Effect of conspecific attraction on the presence of Northern Bobwhites

Researchers and managers have used the tendency of some species of birds to settle near conspecifics (i.e., conspecific attraction) to help establish or reestablish species of conservation concern in targeted habitats. However, most studies of conspecific attraction as a recruitment tool have been conducted with either migratory or colonial-breeding species, and less is known about the possible importance of conspecific attraction for resident species. In 2017 and 2018 in Louisiana, we examined the possible use of conspecific attraction as a management tool for Northern Bobwhites (Colinus virginianus), game birds that are year-round residents. We used an alternating split experimental design across years where Northern Bobwhite vocalizations were broadcast at half of our study sites during the first year of our study and the other half were controls. The following year, experimental sites became controls, and controls became experimental sites. We also assessed land cover at each site to determine if variation in habitat composition at small spatial scales influenced bobwhite presence. We detected six times more Northern Bobwhites at treatment sites (sites with playback) than control sites and found a positive association between the proportion of grass cover and bobwhite presence. These results suggest that a non-migratory, resident species may select breeding locations based, at least in part, on the presence of conspecifics, and that playback of their calls could be incorporated into management plans. Playing back conspecific calls in early spring when Northern Bobwhites are likely searching for breeding locations may facilitate colonization and allow individuals to find locations where managers are attempting to restore their populations.     

Conspecific attraction in a grassland bird, the Baird's Sparrow

ABSTRACT.   Territorial songbirds generally use song to defend territories and attract mates, but conspecific song may also serve as a cue to attract other male songbirds to a breeding site. Although known to occur in some colonial and forest-associated species, only recently have investigators examined conspecific attraction in grassland species. We used a playback experiment to examine the possible role of conspecific attraction for males searching for potentially suitable breeding habitat in a grassland specialist, the Baird's Sparrow ( Ammodramus bairdii ). Experimental playback plots and control plots with similar landscape and vegetation characteristics were established at two sites in North Dakota. Baird's Sparrows colonized three of six experimental plots and none of six control plots. Males on experimental plots established territories adjacent to the playback stations and were sometimes observed counter-singing with the playback of conspecific songs. Vegetation characteristics were similar on all study plots, and did not explain differences in bird density on our treatment plots. Although we found that playback of conspecific songs attracted male Baird's Sparrows to previously unoccupied, potentially suitable habitat, further experiments are needed to examine the importance of conspecific attraction relative to other cues that birds may use, such as vegetation features. The conservation and management implications of conspecific attraction are not completely understood, but the presence of conspecifics should be considered as a potential cue in habitat selection by all species of birds.     

Behavioural mechanisms that undermine species envelope models: the causes of patchiness in the distribution of great bustards Otis tarda in Spain

Despite the general success of species envelope models, capturing the fine-scale detail of patchiness in the distributions of some species is problematic. For great bustards in Spain, apparently suitable habitat patches remain unoccupied and cannot be distinguished from occupied patches in current distribution models. We consider philopatry and conspecific attraction as main behavioural mechanisms which could account for this patchiness, and then look for evidence of their influence on the distribution of great bustards across the whole of Spain. We compared the characteristics of habitat patches classed as suitable by a distribution model according to whether they were actually used or not. Occupied patches were larger than unoccupied patches and over-used in proportion to their size, suggesting aggregation and a metapopulation structure. Arguing that conspecific attraction may serve to transfer information about site history and environmental predictability (at least over a short time period), we compared the coefficients of variation in time-series of vegetation and climatic factors at occupied and unoccupied sites. Great bustards chose sites which were more environmentally stable at critical periods in the breeding cycle, "public information" that can only be gained from others rather than through sampling. There is thus evidence that both metapopulation dynamics and conspecific attraction influence the large scale distribution of great bustards in Spain. We discuss how alternative predictor variables and multi-stage analyses may help us to incorporate behavioural mechanisms into distribution models, but acknowledge that there are limits to the value of species envelope models for animal species making decisions.     

