MIGRATION PHENOLOGY OF WADERS (CHARADRII) ON THE TAIMYR PENINSULA,NORTHERN RUSSIA

Syroechkovski, E.E. Jr. & Lappo, E.G. 1994. Migration phenology of waders (Charadrii) on the Taimyr Peninsula, northern Russia. Ostrich 65:181–190.

Palearctic waders from six flyways breed on the Taimyr Peninsula. They can be observed in winter from Europe to South Africa and Australia. The interval between pre- and postbreeding movements of waders in Taimyr is short. Breeding waders, which spend from 50–70 days on the tundra have a arrival tight schedule, dependent mostly on weather conditions. Most species arrive during the first half of June, with the more northern areas occupied several days later than southern areas. However, Turnstone, Dunlin and Curlew Sandpiper arrive in the optimal art of their breeding ground first, and subsequently occupy sup-optimal areas to the north and the south. In autumn waders migrate in small groups across the tundra. The schedule depends greatly on the breeding success of the year. Large numbers of Ruff and Bartailed Godwit concentrate in high arctic areas, 300–500 km north of their breeding grounds, before commencing southwards migration. Autumn concentrations of waders in intertidal areas are rare.     

Migration strategy and pathogen risk: non‐breeding distribution drives malaria prevalence in migratory waders

Pathogen exposure has been suggested as one of the factors shaping the myriad of migration strategies observed in nature. Two hypotheses relate migration strategies to pathogen infection: the ‘avoiding the tropics hypothesis’ predicts that pathogen prevalence and transmission increase with decreasing non‐breeding (wintering) latitude, while the “habitat selection hypothesis” predicts lower pathogen prevalence in marine than in freshwater habitats. We tested these scarcely investigated hypotheses by screening wintering and resident wading shorebirds (Charadriiformes) for avian malaria blood parasites (Plasmodium and Haemoproteus spp.) along a latitudinal gradient in Australia. We sequenced infections to determine if wintering migrants share malaria parasites with local shorebird residents, and we combined prevalence results with published data in a global comparative analysis. Avian malaria prevalence in Australian waders was 3.56% and some parasite lineages were shared between wintering migrants and residents, suggesting active transmission at wintering sites. In the global dataset, avian malaria prevalence was highest during winter and increased with decreasing wintering latitude, after controlling for phylogeny. The latitudinal gradient was stronger for waders that use marine and freshwater habitats (marine + freshwater) than for marine‐restricted species. Marine + freshwater wader species also showed higher overall avian malaria parasite prevalence than marine‐restricted species. By combining datasets in a global comparative analysis, we provide empirical evidence that migratory waders avoiding the tropics during the non‐breeding season experience a decreased risk of malaria parasite infection. We also find global support for the hypothesis that marine‐restricted shorebirds experience lower parasite pressures than shorebirds that also use freshwater habitats. Our study indicates that pathogen transmission may be an important driver of site selection for non‐breeding migrants, a finding that contributes new knowledge to our understanding of how migration strategies evolve.     

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.     

MHC‐I provides both quantitative resistance and susceptibility to blood parasites in blue tits in the wild

Major histocompatibility complex (MHC) genes are central for the adaptive immune response against parasites. Here, we investigated potential associations among MHC‐I alleles and blood parasite infections in a natural breeding population of a passerine bird, the blue tit Cyanistes caeruleus, in central Spain. We screened both infection status (presence/absence of infection) and infection intensity to the pathogenic blood parasites Haemoproteus and Leucocytozoon. Three MHC‐I alleles (UA104, UA108 and UA117) were associated with higher or lower infection intensities by Leucocytozoon. Interestingly, these associations were dependent on age and were found both among young and adult birds. No MHC alleles were associated with infection intensity by Haemoproteus parasites. In addition, no significant relationships were detected between infection status by Haemoproteus and Leucocytozoon infections and MHC alleles. The very high prevalence of these two parasites in our study population (79–100%) poses challenges to identify associations with infection status and also suggests that clearance of infections may be rare. In conclusion, associations between specific MHC‐I alleles and Leucocytozoon parasites were related to either high or low infection intensities, and hence increased susceptibility or resistance to infection.     

