Titel:	Conservation of threatened grassland birds – Large, nutrient-poor and heterogenous grasslands are of prime importance
Sonstige Titel:	Schutz gefährdeter Brutvögel des Offenlandes - Großes, nährstoffarmes und heterogenes Grünland ist von entscheidender Bedeutung
Autor(en):	Kämpfer, Steffen
ORCID des Autors:	https://orcid.org/0000-0002-1746-3453
Erstgutachter:	Prof. Dr. Thomas Fartmann
Zweitgutachter:	PD Dr. Hienz Düttmann
Zusammenfassung:	Although the value of biodiversity is mostly beyond debate, it is declining on a global scale and at rates unprecedented in human history. Consequently, loss of biodiversity is one of the most fundamental challenges facing humankind. Habitat loss and degradation through land-use change were identified as the most important drivers of species decline in terrestrial ecosystems. Particularly species associated with low-intensity land use and nutrient-poor conditions suffered huge population declines. Additionally, climate change puts further pressure on the remaining habitats and thus becomes another crucial driver of biodiversity loss. Addressing these challenges requires detailed knowledge of species’ ecological demands and how these might change in response to future environmental changes. Therefore, this thesis seeks to gain insights into habitat requirements, breeding, and migration ecology of threatened species. Three grassland bird species of conservation concern were studied as model organisms in natural grassland refuges, the East Frisian Islands (Northwest Germany). In detail the Wheatear (Oenanthe Oenanthe) was treated as a songbird feeding on small insects and larvae, the European Curlew (Numenius arquata) as a representative of grassland breeding waders feeding on vertebrates and earthworms and the Short-eared owl (Asio flammeus) as a raptor species feeding on voles (Mircotus spec.). The studies highlight the importance of open dune grasslands as habitats for the threatened species. The Wheatear preferred highly disturbed habitats characterised by huge amounts of open soil and very short and sparse vegetation. Because such habitats were almost exclusively provided by European rabbits (Oryctolagus cuniculus) the study revealed that rabbits act as ecosystem engineers providing holes for nesting and early successional stages with sparse and short vegetation for foraging. Curlews preferred heterogenous vegetation structures providing areas of open soil and short vegetation for feeding and chick rearing but also areas of intermediate vegetation height for breeding and hiding of chicks. In contrast, Short-eared owls preferred high and dense vegetation for nest building surrounded by intermediate vegetation for foraging. Moreover, litter turned out to be a crucial habitat requisite that provide concealment and shelter from extreme weather and facilitates fledglings’ survival and food availability. All investigated species avoided late successional stages like shrubs and woodlots. In this way, despite differences in nest-site preferences, all species profited from nutrient-poor conditions and relatively high dynamic due to the influence of tides and wind. Both result in sparse, open, and heterogenous vegetation structures and extensive areas of early successional stages which are crucial for feeding. Nevertheless, intermediate stages of succession such as rough grassland, which provide high cover of litter for hiding and improving food availability, also proved important, especially for raptors feeding on voles. In contrast to the East Frisian Islands, the above-mentioned conditions are rare in the intensively used agricultural landscape on the mainland, which makes the discrepancy of breeding densities of threatened species on the islands and the mainland comprehensible. Therefore, the consequent protection of the refuge habitats on the islands but also along the migration routes and wintering areas is crucial for the preservation of the threatened species and should be of high priority for their conservation. As almost 30 % of the curlews recorded with GPS used France as a resting or wintering area, this applies in particular to the wintering areas of the curlew in France, where the introduction of hunting is currently being discussed. At the same time, the restoration of degraded habitats based on the example of the habitats preferred in the refuges is urgently needed to enhance habitat availability and suitability on the mainland. Based on the findings of this thesis, large-scale measures providing heterogenous grasslands are considered the key to the conservation of threatened ground-breeding species. Corresponding habitats might be created through low-intensity land use applying agri-environmental schemes that should encompass rotating fallows (high and dense vegetation rich in litter and voles) and areas of higher land-use intensity featuring disturbance like mowing or grazing (open-soil, short and sparse vegetation). The presented studies indicate that climate change might affect the investigated species through an increasing frequency of extreme weather events with negative impacts on fledglings’ survival and through changes in migration ecology such as wintering areas. Prospective conservation measures should therefore include strategies that anticipate future environmental changes like climate change. At the same time, this highlights the need for consequent political action to counter climate change and (by that) biodiversity loss.
URL:	https://doi.org/10.48693/466 https://osnadocs.ub.uni-osnabrueck.de/handle/ds-2024020210416
Schlagworte:	Biodiversität; Klimawandel; Ökologie; Gefährdete Art; Aves; Brutökologie; Zugökologie; Jagd; Ökosystemingenieur; Wildkaninchen; Steinschmätzer; Brachvogel; Großer Brachvogel; Sumpfohreule; Asio flammeus; Numenius arquata; Oenanthe oenanthe; Nesterfolg; Bruterfolg; Überlebensrate; Habitatwahl; Lebensraumansprüche; Naturschutz; Nationalpark; Biodiversity; Climate change; Ecology; threatened species; Breeding ecology; migration ecology; Hunting; Ecosystem engineer; Wheatear; Curlew; Short-eared owl; Nesting success; Breeding success; survival rate; Habitat preferences; National park
Erscheinungsdatum:	2-Feb-2024
Lizenzbezeichnung:	Attribution 3.0 Germany
URL der Lizenz:	http://creativecommons.org/licenses/by/3.0/de/
Publikationstyp:	Dissertation oder Habilitation [doctoralThesis]
Enthalten in den Sammlungen:	FB05 - E-Dissertationen

Diese Ressource wurde unter folgender Copyright-Bestimmung veröffentlicht: Lizenz von Creative Commons