The increasing intensity of farming of meadows is supposed to be the major cause for strong declines of many meadow breeding birds. The whinchat, Saxicola rubetra, a Palaearctic migratory bird, is an indicator species of open grassland farmed at a low intensity. Originally widespread throughout Switzerland, it is now restricted to mountain and subalpine grassland. We document the changes in meadow cultivation in subalpine farmland from 1988 to 2002, and the breeding performance and density of the whinchat. We explored the impact of habitat degradation on the population dynamics of this meadow bird. The cultivation of hay meadows changed markedly within the 15 years: the onset of mowing was shifted forward by about 20 days, and farmers applied new techniques such as silage and irrigation. This shift was more pronounced in the favourable farmland in the valley bottom (Pradellas) than on the slopes (Vna`). The percentage of successful whinchat broods, ranging from 5% to 78% in different years, strongly depended on mowing date on both sites. In spite of earlier mowing, birds did not change their time schedule of breeding. Breeding success in Pradellas was too low to compensate for mortality (sink population), but because of immigration the number of breeding pairs did not decrease untill 2000. Population size may therefore be a misleading indicator of local population viability. Based on the breeding schedule of whinchats at different altitudes, we recommend mowing dates in agreement with the reproductive cycle of ground nesting meadow birds.

Abstract. Patterns of selection are widely believed to differ geographically, causing adaptation to local environmental conditions. However, few studies have investigated patterns of phenotypic selection across large spatial scales. We quantified the intensity of selection on morphology in a monogamous passerine bird, the barn swallow Hirundo rustica, using 6495 adults from 22 populations distributed across Europe and North Africa. According to the classical DarwinFisher mechanism of sexual selection in monogamous species, two important components of fitness due to sexual selection are the advantages that the most attractive males acquire by starting to breed early and their high annual fecundity. We estimated directional selection differentials on tail length (a secondary sexual character) and directional selection gradients after controlling for correlated selection on wing length and tarsus length with respect to these two fitness components. Phenotype and fitness components differed significantly among populations for which estimates were available for more than a single year. Likewise, selection differentials and selection gradients differed significantly among populations for tail length, but not for the other two characters. Sexual selection differentials differed significantly from zero across populations for tail length, particularly in males. Controlling statistically for the effects of age reduced the intensity of selection by 60 to 81%, although corrected and uncorrected estimates were strongly positively correlated. Selection differentials and gradients for tail length were positively correlated between the sexes among populations for selection acting on breeding date, but not for fecundity selection. The intensity of selection with respect to breeding date and fecundity were significantly correlated for tail length across populations. Sexual size dimorphism in tail length was significantly correlated with selection differentials with respect to breeding date for tail length in male barn swallows across populations. These findings suggest that patterns of sexual selection are consistent across large geographical scales, but also that they vary among populations. In addition, geographical patterns of phenotypic selection predict current patterns of phenotypic variation among populations, suggesting that consistent patterns of selection have been present for considerable amounts of time.

Summary Eggs of known fresh weight were removed from Great Tit nests shortly before hatching and artificially incubated. Four to eight chicks were returned to each nest‐box on their hatching day and reared by foster parents. The effect of egg weight on subsequent growth was studied for 81 nestlings (13 broods), 50 of them (8 broods) up to the 17th day. Hatching success of 275 eggs in the incubator was 67·6% and was not correlated with egg weight. Egg weight had a significant effect on nestling weight up to the 14th day. Young hatched from lighter eggs grew more slowly at the beginning, but recovered before fledging. Mortality after fledging seemed not to be influenced by egg weight. Maximum weight (mean 19 g) was attained between the 12th and the 17th day and was positively correlated with egg weight. The effect of brood‐size (small in the experiments) on growth increased significantly with age. The range of egg weight for a nest had a significant effect on growth at the beginning, but a small and not significant effect after the 10th day. The growth of each brood on any particular day was expressed as a deviation from mean growth. These growth deviations, plotted against date, were similar in all nests and were not correlated with any weather data. The fledging success of 260 early broods was independent of egg weight, but it was positively correlated with egg weight in 78 late broods (data from 1965–71). The ecological importance of egg weight at different times of the breeding season is discussed.

Many farmland‐breeding wader species have declined across Europe, probably due to reductions in reproductive output caused by high nest losses as a result of agriculture or predation, or low chick survival between hatching and fledging. Most studies have focused on nest failures, and the factors affecting post‐hatching survival of chicks are poorly known. In an experimental approach, we fenced parts of the arable foraging areas of Northern Lapwing Vanellus vanellus families to quantify chick survival simultaneously in the presence and absence of ground predators. Lapwing chicks were radiotagged to estimate survival probabilities by daily locations, applying multistate capture–recapture models. During the night, chick survival was considerably lower outside fenced plots than within. During the day, chick survival was higher than at night and did not differ between protected and unprotected plots. This suggests that nocturnal ground predators such as Red Foxes Vulpes vulpes were responsible for a significant proportion of chick mortality. Cumulative survival probability from hatching to fledging was 0.24 in chicks within fenced plots, but virtually zero in chicks outside fenced plots. In farmland, temporary electric fences can be effective in minimizing the impact of ground predators and offer a promising short‐term method to increase fledging success of precocial birds.

In altricial birds, the great effort involved in supplying food to nestlings can create trade-offs in the allocation of resources between the current brood and parental self-maintenance. In poor foraging conditions, parents have to adjust their energy expenditure in relation to the increased foraging costs. However, intra-specific variation in parental energy expenditure has rarely been evaluated in the context of these trade-offs. Here, we quantified the daily energy expenditure (DEE) of parent Barn Swallows Hirundo rustica during the nestling period in relation to foraging conditions while controlling for differences in brood size and nestling age. DEE varied substantially with environmental conditions, increasing by 10 kJ/day per 5°C in ambient temperature, and by 11 kJ/day per hour in day length. Parent birds did not compensate for a poor aerial insect supply on cool days, but reduced their DEE. Parents only slightly buffered a negative energy balance during chick provisioning with stored body reserves. They did not sacrifice their own energy demands to keep up a high energy flow to the brood when foraging conditions were poor. Instead they worked harder when foraging conditions allowed a surplus intake, fully compensating for their additional efforts, and made maximum use of the rich food supply, allowing the brood to accrue body reserves to compensate for low food intake on cold days. This strategy of energy management may have evolved in the context of the adaptation to the aerial foraging mode and to the ephemeral nature of aerial food resources.