Conspecific attraction and nest site selection in a nomadic species,the zebra finch

Conspecific nesting density affects many aspects of breeding biology, as well as habitat selection decisions. However, the large variations in breeding density observed in many species are yet to be fully explained. Here, we investigated the settlement patterns in a colonial species with variable breeding density and where resource distribution could be manipulated. The zebra finch, Taeniopygia guttata, is a classic avian model in evolutionary biology but we know surprisingly very little about nest site selection strategies and nesting densities in this species, and in fact, in nomadic species in general. Yet, important determinants of habitat selection strategies, including temporal predictability and breeding synchrony, are likely to be different in nomadic species than in the non‐nomadic species studied to date. Here, we manipulated the distribution of nesting sites (by providing nest boxes) and food patches (feeders) to test four non‐exclusive habitat selection hypotheses that could lead to nest aggregation: 1) attraction to resources, 2) attraction to breeding conspecifics, and 3) attraction to successful conspecifics and 4) use of private information (i.e. own reproductive success on a site). We found that wild zebra finches used conspecific presence and possibly reproductive success, to make decisions over where to locate their nests, but did not aggregate around water or food within the study areas. Moreover, there was a high degree of inter‐individual variation in nesting density preference. We discuss the significance of our results for habitat selection strategy in nomadic species and with respect to the differential selection pressures that individuals breeding at different densities may experience.     

How do birds search for breeding areas at the landscape level? Interpatch movements of male ortolan buntings

Animal movements at large spatial scales are of great importance in population ecology, yet little is known due to practical problems following individuals across landscapes. We studied the whole Norwegian population of a small songbird (ortolan bunting, Emberiza hortulana ) occupying habitat patches dispersed over nearly 500 km². Movements of colour-ringed males were monitored during ten years, and extensive long-distance dispersal was recorded. More than half of all cases of breeding dispersal took place within one breeding season, and males moved up to 43 km between singing territories, using 1–22 d. Natal dispersal was usually to a habitat patch close to the natal patch, or within the natal patch if it was large. Breeding dispersal movements were often long-distance, beyond neighbouring patches, and up to 11–19 patches were overflown. Movements of at least 6–9 km across areas of unsuitable habitat occurred regularly. The number of patches visited was low (1–4) even though search costs in terms of time spent moving from one site to another were relatively low (often only a few days even for distances >10 km). Most males seemed to use a threshold tactic when choosing a patch, but returns to previously visited patches were recorded, including some cases of commuting. In conclusion, male ortolan buntings have a surprising ability to move quickly at the landscape level, and this resulted in a high connectivity of patches. We discuss our results in relation to optimal searching strategies, in particular the use of within-breeding season versus post-breeding season search, conspecific attraction and adaptive late arrival of young birds.     

Managing breeding forest songbirds with conspecific song playbacks

Recent studies confirm that several territorial songbird species use conspecific cues, including song, when selecting habitat. We conducted a controlled experiment with a population of black-throated blue warblers Dendroica caerulescens , a species of concern in boreal hardwood transition forests, to determine whether song playbacks influence settlement patterns. We tested whether conspecific song broadcast during spring arrival attracts black-throated blue warblers during territory establishment, and whether song playbacks shift territories from the previous year's breeding distributions. The results of our experiment demonstrate that song playbacks significantly increased territorial occupancy and shifted territories closer to the speakers. Loss of breeding habitat is implicated in population declines of many songbirds, and our results suggest that song playbacks should be further investigated as a tool for mitigating the effects of disruptive management actions. Additional work should consider the spatial arrangement of playback speakers to avoid attracting birds from safe areas. The demographic consequences of conspecific attraction must also be explored before this technique is widely implemented.     

Prevalence of ectoparasite arthropods in Dupont's Lark Chersophilus duponti – a seriously threatened passerine

A full survey of the ectoparasites of 77 individual Dupont's Larks Chersophilus duponti, from the Iberian High Plateau, detected three species of chewing lice, one of louse flies, and one identified species of mite.     

