Nest distribution, habitat selection and nesting success in endangered waders breeding on managed shore meadows
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
OP-Pohjola Auditorium (L6)
Topic of the dissertation
Nest distribution, habitat selection and nesting success in endangered waders breeding on managed shore meadows
Doctoral candidate
Master of Science in Biology Hanna Algora
Faculty and unit
University of Oulu Graduate School, Faculty of Science, Ecology and Genetics research unit
Subject of study
Biology
Opponent
Professor Terje Lislevand, University of Bergen
Custos
Docent Clemens Küpper, Max Planck Institute for Biological Intelligence
Nest distribution, habitat selection and nesting success in endangered waders breeding on managed shore meadows
European wader populations, particularly species breeding in low-lying shore habitats, are undergoing steep declines due to habitat loss and degradation caused by anthropogenic pressures and climate change. In this thesis, I explore ruff (Calidris pugnax) nesting distribution and the major sources of nest mortality driving their low population growth at managed shore meadows in the Bothnian Bay.
In Chapter 1, I examine which social and environmental cues determine ruff nest distributions in a coastal meadow habitat. I found that ruffs nested closer than expected by chance to the nests of conspecifics and leks, while in some years, they nested further away from the shoreline and meadow edge. This non-random nest distribution in ruffs suggests that females may use social cues and the distance to habitat boundaries when choosing a nest site.
In Chapter 2, I investigate the changing frequency and intensity of wind floods in managed coastal meadows in the northern Baltic Sea. Using long-term breeding (2002–2022) and mareograph data (1970–2023), I assessed the impact of time, water level, and the distance from the shoreline on ruff and southern dunlin (Calidris alpina schinzii) nest survival due to flooding. Nest losses caused by flooding increased over the study periods, with increased nest mortality after a water level rise of 40 cm above theoretical mean sea level in both species. Furthermore, we found that the frequency of such floods has increased during the last 50 years.
Finally, in Chapter 3, I focus on disentangling the drivers of nest failure in ruffs, with a particular focus on nest predation. I assessed the impact of social, spatial, and temporal factors on ruff daily nest survival in three models focusing on distinct sources of mortality. Overall, younger nests and those at an intermediate distance to other nests had the highest daily nest survival, while laying date and distance to paths only affected nest survival in the absence of predation. The use of dummy eggs in vulnerable clutches reduced predation, flooding, and trampling mortality and may provide a valuable management tool to improve nesting success.
This thesis highlights the need for comprehensive studies of nest distributions and mortality sources in waders to ultimately improve their population recovery through informed species and habitat restoration and management.
In Chapter 1, I examine which social and environmental cues determine ruff nest distributions in a coastal meadow habitat. I found that ruffs nested closer than expected by chance to the nests of conspecifics and leks, while in some years, they nested further away from the shoreline and meadow edge. This non-random nest distribution in ruffs suggests that females may use social cues and the distance to habitat boundaries when choosing a nest site.
In Chapter 2, I investigate the changing frequency and intensity of wind floods in managed coastal meadows in the northern Baltic Sea. Using long-term breeding (2002–2022) and mareograph data (1970–2023), I assessed the impact of time, water level, and the distance from the shoreline on ruff and southern dunlin (Calidris alpina schinzii) nest survival due to flooding. Nest losses caused by flooding increased over the study periods, with increased nest mortality after a water level rise of 40 cm above theoretical mean sea level in both species. Furthermore, we found that the frequency of such floods has increased during the last 50 years.
Finally, in Chapter 3, I focus on disentangling the drivers of nest failure in ruffs, with a particular focus on nest predation. I assessed the impact of social, spatial, and temporal factors on ruff daily nest survival in three models focusing on distinct sources of mortality. Overall, younger nests and those at an intermediate distance to other nests had the highest daily nest survival, while laying date and distance to paths only affected nest survival in the absence of predation. The use of dummy eggs in vulnerable clutches reduced predation, flooding, and trampling mortality and may provide a valuable management tool to improve nesting success.
This thesis highlights the need for comprehensive studies of nest distributions and mortality sources in waders to ultimately improve their population recovery through informed species and habitat restoration and management.
Created 12.2.2026 | Updated 13.2.2026