Emberiza Schoeniclus Research Articles

Male reed buntings do not adjust parental effort in relation to extrapair paternity

Parental effort is considered to be costly; therefore, males are expected to provide less care to unrelated offspring. Theoretical models suggest that males should either reduce their care to the entire brood or alternatively distinguish between related and unrelated nestlings and direct provisioning to kin when paternity is in doubt. Reed buntings (Emberiza schoeniclus) have been found to have high levels of extrapair paternity (EPP, i.e., offspring of a male other than the male attending the nest; 55% of offspring), and males are therefore under strong selection pressure to adjust their parental effort according to the proportion of EPP in their brood. In this study, we investigated whether male reed buntings exhibit a reduction in paternal care (incubation and provisioning nestlings) in relation to decreased paternity. We also assess whether males bias their provisioning toward kin. We measured incubation time, provisioning rates, and food allocation to individual nestlings using video recordings at the nests. Microsatellite DNA analysis was used to analyze the paternity of offspring. In direct contrast to a previous study on the same species, our results provided no indication that males lowered their effort with decreased paternity. Furthermore, in nests of mixed paternity, males did not bias their provisioning behavior to kin. It remains to be investigated whether the absence of a relationship between paternity and paternal care can be ascribed to absence of reliable paternity cues or whether the benefits of reducing paternal care did not outweigh the costs in our study population. We found no evidence that the level of paternal care affected male survival or offspring mass, suggesting that both the benefits and costs of any reduction in paternal care would have been low.

No evidence for increased offspring heterozygosity from extrapair mating in the reed bunting (Emberiza schoeniclus)

It has been hypothesized that females mate multiply to increase the heterozygosity of their progeny because heterozygous individuals are assumed to have a fitness advantage. Females can maximize heterozygosity of their offspring by mating with genetically unrelated and/or heterozygous males. We tested these predictions in a socially monogamous passerine, the reed bunting (Emberiza schoeniclus), where extrapair paternity occurs frequently. The results based on genotypes at nine microsatellite loci revealed that females were no less genetically related to the extrapair male(s) (EPMs) than to their pair male (i.e., breeding partner) and that EPMs were no more heterozygous than the males they cuckolded. In addition, a direct comparison of maternal half-siblings naturally raised in the same brood showed that extrapair young were no more heterozygous than within-pair young. Thus, female reed buntings do not seem to mate with EPMs to increase offspring heterozygosity. It is not yet known whether extrapair mating involves any benefits at all to females in this species. Key words: Emberiza schoeniclus, extrapair paternity, genetic benefits, half-sibling comparisons, heterozygosity. [Behav Ecol]

Old female reed buntings (Emberiza schoeniclus) increase extra-pair paternity in their broods when mated to young males

AbstractIn birds, females are generally assumed to determine whether extra-pair copulations occur, and thus most studies on extra-pair paternity (EPP) have focussed on female preference for male traits, whereas female traits have been largely neglected. However, the occurrence of EPP is likely to be a result of behavioural interactions (e.g., mate guarding by the social male and escaping mate guarding by the female), and may be related to individual experience, which is expected to increase with age. We investigated the effect of age on levels of EPP in reed buntings Emberiza schoeniclus, a socially monogamous passerine with extremely high levels of extra-pair young (more than 50% of offspring). In broods of older males the rate of cuckoldry declined, which is in agreement with our previous finding that older males are more successful, either through female choice or through male experience. In contrast, older females tended to increase the level of extra-pair paternity in their broods. When including the age of the partner, we found that young males, but not old males, were cuckolded more by old females than by young females. The increase in EPP with female age is not likely to be due to disassortative mating with respect to age, an increased capacity of older females to raise a brood without male help, nor a male preference for older females. With age, males nor females changed their share in parental effort. We suggest that with increase in age, females become more choosy when selecting the male that sires their offspring, or alternatively, become more experienced at circumventing paternity assurance tactics of young males.

