Feeding ecology of barnacle geese on their spring staging grounds in northern Iceland

The distribution and abundance of barnacle geese, Branta leucopsis. staging in northern Iceland was determined in May 1987 and 1994 A similar proportion of the total population (70%) was located in the two years The distribution differed between the two years, with a higher proportion of the geese found in more westerly sites in 1994 Over 80% of records of birds feeding were on improved agricultural pasture though this made up only 47% of the available feeding habitat Some geese fed on riverine and coastal grasslands but this was in a much smaller proportion than the availability of these habitats The number of geese using a site was positively correlated with the area of improved pasture Birds fed intensively through the day, suggesting that the area is important for the accumulation of nutrient stores No differences in habitat use or feeding behaviour were found between 1987 and 1994     

Identifying important bird habitats in a sub-arctic area undergoing rapid land-use change

Capsule Habitats in lowland South Iceland sustain bird populations of international importance, with highest densities in wet habitats.

Aims In areas important for biodiversity there is an urgent need to assess large-scale variation in the biodiversity value of habitats to inform management. We carried out a large-scale survey to assess the conservation value of sub-arctic, Icelandic bird habitats.

Methods Bird counts were carried out on 200 transects in the five most common vegetated habitat types in South Iceland. Based on these counts, breeding bird density and diversity were compared between habitats and total population sizes of common species in these habitats were calculated.

Results Overall, eight species (seven waders and Meadow Pipit) composed over 95% of all birds counted. The combined density of those species exceeded 275 birds/km² in all habitats. The two wettest habitat types had the highest density of birds.

Conclusion Wet habitats in lowland South Iceland held particularly high densities of breeding birds, notably waders, which constitute populations of international importance. Wet habitat types are generally of higher value for more species, than dryer ones.     

DISTRIBUTION AND NUMBERS OF COASTAL WADERS (CHARADRII) IN THE SOUTHWESTERN CAPE,SOUTH AFRICA,SUMMER 1975–76

Summers, R. W., Cooper, J. & Pringle, J. S. 1970. Distribution and numbers of coastal waders (Charadrii) in the southwestern Cape, South Africa, summer 1975–76. Ostrich 48: 85–97. A survey of the distribution and numbers of waders (suborder Charadrii) in the coastal regions of the southwestern Cape was conducted from November 1975 to February 1976. Forty-four coastal wetlands and 49 sections of coastline were visited between the Olifants and Groot-Brak rivers. The estimated total wader population was 119 008 of which 102 841 (86,4%) were Palaearctic migrants. Langebaan Lagoon and the Berg estuary supported the largest numbers. The Curlew Sandpiper Calidris ferruginea and Sanderling Calidris alba were the most numerous species. The abundance of waders was greater on west coast shores than along the south coast.     

Foraging of a Small Planktivore (<Emphasis Type="Italic">Pseudorasbora parva</Emphasis>: Cyprinidae) and its Behavioral Flexibility in an Artificial Stream

The loss of feeding areas may pose a threat to many wintering waders because increased competition arising from reduced foraging space may force birds either to emigrate or to die. This has been demonstrated to occur in northwest European estuaries, but virtually no studies have been performed in the estuaries of southern Europe, where the loss of supratidal habitats (salines and saltmarshes), rather than intertidal habitats, are currently the main threat to waders’ habitats. If these habitats are lost, waders may be forced to move to the intertidal mudflats, perhaps increasing competition between individuals and ultimately leading to starvation or emigration. We tested this hypothesis in the Mondego estuary, a small estuary on Portugal’s west coast, which is presently under heavy human pressure. We used indirect methods to test for the occurrence of both components of intra-specific competition: interference and prey depletion. We found no evidence that either interference or depletion competition was occurring at present, either on the mudflats or in the salines. Overall, the results suggest that the intertidal mudflats may still be able to accommodate birds displaced from the destroyed supratidal salines, but modelling is required to predict the effect that the combined loss of feeding area and foraging time that this would entail would have on their fitness, and thus numbers.     

