Liigikaitseliselt oluliste ranna-alade kaitsemeetmed - väärtuste hinnang ja lahendused

Suur osa meie kunagistest avatud looduslikest rohumaadest on eelmise sajandi keskpaigast alates kas täielikult metsastunud või siis olulisel määral puudest/põõsastest killustatud. See on toimunud nii loodusliku protsessina niitude majandamise lõppemisel kui ka eelmise sajandi teises pooles toimunud põllumajanduslikult väheväärtuslike maade metsastamiskampaania tulemusena. Poollooduslike koosluste pindala on selle tulemusena oluliselt vähenenud (Luhamaa, Ikonen, Kukk 2001; Helm, Toussaint 2020) ning kaasajal kuuluvad nad koos oma elustikuga ühtede ohustatuimate koosluste hulka. Nende hoidmiseks ja taastamiseks makstakse looduskaitse alustel maadel niitude majandamiseks ja taastamiseks toetusi. Antud toetused eeldavad niidukoosluse olemasolu või selle taastumise potentsiaali. Samas on looduskaitse alustel maadel võimalik saada toetusi seal asuva metsamaa säilitamiseks. Metsatoetuse saamise ainsaks kriteeriumiks on metsamaaks kvalifitseeruva puistu paiknemine Natura kaitsealade võrgustikku kuuluval alal ning kaitsealuste metsaelupaigatüüpide olemasolu ei ole vajalik. Nende kahe toetuse rakendamise tulemusena on paljudes kohtades tekkinud olukord, kus niitudel asuvatele noortele sekundaarsetele puistutele makstakse metsa säilitamiseks toetusi. Kuna niidukoosluste jaoks (nagu enamuse koosluste jaoks) on oluline koosluse suurus ning vähene fragmenteeritus, siis on metsatoetusel otsene negatiivne mõju poollooduslike koosluste majandamise toetusele, kuna kitsad, metsatukkade ja põõsastikega killustunud niidud ei paku avatud niiduelupaikadega kohastunud liikidele (nt kahlajad, kõre) kvaliteetset elupaika (Rannap, Lõhmus, Jakobson 2007; Rannap jt 2017; Żmihorski jt 2016) ja nii ongi kaasajaks suur osa avatud niiduelupaikadest sõltuvatest liikidest Eestis jätkuvalt langeva arvukusega (Kuresoo, Mägi 2005; Elts jt 2013; Leito jt 2014). Käesoleva projekti eesmärgiks oli selgitada välja ranniku lähedal olevatel niitudel paiknevate puistute looduskaitseline väärtus ning hinnata nende mõju ümbritsevate niidualade looduskaitselisele väärtusele.Viitamine: Luhamaa, H., Pehlak, H., Rannap, R., Tali, K. 2020. Liigikaitseliselt oluliste ranna-alade kaitsemeetmed - väärtuste hinnag ja lahendused. "Liigikaitseliselt oluliste ranna-alade kaitsemeetmed - väärtuste hinnang ja lahendused (1.02.2019-10.12.2020)" projekti lõpparuanne.Uuringu koostamist toetas: Keskkonnainvesteeringute Keskuse keskkonnaprogrammi looduskaitse alamprogramm (projekt nr 15419

Genetic differentiation in an endangered and strongly philopatric, migrant shorebird

Background Populations living in fragmented habitats may suffer from loss of genetic variation and reduced between-patch dispersal, which are processes that can result in genetic differentiation. This occurs frequently in species with reduced mobility, whereas genetic differentiation is less common among mobile species such as migratory birds. The high dispersal capacity in the latter species usually allows for gene flow even in fragmented landscapes. However, strongly philopatric behaviour can reinforce relative isolation and the degree of genetic differentiation. The Southern Dunlin (Calidris alpina schinzii) is a philopatric, long-distance migratory shorebird and shows reduced dispersal between isolated breeding patches. The endangered population of the Southern Dunlin breeding at the Baltic Sea has suffered from habitat deterioration and fragmentation of coastal meadows. We sampled DNA across the entire population and used 12 polymorphic microsatellite loci to examine whether the environmental changes have resulted in genetic structuring and loss of variation. Results We found a pattern of isolation-by-distance across the whole Baltic population and genetic differentiation between local populations, even within the southern Baltic. Observed heterozygosity was lower than expected throughout the range and internal relatedness values were positive indicating inbreeding. Conclusions Our results provide long-term, empirical evidence for the theoretically expected links between habitat fragmentation, population subdivision, and gene flow. They also demonstrate a rare case of genetic differentiation between populations of a long-distance migratory species. The Baltic Southern Dunlin differs from many related shorebird species that show near panmixia, reflecting its philopatric life history and the reduced connectivity of its breeding patches. The results have important implications as they suggest that reduced connectivity of breeding habitats can threaten even long-distance migrants if they show strong philopatry during breeding. The Baltic Southern Dunlin warrants urgent conservation efforts that increase functional connectivity and gene flow between breeding areas.Peer reviewe

