Tore Slagsvold

Bird Song Activity in Relation to Breeding Cycle, Spring Weather, and Environmental Phenology

Bird song activity in relation to breeding cycle, spring weather and environmental phenology - statistical data

Nest Site Settlement by the Pied Flycatcher: Does the Female Choose Her Mate for the Quality of His House or Himself?

Here I report the results of nine field experiments with nestboxes made at Trondheim, Norway, during a three year period. By manipulating the positions of nestboxes (i.e. their attractiveness) after male settlement but before female arrival I demonstrated that female Pied Flycatchers Ficedula hypoleuca choose their mates primarily on the basis of nest site quality, not on male quality. Arriving males preferred upright nestboxes to tilted ones, but not to the extent expected from female preference. This was probably related to the fact that constraints of time and energy on the males prevented them from finding the best sites. The conclusion that male and female Pied Flycatchers do not make perfect choices of nest site is important to keep in mind when evaluating models of habitat settlement, such as the density limiting model, the density assessment model and the polygyny threshold model.

Competition between the Great Tit Parus major and the Pied Flycatcher Ficedula hypoleuca in the breeding season.

Literature dealing with competition between the Great Tit and the Pied Flycatcher for nesting sites and food is reviewed, and some data from English and Finnish populations are re-analysed. A preference difference is shown to exist for nesting holes, but because there is a general lack of such places, the two species regularly compete for them. There is some overlap in hunting behaviour and in the food items brought to the young. The interspecific competition may influence breeding numbers and reproductive success, depending on the availability of holes, density of birds, habitat type, and the times of egg-laying. When the interval between the onset of breeding between the two species is short, the flycatcher is favoured.

Autumn population size of the capercaillie Tetrao urogallus in relation to weather

Annual fluctuations in the autumn population size of the Capercaillie Tetrao urogallus at VegArshei in South Norway, 1920-70, were analysed statistically in relation to various meteorological factors to discover short-term effects. The most important weather variables which coincided with a high population size were: an early snowmelt in spring, only a few days of rain at the time of egg-hatching at the beginning of June and only a few days of rain in July. These factors may have operated through their influence on the production of young. The results are discussed in relation to data on the species from other countries.

Competition between the great tit parus major and the pied flycatcher ficedula hypoleuca an experiment

The experiment was carried out in South Norway from 1975 to 1977 (86 nestboxes in 1977). At the time of egg-laying by the Great Tit Parus major every nest-box was made uninhabitable, by various methods, except those which already contained tit nests. This led to increased efforts by the Pied Flycatcher Ficedula hypoleuca to take over tit nests. They were successful in only two out of 40 cases (one Great Tits and one Coal Tits Parus ater, nest) despite a late onset of spring, with delayed laying by the tits. Female flycatchers carried nesting material into another four tit nests. Mutual attacks were frequent and one male flycatcher was killed. Even after the cover of a nestbox had been removed and the entrance hole blocked, the male flycatcher remained singing in the immediate vicinity.