Spatial and temporal feeding segregation of two Icelandic goose species during the spring pre-nesting period

The pre-nesting feeding behaviour of greylag Anser anser and pink-footed geese A brachyrhynchus was studied on agricultural land at low altitude in southern Iceland from 10 April to 8 May 1990 Greylag geese were already present on 12 April increased to 4580 birds by 24 April, but declined to 1300 by 3 May Pink-footed geese arrived around 20 April and numbers continued to increase to a peak count of 11340 on 3 May Over 60% of greylag geese initially used stubble fields on the coast where this habitat was most frequent, but increasingly resorted to grassland and wetland habitats during late April Later-arriving pink-feet predominantly used managed grassland, away from coastal areas At inland grassland sites, greylag numbers peaked on 20 April, pink-feet m early May The early exploitation by greylags was associated with grass growth initiated under protective snow-patches Greylags spent 90 times more time feeding within 1 m of snow patches with enhanced grass growth than expected by chance and their feeding rates near snow patches were faster and their step rates slower than further away By early May, grass growth was uniform and, although snow-patches persisted, no difference in forage quality, goose feeding rates or step rates could be detected It is concluded that, in spring 1990 at least, habitat segregation during spring migration in southern Iceland minimised competition between these two closely related goose species within the same geographical area In areas where both species exploit the same habitat, a two week difference m timing of breeding (and hence phenology of migration) further assures minimal overlap in feeding exploitation     

Survival of the fattest: body stores on migration and survival in red knots Calidris canutus islandica

Severe summer weather in Greenland and Arctic Canada in 1972 and 1974 caused very poor breeding success and elevated adult mortality in red knots Calidris canutus islandica. We show that those individual knots that are known to have survived these summers were in better than average nutritional condition shortly before departure from their late spring staging area in west Iceland. The condition index of previously banded or subsequently recovered birds captured in Iceland was positively related to the number of summers they were known to have survived. Body stores carried from the last spring staging area to the breeding grounds appear to offer Arctic-breeding shorebirds significant selective advantages: they are used for physical transformation from migration to breeding condition, and in years when weather is difficult may enable survival after arrival on the breeding grounds.     

Changes in the waterbird populations of the Oosterschelde (SW Netherlands) as a result of large-scale coastal engineering works

Between 1982 and 1987, the construction of a storm-surge barrier and two secondary dams in the eastern and northern parts of the Oosterschelde/Krammer-Volkerak area resulted in the loss of 33% of the 170 km² of intertidal area in the estuary. Consequences for non-breeding waterbirds were evaluated on the basis of monthly high-tide counts during five seasons before and three seasons after the construction period.In the entire Oosterschelde/Krammer-Volkerak area, numbers of wintering waders decreased but those of ducks increased. Peak numbers and total number of bird-days changed little, but the seasonal pattern shifted from a midwinter maximum to a peak in autumn.In the Oosterschelde (excluding the Krammer-Volkerak), where 17% of the tidal flats disappeared, species feeding mainly on open water remained stable or increased. Species dependent on intertidal areas for foraging (mainly waders and dabbling ducks) generally decreased. Total density of intertidal foragers decreased slightly. In most intertidal species, the Oosterschelde wintering population showed a stronger decrease, or smaller increase, than was shown during the same period by numbers in Britain and Ireland which were taken as an index of the total W-European winter populations. Changes varied considerably between species, and were correlated with their distribution within the estuary. Species concentrated in the eastern sector, where most habitat loss occurred, declined more than species with a more westerly distribution.Results indicate that intertidal foragers forced to move from the enclosed parts of the estuary were not generally able to settle into the remaining intertidal areas. Both dispersal to adjacent areas (mainly by dabbling ducks) and mortality during severe winter weather (in some wader species) may have contributed to the declines. Populations of intertidal foragers apparently were (and consequently still are) close to carrying capacity, and further changes in capacity, as foreseen from geomorphological changes still under way in the estuary, are likely to be reflected in bird populations.Numbers of waders moulting in the Oosterschelde in late summer declined strongly compared to numbers in other seasons. Increased disturbance due to recreational activities may have played a role during this time of the year.     

