Carotenoid plumage hue and chroma signal different aspects of individual and habitat quality in tits

We hypothesized that Blue Tits Cyanistes caeruleus and Great Tits Parus major from low quality habitat (small woods) would have less yellow ventral plumage than those from high quality habitat (large woods) because they moult faster and/or their diet contains fewer carotenoids. They moult faster because they moult later in the season and are subject to more rapidly shortening daylengths. We tested this using a database of the plumage coloration (chroma, hue and lightness) of birds breeding in woods of different sizes, by manipulating the speed of moult in captive Blue Tits, and by counting the abundance and size of caterpillars (the major source of dietary carotenoids) in the diet of nestlings. In accordance with our hypothesis, juveniles of both species (which moult about three weeks later than adults) were about 8% less saturated in colour (lower chroma) than adults, but there was no significant difference in chroma between habitats. However, both species did differ significantly in hue between large and small woods. Blue Tits forced to moult faster in captivity, at a rate similar to that caused by a month's delay in the start of moult, had yellow flank feathers that were 32% less saturated in colour than those allowed to moult more slowly. Blue Tit nestlings in large woods consumed 47% more caterpillar flesh (per gram of faecal material voided) than those in small woods, and Great Tit pulli 81% more. When habitat effects were controlled for in ANOVAs, Blue Tits mated assortatively on the basis of flank hue and Great Tits on the basis of flank lightness. Flank colour therefore has the capacity to provide information about the potential quality of both habitats, and individual birds, to potential colonists and sexual partners.     

The phenology and clutch size of UK Blue Tits does not differ with woodland composition

The deciduous tree-herbivorous caterpillar-insectivorous bird food chain is a well-studied system for investigating the impacts of climate change across trophic levels. To date, across Europe, most attention has focused on the impacts of increasing spring temperature on changes to phenology in Oak-dominated (Quercus spp.) woodlands. Paridae species and Pied Flycatcher Ficedula hypoleuca are the most studied secondary consumers, all of which demonstrate an advancement in reproductive phenology with increases in spring temperature. Shifts in climate and phenology may also impact on reproductive investment in clutch size, and the effects of climate on phenology and clutch size may vary depending on woodland composition. To date, the effects of among-habitat variation in phenology and reproductive investment have received little attention. Insectivorous birds inhabiting woodlands that differ in tree composition may differ in the timing of breeding, due to local tree leafing phenology acting as a cue for egg-laying date and/or clutch size. Moreover, for most insectivorous birds, woodland composition within a territory is likely to be the main determinant of food availability for both adults and chicks. Consequently, if warming springs affect the temporal patterns of food availability differently across different woodland compositions, this may affect the optimal average local phenology for nesting birds. Here, using data from 34 long-term (mean 15 years) nest monitoring sites across the UK, we investigate the effect of woodland tree composition and temperature on Blue Tit Cyanistes caeruleus first egg date (FED) and clutch size. We supplemented the nest monitoring data by quantifying woodland composition, at a site level, through modified point counts. We predict that birds breeding in woodlands with greater proportions of late-leafing species, such as Oak and Ash Fraxinus excelsior, will breed later than those breeding in woodlands with greater proportions of early-leafing species, such as Birch Betula spp. and Beech Fagus sylvatica. We found no evidence for differences in Blue Tit FED or clutch size in relation to the proportion of any of the tree species investigated, after controlling for temperature and latitude (FED: −3.4 and 2.2, clutch size: −0.4 and − 0.2 eggs for one-unit increase in temperature and latitude, respectively). In recent decades and across all sites, clutch size has decreased as spring temperatures have increased, a strategy which could allow birds flexibly to adjust their breeding phenology such that nestling demand coincides with peak food availability. The lack of an effect of woodland composition on Blue Tit phenology suggests Blue Tits do not fine-tune their reproductive phenology to the local tree composition. Whether this lack of evidence for phenological divergence is due to an absence of divergent selection on breeding phenology and clutch size or to gene flow is not clear.     

