Bestandsentwicklung von Vogelarten der Agrarlandschaft in Deutschland 1991-2010 und Schlüsselfaktoren

Anhand verfügbarer Daten zur Flächennutzung in der deutschen Agrarlandschaft sowie der Brutvogelmonitoring-Daten des Dachverbandes Deutscher Avifaunisten werden die Auswirkungen des Wandels der Agrarlandschaft auf die Bestandsentwicklung der häufigen Brutvogelarten Deutschlands dargestellt und interpretiert. Demnach nehmen die 30 typischen Vogelarten der Agrarlandschaft (von insgesamt 112 betrachteten Arten) in Deutschland ganz überwiegend ab. Nach einer Bestandserholung eines Teils der Arten in der 1. Hälfte der 1990er Jahre, vor allem in Ost-Deutschland, sind die Bestände der meisten Arten seit ca. 1996 wieder rückläufig. Dabei scheinen sich die Rückgänge aktuell (seit 2007) zu beschleunigen und sind im Westen Deutschlands deutlich stärker ausgeprägt als im Osten. Phasen mit hohen Anteilen an Ackerbrachen (Stilllegungen) und Ökolandbau erwiesen sich als positiv für die Bestandsentwicklung vieler Feldvogelarten, hohe Anteile an Mais negativ. Die starke Zunahme des Energiemais-Anbaus in der zweiter Hälfte der 2000er Jahre nach Inkrafttreten des Erneuerbare-Energien-Gesetzes und das Verschwinden der Stilllegungsflächen seit 2007 führten dazu, dass aktuell die meisten Arten abnehmen und auch die z.T. starke Zunahme von Arten, die von Stilllegungsflächen profitierten, sich nicht mehr fortsetzt und in Abnahmen umzuschlagen scheint. Die vorliegenden Daten sprechen dafür, dass etwa 10 % Brache notwendig sind (zurzeit <1 %!), um Bestandsrückgänge bei der Mehrzahl der Feldvogelarten zu vermeiden. Die Stilllegungsfläche sollte immer größer bzw. Stilllegungsfl äche plus Ökolandbau sollten mindestens doppelt so groß wie die Maisfläche sein (Verhältnis Stilllegung zu Mais zurzeit 1 : 20 !). Anteile von 33 % Ökolandbau plus 15 % extensive Grünlandnutzung in einem Gebiet von 1.300 km² reichen aus, um die Trends deutlich zu verbessern (Biosphärenreservat Schorfheide-Chorin). In einem großfl ächig von Ökolandbau (95 %) dominierten Teilgebiet im BR Schorfheide-Chorin nahmen deutlich mehr Arten zu als ab. Stichwörter: Brutvogelmonitoring, Bestandstrends, häufi ge Arten, Agrarlandschaft

Identifying migration routes and non-breeding staging sites of adult males of the globally threatened Aquatic Warbler Acrocephalus paludicola

Birds that are long-distance migrants partition their annual cycle among a number of locations over a large spatial range. The conservation of these species is particularly complex because it requires atten-tion to a number of different and distant habitats based on knowledge of migratory phenology, routes and staging areas. In the case of the globally threatened Aquatic Warbler Acrocephalus paludicola, a habitat specialist that breeds in Europe and spends the boreal winter in sub-Saharan Africa, non-breeding staging areas were widely unknown until recently. We applied light-level geolocators to adult male Aquatic Warblers at breeding sites in Belarus and Ukraine. Data from eight retrieved geolocators confirmed a south-west and then westward migration route through Europe via the northern Mediterranean with staging sites on the Iberian Peninsula and occasionally France and north-west Africa. In sub-Saharan Africa, final staging areas were in Mali, either in the Inner Niger Delta or at (presumably) small water bodies in the desert, with one bird most likely staying in the north of Ivory Coast south of the previously assumed range. The birds probably stayed in the final staging areas for most of the non-breeding season, but the logger on only one bird provided data throughout the entire migration cycle. Pre-nuptial migration of the latter was by a more easterly route than the southward migration. Our study suggests that conservation strategies for Aquatic Warbler north of the Sahara should include consideration of unknown staging sites in the northern Mediterranean as well as on the Iberian Peninsula and in north-west Africa. South of the Sahara, our study demonstrates the impor-tance of the Sahel for the conservation of the Aquatic Warbler, including both the major floodplains of the Niger River and small Sahelian wetlands that are under pressure from human development

Legislative Documents

Also, variously referred to as: Senate bills; Senate documents; Senate legislative documents; legislative documents; and General Court documents

Breeding in a postulated wintering site: first evidence for the breeding of Baillon’s Crake Porzana pusilla in Senegambia, West Africa