The impact of macroalgal blooms on the use of the intertidal area and feeding behaviour of waders (Charadrii) in the Mondego estuary (west Portugal)

The present paper examined the possible impact of macroalgal blooms, among other influential factors, on prey abundance and availability to waders, assessing the consequences for feeding behaviour and for the specific patterns of use of the intertidal areas by these birds when macroalgal mats become dense and contiguous covering large areas of the Mondego estuary (west Portugal). Three representative microhabitats were chosen in intertidal flats to control and evaluate the effects of various factors on waders. This study shows that foraging waders did not seem to be indifferent to the effects of some biological factors, sediment characteristics and epistructures when selecting feeding microhabitats. Overall, the results suggest that the predominant and constant negative effects on specific patterns of use of the intertidal sub-areas by the majority of waders were determined by two main factors: gull perturbation and macroalgal biomass. The macroalgal blooms assumed, by their persistence over a period of several months, a different magnitude of effect when compared with sporadic factors such as gull presence. Contrary to the effects on distribution, macroalgal blooms do not influence negatively the feeding behaviour parameters considered. Moreover, we were unable to prove that the presence of macroalgae on the sediment was pernicious to the wader prey organisms, perhaps because the total amount of the area of the estuary affected by weed during the study period never exceeded 36 % and was surrounded by important algal-free areas that ensured a healthy prey population. Nevertheless, on the long-term, an increase of dense and contiguous macroalgal mats due to the progressive eutrophication of the Mondego estuary, covering large areas of the intertidal flats, may affect directly or indirectly all wader species.     

Indirect effects of lemming cycles on sandpiper dynamics: 50 years of counts from southern Sweden

The bird-lemming hypothesis postulates that breeding success of tundra-nesting geese and waders in Siberia follows the cyclic pattern of lemming populations, as a result of predators switching from lemmings to birds when the lemming population crashes. We present 50 years of data on constant-effort catches of red knot Calidris canutus and curlew sandpiper C. ferruginea at an autumn migratory stopover site (Ottenby) at the Baltic Sea, supplemented with literature data on winter censuses of dark-bellied brent goose Branta b. bernicla and white-fronted goose Anser albifrons in northwestern Europe, and waders in Germany and Southern Africa. Number and proportion of juveniles in these bird populations (both our own and literature data) were compared with an index of predation pressure (calculated from the abundance of lemmings on the Taimyr peninsula), and climate indices for the North Eurasia and the North Atlantic regions. The index of predation pressure correlated significantly with the number of juveniles of red knot and curlew sandpiper, but not with number of adults. Also, this index correlated with the reproductive performance of geese and waders reported in the literature. Fourier analysis revealed a significant deviation from random noise with the maximum spectral density at the period length of 3 years for number of juvenile red knots and curlew sandpipers captured at Ottenby, abundance of lemmings, reproduction in arctic fox Alopex lagopus, and reproductive performance in geese on the Siberian tundra. Also, the date of passage at Ottenby for adult red knot and curlew sandpiper showed a spectral density peak at a period length of 3 years, the latter species also showing a peak at a period length of 5-6 years. Passage dates for adult red knot and curlew sandpiper were earlier in years of high predation pressure compared with years of low predation pressure. The fluctuations in reproductive success of the studied Siberian goose and wader species appear to be primarily influenced by biotic factors in the breeding area, rather than by abiotic factors, such as climate oscillations. Annual variations in migratory arctic bird populations may have far reaching effects in habitats along their migration routes and in their wintering areas. We suggest a link between lemming cyclicity in the Northern Hemisphere and predation pressure on Southern Hemisphere benthos, in which the signal is carried between continents by long distance migrating waders.     

Population estimates,trends and habitat associations of breeding Lapwing Vanellus vanellus,Curlew Numenius arquata and Snipe Gallinago gallinago in Northern Ireland in 1999

Capsule Declines in the breeding populations of Snipe, Lapwing and Curlew were recorded between April and June 1999 and compared with previous estimates in 1987.