Parental provisioning behaviour in Pied Flycatchers Ficedula hypoleuca is well adjusted to local conditions in a mosaic of deciduous and coniferous habitat

Capsule Pied Flycatchers are better able than Great Tits to adjust their feeding behaviour to varying conditions in the same area.

Aims Great Tits breeding in a mosaic of deciduous and coniferous forests in the northern temperate region exhibit consistently lower breeding success in their preferred deciduous habitat than in coniferous habitat. This was explained by the unexpectedly poor nestling feeding conditions in deciduous forests of this region. We studied whether the same paradox applies to Pied Flycatchers that occupy the same habitats in the same area.

Methods Parental provisioning behaviour was studied using video‐recording and experimental manipulation. Caterpillar abundance and basic breeding parameters were measured in different habitat types.

Results Parental provisioning frequency and the proportion of caterpillars in nestling diet was lower, while food objects were on average larger, in coniferous compared with deciduous habitat. However, the total volume of caterpillars and adult Lepidoptera delivered to nestlings did not differ between habitats. In contrast to Great Tits, offspring body parameters in Pied Flycatchers did not differ between habitat types.

Conclusions These results demonstrate how the relative suitability of particular habitat types varies between species and is dependent upon geographical location.     

STRUCTURE AND FORAGING PATTERNS OF FLOCKS OF TITS AND ASSOCIATED SPECIES IN AN ENGLISH WOODLAND DURING THE WINTER

Blue Tits were the commonest and most frequent members of mixed-species insectivorous flocks during the winter at Wytham Wood, Oxford. Six common flocking species (Blue Tit, Longtailed Tit, Great Tit, Coal Tit, Marsh Tit and Golderest) made up nearly two-thirds of the birds in the study area. A tentative interspecific social dominance hierarehy was constructed: Great Tit > Blue Tit > Marsh Tit > Coal Tit > Long-tailed Tit and Goldcrest. Blue Tits permitted conspecifics to approach them more closely than did other flock members. Blue Tits most frequently led the flocks, but no more than would be predicted by their abundance. Great Tits, and Marsh Tits and Coal Tits to a lesser extent, defended territories during the winter. Two of the six common species frequented the inner parts of branches (Great Tit, Coal Tit), two the outer parts of branches (Blue Tit, Marsh Tit), and two the twigs (Long-tailed Tit, Goldcrest). Members of each of these species-pairs showed marked differences in height of foraging and/or species of tree frequented. Because of their abundance, the impact of Blue Tits outside of their most highly frequented foraging zones may exceed that of species concentrating in these other zones (e. g., twigs high in trees). The Coal Tit foraged most diversely, the Great Tit least diversely. Species that foraged diversely in one of the three foraging categories (species of tree, substrate, height) usually foraged less diversely than most other species in the other dimensions. Species usually overlapped least in the zones exploited (inner parts of branches, etc.). Great Tits overlapped with other species less than did any other common flock member, and Coal Tits were the next lowest in this regard.     

Food resource matching by foraging tits Parus spp. during spring-summer in a Mediterranean mixed forest; evidence for an ideal free distribution