Numerical and functional responses of breeding passerine species to mass occurrence of geometrid caterpillars in a subalpine birch forest: a 30‐year study

In northern Fennoscandia, the geometrid moths Epirrita autumnata and Operophtera brumata have cyclicities in density with mass occurrence at 10‐year intervals. The larvae of Epirrita and Operophtera attain a size of 2–3 cm and 1.5–2 cm, respectively, and are nutritious food items for passerine birds. To examine whether these larvae have any numerical and/or functional influence on a passerine bird community (mountain birch forest in Budal, central Norway) during a 30‐year period (1972–2001), I estimated their abundance (number of larvae per 100 sweeps) in the birch canopy, and the densities of breeding birds in the passerine community. In addition, from 1972 to 1998, I monitored the nesting success of five of the bird species. The foraging pattern of the most abundant bird species and their gizzard contents (adults and nestlings) were examined in 1972–78 (covering population peaks of both the geometrids). Population peaks of Epirrita occurred in 1975–76, 1985–86 and 1996, and of Operophtera in 1976–77, 1986–87 and 1997–98. The passerine community consisted of eight species that were territorial in all 30 years, one species in 26 years, three species in 14–21 years and three species in 1–4 years. Only the Brambling Fringilla montifringilla population responded numerically to the fluctuations of Epirrita and Operophtera. Brambling was also the only species whose mean clutch size varied between years, and this correlated positively with the density of Epirrita. The mean annual nesting success of Willow Warbler Phylloscopus trochilus, Bluethroat Luscinia svecica and Common Redpoll Carduelis flammea tended to be higher in years with mass outbreaks of Epirrita, but was significantly so only for Reed Bunting Emberiza schoeniclus. The abundance of Operophtera larvae showed no influence on the nesting success of any bird species. The passerines foraged more frequently in the birch canopy in the Epirrita outbreak years (1975–76) than in the years before or after. Gizzard analyses of five adult passerine species and their nestlings showed that Epirrita was the main food item in 1974–76. Even though Operophtera occurred in large numbers in birch trees in 1976 and 1977, only a few larvae were found in the gizzards of the passerines. None of the passerines showed an increase in their population density in the year following the larval outbreaks, but the densities of Willow Warbler and Bluethroat increased in the succeeding year, indicating a higher return rate for these species. The study shows the existence of a dietary response and also indicates a reproductive response to the changes in the abundance of Epirrita in mountain birch forest. The lack of numerical response in the passerines (except the Brambling) to the fluctuation in Epirrita contrasts with the pattern described for passerine communities in northern temperate deciduous forests in North America, where Lepidoptera caterpillars periodically have mass outbreaks.

Factors Affecting Temporal Dynamics of Avian Assemblages in a Heterogeneous Landscape

The influence of the characteristics of habitat fragments on the dynamics of avian communities and the effect that fragments of different sizes have on the stability of the breeding species composition, and also on local extinction, colonisation and turnover rates were studied in an agricultural landscape in southern Poland. The fragments included various habitat types that differed from the matrix. Breeding birds were surveyed using the territory mapping method to assess turnover. Species composition depended on both the spatial structure of a fragment and the features of its surroundings. Local declines and appearances of species had a similar influence on the turnover in all size classes of the fragments. Species that contributed most to the total turnover were: Lanius collurio, Phasianus colchicus, Anas platyrhynchos, Emberiza schoeniclus, Columba palumbus and Sylvia communis. However, there were differences among species contributing most to the turnover according to area size classes. Heterogeneous habitats in a mosaic-like, agricultural landscape do not function as islands. The existence of species in an area with such a level of habitat patchiness can be related primarily to habitat quality, mainly because of poor isolation and the high permeability of isolating habitats.

The breeding ecology of Reed Buntings Emberiza schoeniclus in farmland and wetland habitats in lowland England

We studied the nesting and feeding ecology of Reed Buntings Emberiza schoeniclus breeding on farmland and wetland habitats along the Trent Valley in Nottinghamshire, England. Rank and emergent vegetation accounted for most nests and most foraging by provisioning adults. Caterpillars and spiders accounted for 70% of chick invertebrate prey and all broods were fed cereal grain or other vegetable matter. Variation in the abundance of key invertebrate prey across habitats accounted for the foraging preferences of adult buntings. Depredation was the main cause of nest failure, and survival of nests at the egg stage was positively related to the extent of nest concealment. A measure of total brood biomass was positively related to the abundance of key invertebrate prey within 100 m of nests. Rank and emergent vegetation provided Reed Buntings with greater nest concealment and a richer source of invertebrate prey than agricultural habitats such as set‐aside, cereals and oilseed rape. The provision of rank and emergent vegetation on farmland is likely to increase the nesting opportunities and productivity of Reed Buntings in agricultural landscapes.