Aims To compare populations of non-coastal breeding waders between 1987 and 1999.

Methods In 106 2 km × 2 km square tetrads, observers recorded the number of breeding pairs of waders and habitat details on 1:10 000 scale maps.

Results A significant decline of c. 60% for Lapwing and Curlew, and a non-significant decline of 30% for Snipe was recorded over 12 years. Concentrations of these species were found in County Tyrone, but Counties Antrim, Down and Armagh supported few breeding pairs of any species. Very few pairs of any species were recorded on improved grassland despite its widespread availability.

Conclusion A successful conservation strategy for these species must address the wider countryside and not just key sites. Intensive pastoral farming in upland and lowland areas and activities such as drainage and peat extraction will further reduce the suitability of open habitats for these wader species.     

Patterns of Spatial and Temporal Distribution of Humpback Whales at the Southern Limit of the Southeast Pacific Breeding Area

Understanding the patterns of spatial and temporal distribution in threshold habitats of highly migratory and endangered species is important for understanding their habitat requirements and recovery trends. Herein, we present new data about the distribution of humpback whales (Megaptera novaeangliae) in neritic waters off the northern coast of Peru: an area that constitutes a transitional path from cold, upwelling waters to warm equatorial waters where the breeding habitat is located. Data was collected during four consecutive austral winter/spring seasons from 2010 to 2013, using whale-watching boats as platforms for research. A total of 1048 whales distributed between 487 groups were sighted. The spatial distribution of humpbacks resembled the characteristic segregation of whale groups according to their size/age class and social context in breeding habitats; mother and calf pairs were present in very shallow waters close to the coast, while dyads, trios or more whales were widely distributed from shallow to moderate depths over the continental shelf break. Sea surface temperatures (range: 18.2–25.9°C) in coastal waters were slightly colder than those closer to the oceanic realm, likely due to the influence of cold upwelled waters from the Humboldt Current system. Our results provide new evidence of the southward extension of the breeding region of humpback whales in the Southeast Pacific. Integrating this information with the knowledge from the rest of the breeding region and foraging grounds would enhance our current understanding of population dynamics and recovery trends of this species.     

江苏盐城黑紫鸥（Larus saundersi）繁殖微生境的选择

1999～2001年春夏对江苏盐城国家级自然保护区黑嘴鸥的繁殖微生境进行了调查,黑嘴鸥的繁殖生境包括碱蓬群落（Suaeda glauca）、獐毛群落（Aeluropus littoralis）和大米草群落（Spartina anglica）,通过生境可获得性与可利用性分析,得知黑嘴鸥营巢对碱蓬生境具有正选择性,对獐毛和大米草生境具有负选择性。对繁殖微生境选择研究的结果表明,黑嘴鸥繁殖微生境具有以下特征：植被高度5～25cm,植被盖度20%～60%,底栖生物量大于300g/m^2,距水源距离500～1000m,距人类活动干扰距离大于500m,滩涂开发和人为活动是影响盐城地区黑嘴鸥繁殖微生境选择的重要因素。本文对黑嘴鸥繁殖栖息地的保护和管理提出了一些建议。     

The decline of a population of farmland breeding waders: a twenty-five-year case study

Capsule: Changes in sward height, driven by changes in management, were associated with a large decline in a population of farmland breeding waders.

Aims: To examine the relationship between changes in habitat and numbers of breeding wader on an area of Scottish farmland over the last 25 years.

Methods: Nesting waders in a core survey area of 7.5?km² were monitored annually from 1990 to 2015. An additional 10.3?km² were monitored less frequently. Habitat characteristics of each field were recorded and breeding success by Lapwing determined in a sample of fields.

Results: All species showed large declines over the study period, Oystercatcher Haematopus ostralegus by 95%, Lapwing Vanellus vanellus by 88%, Curlew Numenius arquata by 67% and Redshank Tringa totanus by 87% from peaks of 125, 365, 57 and 53 pairs, respectively. Changes in spring sward height, considered to be due to changes in crop type, were associated with changes in the numbers of breeding waders over time. Productivity by a sample of Lapwings was unchanged through the study period.

