I started my scientific career with studies on parental investment behavior of waders and willow tits, of which I made my PhD-thesis. While testing the “cost of reproduction” –hypothesis with prof. Markku Orell, I entered to the area of long-term population studies. Some controversial results led to an idea of studying maladaptations in newly established northern populations of great and blue tits. The importance of northern latitudes became especially valuable in my following studies on the foraging behavior of northern Parids. The recent advances in our studies concern the effects of climate warming on the ecology of Parids, particularly on their food-web: plants-insects-birds. By applying modern metabarcoding methods, we can now for the first time study the real predator-prey interactions in this context, find possible interspecific competition and/or resource partitioning, and finally study how climate and environmental changes affect the trophic interactions. These studies belonging to our Kvantum project will also determine whether the local populations have evolutionary potential to cope with the rapid phenological changes in the trophic interactions.