Effects of habitat on the use of supplementary food by farmland birds in winter

Providing supplementary food for seed‐eating birds in winter is likely to be a key strategy, in some form, in future efforts to conserve farmland biodiversity. We present interim analyses of data on the bird use of artificial feeding sites under the RSPB‐led BirdAid project and the BTO‐led Winter Food for Birds (WFFB) project, investigating the influence of the habitat context at the local and landscape scales on the use of supplementary food by Yellowhammer Emberiza citrinella, Corn Bunting Miliaria calandra, Tree Sparrow Passer montanus, House Sparrow Passer domesticus, Chaffinch, Fringilla coelebs, Greenfinch Carduelis chloris, Goldfinch C. carduelis and Reed Bunting Emberiza schoeniclus. Our results reveal species‐specificity, rather than general patterns, in relationships between habitat variables and counts. The responses of the only species for which both BirdAid and WFFB provided data, the Yellowhammer, differed between the projects, suggesting that the results were not geographically general. The results fail to indicate justifiable firm habitat prescriptions for site locations that would suit a number of species. Clearer patterns were apparent in results with respect to areas of major habitats in the landscapes surrounding feeding sites, which suggested that local abundance could have an important effect on the use of supplementary food. Future analyses of data from these projects will attempt to separate the competing probable habitat influences on local bird abundance and alternative resource availability.

Extrapair paternity and offspring immunocompetence in the reed bunting, Emberiza schoeniclus

Female promiscuity is widespread in birds, as well as in other taxa. It is often assumed that in bird species with a socially monogamous mating system, females engage in extrapair copulations to obtain indirect (genetic) benefits. ‘Good genes’ and ‘compatible genes’ models predict that extrapair young (EPY) should be of higher quality than within-pair young (WPY), but the empirical evidence for this effect is limited. A recent study, however, indicated an enhanced cellular immunity in EPY in a passerine bird, the bluethroat, Luscinia svecica. To assess the generality of that finding, we replicated the study using the reed bunting, a passerine with an extrapair mating system similar to that of the bluethroat. Using the same immune assay protocol, we found no indication of enhanced cellular immunity in EPY compared with WPY. Female reed buntings thus do not seem to engage in extrapair copulations to achieve the same type of genetic benefit as in bluethroats. Furthermore, EPY in mixed-paternity broods did not grow faster and were not in better body condition close to fledging than WPY. We conclude that our results do not support the hypotheses assuming indirect benefits to female extrapair copulations. It appears that the adaptive value for females of pursuing extrapair fertilizations varies, even between species with similar extrapair mating systems.

Area Requirements Of Passerine Birds In The Reed Archipelago Of Lake Velence, Hungary

I studied the area requirement of reedbed breeding passerine birds on 109 reed islands in Lake Velence, Hungary, in the breeding seasons of 1993 and 1994. The size of the smallest occupied reed island for the observed 8 passerine bird species varied from 0.02 ha (Savi’s Warbler Locustella luscinioides) to 4.14 ha (Bluethroat Luscinia svecica). Three species occupied reed islands which were 8–18 times larger than their territory sizes (Sedge Warbler Acrocephalus schoenobaenus, Moustached Warbler A. melanopogon, and Bluethroat), three species occurred on reed islands 4–4.5 times larger than territory sizes (Great Reed Warbler A. arundinaceus, Reed Warbler A. scirpaceus, and Reed Bunting Emberiza schoeniclus), and two species occurred on islands half the size of their territory sizes in continuous reedbeds (Bearded Tit Panurus biarmicus, Savi’s Warbler). This may suggest that the latter two species can utilise groups of small patches within a territory. The incidence functions showed that the probability of occurrence of the Moustached Warbler and the Bluethroat was not 1 even on the largest reed islands (7–25.7 ha), while it was 1 for the other 6 species. The importance of landscape matrix type in determining minimum area requirements was demonstrated using data on the occurrence of bird species in reed marshes within an agricultural landscape in the Po Plain (Italy). In this landscape much larger minimum areas were found than at Lake Velence.