Conclusion: Short swards, especially bare till, in spring appear to have been important in contributing to the maintenance of an assemblage of breeding waders in mixed arable-pasture farmland. The decline appeared greater than could be accounted for by losses of preferred habitats alone.     

RADAR TRACKS OF PALAEARCTIC WADERS DEPARTING FROM THE COAST OF GHANA IN SPRING

During the northern spring of 1970 and 1971, wader departures were tracked by radar from saltpans on the coast of Ghana near Accra. All but one of the departures headed northeast, and none were directed along the coast. There was a statistically significant difference between the mean heading of April departures (28°± 10°), and May and June departures (41°± 14°). Projected on great circles, all headings were directed towards the known breeding ranges of the wader species wintering at the saltpans.
In ten species, the dates of the first returning birds to the saltpans in 1966, 1968 and 1970 were about three weeks earlier than dates recorded in Senegal. It is likely that those reaching Senegal follow a coastal route, whereas waders wintering at the coast of Ghana and eastwards to Nigeria evidently make a crossing of the Sahara both in autumn and spring.     

Population decline in the spoon-billed sandpiper (<Emphasis Type="Italic">Eurynorhynchus pygmeus</Emphasis>) in northern Chukotka based on monitoring on breeding grounds

The spoon-billed sandpiper is endemic of the northern Russian Far East and one of the rarest wader species in the world. During a field survey (summer 2002) of the coast of Kolyuchinskaya Bay and in lagoons located to the east, it was discovered that the species breeding population has declined by 3–5 times since the 1970s and amounted to only 42–50 breeding pairs. The reasons for this decline are uncertain. They seem to occur outside the breeding grounds, on staging or wintering areas in South Eastern Asia. The breeding productivity of the spoon-billed sandpiper is relatively low, but it did not decrease in recent decades. The breeding success in 2002 was higher than in the 1980s; however, it was still about half of the minimum level necessary to keep the local breeding population stable. Annual survival of the spoon-billed sandpiper is about 5–15% lower than in several other small Calidridinae waders. An increased mortality rather than decreased productivity appears to be responsible for the general decline of the spoon-billed sandpiper population. In the early 2000s, its total world population was estimated at 350–500 breeding pairs. The estimate of the spoonbilled sandpiper population obtained by Flint and Kondratyev (1977) is likely an overestimate.     

渤海湾春秋迁徙期鸻形目鸟类多样性及石油污染的影响

本文报道了春秋迁徙期渤海湾鸻形目鸟类的生境、种类和密度,对各样区的多样性指数和均匀度指数进行了计算和分析,并对石油污染的影响进行了探讨。     

Shifting nonbreeding distributions of migratory fauna in relation to climatic change

The distributions of eight out of nine common species of waders (Charadrii) overwintering on UK estuaries have changed in association with recent climate change. These birds represent a high proportion of various populations from breeding grounds as far apart as Greenland to the west to high‐arctic Russia to the east. During warmer winters, smaller proportions of seven species wintered in south‐west Britain. The distributions of the smaller species show the greatest temperature dependence. The opposite was found for the largest species and no relationship was found for a particularly site‐faithful species. In north‐west Europe, the winter isotherms have a broadly north to south alignment, with the east being colder than the west. The average minimum winter temperatures across the UK having increased by about 1.5°C since the mid‐1980s, the temperatures on the east coast during recent winters have been similar to those of the west coast during the mid‐1980s. On average, estuaries on the east and south coasts of Britain have muddier sediments than those on the west coast and thus support a higher biomass of the invertebrate prey of waders. We suggest that, with global climatic change, the advantage gained by waders wintering in the milder west to avoid cold weather‐induced mortality is diminished. Consequently, more choose to winter in the east and thus benefit from better foraging opportunities. The implications of these results are considered in terms of a site‐based approach to wildlife protection used in Europe and elsewhere.     

