Markus Piha

Improvements in the Finnish Agri-Environment Scheme are Needed in Order to Support Rich Farmland Avifauna

National agri-environment schemes (AESs) aim to promote sustainable farming and protect farmland biodiversity. For efficient maintenance of biodiversity, it is essential to understand the habitat requirements of fauna, and its responses to farming practices. This study examined the importance of different habitat characteristics and habitat heterogeneity for farmland birds in boreal agricultural landscapes, focusing on species in open arable habitats (true field species) and bushy field-edge habitats. Density, species richness, and species composition were studied in a multivariate space, and along environmental gradients. The relevance of the biodiversity-related measures of the Finnish AES regarding the habitat needs of farmland birds was examined. Non-cropped habitat heterogeneity (especially open ditches and habitat patch richness) increased the density and species richness. Crop diversity increased the species richness of true field species. Ordinations revealed a gradient from large open arable to small field areas, and a relation to habitat heterogeneity. The AES places insufficient emphasis on biodiversity issues.

A positive relationship between spring temperature and productivity in 20 songbird species in the boreal zone

Anthropogenic climate warming has already affected the population dynamics of numerous species and is predicted to do so also in the future. To predict the effects of climate change, it is important to know whether productivity is linked to temperature, and whether species’ traits affect responses to climate change. To address these objectives, we analysed monitoring data from the Finnish constant effort site ringing scheme collected in 1987–2013 for 20 common songbird species together with climatic data. Warm spring temperature had a positive linear relationship with productivity across the community of 20 species independent of species’ traits (realized thermal niche or migration behaviour), suggesting that even the warmest spring temperatures remained below the thermal optimum for reproduction, possibly due to our boreal study area being closer to the cold edge of all study species’ distributions. The result also suggests a lack of mismatch between the timing of breeding and peak availability of invertebrate food of the study species. Productivity was positively related to annual growth rates in long-distance migrants, but not in short-distance migrants. Across the 27-year study period, temporal trends in productivity were mostly absent. The population sizes of species with colder thermal niches had decreasing trends, which were not related to temperature responses or temporal trends in productivity. The positive connection between spring temperature and productivity suggests that climate warming has potential to increase the productivity in bird species in the boreal zone, at least in the short term.

Tree sap as an important seasonal food resource for woodpeckers: the case of the Eurasian three-toed woodpecker (Picoides tridactylus) in southern Finland

The Eurasian three-toed woodpecker Picoides tridactylus is considered to be a specialist and obligatory insect-feeder, but the significance of other food sources for its survival and reproduction is unclear. We investigated the importance of tree sap as an alternative food source. We found that three-toed woodpeckers spent up to 33% of their foraging time and 38% of foraging events obtaining phloem sap from coniferous trees in spring before the start of their breeding. Sap use was most common in April and early May, and decreased significantly during nesting in late May and June. The woodpeckers made large numbers of new rows of sap holes in trees in the spring, the maximum being 399 fresh rows in 17 trees during one spring within a single territory. The sap trees were mostly at mature forest edges with rows oriented towards southern open areas indicating that woodpeckers utilized beneficial thermal conditions to obtain sap. These patterns suggest that sap is of high importance especially during the critical period of gaining energy for the start of nesting. We conclude that sap use is an important adaptation that may buffer variation in the availability of insect food in spring, and may increase the probability of three-toed woodpeckers commencing successful breeding.