Genetic differentiation in an endangered and strongly philopatric, migrant shorebird

Populations living in fragmented habitats may suffer from loss of genetic variation and reduced between-patch dispersal, which are processes that can result in genetic differentiation. This occurs frequently in species with reduced mobility, whereas genetic differentiation is less common among mobile species such as migratory birds. The high dispersal capacity in the latter species usually allows for gene flow even in fragmented landscapes. However, strongly philopatric behaviour can reinforce relative isolation and the degree of genetic differentiation. The Southern Dunlin (Calidris alpina schinzii) is a philopatric, long-distance migratory shorebird and shows reduced dispersal between isolated breeding patches. The endangered population of the Southern Dunlin breeding at the Baltic Sea has suffered from habitat deterioration and fragmentation of coastal meadows. We sampled DNA across the entire population and used 12 polymorphic microsatellite loci to examine whether the environmental changes have resulted in genetic structuring and loss of variation. </p

Invertebrate abundance increases with vegetation productivity across natural and agricultural wader breeding habitats in Europe

Grassland breeding waders have been steadily declining across Europe. Recent studies indicating a dramatic decline in grassland invertebrates' abundance and biomass, the key food of most grassland wader chicks, suggest a likely driver of the demise of waders. While agricultural intensification is generally inferred as the main cause for arthropod decline there is surprisingly little information on the relationship between land use intensity and total arthropod abundance in grasslands. Here, we explored those relationships across several key wader breeding habitats by surveying ground-active, aerial and soil-dwelling invertebrate communities in five European countries that range from natural undisturbed bogs to intensively managed grasslands. Using maximum vegetation growth and soil moisture content we investigated how they shape the size of the invertebrate community within and across different countries. We found predominantly positive relationships between grassland invertebrate abundance, biomass and body weight with increasing vegetation growth and soil moisture. Maximum vegetation growth was strongly positively related to ground-active invertebrate abundance and biomass and abundance of soil dwelling invertebrates (mainly earthworms). Body weight of aerial invertebrates furthermore increased with increasing maximum vegetation growth. Our results provide little support for the hypothesis that agricultural practices associated with intensification of grassland management result in an abundance decline of invertebrate prey for wader chicks. Conservation practices aiming to enhance wader chick survival require a careful balancing act between maintaining habitat productivity to secure high prey abundance, and keeping productivity low enough to maintain open swards that do not need to be cut before chicks have fledged

A global threats overview for Numeniini populations: synthesising expert knowledge for a group of declining migratory birds

The Numeniini is a tribe of thirteen wader species (Scolopacidae, Charadriiformes) of which seven are near-threatened or globally threatened, including two critically endangered. To help inform conservation management and policy responses, we present the results of an expert assessment of the threats that members of this taxonomic group face across migratory flyways. Most threats are increasing in intensity, particularly in non-breeding areas, where habitat loss resulting from residential and commercial development, aquaculture, mining, transport, disturbance, problematic invasive species, pollution and climate change were regarded as having the greatest detrimental impact. Fewer threats (mining, disturbance, problematic native species and climate change) were identified as widely affecting breeding areas. Numeniini populations face the greatest number of non-breeding threats in the East Asian-Australasian Flyway, especially those associated with coastal reclamation; related threats were also identified across the Central and Atlantic Americas, and East Atlantic flyways. Threats on the breeding grounds were greatest in Central and Atlantic Americas, East Atlantic and West Asian flyways. Three priority actions were associated with monitoring and research: to monitor breeding population trends (which for species breeding in remote areas may best be achieved through surveys at key non-breeding sites), to deploy tracking technologies to identify migratory connectivity, and to monitor land-cover change across breeding and non-breeding areas. Two priority actions were focused on conservation and policy responses: to identify and effectively protect key non-breeding sites across all flyways (particularly in the East Asian - Australasian Flyway), and to implement successful conservation interventions at a sufficient scale across human-dominated landscapes for species’ recovery to be achieved. If implemented urgently, these measures in combination have the potential to alter the current population declines of many Numeniini species and provide a template for the conservation of other groups of threatened species

Habitats supporting wader communities in Europe and relations between agricultural land use and breeding densities: A review

