No abstract

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.

Partial migration - a part of a population migrates and another part stays resident year-round on the breeding site - is probably the most common type of migration in the animal kingdom, yet it has only lately garnered more attention. Theoretical studies indicate that in partially migratory populations, the proportion of resident individuals (PoR) should increase in high latitudes in response to the warming climate, but empirical evidence exists for few species. We provide the first comprehensive overview of the environmental factors affecting PoR and the long-term trends in PoR by studying 27 common partially migratory bird species in Finland. The annual PoR values were calculated by dividing the winter bird abundance by the preceding breeding abundance. First, we analysed whether early-winter temperature, winter temperature year before or the abundance of tree seeds just before overwintering explains the interannual variation in PoR. Secondly, we analysed the trends in PoR between 1987 and 2011. Early-winter temperature explained the interannual variation in PoR in the waterbirds (waterfowl and gulls), most likely because the temperature affects the ice conditions and thereby the feeding opportunities for the waterbirds. In terrestrial species, the abundance of seeds was the best explanatory variable. Previous winter's temperature did not explain PoR in any species, and thus, we conclude that the variation in food availability caused the interannual variation in PoR. During the study period, PoR increased in waterbirds, but did not change in terrestrial birds. Partially migratory species living in physically contrasting habitats can differ in their annual and long-term population-level behavioural responses to warming climate, possibly because warm winter temperatures reduce ice cover and improve the feeding possibilities of waterbirds but do not directly regulate the food availability for terrestrial birds.

Bird migration phenology shows strong responses to climate change. Studies of trends and patterns in phenology are typically based on annual summarizing metrics, such as means and quantiles calculated from raw daily count data. However, with irregularly sampled data and large day-to-day variation, such metrics can be biased and noisy, and may be analysed using phenological functions fitted to the data.Here we use count data of migration passage from a Finnish bird observatory to compare different models for the phenological distributions of spring migration (27 species) and autumn migration (57 species). We assess parsimony and goodness-of-fit in a set of models, with phenological functions of different complexity, optionally with covariates accounting for day-to-day variability. The covariates describe migration intensities of related species or relative migration intensities the previous day (autocovariates).We found that parametric models are often preferred over the more flexible generalized additive models with constrained degrees of freedom. Models corresponding to a mixture of two distinct passing populations were frequently preferred over simpler ones, but usually no more complex models are needed. Slightly more complex models were favoured in spring compared to autumn. Related species' migration activity effectively improves the model by accounting for the large day-to-day variation.Autocovariates were usually not that relevant, implying that autocorrelation is generally not a major concern if phenology is modelled properly. We suggest that parametric models are relatively good for studying single-population migration phenology, or a mix of two groups with distinct phenologies, especially if daily variation in migration intensity can be controlled for. Generalized additive models may be useful when the migrating population composition is unknown. Despite these guidelines, choosing an appropriate model involves case-by-case assessment or the biological relevance and rationale for modelling phenology.

Timing of spring migration and breeding and their interaction with climate change has been widely studied in recent years, but the possible changes in timing of autumn migration have gained less attention. This work focuses on autumn migration and provides the first multi‐species individual‐based study of how hatching date affects the autumn migration date and migration age by using nestling ring data and re‐trappings of the same individuals during the autumn migration at the Hanko Bird Observatory, Finland. We studied three potentially multibrooded passerines (great tit, blue tit and coal tit) and two single‐brooded birds of prey (goshawk, sparrowhawk), all partially migratory short‐distance migrants. Individuals from late broods migrated at a younger age in all tit species and also in hawks the late hatched individuals tended to migrate at a younger age than the early‐hatched individuals. Late‐hatched individuals migrated later than early‐hatched individuals in blue and coal tits, where the latest hatchers represented second brood individuals. Based on our results, the time from hatching to autumn migration is not constant even among individuals of the same population. Our study indicates that climate warming induced advancement of avian breeding may cause changes in the timing of autumn migration through the frequency of second broods.

Monitoring of bird populations is based primarily on volunteer birdwatcher activity in Finland. Hence, development of online user interfaces and data availability have become a priority in order to encourage bird watchers to participate in monitoring schemes. Most Finnish bird monitoring is managed by the Finnish Museum of Natural History LUOMUS, which oversees a wide spectrum of long-running programs including: a bird ringing (banding) scheme running since 1913, a winter bird census established in 1956, a breeding bird census initiated in 1975, a raptor monitoring program started in 1982, and, a nest recording scheme ongoing since the 1940s. In 2018, more than 1,500 volunteer birdwatchers participated in LUOMUS bird monitoring schemes. Data gathered from these programs constitute our basis of knowledge on national bird populations and demographic trends and are actively incorporated in conservation, scientific, land-use planning, and administrative purposes in Finland. In principle, all data are open and freely accessible via the Finnish Biodiversity Information Facility (FinBIF), however, the law prohibits authorities from distributing species occurrence data if this causes an increased threat to certain endangered species. Accordingly, sensitive data details are not available. Reporting valuable fieldwork data can sometimes be demanding. As such, developing user-friendly interfaces for data portals is critical to facilitating volunteer activity. Essential tools for volunteers include a simple login, smooth and augmented data input, automated validation of data, and, perhaps most importantly, ease of access to up-to-date data. Crucial to administrators are system reliability, operability, and easy data management. Comprehensive data validation and visualization tools and extensive search functions aid in revealing errors and thereby increase data quality. Finally, simple query tools and easy access to data are of paramount importance for smooth abd flexible use of the data. Keeping in mind these demands, we have developed the main FinBIF platform and project-specific user interfaces in order to facilitate participation in bird monitoring programs. We will introduce these user interfaces and our achievements and challenges in the development process.

No abstract