Biometrics, sex ratio and migration periods of Reed Buntings Emberiza schoeniclus wintering in the Tajo Basin, Spain

We analysed capture and biometric data of 2,408 Reed Buntings Emberiza schoeniclus ringed at Carrizal de Villamejor, Tajo Basin, Central Spain. Reed Buntings showed a clear sexual size dimorphism; males had longer wings and were heavier than females. Body condition, as determined from the residuals of a regression of weight on wing length, was highest in males, particularly during midwinter. Mean wing length, especially of the males, decreased over the winter, probably due to feather wear and abrasion, but possibly also due to older and larger males departing earlier. Maximum mean weights were recorded in spring pre‐migratory periods and minimum weights occurred in October, during the final stages of autumn migration. Female:male ratios were 3:1 in the population during winter. The ratio was at a minimum in October and at a maximum in March, which suggests that females arrived and left later than males. The earliest males arrive at Carrizal de Villamejor in autumn approximately 10 days before the earliest females, and also depart in spring 10 days sooner.

Novel polymorphic microsatellite markers for paternity analysis in the red‐capped robin (Petroica goodenovii: Aves)

AbstractSeven microsatellite loci were isolated and characterized from the red‐capped robin Petroica goodenovii, using nonradioactive polymerase chain reaction (PCR)‐based techniques to screen an enriched genomic library. Five loci showed no evidence of null alleles and were variable [mean heterozygosity (HE) = 0.440, mean number of alleles = 8]. Cross‐amplification using primers for microsatellites in Phylloscopus occipitalis and Emberiza schoeniclus yielded another two polymorphic loci. The combined set of five red‐capped robin and two cross‐amplified loci are suitable for paternity assignment (exclusion probability for seven unlinked loci = 0.9760).

北海道西部におけるオオジュリンの帰還調査

The incidence of return to their breeding grounds by the Reed Bunting Emberiza schoeniclus was investigated in western Hokkaido during six seasons (1997-2002). During this survey period, a total of 1, 568 individuals (508 adults, 411 juveniles and 639 nestlings) were given leg bands in the breeding season (Apr. 1-Sept. 10). A total of 150 birds were recaptured after one year, indicating the estimated minimum return rate in the next year as being 9.57%. The return rate dropped exponentially over subsequent years, falling to 1% or less 4-5 years later. The rate of return after one year in adult birds, juveniles and nestlings was 14.37%, 10.22% and 5.48%, respectively. There was no difference in the rate of return between adult males and females. It is conceivable that the true return rate may be higher than our estimates, because not all the returned individuals were necessarily captured by the end of this survey period.

Three new species of the ectoparasitic mites of the genus Syringophiloidus Kethley, 1970 (Acari: Syringophilidae) from passeriform birds from Slovakia.

Three new quill mite species of the genus Syringophiloidus Kethley, 1970 (Acari: Syringophilidae) from Slovakia are described and figured: S. bombycillae sp. n. from the waxwing Bombycilla garrulus (L.) (Passeriformes: Bombycillidae), S. schoeniclus sp. n. from the reed bunting Emberiza schoeniclus L. (Passcriformes: Emberizidae) and S. montanus sp. n. from the tree sparrow Passer monlanus (L.) (Passeriformes: Ploceidae). A key to all known species of the genus Syringophiloidus is given.

Declines of ground-nesting birds in two areas of upland farmland in the south Pennines of England

CapsuleWe present evidence of large declines in numbers of breeding waders and passerines in some upland areas since the 1970s. Aims Changes in numbers of ground-nesting birds are documented for two areas of the Pennines and are qualitatively related to recent land-use history. Methods Territory mapping was used to estimate bird numbers on two areas (76 and 99 ha) in the Pennines for which more than 10 consecutive years of data were available from the BTO's Common Birds Census archives. Results At both sites there were large declines in Lapwing Vanellus vanellus, Snipe Gallinago gallinago, Skylark Alauda arvensis, Twite Carduelis flavirostris and Reed Bunting Emberiza schoeniclus. The two sites differed in the timing of the declines but for Twite the trends were almost identical. By the late 1990s, numbers of most ground-nesting birds were far lower than in the 1970s. There was relatively little change in numbers of species breeding at either site. Conclusions Progressive changes in land-use, involving loss of rough grassland and a switch from dairy to sheep farming, may have contributed to the declines at one of the sites. However, there was no obvious change in land-use or habitat loss at the other site where population declines began 5 to 10 years earlier. Such declines have probably occurred widely in moorland-edge areas during the last 30 years and multiple factors may be responsible.

