Cavity-nesting Bird Species Research Articles

Culicoides paolae and C. circumscriptus as potential vectors of avian haemosporidians in an arid ecosystem

BackgroundHaemosporidians are the most important vector-borne parasites due to their cosmopolitan distribution and their wide range of hosts, including humans. Identification of their vectors is critical to highlight ecologically and epidemiologically relevant features such as host specificity or transmission routes. Biting midges of the genus Culicoides are considered the main vectors of Haemoproteus spp., yet important information on aspects such as vector feeding preferences or vector-host specificity involving haemosporidian parasites is frequently missing.MethodsWe assessed the abundance of Culicoides circumscriptus and C. paolae and blood sources of the latter at the nests of cavity-nesting bird species (mainly the European roller Coracias garrulus) and in their surroundings. We also explored the prevalence and genetic diversity of avian haemosporidians in parous females of both species.ResultsBoth C. circumscriptus and C. paolae were abundant in the study area and common at European roller nests. Culicoides paolae had a diverse ornithophilic diet, feeding on at least seven bird species. Human DNA was also detected in the blood meal of some individuals. Four Haemoproteus lineages, including a new one reported here for the first time, were isolated from parous females of both biting midges.ConclusionsCulicoides circumscriptus and C. paolae can play a locally important role in the transmission dynamics of Haemoproteus parasites in a community of cavity-nesting bird species in an arid ecosystem.

How Important are Nest Cavities Made by the Three-Toed Woodpecker Picoides tridactylus for Cavity-Nesting Forest Bird Species?

Woodpeckers are important primary excavators that produce nest-sites that are also used by several other cavity-nesting animals. However, the value of nest sites produced by different woodpecker species for other cavity-nesters is not generally known. We studied old Three-toed Woodpecker Picoides tridactylus cavities to examine their importance for other cavity-nesting forest bird species. Over a 31-year period (1987–2017), we annually monitored the occupancy of 655 cavities excavated by the Three-toed Woodpecker in 86 territories of the species in a 170-km2 area in southern Finland. Eight bird species used old Three-toed Woodpecker cavities for breeding, and the occupancy of these cavities by all secondary users was 21.3%. The expected mean number of lifetime occupancies by secondary cavity-nesters for a single cavity was 2.03. This is equivalent to a mean of two cavities occupied per territory per year, if we assume that Three-toed Woodpeckers produce a new cavity every year. The actual numbers of annually occupied cavities by secondary cavity-nesters can be substantially lower especially in territories that are not constantly occupied by the Threetoed Woodpecker. Based on the use of old cavities and densities of secondary cavity-nesting bird species, we conclude that cavities made by Three-toed Woodpeckers are most significant for the species itself, which accounted for 23.3% of nests in old Three-toed Woodpecker cavities. When Three-toed Woodpeckers reused an old cavity rather than occupy a freshly excavated cavity, 93% of cavities selected were originally excavated by Three-toed Woodpeckers. In addition, old cavities are important for the Pygmy Owl Glaucidium passerinum — up to 26–31% of breeding attempts were in old Three-toed Woodpecker cavities. The importance of old cavities for other hole-nesting bird species like the Pied Flycatcher Ficedula hypoleuca or the Great Tit Parus major was rather minor considering their densities within woodpecker territories.

Sequential Use of Tree Cavities by Birds and Nest Web in a Riparian Forest in Southwest India

We studied the sequential use of tree cavities by the cavity-nesting bird community in a riparian forest ecosystem of south-western India during 2013–2015. During the study period, a total of 376 nests of 20 cavity-nesting bird species comprising six primary and 14 secondary cavity nesters were located in the riparian forest. The cavity use pattern showed that one-third of the cavities were reused by birds and that the majority of the reused cavities were located in live trees. A lesser proportion (5%) of cavities used by birds was reused by other animal taxa. Competition for nest cavity use was observed among bird species in which Common Myna Acridotheres tristis was found to be the major competitor. A strong correlation was found between the bird body mass and nest cavity dimensions. Cluster analysis based on tree and cavity characteristics divided the avian community into five groups. We constructed a nest web for community structure that showed cavity resource use by various primary and secondary cavity-nesters. Woodpeckers (Greater Golden-backed Woodpecker Chrysocolaptes guttacristatus, White-naped Woodpecker C. festivus, and Browncapped Pygmy Woodpecker Dendrocopos nanus) as well as barbets (Brown-headed Barbet Psilopogon zeylanica, Coppersmith Barbet P. haemacephala and White-cheeked Barbet P. viridis) formed the key excavators in the riparian forest. While many of the smaller secondary cavity-nesting birds depend on the excavated cavities for nesting and reproduction, large-sized birds used decay formed cavities.

