Unravelling the complexities of a boreal bird-insect food web influenced by climate change

While ongoing climate change is expected to strongly affect the natural world around us, we currently have little understanding of its influence on many species, let alone entire ecosystems. New methods like metabarcoding, which can identify species based on unique DNA sequences in bulk samples collected from the environment, are allowing us to investigate such questions for the first time. In this research, which forms part of my doctoral dissertation, we aim to investigate the diets of five species of small passerine birds using this methodology, continuing and expanding long-running monitoring of these birds near Oulu. Some of the studied species are recent arrivals to the area, while others have seen strong declines in the last decades. The dietary information will give us insights that can help explain these population trends, such as differing habitat requirements or possible competition between the birds. In addition, we will connect our findings to recently published data on local geographic shifts and population declines of their most important prey. All required samples have been collected and prepared for lab analysis at the time of writing. Most have already been successfully used for DNA extraction, amplification and sequencing, and the remainder would be ready before the start of the applied-for funding period, using previously obtained funding. The subsequent aim is to finalize my doctoral studies by writing the dissertation and articles. These articles would specifically look into questions on: 1) niche differentiation, competition and other interactions between the birds; 2) variation and consistency in diets between different years; 3) population and range changes in the birds and their most common prey in recent decades. The overall goal is to better understand the complexity of this dynamic food web, and to gain knowledge of how such systems might further change in the decades to come.