Habitat selection of passerine birds nesting in the Ebro Delta reedbeds (NE Spain): Management implications

In this study, we explored the habitat associations of the five most abundant passerine species nesting in the Ebro Delta reedbeds (NE Spain). Habitat characteristics (water depth, vegetation height and density, and plant-species composition) and abundance of all passerine species were measured at each of the 68 sampling points. The sampled area included most of the reedbeds in the Ebro Delta. Sampling points were classified according to the habitat paramenters measured using cluster analysis. The resulting four habitat types differed in the composition and attributes of their passerine communities. The abundance of the great reed warbler (Acrocephalus arundinaceus) and reed warbler (Acrocephalus scirpaceus) was greatest in tall, permanently inundated and almost monospecific Phragmites reedbeds. In contrast, the numbers of the reed bunting (Emberiza schoeniclus) and Savi’s warbler (Locustella luscinioides) were greatest in areas of drier soils and a denser basal stratum. Finally, the fan-tailed warbler (Cisticola juncidis) showed no clear habitat association. In the Ebro Delta, reedbed management includes freshwater inputs and burning of standing reeds. These practices promote tall, permanently inundated reedbeds with minimal detrital accumulation. Bird species richness and diversity were greater in less intensely-managed habitats, but only diversity was significant (p<0.001). We conclude that, since reedbeds are important habitats for several scarce bird species, and the abundance of these species seem to be influenced by vegetation structure, bird conservation considerations should be incorporated into future reedbed management practices.

The selection of stubble fields by wintering granivorous birds reflects vegetation cover and food abundance

Summary Fields left fallow after harvest (i.e. stubble fields) support high wintering densities of many species of granivorous bird. We examined correlates of use by eight such species of different types of intensively managed wheat and barley stubble fields, organic wheat fields and set‐aside fields on mixed lowland farmland in central England. Field occupancy was studied in relation to the physical characteristics of fields and seed abundance. Higher seed abundance was associated with greater occupancy by linnet Carduelis cannabina, grey partridge Perdix perdix, chaffinch Fringilla coelebs, yellowhammer Emberiza citrinella, reed bunting Emberiza schoeniclus and corn bunting Miliaria calandra. Larger areas of bare earth within stubble fields were associated with greater occupancy by linnet, yellowhammer, reed bunting and corn bunting, but lower occupancy by woodpigeon Columba palumbus. On conventional intensively farmed sites, seed abundance and area of bare earth were significantly greater on barley stubbles than on wheat stubbles. Seed numbers fell throughout the winter in all stubble types, although reductions were greatest on intensive barley stubbles, intermediate on intensive wheat stubble and lowest on undersown organic wheat stubbles. Within fields occupied by linnets, areas used for feeding had significantly greater quantities of seeds known to be important in their diet. Feeding areas also had a greater area of bare earth than randomly selected ‘non‐feeding areas’. Linnets and reed buntings were rarely found on fields where densities of weed seeds important in their diets fell below 250 seeds m−2. In autumn, yellowhammers and grey partridges rarely fed on fields where cereal grain density was below 50 m−2. However, in spring, both species fed on these fields irrespective of grain density, perhaps indicating a switch to other food sources. We suggest that land managers wishing to maximize the value of overwinter stubble fields for granivorous birds locate such fields where there is a substantial natural regeneration of weed flora and where previous cropping (e.g. barley) is likely to offer a sparse stubble with substantial areas of bare ground.

Population Memetic Analysis of Variation of Song, Geographical Distribution and Bill Morphology in the Reed Bunting

We applied population memetic models to the analysis of cultural variation among 11 European reed bunting (Emberiza schoeniclus) populations belonging to two subspecies groups differing in bill morphology. We tested whether patterns of meme diversity within and among populations and between the two subspecies groups correspond to patterns of variation in bill morphology. Within-population meme diversity was high and the degree of memetic divergence within groups was significant and higher among southern thick billed populations than among northern thin billed populations. There was, however, no significant memetic difference between the two subspecies groups. Tests of correlation between all groups indicated that memetic variation is associated with geographical distance and not with morphological variation. The results suggest a demographic structure of reed bunting populations similar to that of island populations of other bird species. The lack of memetic differences between them indicates that populations are not culturally isolated, despite the morphological, ecological and genetic differences. We discuss possible evolutionary explanations of the patterns of variation found.