Urban core areas are important for species conservation: A European-level analysis of breeding bird species

Natural habitats and species richness have decreased due to the urbanization. The main aim of this study was to determine whether heavily urbanized town centers can also harbor threatened bird species. Twenty-six threatened species nested in the most urbanized areas of European towns. Species-rich areas had a high number of threatened species, indicating that overall species richness could be used as a surrogate for the large number of threatened bird species. Threatened species were more likely to be found in town centers as their distribution range increased. Neither landscape nor plot-level variables explained the species richness of threatened species, which was likely due to the homogeneous habitat structure of urban core zone areas in Europe. The occurrence of Falco tinnunculus increased with increases in human density within a built-up area. The occurrence of Hirundo rustica and Muscicapa striata decreased with increases in the proportion of built-up areas in the surrounding landscape. The occurrence of Delichon urbica and Muscicapa striata decreased with increases in habitat diversity and the proportion of buildings in the study plot. The most common threatened bird species nested in cavities or buildings. The availability of suitable nesting sites or protection from predators can support the occurrence of cavity nesters in towns. We suggest that modern architecture should account for the breeding habitat needs of cavity-nesting species in building design and that urban green management must consider the occurrence of old trees with cavities or alternatively use nest boxes to support the occurrence of threatened, cavity-nesting bird species.

Cavities shield birds from effects of artificial light at night on sleep.

Light pollution is an ever increasing worldwide problem disrupting animal behavior. Artificial light at night (ALAN) has been shown to affect sleep in wild birds. Even cavity-nesting bird species may be affected when sleeping inside their cavity. Correlational studies suggest that light from outside the cavity/nest box, for example from street lights, may affect sleep. We used an experimental design to study to what extent nest boxes shield animals from effects of ALAN on sleep. We recorded individual sleep behavior of free-living great tits (Parus major) that were roosting in dark nest boxes and exposed their nest box entrance to ALAN the following night (1.6 lux white LED light; a similar light intensity as was found at nest boxes near street lights). Their behavior was compared to that of control birds sleeping in dark nest boxes on both nights. Our experimental treatment did not affect sleep behavior. Sleep behavior of birds in the control group did not differ from that of individuals in the light treated group. Our results suggest that during winter cavities shield birds from some effects of ALAN. Furthermore, given that effects of ALAN and exposure to artificial light are species-, sex-, and season-dependent, it is important that studies using wild animals quantify individual exposure to light pollution, and be cautious in the interpretation and generalization of the effects, or lack thereof, from light pollution. Rigorous studies are necessary to examine individual light exposure and its consequences in cavity- and open-nesting birds.

Diet of sympatrically breeding Southern Carmine Bee-eater Merops nubicoides and White-fronted Bee-eater Merops bullockoides

The Southern Carmine Bee-eater Merops nubicoides and White-fronted Bee-eater Merops bullockoides are insectivore, cavity-nesting bird species, both of which occur in the Zambezi Region, north-eastern Namibia. I examined there the diet composition of these species by an analysis of prey remnants. The Southern Carmine Bee-eater chick's diet consisted of exclusively insects, represented by seven orders. The most numerous were orthopterans and beetles (40.9% and 26.1%, respectively; n = 582 prey items). Hymenopterans (18.7%) and bugs (12.9%) supplemented the diet, whereas dragonflies (Odonata) and moths (Lepidoptera) were preyed only occasionally. In the diet of the White-fronted Bee-eater, nesting at the same site, beetles were the most important prey (81.2% of all 101 prey items identified), with scarabaeids comprising more than half of the beetle diet. In comparison with the White-fronted Bee-eater, a lower proportion of beetles, but much larger proportion of orthopterans were recorded in the diet of the Southern Carmine Bee-eater. In both bee-eater species, hymenopterans appear to be less important than was expected. The essential difference in the proportion of main prey groups recorded in Southern Carmine and White-fronted Bee-eaters breeding at the same site may represent a shift in food niche due to both temporal segregation in breeding, and differences in food preferences (feeding sites).