We report the discovery of the first breeding population of Baillon’s Crake Porzana pusilla in Senegambia, West Africa. From winter 2007–2010, 278 Baillon’s Crakes were caught within and immediately north of Parc National des Oiseaux du Djoudj in the Senegal delta, as well as in a wetland in The Gambia at Pakali Ba. The records included 169 juvenile Baillon’s Crakes, 23 of which were not fully fledged and were undoubtedly hatched in the area. The distribution of five assigned age intervals revealed that two consecutive broods were probably hatched within the breeding period, which is estimated to extend from September until February. During that period, the shallow Scirpus- and Sporobolus-marshes are still flooded and offer optimal habitat. The high number of captures suggests that a large population occurs in the Senegal delta. Furthermore, the species may be more abundant in Sahelian wetlands than was previously assumed. Sub-Saharan populations of P. pusilla are usually considered resident. However, due to limited seasonal availability of favourable habitats, the Senegambian population is probably migratory, but where this population occurs during the dry season is unknown.OSTRICH 2012, 83(2): 79–8

Habitat selection of the globally threatened Aquatic Warbler Acrocephalus paludicola at the western margin of its breeding range and implications for management

The globally threatened Aquatic Warbler Acrocephalus paludicola is an umbrella species for fen mires and is at risk of extinction in its westernmost breeding population due to severe habitat loss. We used boosted regression trees to model Aquatic Warbler habitat selection in order to make recommendations for effective management of the last remnant habitats. Habitat data were collected in the years 2004-2006 in all remaining breeding sites in Pomerania (eastern Germany and western Poland) as well as in recently abandoned sites. Models were validated using data from similar Aquatic Warbler habitats in Lithuania. The probability of occurrence of Aquatic Warblers in late May/early June was positively associated with low isolation from other occupied sites, less eutro- phic conditions, a high proportion of area mown early in the preceding year, high availability of vegetation 60-70 cm high, high prey abundance and high habitat heterogeneity. Early summer land management is needed in the more productive sites to prevent habitat deterioration by succession to higher and denser vegetation. As this also poses a serious threat to broods, management that creates a mosaic of early and late used patches is recommended to preserve and restore productive Aquatic Warbler sites. In less productive sites, winter mowing can maintain suitable habitat conditions. Aquatic Warbler-friendly land use supports a variety of other threatened plant and animal species typical of fens and sedge meadows and can meet the economic interests of local land usersVytauto Didžiojo universitetasŽemės ūkio akademij

Prevalence and diversity of Plasmodium and Haemoproteus parasites in the globally-threatened Aquatic Warbler Acrocephalus paludicola

The diversity and prevalence of malaria parasites of the genera Plasmodium and Haemoproteus were determined in the globally-threatened Aquatic Warbler Acrocephalus paludicola. Birds were sampled during migration in Portugal and at the wintering quarters in Senegal and parasites were detected using molecular methods. Only three generalist parasite lineages (Plasmodium) were found. There were no significant differences in the prevalence of parasites between sexes in Europe, but adults had higher prevalence than first-year birds, and birds in Europe had higher prevalence than those captured in Africa. When comparing with other Acrocephalus species and taking sample size into account, Aquatic Warblers had the lowest prevalence and, together with another threatened species, the Seychelles Warbler Acrocephalus sechellensis, the lowest diversity of malaria parasites. We hypothesize that the low diversity of parasites and absence of specialist lineages of Aquatic Warblers are caused by its small population size and fragmented distribution. Furthermore, Aquatic Warblers’ extreme habitat specialization may decrease their exposure to malaria parasites, but other explanations such as high mortality (which would constraint the sampling of infected birds) or, in contrast, very efficient immunological system in clearing the infections cannot be ruled out. This study contributes to explain variation in prevalence and diversity of malaria parasites among hosts

Identifying the potential wintering sites of the globally threatened Aquatic Warbler Acrocephalus paludicola using remote sensing

The Aquatic Warbler is a threatened Afro-Palaearctic migrant with a largely unknown distribution in the winter (non-breeding) season. Protection of wintering sites may be crucial for the conservation of the species. Previous studies have identified extensive areas of north-western sub-Saharan Africa that could potentially be occupied by the species during winter. However, these studies have not necessarily differentiated between potentially suitable and unsuitable  habitat types at a spatial resolution appropriate for targeting field surveys. To identify specific sites that could be occupied by non-breeding Aquatic Warblers  at a scale appropriate for targeted field surveys, we adopted a modelling  approach that combined recent sightings from Djoudj, Senegal, with land cover and climate data. We produced maps of potential distribution using three maximum entropy models. While a paucity of sightings prevented a full test of these maps on independent records, the areas that were predicted to be potentially occupied included areas around which there are historical records. We  suggest field surveys should be targeted towards sites in the Inner Niger Delta and a number of marshes along and away from the Niger River in Mali, and to sites in southern Mauritania.OSTRICH 2011, 82(2): 81–8