We analysed whether patterns of microhabitat use by Blue Tits Parus caeruleus , Great Tits Parus major and Crested Tits Parus cristatus inhabiting a mixed forest consistently matched the patterns of food availability experienced by foraging birds during spring-summer. The use of five microhabitats by each bird species (the foliage of three tree species, shrubs and ground) and the availability of food in trees during the prebreeding, breeding and post-breeding periods of the birds' annual cycle were measured. All three tit species foraged mainly in the outer part of tree canopies (small branches and leaves or needles). Tit distributions between tree species matched food resource distributions irrespective of overall food resource levels, which varied four-fold between the study periods, and tit species. Tits also exploited secondary microhabitats (shrubs and ground) in periods of low food availability; Blue Tits tended to use shrubs, whereas Great and Crested Tits foraged on the ground. Between-trees distributions fitted that expected from an ideal free distribution, suggesting that food availability and intraspecific exploitative competition were the main factors governing tree use by tits. In contrast, patterns of use of secondary microhabitats (shrubs and ground) seemed to indicate a role for the species-specific morphological configurations of each tit species since Blue Tits are better adapted to hang and tended to forage in shubs, whereas Great and Crested Tits are better adapted to feed on horizontal surfaces and tended to forage on the ground. No evidence of interspecific interactions was observed. Overall, the results pointed to an independent exploitation of Mediterranean mixed forest by each bird species, food availability and food accessibility being the main factors affecting microhabitat use by foraging tits.     

Habitat and diet variability of two coexisting tit species in central European forests

Capsule: Blue Tits and Great Tits occupied different habitats within forests in Central Europe but their nestlings shared a similar diet.

Aims: To quantify the differences in offspring diet and territory habitat between Great Tits Parus major and Eurasian Blue Tits Cyanistes caeruleus in two European forests, and to test whether the ecological niches of the two species overlap.

Methods: Research was conducted on Great Tits and Eurasian Blue Tits, breeding in nest boxes in two forests near Kraków, Poland, during years: 2009, 2011 and 2012. Nine days after hatching, food items were collected from offspring using neck-collars. Habitat parameters surrounding each nest box were quantified.

Results: Great Tit territories were in old Oak-Hornbeam forest, whereas Blue Tits often nested in mixed forest. There were no significant differences between the two bird species in the variation in their caterpillar diets for which both species were highly variable. Great Tits collected more caterpillars of Noctuidae per nest than did Blue Tits in 2009 and 2011 in Niepo?omice Forest; Blue Tits collected more Tortricidae in 2011 and more spiders every year. In Krzyszkowice Forest in 2012, tits fed their nestlings in different periods and did not differ in the proportion of caterpillars. Habitat affected diet differently in each species.

Conclusion: Although Great Tits and Blue Tits occupied different territories in each forest and year of research, the diets of both species’ nestlings contained similar species of invertebrates. The overlaps of the birds’ environmental needs are specific at a local scale.     

Differences in the onset of laying between island and mainland Mediterranean Blue Tits Parus caeruleus: phenotypic plasticity or genetic differences?

Blue tits Parus caeruleus breeding in deciduous or in evergreen woodlands on the mainland of Europe start to lay 3–4 weeks earlier than Blue Tits on the island of Corsica breeding in evergreen woodlands. A similar difference in average laying date between the two Blue Tit populations has been found in a relatively small sample of captive birds held in outdoor aviaries on the mainland. To provide data on the habitat contrast in Corsica for comparison with that on the mainland, a new study area was started in one of the few deciduous woodlands on Corsica. In addition, new data on laying dates of captive Blue Tits were gathered to increase the sample size of independent pairs in aviaries. This study shows that the habitat effect (deciduous ν evergreen woodland) on the average laying date of Blue Tits is relatively small in comparison with the geography effect (European mainland ν Corsica). The laying date differences between mainland and insular Blue Tits persisted whatever the type of habitat (deciduous, evergreen or outdoor aviaries on the mainland). The data support the hypothesis that the observed differences in the onset of laying between the mainland and insular Blue Tits were mainly influenced by genetic effects and relatively little by non-genetic maternal effects of by genotype—environment interactions.     