Wading birds can be found breeding in a myriad of habitats and ecosystems across Europe that vary widely in their land-use intensity. Over the past few decades, wader breeding populations have declined steeply in habitats ranging from natural undisturbed ecosystems to intensively managed farmland. Most conservation science has focused on factors determining local population size and trends which leave cross-continental patterns and the associated consequences for large-scale conservation strategies unexplored. Here, we review the key factors underlying population decline. We find land-use intensification in western Europe and mostly agricultural extensification and abandonment in northern, central and eastern Europe to be important drivers. Additionally, predation seems to have increased throughout the breeding range and across all habitats. Using collected breeding density data from published and grey literature, we explore habitat specificity of wader species and, of the most widely distributed species, how breeding densities change across a land-use intensity gradient. We found that two-thirds of all examined wader species have relatively narrow breeding habitat preferences, mostly in natural and undisturbed ecosystems, while the remaining species occurred in most or all habitats. The most widespread generalist species (black-tailed godwit, northern lapwing, common redshank, Eurasian oystercatcher, common snipe and ruff) demonstrated peak breeding densities at different positions along the land-use intensity gradient. To conserve both diverse wader communities and viable meta-populations of species, a diversity of habitats should be targeted ranging in land-use intensity from natural ecosystems to medium intensity farmland. Alongside, strategies should be designed to moderate predation of wader clutches and chicks

Status of the Baltic Dunlin Calidris alpina in Lithuania

Breeding Dunlins in Lithuania have not attracted much attention since fieldwork for the Lithuania Bird Atlas in the 1990s. In order to assess the present status of the threatened Baltic Dunlin population in Lithuania, we surveyed most of the former key breeding sites for the species in May 2011 and recorded current land use. We found no breeding Dunlins in Lithuania and at the majority of the former breeding sites current land use no longer affords suitable habitat. Dunlins have suffered from a reduction in the intensity of grazing and a lowering of the water table in their former coastal meadow habitats. A broad suite of other meadow breeding waders have also disappeared from these areas; moreover the globally red-listed Aquatic Warbler Acrocephalus paludicola has declined markedly in the same habitatVytauto Didžiojo universitetasŽemės ūkio akademij

Coastal grassland wader abundance in relation to breeding habitat characteristics in Matsalu Bay, Estonia

Wader populations have been declining worldwide, providing a fundamental question as to which environmental factors limit population growth. Many studies have focused on the effects of habitat change on wader populations as a result of climate change, agricul-tural intensification or abandonment of arable land. However, there are few studies inves-tigating the relationship between wader distribution/abundance and prey abundance. This study focused on the relationship between breeding wader abundance, habitat character-istics and prey abundance on different types of coastal and floodplain grasslands. The study was carried out in the Matsalu Bay area, Western Estonia between 2001 and 2005. Results showed that most wader species were strongly related to habitat flooding type but not to plant species richness or evenness or mean vegetation coverage. Abundance of epigeic earthworms at a site was positively correlated with wader species diversity and abundance, as well as at the individual species level for abundance of Northern Lapwing Vanellus vanellus, Black-tailed Godwit Limosa limosa and Redshank Tringa totanus

Cross-continental differences in Black-tailed Godwit breeding densities are best explained by arthropod abundance in the chick-hatching period

The endangered continental Black-tailed Godwit (Limosa limosa limosa) is a migratory ground-nesting wader breeding in a wide variety of open, wet habitats across Europe. Conservation research has concentrated on the causes of population decline, but we know surprisingly little about whether any resources limit local breeding populations and if so, whether these are resources for the adults or the chicks. We collected data from 63 key breeding sites in five countries across Europe to test whether, after correcting for differences in surveyed areas, the size of Godwit breeding populations was related to environmental variables (vegetation biomass, soil moisture) or food resources for adult birds (soil invertebrates) or chicks (vegetation dwelling arthropods) measured during different times of the reproductive cycle. We found the number of Godwit territories to be positively related to arthropod abundance during the chick-hatching period. We found additional, weaker support for a positive relation between Godwit territory numbers and the abundance of soil-dwelling invertebrates (mostly earthworms) at clutch laying, but not at chick-hatching. These relationships were observed across countries, while we found little support for relationships within countries, possibly due to the smaller range in conditions that exist within countries. Both vegetation growth and soil moisture weren’t related to Godwit territory numbers. Our results suggest that food abundance for chicks, and to a lesser extent adult birds, are key factors determining the size of local Godwit breeding populations. Conservation management aiming to enhance local Godwit populations should therefore consider the impacts of management strategies on the arthropod prey of chicks