Local temperatures predict breeding phenology but do not result in breeding synchrony among a community of resident cavity-nesting birds

Weather and ecological factors are known to influence breeding phenology and thus individual fitness. We predicted concordance between weather conditions and annual variation in phenology within a community of eight resident, cavity-nesting bird species over a 17-year period. We show that, although clutch initiation dates for six of our eight species are correlated with local daily maximum temperatures, this common driver does not produce a high degree of breeding synchrony due to species-specific responses to conditions during different periods of the preceding winter or spring. These “critical temperature periods” were positively associated with average lay date for each species, although the interval between critical periods and clutch initiation varied from 4–78 days. The ecological factors we examined (cavity availability and a food pulse) had an additional influence on timing in only one of our eight focal species. Our results have strong implications for understanding heterogeneous wildlife responses to climate change: divergent responses would be expected within communities where species respond to local conditions within different temporal windows, due to differing warming trends between winter and spring. Our system therefore indicates that climate change could alter relative breeding phenology among sympatric species in temperate ecosystems.

Home, dirty home: effect of old nest material on nest-site selection and breeding performance in a cavity-nesting raptor.

The quality of a breeding site may have major fitness consequences. A fundamental step to understanding the process of nest-site selection is the identification of the information individuals use to choose high-quality nest sites. For secondary cavity-nesting bird species that do not add nest lining material, organic remains (faeces, pellets) accumulated inside nest cavities during previous breeding events may be a cue for high-quality nest-sites, as they contain information about past successful breeding and may improve thermal insulation of eggs during incubation. However, cavities in which breeding was successful might also contain more nest-dwelling ectoparasites than unoccupied cavities, offering an incentive for prospective parents to avoid them. We exposed breeding cavity-nesting lesser kestrels (Falco naumanni) to nestbox dyads consisting of a dirty (with a thick layer of organic substrate) and a clean nestbox (without organic material). Dirty nestboxes were strongly preferred, being occupied earlier and more frequently than clean ones. Hatching success in dirty nestboxes was significantly higher than in clean ones, suggesting a positive effect of organic nest material on incubation efficiency, while nestbox dirtiness did not significantly affect clutch and brood size. Nestlings from dirty nestboxes had significantly higher ectoparasite load than those from clean nestboxes soon after egg hatching, but this difference was not evident a few days later. Nest substrate did not significantly affect nestling growth. We concluded that nest substrate is a key driver of nest-site choice in lesser kestrels, although the adaptive value of such a strong preference appears elusive and may be context-dependent.

Effects of landscape composition and native oak forest configuration on cavity-nesting birds of North Africa

In the Kroumirie ecoregion of northwestern Tunisia, habitat fragmentation and degradation are the main drivers of contemporary landscape change. Continuous native oak forests have been converted into heterogeneous landscapes characterized by small forest fragments surrounded by a scrubby matrix. We examined the response of five species of cavity-nesting birds to these phenomena because they play a keystone role in these forest ecosystems. We quantified the relative effects of landscape composition and the configuration of mature oak forest on the occurrence of the focal species. We hypothesized that the occurrence of all focal species would increase with forest cover, whereas the effects of matrix type and mature forest configuration would be species-specific. For each focal species, we tested a set of 12 candidate models predicting their occurrence. Each model included landscape metrics describing oak forest configuration and landscape composition. We applied multimodel inference and model averaging on generalized linear models. Forest cover at the landscape level was the main driver of species occurrence. Secondary cavity-nesters responded positively to the proportion of oak forest at landscape and local scales, whereas the five focal species responded negatively to the proportion of low scrub. Great spotted woodpecker (Dendrocopos major) and Levaillant’s woodpecker (Picus vaillantii) responded positively to both forest amount and high scrub, suggesting a landscape complementation process. Lesser spotted woodpecker (D. minor) was the only species responding to forest configuration, possibly as a result of landscape supplementation. High scrub appeared to moderate the contrast between low scrub and forest fragments for primary cavity-nesters. However, it did not influence the occurrence of secondary cavity-nesters (e.g., Atlas flycatcher Ficedula speculgera and short-toed treecreeper Certhia brachydactyla). If an increase in the amount of mature oak forest cannot be achieved over the short term, the maintenance of high scrub around forest fragments and an improvement in the quality of low scrub through the addition of vertical structure should increase the frequency of occurrence of many of our focal species in oak forest of the Mediterranean Basin.