WADERS (CHARADRII) AND OTHER SHOREBIRDS AT CAPE RECIFE,ALGOA BAY,SOUTH AFRICA: SEASONALITY,TRENDS, CONSERVATION,AND RELIABILITY OF SURVEYS

Spearpoint, J. A., Every, B. & Underhill, L. G. 1988. Waders (Charadrii) and other shorebirds at Cape Recife, Algoa Bay, South Africa: seasonality, trends, conservation, and reliability of surveys. Ostrich 59: 166–177.

A total of 126 surveys of waders (Charadrii) and other shorebirds were made along 4 km of shore northwest of Cape Recife. The surveys were conducted bv two observers who counted independently of each other. The variability between observers was least for conspicuous species such as Whitefronted Plover, Blacksmith Plover, African Black Oystercatcher, Whimbrel and Grey Plover, but greatest for cryptic species such as Ringed Plover and for species which formed a minority in mixed flocks such as Curlew Sandpiper and Little Stint. Variability of surveys within years and between years is also considered. Turnstones and Sanderlings were the most abundant waders in summer. Of the Palaearctic waders, Turnstones, Grey Plovers, Sanderlings, Greenshanks and Whimbrels overwintered. In contrast, Ringed Plovers, Curlew Sandpipers, and Little Stints rarely overwintered. Little Egrets, Threebanded Plovers and Water Dikkops occurred mainly in winter. It is recommended that surveys to estimate numbers of Palaearctic waders in summer and winter should be conducted in December, January or February and June or July, respectively. Because of three-year cycles in breeding productivity of certain waders, surveys should be extended over at least three years. There was evidence that waders associated with rocky shores increased in numbers during the study period: this coincided with the erosion of sandy beaches near Cape Recife. Density, biomass and daily field metabolic rates, expressed on an area basis, were similar to those in eastern Scotland. Nine species of tern utilized Cape Recife. It is recommended that the bait-collecting regulations be enforced, that vehicles be prohibited on the beach, and that the tern roost and breeding site be fenced off to create a sanctuary.     

WADER POPULATIONS (CHARADRII) OF THE MARINE LITTORAL OF THE CAPE PENINSULA,SOUTH AFRICA

Pringle, J. S. & Cooper, J. 1977. Wader populations (Charadrii) of the marine littoral of the Cape Peninsula, South Africa. Ostrich 48: 98–105.

Waders (Charadrii) were counted regularly on two stretches of coastline, totalling 5,6 km, on the Cape Peninsula from January 1975 to July 1976. Eight Palaearctic species and seven indigenous species were observed. Arrival of migrants extended from mid-August to January. Autumn departure of Curlew Sandpipers Calidris ferruginea occurred approximately six weeks before departure of Sanderlings C. albu. No overwintering populations of migrant waders were observed. Information is presented which suggests that overwintering Turnstones Arenaria interpres, but not Sanderlings, Maycongregate at a sheltered coastal wetland. Observations of marked birds suggest that individual Sanderlings regularly use particular feeding localities. Populations of indigenous waders showed little seasonal variation in numbers, Flocking was observed in winter.     

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.     

Clutch size and egg size in the breeding strategy of Montagu's Harrier Circus pygargus in a Mediterranean area

First-summer set-aside fields held more breeding species and higher wader densities than in the previous summer. They held more breeding species and higher densities of waders, Partridges (Perdix perdix) and Skylarks (Alauda arvensis) than fields in crop. Mowing nullified many breeding attempts. Corn Buntings bred in some first-summer set-aside fields but numbers were lower in other cases. Later years of set-aside held lower densities and fewer species. Densities of waders and Partridges in first-summer set-aside exceeded those in the first year of resumed cropping.     