Predation-Related Costs and Benefits of Conspecific Attraction in Songbirds—An Agent-Based Approach

Songbirds that follow a conspecific attraction strategy in the habitat selection process prefer to settle in habitat patches already occupied by other individuals. This largely affects the patterns of their spatio-temporal distribution and leads to clustered breeding. Although making informed settlement decisions is expected to be beneficial for individuals, such territory clusters may potentially provide additional fitness benefits (e.g., through the dilution effect) or costs (e.g., possibly facilitating nest localization if predators respond functionally to prey distribution). Thus, we hypothesized that the fitness consequences of following a conspecific attraction strategy may largely depend on the composition of the predator community. We developed an agent-based model in which we simulated the settling behavior of birds that use a conspecific attraction strategy and breed in a multi-predator landscape with predators that exhibited different foraging strategies. Moreover, we investigated whether Bayesian updating of prior settlement decisions according to the perceived predation risk may improve the fitness of birds that rely on conspecific cues. Our results provide evidence that the fitness consequences of conspecific attraction are predation-related. We found that in landscapes dominated by predators able to respond functionally to prey distribution, clustered breeding led to fitness costs. However, this cost could be reduced if birds performed Bayesian updating of prior settlement decisions and perceived nesting with too many neighbors as a threat. Our results did not support the hypothesis that in landscapes dominated by incidental predators, clustered breeding as a byproduct of conspecific attraction provides fitness benefits through the dilution effect. We suggest that this may be due to the spatial scale of songbirds’ aggregative behavior. In general, we provide evidence that when considering the fitness consequences of conspecific attraction for songbirds, one should expect a trade-off between the benefits of making informed decisions and the costs of clustering.     

Finding a place to live: conspecific attraction affects habitat selection in juvenile green and golden bell frogs

Conspecific attraction plays an important role in habitat selection of several taxa and can affect and determine distribution patterns of populations. The behaviour is largely studied and widespread among birds, but in amphibians, its occurrence seems limited to breeding habitats of adults and gregarious tadpoles. The Australian green and golden bell frogs (Litoria aurea) have suffered considerable shrinking of their original distribution in south-eastern Australia since the 1970s. Currently, with only about 40 populations remaining, the species is considered nationally threatened. In natural conditions, these frogs are aggregated in the landscape and do not seem to occupy all suitable ponds within the occurrence area. To date, studies focusing on the frogs’ habitat have failed in finding a general habitat feature that explains current or past occupancy. This led us to the hypothesis that social cues may play a key role in habitat selection in this species. Using two choice experiments, we tested the preference of juvenile green and golden bell frogs for habitats containing cues of conspecifics of similar size versus habitats without conspecific cues. Tested frogs did not show a preference for habitats containing only scent from conspecifics but did prefer habitats where conspecifics were present. Our results show that conspecific attraction is a determining factor in juvenile green and golden bell frog habitat selection. To our knowledge, this is the first time the behaviour is shown to occur in juvenile frogs in the habitat selection context. From a conservation management point of view, the behaviour may help to explain the failure of reintroductions to areas where the frogs have been extinct, and the non-occupation of suitable created habitats in areas where they still inhabit and develop appropriated management strategies.     

Distribution dynamics of a great bustard metapopulation throughout a decade: influence of conspecific attraction and recruitment

Dispersing individuals can use conspecifics as indicators of habitat quality and aggregate at traditionally occupied sites, leaving other favourable patches unoccupied. Here we test the predictions of the conspecific-based habitat selection hypothesis on a Spanish great bustard (Otis tarda) metapopulation, currently fragmented due to recent human-induced habitat changes. The number of birds had increased by 23% between 1988 and 1998, but not consistently among leks. Leks that were large in 1988 increased, while those that were small decreased, which suggests that dispersing individuals used the numbers of conspecifics as cues for breeding-site selection. Moreover, leks with high productivity increased, while those with low productivity decreased. Finally, lek distribution was markedly stable throughout the decade, with no establishment of new leks, and suitable habitat patches remained unoccupied, as predicted by the conspecific attraction hypothesis. These results were corroborated by a simulation model which incorporated natal dispersal rates between leks as obtained through radio-tracking of 15 birds that survived throughout their 4-year dispersal period. In conclusion, in spite of the apparent increase in total numbers throughout the decade, both conspecific attraction and local differences in reproductive success contributed to a more aggregated distribution, increasing the species' vulnerability to local catastrophes, and the risks of reduced genetic diversity and extinction of small leks.     

