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The development of nestlings depends on both biological and weather factors. However, their combined effect differs among bird species. In this study, the impacts of three temperature variables, precipitation, wind speed, timing of breeding, brood size and hatching order on the growth of Eurasian bittern Botaurus stellaris chicks were analysed. Measurements of 183 nestlings from 57 nests were made at fishpond complexes in eastern Poland. Relative growth rates (RGR) were calculated on the basis of tarsus length and body mass. Generalised linear mixed models showed that brood size, hatching order and precipitation were the most important factors. Nestlings in broods of two and three grew faster than those from broods of four and five. In the largest broods, the fifth-hatched chicks had lower growth rates; this also applied to the oldest chicks in all brood-size categories. Nestlings from late-season nests showed enhanced mass and tarsus growth, while heavier precipitation and strong winds depressed growth rates. The study emphasises that even among bitterns breeding in food-rich habitats like fishponds, the chicks in largest broods run the risk of lower growth rates.
Urbanization and subsequent disturbance, habitat alteration and fragmentation are usually seen as major threats to biodiversity. However, habitat alterations might also create new habitat types that can be used by the local fauna. Here, we tested whether hole-nesting passerines use forest edges next to open grassland areas for reproduction by assessing five golf courses in the Helsinki region in southern Finland. We found a major effect in all species breeding at our sites (great tit, Parus major; blue tit, Cyanistes caeruleus; pied flycatcher, Ficedula hypoleuca): both nest occupancy and the number of offspring were significantly higher at the artificial edges than 50 m into the original forests. We conclude that man-made suburban forest edges provide suitable habitat for nesting, which could be further improved with the addition of nest boxes.
We investigated the microhabitat characteristics of song posts used by males of the aquatic warbler in Biebrza National Park (Poland). On average, song posts were located at a height of 94 cm and 32 cm from the top of the plant. Males preferred singing from living plants in habitat patches with tall vegetation and a low water level. The only factor significantly affecting the place chosen for singing was vegetation height, and males sang from a higher location as vegetation height increased. Where only lower vegetation was available, males used relatively higher places for singing in comparison with the total plant height. These observations support the hypothesis predicting the optimization of song post height.
We surveyed 13 Finnish and 13 Swedish poinsettia greenhouses in 2006 for Bemisia tabaci biotype Q (currently B. tabaci Mediterranean) and determined the biotype status of B. tabaci populations with PCR followed by an RFLP assay. We collected approximately 100 adult whiteflies from yellow sticky traps or from plants and stored them in 80% ethanol until DNA extraction. Total nucleic acids of two to five whiteflies per sample were extracted using FTA cards or a modified Chelex method. We showed that biotype Q was present in 10 out of 13 whitefly samples from Finnish poinsettia greenhouses and in 12 out of the 13 Swedish poinsettia greenhouses sampled. We also determined the whitefly biotypes from yellow sticky traps. The common occurrence of insecticide-resistance-prone biotype Q whiteflies on poinsettia imported into Finland and Sweden, both protected zones for B. tabaci, emphasizes the importance of preserving the quarantine status of the pest to prevent permanent establishment. Nonetheless, the increasing occurrence of a resistance-prone biotype on imported plant material will complicate preservation of the protected zone status if solely insecticides are used to control the pest.
Population demographics of northern ungulates are influenced by density and weather conditions. For caribou and reindeer (Rangifer tarandus) that dig in the snow for winter food, snow accumulation and duration of the snow layer are suggested to be influential. Indices based on large-scale alterations of atmospheric pressure such as the North Atlantic Oscillation (NAO) are connected to climate change and may predict ecological processes better than does local weather. Some empirical evidence of the effects of climate variation is available for Arctic and alpine populations but practically none for sedentary, boreal reindeer. We examined the effects of population density, winter and spring NAO, snow accumulation, and the timing of snowmelt on reproductive success (here the calf/female ratio) and on mean summer body mass of calves in a north-boreal, free-ranging herd of semi-domesticated reindeer in northeastern Finland. In this herd, day of snowmelt explained variation in the calf/female ratio and in the midsummer body mass of calves, more so than NAO, winter snow depth and population density.
Territory size generally varies with habitat quality, including vegetation structure, food abundance and available space. Bobolink (Dolichonyx oryzivorus), a semi-colonial species, is known to respond to these habitat quality factors individually, though no previous study has examined these factors simultaneously in relation to territory size. We examined the relationship between bobolink territory size and vegetation structure, prey abundance and patch size in hayfields of southern Ontario, Canada. All three factors were influential in explaining variation in territory size. Important prey items were more abundant in small territories. These small territories also had taller and denser vegetation, deeper litter, and less bare soil. Territory size was related to patch size, with smaller territories on smaller fields. We compared our results with other studies that have found links between territory size and individual variables, including factors not in our models.
The ringed seal (Phoca hispida) is dependent on sufficient ice and snow cover for a breeding habitat. Therefore, climate change has a negative effect on pup survival. We developed methods to estimate perinatal mortality and to mitigate the effects of mild winters on the critically endangered subspecies (P. h. saimensis). Underwater surveys were used for collecting pup carcasses and placentas. Lanugo pup mortality was 13.5% and Brucella sp. was not found in the placentas. Camera traps showed sporadic human and medium-sized carnivore activity in the breeding habitat. Although carnivore activity was most intensive at lair sites, no penetration of the lairs was observed. We developed a method to mitigate the effects of poor snow cover by piling up snowdrifts (n = 117) at potential lair sites. Seals subsequently occupied 62% of these snow drifts. We suggest that the methods developed in this study should be implemented to conserve the Saimaa ringed seal.