Pair bond and breeding success in Blue Tits Parus caeruleus and Great Tits Parus major

Data from 939 nests of the Blue Tit Parus caeruleus and 1008 nests of the Great Tit P. major from nestboxes provided in superabundance in mixed forest study sites between 1976 and 2001 were analysed to examine the effects of mate retention on breeding success and the relationship between mate fidelity and site fidelity. Most birds retained their former partner (76% in Great Tits and 65% in Blue Tits). The probability of a pair divorcing was affected by male age in Great Tits, divorce being more likely in pairs with first‐year males. Great Tit pairs breeding together for a second season bred earlier, but had no higher breeding success than pairs breeding together for the first time. In Blue Tits laying date and start of incubation tended to be earlier in pairs breeding together for a second season, but hatching and fledging dates were not earlier than in other pairs. Great Tit pairs breeding together for two consecutive seasons bred earlier in the second season than in the first, but breeding success did not differ significantly between years. In both species, breeding performance did not differ between pairs that divorced after a season and pairs that stayed together. Thus breeding success did not determine whether a pair divorced or bred together again. Neither Blue Tits nor Great Tits improved their breeding performance through divorce. Blue Tit females even had fewer fledglings in the year after divorce than in the year before. Mate retention affected breeding site fidelity. Blue Tit females had greater breeding dispersal distances between consecutive years when re‐mating than when breeding again with the same mate. In Great Tits both males and females dispersed more when re‐mating than when retaining the former partner, suggesting that mate retention increased the chance of retaining the breeding site. In both species, breeding dispersal distances did not differ between pairs that divorced and pairs in which one mate disappeared. Because no major advantage of mate retention was evident, we suggest that mate retention evolved under different conditions than those found in study sites with high breeding densities and a superabundance of artificial nesting sites.     

Habitat and laying date of Great and Blue Tit Parus major and P. caeruleus

Using 19 year's data from nine study areas at Ghent we investigated the effect of habitat on laying date, and found it to be quite different for Great and Blue Tits. In Great Tits we found a clear gradient in laying dates from urban over suburban to rural habitats. Blue Tits laid earliest in a suburban habitat and latest in a rural habitat. All other areas, including urban, suburban and rural ones, formed one intermediate group. The overall average laying date for the Great Tit, 18.9 April, was slightly earlier than that of the Blue Tit, 19.4 April. In urban areas Great Tits laid significantly earlier than Blue Tits, in optimal oak habitat and in one suburban area Blue Tits laid earlier, whereas in the five remaining areas no significant differences between the two species were found.
We argue that the differences in laying dates, although correlated to temperature, are probably caused by differences in the timing of food availability. We suggest that differences in laying dates of Great and Blue Tits are caused by a different response to environmental variations through differences in feeding ecology.     

不同纬度洞巢鸟类对人工巢箱的利用及差异

迄今对洞巢鸟类生活史特征的纬度变异（特别是热带洞巢鸟类的繁殖）了解还十分有限。我们于2018年3至8月,分别在海南吊罗山（热带）、河南董寨（亚热带）和河北塞罕坝（温带）的林缘地带,悬挂相同规格的人工巢箱招引洞巢鸟类繁殖,用以比较不同地理区域的洞巢鸟类对人工巢箱的利用情况及其孵化成效和繁殖成功率。野外共悬挂577个木制巢箱,3个研究地的利用率在海南吊罗山为最低（32.6%）,河南董寨最高（92.0%）。3个地点均有大山雀（Parus cinereus）入住（占总巢数的84.3%）,其孵化成效和繁殖成功率在3个地点不存在显著差异（P > 0.05）。但在河北塞罕坝,大山雀的孵化成效（75.7%）和繁殖成功率（65.7%）显著低于同域繁殖的褐头山雀（Poecile montanus）（97.7% 和97.7%）和煤山雀（Periparus ater）（93.5%和90.3%）（P < 0.05）。研究表明,3个地理区域利用巢箱繁殖的洞巢鸟的种类、数量以及对巢箱的利用率均存在差异,但对于广布种大山雀来说,地理位置的差异并不影响其孵化成效和繁殖成功率。     

Prey selection and foraging performance of breeding Great Tits Parus major in relation to food availability