Earlier spring staging in Iceland amongst Greenland White-fronted Geese <Emphasis Type="Italic">Anser albifrons flavirostris</Emphasis> achieved without cost to refuelling rates

Greenland White-fronted Geese wintering in Ireland and Britain stage for 3 weeks in Iceland in spring before migrating onwards to breeding areas in west Greenland. The geese now depart their wintering quarters 12–15 days earlier than in 1973 because they attain necessary fat stores earlier than in previous years. Icelandic temperatures at critical midway staging areas have shown no significant change since 1973, creating a potential mismatch in food availability along the migratory route. Greenland White-fronted Geese have shifted from consuming below-ground plant storage organs in Iceland in spring to grazing managed hayfields created since the 1950s where fresh grass shoot growth occurs despite sub-zero temperatures, when traditional natural foods are physically inaccessible to staging geese due to frozen substrates. Rates of fat accumulation (measured by field scores of abdominal profiles) and mass change (measured in captured geese) were the same in the springs of 1997, 1998 and 1999 as in that of 2007 when the migration episode was 10 days earlier. Hence, earlier arrival in Iceland in 2007 did not occur at cost to refuelling rates there. The shift to acquiring energy from artificial grasslands has enabled Greenland White-fronted Geese to arrive in Iceland earlier, but has apparently not impaired their ability to accumulate fat reserves required for onwards migration, which occurs at the same rate, only earlier in the spring.     

TRENDS IN THE INSHORE RIGHT WHALE POPULATION OFF SOUTH AFRICA, 1969–1987

Results of annual aerial surveys of the right whale population along the southern coast of South Africa from 1971 to 1987 are analysed. About 91.5% of cows with calves and 82% of unaccompanied adults on the South African coast in spring are found within the standard survey area, with some indications that the range is expanding up the west coast. In the nearshore region, most right whales (90%) are found within 1.85 km, and all cows with calves within 0.93 km, of the coast. Within the standard survey area, specific areas of concentration can be predictably identified, both for cows with calves and unaccompanied adults. Although total counts (and counts expressed per hour flown) have increased overall, by a best estimate of 6.8% (95% CL 4.6, 9.0) per year from 1971 to 1987, some concentration areas for both classes have failed to show an increase over the same time period. Photographic flights since 1979 have permitted the movements of individually identified adult females to be monitored between successive calves. In at least one concentration area for which no overall increase between 1971 and 1987 was apparent (Mossel Bay), a large net emigration rate was found, nearly all of which involved a shift to the main nursery area to the west, off De Hoop. Reasons for the dissimilar dynamics of different concentration areas are not yet known.     

Ecosystem recharge by volcanic dust drives broad‐scale variation in bird abundance

Across the globe, deserts and volcanic eruptions produce large volumes of atmospheric dust, and the amount of dust is predicted to increase with global warming. The effects of long‐distance airborne dust inputs on ecosystem productivity are potentially far‐reaching but have primarily been measured in soil and plants. Airborne dust could also drive distribution and abundance at higher trophic levels, but opportunities to explore these relationships are rare. Here we use Iceland's steep dust deposition gradients to assess the influence of dust on the distribution and abundance of internationally important ground‐nesting bird populations. Surveys of the abundance of breeding birds at 729 locations throughout lowland Iceland were used to explore the influence of dust deposition on bird abundance in agricultural, dry, and wet habitats. Dust deposition had a strong positive effect on bird abundance across Iceland in dry and wet habitats, but not in agricultural land where nutrient levels are managed. The abundance of breeding waders, the dominant group of terrestrial birds in Iceland, tripled on average between the lowest and highest dust deposition classes in both wet and dry habitats. The deposition and redistribution of volcanic materials can have powerful impacts in terrestrial ecosystems and can be a major driver of the abundance of higher trophic‐level organisms at broad spatial scales. The impacts of volcanic ash deposition during eruptions and subsequent redistribution of unstable volcanic materials are strong enough to override effects of underlying variation in organic matter and clay content on ecosystem fertility. Global rates of atmospheric dust deposition are likely to increase with increasing desertification and glacier retreat, and this study demonstrates that the effects on ecosystems are likely to be far‐reaching, both in terms of spatial scales and ecosystem components.