Prevalence of malaria and related haemosporidian parasites in two shorebird species with different winter habitat distribution

Parasites can have strong effects on host life-history and behaviour, and result in changes in host population dynamics and community structure. We applied a PCR-based technique and examined prevalence of malaria and related haemosporidian parasites in two arctic breeding shorebird species: the Semipalmated Sandpiper (Calidris pusilla) and the Pectoral Sandpiper (C. melanotos). During the non-breeding season, Semipalmated Sandpipers inhabit coastal marine habitats, whereas Pectoral Sandpipers are found in inland areas. In accordance with the hypothesis that the risk of parasite infection is higher in a species wintering in freshwater areas, we found Plasmodium sp. infection during the breeding season only in Pectoral Sandpipers, whereas Semipalmated Sandpipers were parasite free. However, even in Pectoral Sandpipers sampled in the arctic, prevalence of malaria parasites was very low (<3% of individuals, n = 114). Overall, three different Plasmodium sp. lineages were found, one of which has never been described before.     

A NEW GEOGRAPHICAL RACE OF THE GOLDEN-TAILED WOODPECKER FROM SOUTH-EASTERN AFRICA,WITH NOTES ON THE OTHER SOUTH AFRICAN FORMS

Maclean, G. L. 1974. Egg-covering in the Charadrii. Ostrich 45: 167–174.

Deliberate egg-covering in the Charadrii (waders) occurs in at least 13 species in four families (Jacanidae, Glareolidae, Charadriidae and Thinocoridae). The habit is most widely developed in the genus Gharadrius, of which at least four species cover their eggs. Egg-covering is done by kicking material over the eggs with the feet in most species, but in the Glareolidae and probably some other groups, only the bill is used.

The primary function of egg-covering appears to be concealment, but the secondary function of thermoregulation appears to have become almost as important in a few species, especially as a device to insulate the eggs against exposure to the sun. It is not surprising that egg-covering is most highly evolved in tropical and subtropical regions where predator-pressureMaybe higher, and the danger of overheating by direct sun is greater, than elsewhere.     

Warmer springs advance the breeding phenology of golden plovers Pluvialis apricaria and their prey (Tipulidae)

Most studies of climate-driven changes in avian breeding phenology have focused on temperate passerines, yet the consequences of such environmental change may be more deleterious for other avian taxa, such as arctic and sub-arctic waders (Charadrii). We therefore examine large-scale climatic correlates of the breeding phenology of one such species (golden plover Pluvialis apricaria), and the timing of emergence of their adult tipulid prey, to assess the potential for climate change to disrupt breeding performance. Golden plover first-laying dates were negatively correlated with both March and April temperature, the mean laying date of first clutches was additionally negatively correlated with March rainfall. The timing of final laying dates were negatively correlated with April temperature only. The timing of tipulid emergence was negatively correlated with May temperature. In combination with historical climatic data, these models suggest a 9-day advancement of golden plover first-laying dates occurred during the 1990s, although this remains within the range of natural variation for the twentieth century. The magnitudes of predicted changes in mean and final laying dates, and the timing of tipulid emergence, were smaller. Climate predictions for 2070-2099 suggest potential advances in first-laying dates by 25 days, whilst the timings of mean and final laying dates are predicted to change by 18 days and 13 days, and tipulid emergence by 12 days. Given the importance of adult tipulids to young golden plover chicks, these changes may result in a mismatch between the timing of first-laying dates and tipulid emergence, so reducing the success of early breeding attempts. Modelling suggests that these changes could reduce breeding success in a South Pennines population by about 11%.     

Incubation in uni-parental Arctic breeding waders

Bruinzeel, L., Tulp, I., Jukema, J. & Stepanova, O. 2000. Incubation in mi-parental arctic breeding waders. Ostrich 71 (1 & 2): 345.