Use of Restored Riparian Habitat by the Endangered Least Bell's Vireo (Vireo bellii pusillus)

A primary objective of riparian restoration in California is the creation of habitat for endangered species. Four restoration sites in San Diego County were monitored between 1989 and 1993 and evaluated for their suitability as nesting habitat for Vireo bellii pusillus (Least Bell's Vireo), a state and federally endangered obligate riparian breeder. Vegetation structure at each site was quantified annually and compared to a model of canopy architecture derived from Least Bell's Vireo territories in natural habitat. Vireo use of restored habitat was documented through systematic surveys and nest monitoring. By 1993, only one site in its entirety met the habitat suitability criteria of the model, but portions of each site during all years did so. Differences between sites in the time required to develop suitable habitat—well-developed layered vegetation from the ground to under 8m in height)—were attributable largely to variation in annual rainfall. Vireos visited restoration sites to forage as early as the first growing season, but they did not establish territories or nest there until at least part of the site supported suitable habitat as determined from the model. Placement of territories and nests coincided with patches of dense vegetation characteristic of natural nesting areas. Occupation of restored sites was accelerated by the presence of adjacent mature riparian habitat, which afforded birds nest sites and/or foraging habitat lacking in the planted vegetation. Vireos nesting in restored habitat achieved success comparable to that of vireos nesting in surrounding natural habitat, and there was no evidence that productivity was reduced in created areas. These findings indicate that creating nesting habitat for this target species is feasible and suggest that the critical components of vireo nesting habitat have been captured in both the design and quantitative assessment of restoration sites.     

Heterospecific attraction and food resources in migrants' breeding patch selection in northern boreal forest

We studied experimentally how heterospecific attraction may affect habitat selection of migrant passerine birds in Finnish Lapland. We manipulated the densities of resident tit species (Parus spp.). In four study plots residents were removed before the arrival of the migrants in the first study year, and in four other plots their densities were increased by releasing caught individuals. In the second year the treatments of the areas were reversed, allowing paired comparisons within each plot. We also investigated the relative abundance of arthropods in the study plots by the sweep-net method. This allowed us to estimate the effect of food resources on the abundance of birds. The heterospecific attraction hypothesis predicts that densities of migrant species (especially habitat generalists) would be higher during increased resident density. Results supported this prediction. Densities and number of the most abundant migrant species were significantly higher when resident density was increased than when they were removed. On the species level the redwing (Turdus iliacus) showed the strongest positive response to the increased abundance of tits. Migrant bird abundances seemed not to vary in parallel with relative arthropod abundance, with the exception of the pied flycatcher (Ficedula hypoleuca) which showed a strongly positive correlation with many arthropod groups. The results of the experiment indicate that migrants can use resident tit species as a cue to a profitable breeding patch. The relationship between the abundance of the birds and arthropods suggests that annual changes in food resources during the breeding season probably do not have a very important effect on bird populations in these areas. The results stress the importance of positive interspecific interactions in structuring northern breeding bird communities. Received: 1 September 1997 / Accepted: 22 January 1998     

Multiple Plumage Ornaments as Signals of Intrasexual Communication in Golden‐Winged Warblers

Avian plumage represents some of the greatest diversity in integument coloration of all animals. Plumage signals are diverse in function, including those that allow for assessing potential mates or the mitigation of agonistic interactions between rivals. Many bird species possess multiple ornamental traits that have the potential to serve as multiple or redundant signals. For example, male golden‐winged warblers (Vermivora chrysoptera) have brilliant carotenoid‐based yellow crowns, melanin‐based black throats, and structurally based white patches on their outer tail feathers. Using a correlative approach, we investigated whether plumage ornaments have the potential to reliably signal ability to acquire higher quality territory, aggressive response to simulated territorial intrusions, and reproductive success. We found that both crown chroma and tail brightness were significantly related to habitat quality and aggression; more ornamented birds held territories with higher quality habitat and were less aggressive toward simulated conspecific stimuli. Older birds sang less threatening songs than younger birds and were more likely to sing their mate attraction song type (type 1) rather than songs typically reserved for agonistic interactions (type 2). Finally, despite our previous research demonstrating that habitat strongly predicts reproductive success in this warbler population, we found no evidence of a direct link between ornamentation and reproductive success. Overall, these data suggest that younger males, and those with lower quality ornaments, compensate with more aggressive behaviors. Additional research is needed to investigate the dynamics between behavioral traits and ornaments to better understand complex signaling and how golden wing signals function in conspecific interactions (male–male interactions and mate‐choice).     