Resident and cavity-nesting avian community is affected by amount but not age of white pine in central Ontario mature mixedwood forests

Forests with old-growth white pines have been severely reduced compared with historical levels. We examined resident and cavity-nesting bird species abundances in winter and the breeding season, because some of these species may prefer old-forest habitats for breeding. We counted birds over 10 years in four mixedwood types: old pine, mature pine, mature nonpine, and selection-harvested stands. We expected that old pine stands would be selected by some species because of abundant snags and large trees for foraging. We assessed habitat use among years and changes following harvesting. Counts of nomadic species varied across years but counts for others did not. Species used old and mature pine mixedwoods equally and more than nonpine or harvested stands in winter and for breeding, but old stands were not preferred. Important variables included percent pine and large tree density. Selection harvesting benefitted Yellow-bellied Sapsuckers but reduced counts of Black-capped Chickadees and Brown Creepers. Black-capped Chickadees changed habitats between seasons and in some years. Black-backed Woodpeckers were most common in pine stands but abundant in harvested stands for 2 years following cutting. Regardless of stand age, large (>40 cm) pines provide important habitat for residents and cavity nesters.

Post-breeding courtship: public information about breeding habitat quality?

Animals can estimate breeding habitat quality by monitoring social information provided by the behaviours of others. While it is accepted that the value of public information erodes with distance from the source of information, the spatial and temporal ecology of public information acquisition and use is not well understood. Published accounts of the acquisition of public information for breeding habitat selection show a study bias towards the period corresponding to the breeding season. Here, we explored the idea that post-breeding courtship is a reliable source of performance social information about breeding habitat quality that can be used by nest-site prospectors. We revealed that post-breeding courtship can be used as performance social information for breeding habitat selection in a sedentary, cavity-nesting bird species, the Eurasian Tree Sparrow Passer montanus. First, the occurrence of the autumn nest at a nest box was positively associated with the nest box’s breeding performance in both the preceding and subsequent breeding seasons. Second, nest boxes with owners that showed higher post-breeding courtship activities attracted more prospectors. Namely, more prospectors visited nest boxes momentarily occupied by both owners and containing complete autumn nests at the end of autumn compared to nest boxes momentarily occupied by single owners and containing incomplete autumn nests. We suggest that post-breeding courtship represents performance social information about breeding habitat quality that is accessible to more potential observers than performance social information available during the breeding period is. Also, post-breeding courtship can be even more reliable performance social information than that available during the breeding period because it integrates information provided by informed individuals on the nest site’s breeding performance and post-breeding attractiveness (i.e. use).

WOODEN VERSUS INSULATED METAL NESTBOXES: A COMPARISON OF REPRODUCTIVE SUCCESS AND USE BY SONGBIRDS

ABSTRACTWe compared reproductive success of Tree Swallow (Tachycineta bicolor) and House Wren (Troglodytes aedon) nests in wooden nestboxes to insulated metal nestboxes to determine if a new insulated metal nestbox design is a safe alternative to wooden nestboxes. We also examined the preference of four species of cavity-nesting birds to nest in wooden versus metal nestboxes. No significant differences were found among clutch size, hatching success, and the number of fledglings produced in Tree Swallow and House Wren nests between the two types of nestboxes. Therefore, insulated metal nestboxes appear to be a safe alternative to wooden nestboxes. Metal nestboxes were preferred by Tree Swallows to wooden nestboxes (χ2 = 6.5, n = 25, p = 0.01). However, wooden nestboxes were preferred to metal nestboxes as a first choice for nesting 77.1% of the time for all four species. House Wrens, Eastern Bluebirds (Sialia sialis), and House Sparrows (Passer domesticus) all preferred wooden to metal nestboxes (Fisher's Exact Tests, all p < 0.001). Thus, insulated metal boxes are safe, but may not attract desirable species, such as Eastern Bluebirds, when compared to traditional wooden Peterson-style boxes.

