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Helsinki, Finland

Lodenius M.,University of Helsinki | Solonen T.,Luontotutkimus Solonen Oy
Ecotoxicology | Year: 2013

Published results concerning metal levels in feathers of birds of prey were listed and evaluated. Mercury concentrations have been studied most and the background values normally vary between 0.1 and 5 mg/kg dry weight the highest concentrations being in birds from aquatic food chains. Pollution causes elevated levels of mercury in feathers. The concentrations of cadmium, copper, lead and zinc show reasonable variation between species, areas and time periods. Feathers of birds of prey have proved to be good indicators of the status of environmental heavy metal pollution. Special attention should be paid to clean sampling and preparation of samples. Interpretation of the results requires knowledge on food habit, molting and migration patterns of the species. Several species representing different food chains should be included in comprehensive monitoring surveys. Chick feathers reflect most reliably local conditions. © 2013 Springer Science+Business Media New York.

The onset of breeding in boreal owls might be linked to food supply, weather conditions or both, but the relative importance of each is poorly understood. The primary goal of this study was to discuss the impact that fluctuating food supply and various climatic factors have on the timing of breeding in northern Tawny Owls Strix aluco in rural and urban environments. The timing of breeding was significantly earlier in urban territories than in rural ones. In accordance with earlier findings, very early clutches occurred mainly in urban habitats. In association with being significantly earlier in urban than in rural habitats, the breeding of Tawny Owls began earlier the higher the (autumn) vole levels and the milder the preceding winter. Owls bred earlier the more there were voles and snow simultaneously. It seems that the state of readiness to start egg laying in urban habitats is in general higher than elsewhere and therefore favourable large-scale environmental conditions may also activate breeding earlier there than in rural areas. © 2013 Dt. Ornithologen-Gesellschaft e.V.

Solonen T.,Luontotutkimus Solonen Oy | Hilden M.,University of Helsinki
Ornis Fennica | Year: 2014

Urbanization and climate change are two environmental factors that have most prominently affected breeding phenology of birds during recent decades. We examined such relationships in rural, suburban and urban nest box populations of Great Tits Parus major and Blue Tits P. caeruleus in the capital region of Finland in the 1980s and 1990s. We expected that mild winters and high spring temperatures may advance the breeding season of tits, but less so in urban habitats, where breeding should in any case start earlier than elsewhere. On average, Blue Tits began egg laying a few days earlier in spring than Great Tits. Contrary to expectations, tits bred later in the urban parks of the city than in other habitats,whereas breeding was earliest in suburban areas. It seems that these intermediate habitats, in some way, offer the advantages of both rural and urban habitats. During the study period, the timing of breeding in tits showed advancing temporal trends in rural habitats, and in the Blue Tit also in urban habitats. The effect of increasing winter temperatures on laying dates was mainly minor, but a significant delay emerged in urban Great Tits. The main effect of increasing April temperatures on laying dates was a significant advancement. In urban habitats, however, the advancing effect was in Great Tits significantly stronger and in Blue Tits significantly weaker than in other habitats. The results suggest that breeding of tits may advance also with warming climate but some urban populations might be more resistant to climate change than rural ones.

Solonen T.,Luontotutkimus Solonen Oy | Ahola K.,Tornihaukantie 8 D 72 | Karstinen T.,Juusinkuja 1
Environmental Monitoring and Assessment | Year: 2015

Voles are often considered as harmful pests in agriculture and silviculture. Then, the knowledge of their abundance may be of considerable economical importance. Commonly used methods in the monitoring of vole abundances are relatively laborious, expensive, and spatially quite restricted. We demonstrate how the mean clutch size of the tawny owl Strix aluco may be cost-effectively used to predict relative densities of voles over large areas. Besides installing a number of suitable nest boxes, this vole monitoring system primarily includes only the inspection of the nest boxes and counting the number of tawny owl eggs found two times during a few weeks period in spring. Our results showed a considerable agreement between the fluctuations in the mean clutch size of tawny owls and the late spring abundance indices of small voles (Myodes, Microtus) in our study areas in southern Finland. The mean clutch size of the tawny owl reflected spring vole abundance over the spatial range examined, suggesting its suitability for general forecasting purposes. From the pest management point of view, an additional merit of the present method is that it may increase numbers of vole-eaters that provide biological control of vole populations. © 2015, Springer International Publishing Switzerland.

Solonen T.,Luontotutkimus Solonen Oy | Jokimaki J.,Finnish Forest Research Institute | Jokimaki J.,University of Lapland
Bird Conservation International | Year: 2011

We conducted three-visit surveys of 1-km2 plots and traditional Finnish single-visit line transects (considering only the 50 m wide main belt) to evaluate these methods in censusing of a predetermined set of 23 target species known to prefer old forests in three regions in Finland. The efficiency of the two methods was compared on the basis of the number of territories recorded per hour. An attempt was made to find indicators of the occurrence of suitable habitats for species preferring old forest in general, including the rarest ones, and so also largely indicating total diversity of forest bird fauna of the study area. The total number of pairs observed per hour and the abundance of sedentary bird species were significantly higher in the square surveys than in the main belt of the line transects. There were significant positive relationships between the densities of relatively abundant (density > 1.0 pairs km-2) and less abundant target species. There emerged five common forest bird species that seemed to form a suitable set of indicators of the occurrence of habitats for birds preferring old forest in the northern boreal zone: Great Spotted Woodpecker Dendrocopos major, Mistle Thrush Turdus viscivorus, Willow Tit Parus montanus, Eurasian Treecreeper Certhia familiaris, and Eurasian Bullfinch Pyrrhula pyrrhula. We concluded that sedentary species preferring old forest are good candidates for indicators to characterize some threatened aspects of forest bird diversity. © Copyright BirdLife International 2010.

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