Survival, ranging, habitat choice and diet of the Northern Goshawk Accipiter gentilis during winter in Northern Finland

The winter ecology of the Northern Goshawk Accipiter gentilis was studied in northern Finland in 1991-95. The data consist of 26 radiomarked hawks, of which 331 day and 299 night positions were located. Average range size was 9894 ha for males (minimum convex polygon, n = 4) and 6282 ha for females ( n = 11). Ranges calculated by the 75% harmonic mean contour gave range areas of 3283 ha for males ( n = 3) and 2753 ha for females ( n = 11). Harmonic mean centres concentrated near human settlements, implying better food availability there compared with woodland areas. Some Goshawks preyed upon animals living in the city dump in late winter. Goshawks preferred deciduous and mature conifer forests and avoided open areas such as fields and bogs. They also avoided very heterogeneous sites. The winter diet consisted mostly of Mountain Hares Lepus timidus (30.9%), Red Squirrels Sciurus vulgaris (23.6%), Brown Rats Rattus norvegicus (12.7%) and forest grouse Tetraonidae (27.1%), of which Black Grouse Tetrao tetrix was the most important (14.5%). By weight, hares constituted 70% of the biomass consumed.     

Community concordance between bryophyte and insect assemblages in boreal springs: a broad-scale study in isolated habitats

1. We examined species–environment relationships and community concordance between aquatic bryophytes and insects in boreal springs. We sampled bryophytes (Marchantiophyta and Bryophyta), benthic macroinvertebrates and environmental variables in 138 springs in Finland, spanning a latitudinal gradient of 1000 km. Macroinvertebrates were subdivided into two groups: Ephemeroptera, Plecoptera, Trichoptera and Coleoptera (EPTC taxa) and chironomid midges (Diptera; Chironomidae). Our aim was to test whether EPTC taxa could be used as surrogates in biodiversity surveys and bioassessment for the two less-well known organism groups, chironomids and bryophytes.
2. Bryophyte assemblages were clearly differentiated along gradients in thermal conditions and water chemistry (pH, conductivity). Chironomids and EPTC were also differentiated in relation to thermal conditions and, to a lesser extent, physical habitat variables, but were only weakly associated to spring water chemistry. Chironomid and EPTC assemblages were more concordant with each other than with bryophytes, but all concordances were relatively weak.
3. Our results suggest that even if the overall compositional patterns of the three taxonomic groups were significantly concordant, the relative importance of environmental drivers underlying their community compositions differed strongly. The results thus imply that spring bryophytes and insects are relatively poor surrogates for each other. The proportion of spring specialists was highest in bryophytes, promoting their primacy for spring bioassessment and biodiversity conservation. We suggest that adequate variation in water chemistry be assured to protect spring bryophyte biodiversity, whereas preserving the physical variation of springs is more important for macroinvertebrates.     

Species traits explain recent range shifts of Finnish butterflies

This study provides a novel systematic comparative analysis of the species characteristics affecting the range margin shifts in butterflies towards higher latitudes, while taking phylogenetic relatedness among species into account. We related observed changes in the northern range margins of 48 butterfly species in Finland between two time periods (1992–1996 and 2000–2004) to 11 species traits. Species with positive records in at least ten 10 km × 10 km grid squares (in the Finnish National Butterfly Recording Scheme, NAFI) in both periods were included in the study. When corrected for range size change, the 48 butterfly species had shifted their range margins northwards on average by 59.9 km between the study periods, with maximum shifts of over 300 km for three species. This rate of range shifts exceeds all previously reported records worldwide. Our findings may be explained by two factors: the study region is situated in higher latitudes than in most previous studies and it focuses on the period of most prominent warming during the last 10–15 years. Several species traits exhibited a significant univariate relationship with the range margin shift according to generalized estimation equations (GEE) taking into account the phylogenetic relatedness among species. Nonthreatened butterflies had on average expanded their ranges strongly northwards (84.5 km), whereas the distributions of threatened species were stationary (−2.1 km). Hierarchical partitioning (HP) analysis indicated that mobile butterflies living in forest edges and using woody plants as their larval hosts exhibited largest range shifts towards the north. Thus, habitat availability and dispersal capacity of butterfly species are likely to determine whether they will be successful in shifting their ranges in response to the warming climate.