Reproductive success of cavity-nesting birds in partially harvested woodlots

Cavity-nesting birds are dependent on large declining and dead trees that are frequently removed during partial harvesting. We compared breeding densities, nest survival, nest site characteristics, food abundance, and reproductive parameters of six species of cavity-nesting birds in partially harvested and reference woodlots in southwestern Ontario, Canada. Silvicultural practices significantly altered woodlot structure, with treatment-specific effects on bark arthropod biomass, fledging dates for the Red-bellied Woodpecker ( Melanerpes carolinus (Linnaeus, 1758)), and site suitability for the Yellow-bellied Sapsucker ( Sphyrapicus varius (Linnaeus, 1766)). Red-bellied Woodpecker, Downy Woodpecker ( Picoides pubescens (Linnaeus, 1766)), and Hairy Woodpecker ( Picoides villosus (Linnaeus, 1766)) experienced lower breeding densities in recently cut sites. Daily survival rates were generally greater for nests positioned higher up in large trees and for Northern Flicker ( Colaptes auratus (Linnaeus, 1758)) nests excavated in healthy and hard wood. Conversely, the Black-capped Chickadee ( Poecile atricapillus (Linnaeus, 1766)) had higher daily survival rates in low, small trees (<10 cm diameter at breast height) and sites with lower arthropod abundance. We conclude that although partial harvesting has the potential to decrease cavity-nesting bird breeding densities, conscientious cavity tree retention during harvest may provide suitable nesting sites that maintain high rates of nest success, regardless of the silvicultural treatments that we examined. However, further research is required to monitor these trends beyond a single harvesting rotation.

Nest niche dynamics of Meyer's Parrot Poicephalus meyeri in the Okavango Delta, Botswana

Meyer's Parrot Poicephalus meyeri is the only cavity-nesting bird species that breeds during winter in the Okavango Delta. This is facilitated by exclusive access to arthropod larvae incubating inside and feeding on fruits and pods in their diet. To minimise predation risk and overcome low overnight temperatures they have specialised, non-random nest cavity preferences that restrict them to 4.5% of the available nest cavities in the study area. Here we evaluated the nest niche of Meyer's Parrot by studying the nest tree preferences and ecological context of all nest cavities to determine factors that may restrict breeding success in disturbed or altered habitat. Although specific nest tree preferences were significantly different between host tree species, Meyer's Parrot preferred trees greater than 14 m in height that were in relatively poor condition (e.g. portion of the canopy dead). A comparison of nest tree characteristics (n = 75) and the availability of these tree specifications in a representative sample of the different habitat types (n = 1 129) within the sample area indicated that Meyer's Parrot are dependent on riverine forest, Acacia-Combretum marginal woodland and dry mopane woodland for nesting opportunities. Disturbance to hardwood trees by African elephants Loxodonta africana and fungal attack (e.g. Coriolus versicolor) are likely important dynamics in supporting healthy Meyer's Parrot populations and cavity-nesting bird communities.

Partial Predation at Cavity Nests in Southern Pine Forests

Abstract Although open-cup nesting birds regularly experience partial predation events, little is known about partial predation for cavity-nesting birds. Here we report on 12 partial predation events for 5 species of cavity-nesting birds inhabiting southern pine forests. Snakes, small mammals, and woodpeckers were the primary predators; many were documented by direct visual observation or video photography. We documented two types of outcomes from partial predation events: partial failure, i.e., a single partial predation event followed by successful fledging of >1 young; and complete failure, i.e., multiple, sequential partial predation events that result in total nest failure. We propose the “plate too full” and “eat and run” hypotheses to explain partial nest predation in birds and discuss the characteristics of cavities that may facilitate this phenomenon.

Horsehair Worms (Gordius robustus) in Nests of the Western Bluebird (Sialia mexicana): Evidence for Anti-Predator Avoidance?

Hairworms (Nematomorpha: Gordiida) are internal parasites that alter the behavior of their terrestrial insect host, forcing it to enter the water to reach its reproductive habitat. After reproduction of the free-living adults, the larvae encyst in aquatic insects and are retained upon metamorphosis of the insect into an adult fly. This paratenic host links the aquatic and terrestrial environments after its consumption by omnivorous or predatory insects. Therefore, hairworms are usually only associated with invertebrates, and few reports discuss hairworm interactions with vertebrate species. Here, we report on the finding of horsehair worms in nests of a cavity-nesting bird species in Los Alamos County, New Mexico. From 2004 to 2008, 7 nests within nest boxes occupied by the western bluebird (Sialia mexicana) contained 8 hairworms that were identified as Gordius robustus. All of the nest boxes with worms were less than 100 m from stagnant or low-flowing streams. The most likely explanation for the presence of the worms in the nests is that worms engaged in anti-predator avoidance after their insect hosts were collected and before digestion by nestling birds.