We studied the nestling diet and the foraging performance of Great Tits in relation to prey abundance in the field. Numerous experimental studies present data on foraging decisions in captive Great Tits. Little is, however, known about prey selection in the field in relation to the food available and the consequences this has for the food delivery rate to nestlings. Since the foraging performance of the parents is one of the main determinants of fledging weight and juvenile survival, foraging behaviour is an important part of Great Tit reproduction. During the early breeding season up to 75% of the prey biomass delivered to the nestlings were spiders, which is in contrast with other studies. Only when caterpillars reached a size of 10–12 mg (approximately the average size of the spiders caught at that time) did the Great Tits change their preferences and 80–90% of the delivered prey masses were caterpillars, as reported by other authors. This 'switching' between prey occurred within a few days. It was not related to the changes in abundance but to size of caterpillars. The rate at which caterpillars were delivered to the nestlings (in mg/nestling/h) was strongly correlated with the caterpillar biomass available (in mg/m of branches) and nestling growth rate was significantly influenced by the mass of available caterpillars. The results provide evidence why perfect timing of breeding is so important for the Great Tit, and contribute to the understanding of the causal link between food supply, growth and breeding success.     

Do Blue Tits time their breeding based on cues obtained by consuming buds?

ABSTRACT.   Many temperate-zone birds must track seasonal variation in food availability to time breeding and enhance reproductive success. However, the external cues birds use to fine-tune sexual development and timing of reproduction remain unclear. One possibility is that birds may use chemical substances in plants and bud tissues as a reliable predictor of leaf flush and the appearance of caterpillars, the preferred prey of many insectivorous birds during the breeding season. However, few data on seasonal shifts in key plant material consumption are available. To test this hypothesis, we examined the gizzard contents of Corsican Blue Tits ( Cyanistes caeruleus ), a small passerine bird with a breeding schedule tightly linked to the phenology of oak trees. We quantified and compared the consumption of tree buds by birds captured during winter (nonbreeding) and early spring (prebreeding) and found that bud use by Blue Tits was limited and constant through time. Fewer than 30% of birds had buds in their gizzards during the critical prebreeding period, and these items represented less than 1% of gizzard contents. It is unlikely that this limited use of buds allowed birds to track a potential chemical signal at the time of reproductive decision making. Unless more data on the consumption of plant material become available, we suggest that other environmental factors be examined to help identify the cues used by temperate-zone birds to time their reproduction.     

The effect of nestboxes on breeding populations of birds in broadleaved temperate woodlands

Removal of nestboxes from a semi-mature, broadleaved woodland caused a decrease in the number of breeding pairs of Great Tits, but did not significantly reduce breeding densities of Blue Tits. Breeding densities of warblers were unaffected by changes in the population of Great Tits. In the absence of nestboxes, intraspecific competition for natural nestholes was more intense amongst Great Tits than Blue Tits. Great Tits tended to occupy larger holes on or near the trunk, while Blue Tits used smaller holes on side branches. Nesting success for both species was lower in natural cavities than nestboxes, due to a higher percentage of total nest failures. The reintroduction of nestboxes did not produce an immediate rise in the breeding population of Great Tits; possible reasons for this are discussed.     

The effect of nestboxes on breeding populations of birds in broadleaved temperate woodlands

Removal of nestboxes from a semi-mature, broadleaved woodland caused a decrease in the number of breeding pairs of Great Tits, but did not significantly reduce breeding densities of Blue Tits. Breeding densities of warblers were unaffected by changes in the population of Great Tits. In the absence of nestboxes, intraspecific competition for natural nestholes was more intense amongst Great Tits than Blue Tits. Great Tits tended to occupy larger holes on or near the trunk, while Blue Tits used smaller holes on side branches. Nesting success for both species was lower in natural cavities than nestboxes, due to a higher percentage of total nest failures. The reintroduction of nestboxes did not produce an immediate rise in the breeding population of Great Tits; possible reasons for this are discussed.     

