Effects of land use changes on wading bird populations
Aldís Erna Pálsdóttir, for her doctoral project in Biology at the University of Iceland.
Description of project
Aldís Erna Pálsdóttir, received a grant in 2016 for her doctoral project "Effects of changes in land use on wading bird populations" in Biology at the University of Iceland.
We got her to tell us briefly about her project.
Biodiversity is declining globally and the main reasons for this are increased human activity. In the lowlands of Iceland, human activity has increased considerably in recent decades, but this is accompanied by major changes in land use, such as the construction of structures or changes in cultivation. The aim of this study was to investigate whether and how four types of human land use (roads, cottages, power lines and cultivated forests) had an effect on the density and species composition of peahens in the immediate environment. Areas were chosen in the lowlands of Iceland where these types of land use could be found and birds were counted. Two species (woodpecker and wagtail) either showed no effect or were found in higher densities near the aforementioned types of structures. On the other hand, there were six species (tufted tit, border shrike, shrike, tern, spoi and stilt) that were found in lower densities near at least one type of land use. Around roads and forests, it was possible to estimate how large the affected area was, which measured ~200 m beyond the perimeter.
Heidlóa and spói showed the strongest effects, or negative effects of 4 (Spói) and 3 (Heidlóa) types of land use, but between 40-55% of the world population of these species breed in Iceland, and we therefore have a duty to protect these species and their habitats. These results show in black and white that if commercial forests, power lines, roads and houses are placed in open habitats, they can have a decisive effect on the populations of these species.
The table shows the negative effects of structures on the selected bird species that were investigated, i.e. Whimbrel, Golden plover, Godwit, Dunlin, Redshank, Meadow pipit, Oystercatcher, Common snipe, Redwing. The top line shows which types of structures/infrastructure were examined for impact, from left: plantation forest, power lines, summer houses, roads. A “vulnerability index” was also calculated for each species based on the density of the species in question, together with the development of the number of individuals over the past 10 years at selected counting points that took place during the last 10 days of June each year along road junctions. The results show that most of the peat birds are declining, with the exception of the grebe and the woodpecker, which are either staying the same or increasing in number.
To put the results in context with bird density, the results were compared with counts that have been repeated at the same points every year since 2011 in the South, where there have been major changes in land use. The results indicate that while the number of woodpeckers is increasing and the number of barn owls is stable, the number of all the other species that were studied here is decreasing. The proposed changes in land use in the lowlands of Iceland must therefore be planned with the aim of minimizing negative impacts on the plovers, but Iceland has international responsibility for many of these species and the protection of the large open habitats that are still present should be a priority.
Image showing the location of all bird counts that were carried out in 2017-2019. The colors indicate what was counted around, forestry (green), power lines (pink), summer houses (blue) and roads (yellow).
Further research needed
Although the study found that plovers are generally found in lower densities near various types of land use and structures, we still don’t know why. That’s why we started another study in 2022, which aims to check if and how the nesting success of these bird species changes with distance from structures and cultivated forests. That investigation is ongoing.
The fund provided important support
The grant received from the Science Foundation of Southland enabled us to travel around the research area that extended from Snæfellsnes all the way to Kirkjubæjarklaustri. The number of bird counts in this project was carried out in the Southern Lowlands, and these results therefore give a good picture of what is happening with peahens in this area. A large number of landowners who gave permission for data collection on their land were contacted, and they deserve a lot of thanks.