Nest-Site Selection and Nesting Success of Cavity-Nesting Birds in High Elevation Forest Drainages

ABssAcr.-We identified habitat features that characterized successful and unsuccessful nest sites, nest sites vs. random sites, and differences among coexisting species of cavitynesting birds for 356 nests in central Arizona. Live and, more commonly, dead quaking aspens (Populus tremuloides) were used for 88% of all nest sites, but aspens constituted only 12% of all trees in random plots (n = 152). Nest patches (11.3-m-radius circle centered on the nest tree) of most bird species contained significantly more aspens and conifers, which provided foraging substrates for cavity-nesting species, than random plots, but the patches had fewer deciduous trees (except aspens). Thus, more potential nest sites and foraging substrates existed in chosen nest patches than in random plots. Failed nests generally were more concealed by foliage and were closer to conifers. Nest success was lower for species with lower nest height. Reduced nest success at lower and more concealed nests may occur because predators are more successful. Nonexcavator species had lower nesting success than excavator species possibly because they nested lower, had greater nest concealment, used older cavities, and tended to have smaller body mass. Received 21 May 1990, accepted 26 November 1990.

Spatial nest-box selection of cavity-nesting bird species in response to proximity to recreational infrastructures

Human disturbance associated with recreational infrastructures can affect avian behaviour, such as, for example, nest-site choice, but differential tolerance to human disturbance among species likely influences the nest distribution of the overall bird community. From 2004 to 2007, we analysed the spatial influence of recreational trails and buildings on nest-box selection of cavity-nesting bird species in a reforested area in Madrid, central Spain. Nest boxes were mainly occupied by House Sparrows ( Passer domesticus), Tree Sparrows ( Passer montanus) and Great Tits ( Parus major). We analysed whether differences between used–unused nest boxes and among nest boxes occupied by different species were related to our disturbance variables. We employed Generalized Linear Models that also statistically controlled for habitat structure and edge effects on bird distribution. Proximity to buildings, rather than trails, always proved to be the most explicative variable of nest-box use by the different species. The nest boxes occupied by House Sparrows were located closer to buildings than the ones occupied by Tree Sparrows or Great Tits. Nonrandom patterns of nest-box occupation with respect to sources of human disturbance might be due to the different tolerance levels of each species. Alternatively, man-made structures such as buildings might favour human-associated species, a circumstance which could change the outcome of heterospecific interactions. In any case, our results support the idea that recreational buildings may affect nest-box selection in breeding bird communities, and that a proper infrastructure layout may help to reconcile leisure activities with the conservation of the natural areas with recreational uses.

Nest biology of urban populations of cavity-nesting birds

Nesting features of four species of cavity-nesting birds—common starling (Sturnus vulgaris L.), great tit (Parus major L.), common redstart (Phoenicurus phoenicurus L.), and pied flycatcher (Ficedula hypoleuca Pall.)—have been studied in city. Under urban conditions, number of eggs in a nest of a redstart is significantly larger, while for great tit and pied flycatcher it is significantly smaller; differences between the populations of starling are insignificant. Success of reproduction for the cavity-nesters is significantly higher in a city and exceeds the reference value for all the species by 10–20%. The number of chicks per a reproduction attempt is also higher in city for all the species. Starling population in city exceeds the reference population in the success of reproduction mainly due to a decrease in the percentage of abandoned eggs. The main reasons for an increase in the reproduction success of other species at the urbanized locality are weakened pressure of predators and a decrease in the percentage of abandoned broods.

Are nest sites actively chosen? Testing a common assumption for three non-resource limited birds

Many widely-accepted ecological concepts are simplified assumptions about complex situations that remain largely untested. One example is the assumption that nest-building species choose nest sites actively when they are not resource limited. This assumption has seen little direct empirical testing: most studies on nest-site selection simply assume that sites are chosen actively (and seek explanations for such behaviour) without considering that sites may be selected randomly. We used 15 years of data from a nestbox scheme in the UK to test the assumption of active nest-site choice in three cavity-nesting bird species that differ in breeding and migratory strategy: blue tit ( Cyanistes caeruleus), great tit ( Parus major) and pied flycatcher ( Ficedula hypoleuca). Nest-site selection was non-random (implying active nest-site choice) for blue and great tits, but not for pied flycatchers. We also considered the relative importance of year-specific and site-specific factors in determining occupation of nest sites. Site-specific factors were more important than year-specific factors for the tit species, while the reverse was true for pied flycatchers. Our results show that nest-site selection, in birds at least, is not always the result of active choice, such that choice should not be assumed automatically in studies of nesting behaviour. We use this example to highlight the need to test key ecological assumptions empirically, and the importance of doing so across taxa rather than for single “model” species.