An inter-regional approach to intraspecific variation in habitat association: Rock Buntings Emberiza cia as a case study

The habitat association approach has been increasingly used in ecology to resolve problems in wildlife conservation and management. One problem related to habitat association studies is that they are restricted to small geographical areas within a species' range, and thus they are applicable to only a limited set of environmental conditions utilized by the species. In addition, very few studies address why the preference for specific habitat components may be adaptive for the species in question. The objective of this study was to examine how consideration of populations of a species from two dramatically different environments affects the results of habitat association modelling for a ground-nesting passerine, the Rock Bunting Emberiza cia . At a regional scale, a trend to defending breeding habitat patches with relatively higher stone cover was confined to birds from a temperate region in Slovakia. In contrast, in a semi-arid region in southeastern Spain, Rock Buntings preferred to use breeding habitat patches that had relatively higher grass cover. Combining data from both regions, breeding Rock Buntings showed a general pattern of using habitat patches close to hedges, with low bush cover, high ditch density and a steep slope. Whereas regional habitat association models appear to be sensitive to the particularities of the breeding environment, our study suggests that Rock Bunting breeding habitat association is constrained by the adults' tactics to protect themselves against predators. Although the birds prefer to nest in patches of low vegetation, the better to see nearby predators, these patches are ideally close to taller vegetation that can be used to provide cover when evading predators, and they are also of a rugged profile that helps the birds to approach and leave the nest stealthily.     

Habitat selection rules in breeding mallards (Anas platyrhynchos): a test of two competing hypotheses

Ideal preemption and conspecific attraction are alternative hypotheses of the habitat selection rules used by individuals. According to the former an occupied site is assumed to be preempted and therefore not available for later arriving individuals, whereas according to the latter individuals are assumed to be attracted by conspecifics to occupied sites, rather than avoiding them. We studied these competing hypotheses in breeding mallards (Anas platyrhynchos) by a cross-over experiment in 2 years, introducing birds onto lakes before migratory wild mallards arrived. If mallards use the ideal preemptive rule, breeding density of wild mallards in experimental lakes should be lower and they should be occupied less frequently than control lakes, but if mallards use the conspecific attraction rule the reverse should be true. Our results allowed us to reject the ideal preemptive rule whereas the conspecific attraction rule was to some extent supported. We discuss these findings in relation to population limitation. The results suggest that the local breeding population studied is not limited by spacing behaviour related to habitat selection. Received: 14 July 1997 / Accepted: 17 November 1997     

Habitat selection and reproductive success of Ortolan Buntings Emberiza hortulana on farmland in central Sweden – the importance of habitat heterogeneity

Many granivorous birds have shown severe population declines in Europe during recent decades. The aim of the present study was to analyse habitat preferences and reproductive success of one such species, the Ortolan Bunting Emberiza hortulana, in different farmland habitats in south‐central Sweden. Four seemingly different land‐use types were preferred: permanent set‐asides, short rotation coppice, and grazed and unmanaged semi‐natural pastures. Territories and random sites differed considerably in the proportion of these preferred land‐use types; 39% of territories had > 70% preferred habitat (at the 100‐m scale) compared to 5% of random sites. In contrast, 22% of territories and 65% of random sites had no preferred habitats. All the preferred habitats had heterogeneous ground vegetation characterized by patches with bare ground, or at least sparse ground vegetation, intermixed with patches with taller vegetation. Ortolan Buntings also preferred a heterogeneous habitat structure with occurrence of field islets, shrubby edges, barns and electric wires, which could act as song posts or suitable nest‐sites, in 88% of territories. At a larger (1‐km square) scale, territories occupied by pairs aggregated strongly in areas with high proportions of preferred habitats. The number of territories with single males correlated positively with the number of pairs, which suggests that conspecific attraction may influence territory distribution. No measured habitat factors were related to reproductive success. However, due to habitat preferences and the higher proportion of paired males in one habitat type (set‐aside), the production of young (fledglings/ha) is expected to be higher in set‐asides, as well as in short‐rotation coppices and semi‐natural pastures. Thus, these habitats are important for the conservation of the Ortolan Bunting. Large areas with habitat structures such as field islets are especially important because the Ortolan Bunting breeds in aggregations in these areas.     

