winter before moving to predominantly saltmarsh and farmland in late winter and early spring. Night-time feeding occurred throughout and made a considerable contribution to the birds' daily energy budget, at times accounting for >50% of energy intake. Nocturnal feeding, however, is limited to the intertidal, possibly because of predation risk on terrestrial habitat, and increases with moonlight. The amount of Zostera spp., declined dramatically after the arrival of birds, predominantly, but not entirely, due to consumption by the birds. Birds gained fat reserves in the first 2 months but then this was dramatically lost as their major food source collapsed and their daily energy intake declined. Single birds consistently fared worse than paired birds and pairs with juveniles fared better than those without suggesting a benefit of having a family to compete for food. Many birds leave the Lough at this time of reduced Zostera spp. for other sea inlets in Ireland but some remain. Body condition of the latter gradually improved in early spring and reflected a heavy reliance on terrestrial habitats, particularly farmland, to meet the birds' daily energy requirements. However, even in the period immediately before migration to the breeding ground, the birds did not regain the amount of abdominal fatness observed in November. The dramatic changes in available food and requirements of the birds drive the major changes seen in foraging behaviour as the birds evade starvation in the wintering period.