Provision of nestboxes raises the breeding density of Great Tits Parus major equally in coniferous and deciduous woodland

Nestbox provision is a technique used to increase nest-site availability for secondary cavity-nesting birds. However, little is known about the demographic consequences of nestbox provision in different habitat types. To assess how nestbox provision affects the density of hole-nesting birds simultaneously in two contrasting habitats, we compared the breeding density of Great Tits along transects without nestboxes with that in transects where nestboxes were provided. Although the initial density of breeders was considerably higher in the deciduous habitat than in the coniferous habitat, provision of nestboxes increased density by a similar number of additional pairs in each habitat type. Thus, the provision of nestboxes in managed coniferous forests may be as effective in increasing the breeding opportunities of cavity nesters as in deciduous stands. Moreover, previous research showed that pairs in deciduous habitat with nestboxes have consistently lower breeding success than those in coniferous habitat with nestboxes. It is possible that the addition of nestboxes in the preferred habitat increased density to such an extent that density-dependent effects became apparent.     

Nestbox orientation: a species-specific influence on occupation and breeding success in woodland passerines

Capsule Nestbox orientation has species-specific influences on nestbox occupation and breeding success for woodland passerines.

Aims To determine if nestbox orientation had an influence upon nestbox selection or breeding success for three co-occurring woodland passerines.

Methods We analysed 15 consecutive years of breeding data (1990–2004) from 295 nestboxes in the UK using circular statistical analyses to examine the influence of orientation upon nestbox occupation and breeding success for three species, Blue Tit Cyanistes caeruleus, Great Tit Parus major and Pied Flycatcher Ficedula hypoleuca.

Results The three species used nestboxes of all orientations during the 15-year period. The frequency of nestbox occupation by Great Tits correlated with orientation (the mean number of nests in boxes oriented south-southwest was lower than the mean number of nests in boxes facing other directions). There was no such relationship for Blue Tits or Pied Flycatchers. Nestbox orientation influenced the breeding success of Pied Flycatcher (the mean number of young to fledge from boxes oriented south-southwest was lower than from boxes facing other directions). There was no such relationship for Blue or Great Tits.

Conclusion Nestbox orientation can be an important influence on occupation and breeding success, but this differed between species. Intriguingly, although the directionality reduced nestbox occupation (Great Tit) and breeding success (Pied Flycatcher) was the same (south-southwest), there was a disparity in the influence of orientation for Great Tit (orientation influenced the frequency of occupation but not success) and Pied Flycatcher (orientation did not influence occupation but did affect success). We discuss these disparities, considering the possible influences of mating strategy, breeding phenology, nestbox microclimate and offspring quality.     

National‐scale analyses of habitat associations of Marsh Tits Poecile palustris and Blue Tits Cyanistes caeruleus: two species with opposing population trends in Britain

Capsule Marsh Tits were strongly associated with both the amount and species diversity of woodland understorey; Blue Tits were associated with large trees and deadwood.

Aims To gather quantitative information on the habitat requirements of Marsh Tits, in comparison with those of Blue Tits, across a large number of sites in England and Wales, and secondly to evaluate the range of habitat conditions likely to encourage the presence, and increase the abundance of, each species.

Methods Counts of birds were made at each of 181 woods across England and Wales, and habitat data were collected from the same locations in each woodland. Marsh Tit and Blue Tit presence and abundance were related to habitat characteristics, interspecific competition and deer impact.

Results Shrub cover and species diversity were important for the presence and abundance of Marsh Tits, across their geographical range in Britain. Blue Tits were associated with large trees and deadwood.

Conclusion Our results support the hypothesis that changes in woodland management, leading to canopy closure and a decline in the understorey available, could have had an impact on Marsh Tits, and may have led to the observed population decline. These same changes were also consistent with population increase in Blue Tits.     