Little Stints Calidris minuta are amongst the smallest breeding waders. This, in combination with the fact that they have a peculiar breeding system, in which each adult takes care of her/his own nest and young, puts high demands during incubation. Due to uni-parental feeding system, feeding time is limited. The accumulation of he1 stores prior to breeding may be crucial to get through the 21-day incubation period. Incubation rhythms, body mass dynamics and energy expenditure of Little Stints was studied at Medusa Bay, Western Taimyr in the summer of 1996. Repeated body mass measurements during incubation were taken by catching the birds on the nest. Concurrently, we measured nest attentiveness, using Tiny Talk dataloggers and temperature sensitive probes, which were placed in the nests. Arthropod availability was measured to estimate food availability. In comparison, body mass dynamics were also studied in Curlew Sandpiper, another uni-parental breeder, but three times bigger. The first (preliminary) results of this study were presented.     

Synergies between site protection and agri‐environment schemes for the conservation of waders on lowland wet grasslands

Two conservation strategies have been put in place in Europe to address precipitous population declines of wading birds that breed on lowland wet grasslands. These are site protection and agri‐environment schemes (AESs) and the two are rarely compared, or their synergy assessed. Increasingly, efforts to recover populations of previously widespread species follow a landscape‐scale approach whereby habitat improvement takes place at key sites through partially overlapping protected area management and AESs. To investigate whether site protection and AESs improve the conservation status of breeding waders and how these interact, we partially repeated a 2002 survey of breeding waders on protected areas (nature reserves and Sites of Special Scientific Interest) and sites with wader‐specific AES options in England in 2009 and 2010. We then assessed the individual and combined effects of these delivery mechanisms on field occupancy, breeding density and population change of four species of declining wader (Northern Lapwing Vanellus vanellus, Common Snipe Gallinago gallinago, Eurasian Curlew Arquata numenius and Common Redshank Tringa totanus). Although results for Curlew differed from the other species, in general field occupancy was positively influenced by conservation delivery mechanisms, with the highest occupancy and breeding densities on land where site protection was combined with wader‐specific AES options. Field occupancy varied between different types of AES, with higher occupancy associated with higher‐level options in fields, particularly those on nature reserves. Outside nature reserves, the history of AES management did not influence wader populations, but within nature reserves and on fields that gained AES management between 2002 and 2009–2010, populations of Curlew and Snipe were more likely to have persisted and population change in Snipe and Lapwing was more positive. We conclude that the conservation of breeding waders will be most effective when site protection and AES management are combined on the same land. Using limited AES money to support management for breeding waders on, around and between the existing network of protected sites will protect remaining populations while presenting opportunities for population expansion in future.     

Do Arctic waders use adaptive wind drift?

We analysed five data sets of flight directions of migrating arctic waders in relation to winds, recorded by tracking radar and optical range finder, in order to find out if these birds compensate for wind drift, or allow themselves to be drifted by winds. Our purpose was to investigate whether arctic waders use adaptive wind drift strategies or not. The data sets were collected in Siberia (two sets) and Canada during post-breeding (autumn) migration, and in Mauritania and South Sweden during pre-breeding (spring) migration. Both significant drift and compensation effects were found in three of the data sets, Canada, Mauritania and South Sweden. Almost no compensation was found in birds departing in easterly directions from the Siberian tundra (complete drift), while no drift effect was found in birds departing in westerly directions (complete compensation). There were indications that at least some populations of waders may use an adaptive drift strategy consisting of drift at high altitude and/or in high wind speed combined with compensation at low altitude and/or in lower wind speeds, but support for this idea was rather weak and not consistent. Our results were instead more in accordance with the adaptive drift theory that predicts initial drift during the migratory journey, followed by compensation during later stages as the birds are approaching their destinations. Such a strategy implies that arctic waders, at least adult birds, have the capacity of true navigation. A comparison with earlier studies of migrating arctic waders from different parts of the world show that all results so far may be interpreted in accordance with this general adaptive drift strategy. An element of non-adaptive drift can, however, not be completely ruled out.     