The importance of arable habitat for farmland birds in grassland landscapes

Summary Over the last 25 years, populations of seed‐eating birds have declined severely over most of western Europe. Local extinctions have occurred in grassland‐dominated areas in western Britain, which may be influenced by loss in habitat diversity and a decline in the amount of arable cultivation. We used the large‐scale British Breeding Bird Survey of 1998 to investigate the importance of arable habitat within grassland landscapes for 11 common seed‐eating birds and four similar sized insectivores. Generalized linear models were used to model the number of birds recorded in agricultural habitat within survey squares as a function of the amount of arable habitat present. Numbers of grey partridge Perdix perdix, skylark Alauda arvensis, tree sparrow Passer montanus, corn Miliaria calandra and reed buntings Emberiza schoeniclus, yellowhammer Emberiza citrinella and whitethroat Sylvia communis increased with the amount of arable habitat present in a survey square; the numbers of house sparrow Passer domesticus, four finch species, dunnock Prunella modularis, robin Erithacus rubecula and blackcap Sylvia atricapilla did not. The positive association between numbers of some species and arable habitat within 1‐km squares was strongest where arable habitat was rare in the surrounding area, and weakest or even reversed when arable habitat was common. These results demonstrate the scale‐dependence of bird–habitat associations in agricultural landscapes, only demonstrable where data are available at fine grain over large geographical areas. These results support the hypothesis that range contractions (i.e. local extinctions) of some granivorous species have occurred because of contraction in arable cultivation. The loss of arable habitat where it is scarce may be causing declines in some areas, even though intensification of arable management is thought to be the main cause of declines elsewhere. Agri‐environment schemes may need to vary between regions, for example to encourage arable cultivation in pastoral areas.

Contrasting patterns of change in the distribution and abundance of farmland birds in relation to farming system in lowland Britain

AbstractPatterns of change in distribution (presence/absence) and abundance since the late 1960s were examined in 20 species of farmland bird in southern Britain in predominantly arable (eastern), predominantly mixed (central) and predominantly grassland (western) regions. Comparisons were made between changes in distribution and in abundance to determine whether these measures show similar relationships to environmental change. Local extinctions of selected species and reductions in species richness were significantly greater in the predominantly grassland region. Decreases in abundance were greatest in seven species in the predominantly arable region, two in the mixed region and nine in the grassland region. Changes in distribution and abundance showed consistent patterns in three species, turtle dove Streptopelia turtur L., yellow wagtail Motacilla flava L. and reed bunting Emberiza schoeniclus L. In another four species, grey partridge Perdix perdix L., lapwing Vanellus vanellus L., tree sparrow Passer montanus L. and corn bunting Miliaria calandra L., decreases in abundance were greatest in the arable region, yet declines in distribution were lowest. For other individual species, changes in distribution were too small to draw any conclusions in relation to farm type. We suggest that modern grassland systems are suboptimal habitats compared to arable or mixed agricultural land for many farmland species that occur at relatively low density in the more western, grass‐dominated region. Declines in abundance are therefore more likely to lead to local extinction in these areas than in eastern areas where abundance is higher. However, the role of changes in grassland management on bird populations requires further research. It is suggested that conclusions drawn from changes in distribution alone, in the absence of supporting data on changes in abundance, may be misleading where the aim is to assess how large‐scale spatial dynamics of populations relate to environmental change.

MIGRATING BIRDS STOP OVER LONGER THAN USUALLY THOUGHT: AN IMPROVED CAPTURE–RECAPTURE ANALYSIS

Migrating animals often divide their journey into alternating phases of migration bouts and stopping over. For investigating many questions of migration ecology it is crucial (1) to estimate the duration of stopover phases, and (2) to test whether animals of different groups differ in their stopover behavior. Using recent advances in capture–recapture statistics, we show how total stopover duration can be estimated from capture–recapture data. The probabilities of immigration are estimated and modeled by recruitment analysis and are converted into the time the animals spent at the stopover place before capture; the probabilities of emigration are estimated and modeled by survival analysis and are converted into the time the animals spent at the stopover place after capture. The sum of the two parts is the total stopover duration. Tests for differences between groups can be addressed by an appropriate model selection procedure. Two examples of migrating passerine birds at a stopover site in Switzerland illustrate this method. Mean total stopover duration was 12.3 d for Reed Warblers and 7.1 d for Reed Buntings. This was considerably higher than values obtained by the minimum stopover duration estimation (6.0 and 4.4 d, respectively). Because of the fundamental weaknesses of the minimum stopover duration estimation, which has been widely used in migration ecology, many findings obtained by this method need to be reconsidered.