Postfledging habitat selection of juvenile middle spotted woodpeckers: a multi-scale approach

Despite its relevance for the persistence of populations, the ecological mechanisms underlying habitat use decisions of juvenile birds are poorly understood. We examined postfledging habitat selection of radio-tracked juvenile middle spotted woodpeckers Dendrocopos medius at multiple hierarchically-nested spatial scales in NW Spain. At the landscape and home range scales, old oak forest was the most used and selected habitat, young oak forests and pine plantations were avoided, and riverside forests were used as available. At a lower scale, birds selected larger diameter trees for foraging. Home ranges had higher densities of large deciduous trees (mainly oaks Quercus spp., but also poplars Populus spp. and willows Salix spp. >22  cm and >33  cm DBH) selected for foraging by juveniles than non-used areas. These results suggest that foraging conditions may drive, at least partly, habitat use decisions by juvenile birds. We also discuss the potential influence of intraspecific competition, the search for a future breeding territory in the early postfledging period and predation avoidance on habitat use decisions by juvenile birds. Contrary to previous studies on migrant forest birds, postfledging juvenile woodpeckers selected the same habitat as for the breeding adults (i.e. old oak forest), indicating that migrant and resident specialist avian species may require different conservation actions. Conservation strategies of woodpecker populations should consider the protection of old oak forests with high densities of large trees to provide suitable habitat to breeding adults and postfledging juveniles. The habitat improvement for this indicator and umbrella species would also favour other organisms that depend on characteristics of old-growth oak forests.     

Haemoglobin concentration and body condition of nestling Great Tits Parus major : a comparison of first and second broods in two contrasting seasons

The physiological condition of nestling altricial birds depends on the quantity and quality of food delivered to them by parents. One indicator of the condition of Great Tit Parus major nestlings is the haemoglobin concentration in their blood. The present study demonstrates the influence of weather conditions (temperature and rainfall) on nestling haemoglobin concentrations during two consecutive breeding seasons in two different habitat types (parkland vs. woodland) in the city of Łódź in Central Poland. This influence probably results from the effects of weather on the trophic base of the Tits. Dry, hot weather strongly affected bush and herbal foliage later in the breeding season (mid-June to mid-July) in 2006, presumably by interfering with the development of herbivorous arthropod populations. This in turn caused food shortages for second broods of Great Tits, which resulted in nestlings having low haemoglobin levels. In the following year, temperature was on average lower, and rainfall was regular but not very heavy. These conditions enabled the development of arthropod assemblages, and the trophic base for birds was much richer. Haemoglobin concentrations in the blood of nestlings from second broods were significantly higher than those of first broods and, unexpectedly, second-brood nestlings in 2007 were on average in better physiological state than first-brood nestlings in 2006 in both habitats. The relationship between haemoglobin concentration, brood category and year was very similar to that for nestling body mass. However, it was independent of both body mass and brood size. In some years and under certain conditions, second broods can be more successful than first broods.     

Zum Einflu? einer Autobahn im Bau und w?hrend des Betriebs auf die Brutbiologie von Kohlmeisen (Parus major) und Blaumeisen (P. caeruleus)