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.     

Malaria infections reinforce competitive asymmetry between two Ficedula flycatchers in a recent contact zone

Parasites may influence the outcome of interspecific competition between closely related host species through lower parasite virulence in the host with which they share the longer evolutionary history. We tested this idea by comparing the prevalence of avian malaria (Haemosporidia) lineages and their association with survival in pied and collared flycatchers (Ficedula hypoleuca and F. albicollis) breeding in a recent contact zone on the Swedish island of Öland. A nested PCR protocol amplifying haemosporidian fragments of mtDNA was used to screen the presence of malaria lineages in 1048 blood samples collected during 6 years. Competitively inferior pied flycatchers had a higher prevalence of blood parasites, including the lineages that were shared between the two flycatcher species. Multistate mark–recapture models revealed a lower survival of infected versus uninfected female pied flycatchers, while no such effects were detected in male pied flycatchers or in collared flycatchers of either sex. Our results show that a comparatively new host, the collared flycatcher, appears to be less susceptible to a local northern European malarial lineage where the collared flycatchers have recently expanded their distribution. Pied flycatchers experience strong reproductive interference from collared flycatchers, and the additional impact of species‐specific blood parasite effects adds to this competitive exclusion. These results support the idea that parasites can strongly influence the outcome of interspecific competition between closely related host species, but that the invading species need not necessarily be more susceptible to local parasites.     

Population changes of breeding waders on farmland in relation to agri-environment management

Capsule Population response of breeding waders to agri-environment management varied between management options and species; implementation has been on too small a scale to reverse national population declines.

Aims To test whether numbers of five breeding wader species have shown a more positive response between 1992 and 2005, at sites with appropriate agri-environment management, than at sites that have remained outside such schemes.

Methods Using data from 60 pairs of farmland study areas in Scotland first surveyed in 1992/93, before agri-environment scheme (AES) implementation, and again in 2005, after scheme implementation, we tested at both site and field scales whether changes in the abundance of five breeding wader species were associated with AES management options designed to benefit these species.

Results Changes in breeding wader abundance were more positive on sites in AES, especially for Northern Lapwings Vanellus vanellus and Common Redshanks Tringa totanus, even though management had not been targetted specially at breeding waders on those sites. However, AES management was associated only with modest population increase for Common Redshanks, and a reduction in the magnitude of decline for Northern Lapwings. At the field scale, there was evidence for Northern Lapwings, Common Redshanks and Common Snipe Gallinago gallinago that options which limited grazing and other agricultural activity were associated with more positive outcomes than those which also manipulated water levels.

Conclusions AES management for breeding waders slowed, and in some cases reversed, breeding wader decline at field and farm scales. These benefits were from options that limited grazing and agricultural operations during the breeding season, but not those that also aimed to raise water levels. A possible explanation is that when wetland options are applied to agriculturally marginal fields, grazing reduction or abandonment, and succession to rank vegetation cover then occur over the course of 5-year agreements, with detrimental effects for breeding waders. Verification arrangements need to be robust enough to guard against this. Levels of agri-environment provision in 2005 were too limited and too poorly targeted at remaining key areas for breeding waders to be able to halt or reverse national population declines.     

The feeding strategy of the dunlin (Calidris alpina L.) in artificial and non-artificial habitats at Ria de Aveiro,Portugal