Precise direct tracking and remote sensing reveal the use of forest islands as roost sites by Purple Martins during migration

Direct tracking methods in combination with remote sensing data allow examination of habitat use by birds during migration. Species that roost communally during migration, such as some swallows, form large aggregations that can attract both avian and terrestrial predators. However, the extent to which they might use patchy habitats that could reduce predation risk during migration is unknown. We tested the hypothesis that Purple Martins (Progne subis) use forest islands (patches of suitable forest habitat surrounded by unsuitable habitat) as roost sites during migration between breeding sites in North America and overwintering sites in South America. We used high‐precision (< 10 m), archival GPS units deployed and retrieved during the 2015 and 2016 breeding seasons, respectively, at 12 colonies located across eastern North America. We found that Purple Martins roosted in forest islands more often than expected based on availability during both spring and fall migration. Despite an apparent association with urban habitats by Purple Martins based on observational and radar data in North America during the fall, the roost locations we identified during spring and fall migration were not more closely associated with urban areas than random locations. The use of forest islands during both spring and fall migration suggest that Purple Martins may use these habitats to reduce predation risk during migration. Our results suggest that some species of birds may use similar habitats as stopover sites during migration and that patches of forest habitat may be important conservation targets for Purple Martins and other species. Identifying habitat use during migration represents an important advance in support of full annual‐cycle conservation of Purple Martins and other migratory species with declining populations.     

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.     

Rapid climate‐driven loss of breeding habitat for Arctic migratory birds

Millions of birds migrate to and from the Arctic each year, but rapid climate change in the High North could strongly affect where species are able to breed, disrupting migratory connections globally. We modelled the climatically suitable breeding conditions of 24 Arctic specialist shorebirds and projected them to 2070 and to the mid‐Holocene climatic optimum, the world's last major warming event ~6000 years ago. We show that climatically suitable breeding conditions could shift, contract and decline over the next 70 years, with 66–83% of species losing the majority of currently suitable area. This exceeds, in rate and magnitude, the impact of the mid‐Holocene climatic optimum. Suitable climatic conditions are predicted to decline acutely in the most species rich region, Beringia (western Alaska and eastern Russia), and become concentrated in the Eurasian and Canadian Arctic islands. These predicted spatial shifts of breeding grounds could affect the species composition of the world's major flyways. Encouragingly, protected area coverage of current and future climatically suitable breeding conditions generally meets target levels; however, there is a lack of protected areas within the Canadian Arctic where resource exploitation is a growing threat. Given that already there are rapid declines of many populations of Arctic migratory birds, our results emphasize the urgency of mitigating climate change and protecting Arctic biodiversity.     

Is the range size of migratory birds constrained by their migratory program?

Aim Intuitively, species in which the individuals migrate long distances between summer and winter quarters should be more likely to disperse and colonize new breeding areas than resident species. However, it has repeatedly been noted that many bird species with large ranges are residents. This paradox was tested on land birds breeding in the boreal forest of the Palaearctic, the largest uninterrupted stretch of habitat on earth. Methods The longitudinal distribution of two land bird communities on each side of the Eurasian continent, in Scandinavia and eastern Siberia, were used to test whether migratory birds indeed have a lower colonization success than resident birds. Results The migratory species are significantly less likely than resident species to have a range including both regions. The pattern held true even after controlling for latitudinal effects and local abundance, and was also observed at the level of genus and family. Main conclusions The relatively low colonization success of migratory species into new breeding areas may be because these new areas require novel migratory programs (migratory distance, direction and timing) in order for the birds to reach suitable wintering grounds.