Zusammenfassung Im Februar 1992 wurde an der in Bau befindlichen Autobahn BAB 66 zwischen Steinau und Schlüchtern (5021'N, 0931'E) ein Nistkastenkontrollgebiet mit 310 Nistkästen eingerichtet, um die Auswirkungen der Autobahn vor und nach Inbetriebnahme auf die Brutbiologie von Meisen zu untersuchen. Als Vergleichsgebiete dienen ein direkt benachbartes sowie ein ca. 5 km entferntes Untersuchungsgebiet. Zum Vergleich der Gewichtsentwicklung der Nestlinge wurde ein drittes autobahnfernes Gebiet herangezogen.In einzelnen Jahren finden sich zwischen den Gebieten Unterschiede in der Zusammensetzung der Brutpopulation, der Besetzungsrate der Nistkästen, dem Legebeginn, der Gelegegröße, der Schlüpfrate oder im Bruterfolg. Diese Unterschiede treten in verschiedenen Jahren und in unterschiedlichen Gebieten auf, so daß sich keine generelle Abweichung des Gebietes an der Autobahn von den straßenfernen Gebieten feststellen läßt. Die Eröffnung der Autobahn hatte keinen Effekt auf die untersuchten Parameter.Die Gewichte der Nestlinge im Gebiet an der Autobahn waren im Jahr 1996 nur am 12. und 13. Nestlingstag signifikant geringer als die Gewichte der Nestlinge in einem autobahnfernen gleichartig strukturierten Biotop. Die Ausflugsgewichte der Jungvögel an der A66 liegen jedoch ca. 2 g höher als in städtischen Biotopen.Störungen durch den Straßenverkehr, wie sie von anderen Autoren berichtet werden, ließen sich in unserem Untersuchungsgebiet nicht feststellen. In diesem Zusammenhang werden die geringe Störungsempfindlichkeit der Kohl- und Blaumeisen sowie der bisher geringe Verkehr auf der Autobahn diskutiert.

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The impact of a motorway in construction and after opening to traffic on the breeding biology of Great Tit (Parus major) and Blue Tit (P. caeruleus)

Summary In February 1992, a study area (A 66) with 310 nestboxes was installed along the construction line of a four laned motorway between Steinau and Schlüchtern (5021'N, 0931'E). One area in the immediate neighbourhood (VG1) and one 5 km distant (VG2) from the study area at the motorway (see Fig. 1) served as controls for comparison. In all three areas, the nestboxes were checked weekly during the breeding season from the beginning of May until July. Species composition of the birds using nestboxes, rate of occupation of nestboxes, and, for Great Tits (Parus major) and Blue Tits (P. caeruleus), date of the first egg, clutch size, hatching rate and number of birds fledged were recorded. The study included 5 breeding seasons from 1992 to 1996, 3 years during the period of construction and 2 years after the opening of the motorway to traffic in December 1994. In 1996, the nestling weight of 20 broods of Great Tits at the A66 was recorded daily and compared with that of all nestlings in another study area (VG3, see Fig. 1).The data were analyzed separately for each year. Distributions of frequencies were analyzed with the x² test, the other data with the Kruskal-Wallis-Test (H-Test). In case of significant differences between the study areas, the Mann Whitney U-test was used to determine which study area differed from the others. Nestlings bodymass was compared using the t-test.The species composition was similar in all three areas (Fig. 2), and it did not change after the opening of the motorway to traffic. The rate of occupation of the nestboxes, dates of laying of the first egg, clutch size, hatching rate and breeding success vary between years and between study areas (Table 1 to 5); data that differ significantly from those of two other areas are indicated by bold print. Such differences were observed in various years and involved all three areas. In study area A66, clutch size of Great Tits was higher in 1993; hatching success of Great Tits was lower in 1994 and that of Blue Tits was lower in 1993. However, there was no general trend that area A66 at the motorway was different from the other areas, either before or after being opened to the traffic. The weight of nestlings in study area A66 at the motorway was similar to that in comparable area nearby; only on day 12 and 13 after hatching was it slightly lower (Tab. 6). The last measurement on day 15 indicates a nestling weight of 16.2 g for the area at the motorway, which is in normal for deciduous forest habitats and approximately 2 g higher than that recorded in urban habitats.In brief, the motorway did not affect the species composition, rate of occupied nestboxes or the various breeding parameters; in particular, the moving traffic after opening did not seem to have any effect. The breeding parameters from the study area at the motorway were typical for the Schlüchtern region. Density reductions in breeding populations, as discussed by several authors, or disturbances caused by moving traffic, as previously reported, were not observed in our study. However, our key species, Great Tits and Blue Tits, are not generally very sensitive to interferences. Also, the level of traffic on the motorway was still rather low. This must be considered when our findings are generalized.