Usually waders (Aves, Charadrii) feed in the inter-tidal zone over the low tide period and roost over high tide. But occasionally when their energetic needs increase, due to adverse weather conditions or to a need to store fat to fuel migration, the birds also feed during high tide, sometimes in agricultural land. At the Ria de Aveiro, about 44% (corresponding to 4500 birds) of the wintering dunlin (Calidris alpina) use artificial salt pan habitats throughout the winter whilst the others utilize natural intertidal habitats, mainly mudflats. The dunlin that feed intertidally in natural areas, such as the Canal de Mira, do not feed over high tide. In contrast, the birds that use the salt pan area feed both during low tide, in abandoned salt pans whose walls are breached and thus allow access to the tide, and high tide, in active salt pans, and keep on doing so throughout the winter. The energetic needs of both groups of birds are thought to be similar. However, the benthos of the abandoned salt pans seem to be different, and poorer in energetic terms, from those of the natural mudflats. It is argued that dunlin wintering in the salt pan area must compensate for this by feeding over high tide in active salt pans. Rather than just being a means of obtaining more energy at certain times of high energy demand, it would seem that feeding in active salt pans over high tide should be considered as a normal component of the feeding strategy of these birds, a strategy that is different from those wintering in the natural mudflats. These findings highlight the importance of the salt exploitation industry to waders and also show that artificial habitats can support large numbers of wintering waders.     

Hookworm infection,anaemia and genetic variability of the New Zealand sea lion

Hookworms are intestinal blood-feeding nematodes that parasitize and cause high levels of mortality in a wide range of mammals, including otariid pinnipeds. Recently, an empirical study showed that inbreeding (assessed by individual measures of multi-locus heterozygosity) is associated with hookworm-related mortality of California sea lions. If inbreeding increases susceptibility to hookworms, effects would expectedly be stronger in small, fragmented populations. We tested this assumption in the New Zealand sea lion, a threatened otariid that has low levels of genetic variability and high hookworm infection rates. Using a panel of 22 microsatellites, we found that average allelic diversity (5.9) and mean heterozygosity (0.72) were higher than expected for a small population with restricted breeding, and we found no evidence of an association between genetic variability and hookworm resistance. However, similar to what was observed for the California sea lion, homozygosity at a single locus explained the occurrence of anaemia and thrombocytopenia in hookworm-infected pups (generalized linear model, F = 11.81, p < 0.001) and the effect was apparently driven by a particular allele (odds ratio = 34.95%; CI: 7.12–162.41; p < 0.00001). Our study offers further evidence that these haematophagus parasites exert selective pressure on otariid blood-clotting processes.     

Managing coastal grasslands for an endangered wader species can give positive results only when expanding the area of open landscape

The rapid loss of wetlands during the 20^th century has caused a severe decline in the biota associated with these habitats. In Europe, the loss of wet grasslands has seriously affected breeding waders, whose numbers have halved in the past 50 years and remaining populations are facing fragmented, low quality habitats. To improve the remaining sites as breeding grounds for these birds, the exact habitat requirements of the species need to be known. Our study was carried out in Boreal Baltic coastal grasslands in Estonia, where land abandonment has been the main reason behind waders’ population declines in the past decades. Hence, we focus on partially overgrown fields, aiming to ascertain habitat characteristics determining the breeding site selection of meadow birds, especially the endangered Southern Dunlin (Calidris alpina schinzii).We studied the breeding site selection of four wader species (Southern Dunlin, Common Redshank (Tringa totanus), Northern Lapwing (Vanellus vanellus) and Common Snipe (Gallinago gallinago)) in 23 coastal grasslands over two years. We analysed seven habitat characteristics which could influence the breeding habitat selection of these species.Our study demonstrates that breeding sites of all studied wader species are located closer to wet areas and coastline and further away from woodland. Also, the height of the ground level has an impact on the breeding probability, with lower areas favoured. Concerning the Southern Dunlin, our results show that on sites where the species was absent, suitable breeding sites, regarding the distance from woodland edge, were absent. Thus, reforestation of grasslands may be the key reason behind the poor population status of the species. We also demonstrated that proximity of reed beds did not influence the breeding site selection of waders – a result which contradicts current wet grassland management suggestions.Expanding the open landscape, maintaining a large quantity of wet features suitable for foraging and preventing overgrowth of coastline and lower parts of the meadow makes the habitat optimal for breeding waders. Concerning the growth of the population size and spatial distribution of the Southern Dunlin, removal of woodlands adjacent to grasslands is crucial.