Nest Cup Research Articles

The evolution of egg shape in birds: selection during the incubation period

A recent broad comparative study suggested that factors during egg formation – in particular ‘flight efficiency’, which explained only 4% of the interspecific variation – are the main forces of selection on the evolution of egg shape in birds. As an alternative, we tested whether selection during the incubation period might also influence egg shape in two taxa with a wide range of egg shapes, the alcids (Alcidae) and the penguins (Spheniscidae). To do this, we analysed data from 30 species of these two distantly related but ecologically similar bird families with egg shapes ranging from nearly spherical to the most pyriform eggs found in birds. The shape of pyriform eggs, in particular, has previously proven difficult to quantify. Using three egg‐shape indices – pointedness, polar‐asymmetry and elongation – that accurately describe the shapes of all birds’ eggs, we examined the effects of egg size, chick developmental mode, clutch size and incubation site on egg shape. Linear models that include only these factors explained 70–85% of the variation in these egg‐shape indices, with incubation site consistently explaining > 60% of the variation in shape. The five species of alcids and penguins that produce the most pyriform eggs all incubate in an upright posture on flat or sloping substrates, whereas species that incubate in a cup nest have more spherical eggs. We suggest that breeding sites and incubation posture influence the ability of parents to manipulate egg position, and thus selection acting during incubation may influence egg‐shape variation across birds as a whole.

Video Evidence of Siblicide and Cannibalism, Movement of Nestlings by Adults, and Interactions with Predators in Nesting Hen Harriers

During a nest-camera study of Hen Harriers (Circus cyaneus), we recorded siblicide, cannibalism, movement of nestlings by adult birds, and interactions with predators. We deployed cameras at 13 nests across three study areas in Ireland between 2008 and 2010. At a nest with two well-developed nestlings (approximately 25–30 d old), the older nestling killed its sibling and fed on it. This was the first documented case of siblicide in this species, to our knowledge. Recordings also revealed three other events of cannibalism in which one of the nestlings in a brood died from unknown causes and was then eaten by its siblings (n = 1), by the adult male (n = 1), or was used by the adult female to feed the remaining nestlings (n = 1). At two nests, recordings showed the adult female picking up and moving nestlings that were outside the nest cup. In addition, cameras recorded two instances of full brood predation by red fox (Vulpes vulpes) and an attack on a nest by a female Eurasian Kestrel (Falco tinnunculus) that had no apparent consequences for the nestlings or the female Hen Harrier. The behaviors reported here, which are difficult to observe directly, may have important consequences for our understanding of productivity and population dynamics of Hen Harriers.

Infrared thermography provides insight into the thermal properties of bird nests

Thermal properties of nests have been investigated using a variety of techniques. Infrared (IR) thermography has the advantage of being a non-invasive technique allowing the integrity of the nest wall to be retained during measurement. This study investigated the insulative properties of nests of the Eurasian Bullfinch (Pyrrhula pyrrhula), the Common Blackbird (Turdus merula) and the Song Thrush (Turdus philomelos) using IR thermography. Nests were inverted over a heat source and the temperature of the external nest surface was recorded. Bullfinch nests were less insulated than thrush nests. Including foil inside the nest cup decreased the amount of convection through the open walls of Bullfinch nests. Removal of the outer nest and cup lining of thrush nests only slightly decreased the degree of insulation offered by the nest indicating an important insulative role for the substantial ‘mud cup’ in these nests. The results suggested that the nest wall is not sealed and convection currents may a play a significant role in nest insulation. In conjunction with a steady-state heat source IR thermography is useful in assessing the insulative properties of bird nests.

Artificial nests for Barn Swallows Hirundo rustica: a conservation option for a declining passerine?

ABSTRACTCapsule: Barn swallows Hirundo rustica using artificial nest cups had greater reproductive success than those building and using natural nests.Aims: To quantify reproductive success of Barn Swallows breeding in artificial man-made nests and compare with those using natural nests.Methods: In 2012–16, the breeding attempts of 231 pairs of Barn Swallows were monitored in artificial and natural nests in an urban habitat in Denmark.Results: Pairs breeding in old natural nests and artificial nests bred earlier, laid more eggs, and produced more nestlings and fledglings than pairs breeding in new natural nests. Inter-clutch intervals were shorter in Barn Swallow pairs using artificial nests and old natural nests. Nest cup volume and nest volume of newly built nests were significantly larger and more variable than artificial nests excluding an effect of nest size as an explanation for the larger clutches laid in artificial nests. Increased energy and time costs of nest construction may have reduced reproductive success for pairs building natural nests.Conclusion: Artificial nests were readily accepted by Barn Swallows, they had a similar low predation rate as natural nests, and they proved to be a possible conservation option for this declining passerine breeding in urban habitats as evidenced by their 75% higher reproductive success in artificial nests.

Simulated Rainfall Reduces the Insulative Properties of Bird Nests

Bird nests are variable in design but all are constructed for the purpose of incubation. The potentially onerous energetic costs of incubation have meant that previous studies have focussed on thermal insulation but nests are often exposed to a variety of environmental factors, including rainfall. Those few studies that have investigated the effects of water on nests have saturated the walls by soaking but this may not reflect what a nest would typically encounter in situ during rainfall. Here, nests of four species of songbird (Common Chaffinch Fringilla coelebs, Common Linnets Linaria cannabina, Meadow Pipits Anthus pratensis, and Whinchats Saxicola rubetra) were investigated using temperature loggers to determine the effect of simulated rainfall on nest wall insulation. Simulated rainfall, produced by water dripping through a coffee percolator, significantly reduced the insulatory values of nests, and significantly increased the rate of cooling of temperature loggers inside the nest cup. No significant effect of species, or nest mass, was observed. Even when wet nest walls provided some insulation but whether this is attributable to the nest materials chosen by each species was not clear. The nest site chosen by the birds may also offer considerable protection from the weather. Further research is needed to better understand how rainfall affects the insulative properties of nests in situ.

Experimentally increased nest temperature affects body temperature, growth and apparent survival in blue tit nestlings

The thermal environment experienced by birds during early postembryonic development may be an important factor shaping growth and survival. However, few studies have directly manipulated nest temperature (Tn) during the nestling phase, and none have measured the consequences of experimental heat stress on nestlings’ body temperature (Tb). It is therefore not known to what extent any fitness consequences of development in a thermally challenging environment arise as a direct, or indirect, effect of heat stress. We, therefore, studied how experimentally increasedTnaffectedTbin 8–12 d old blue titCyanistes caeruleusnestlings, to investigate if increased thermoregulatory demands to maintain normothermicTbinfluenced nestling growth and apparent long‐term survival. Nestlings in heated nest‐boxes had significantly higherTbcompared to unheated nestlings during most of the experimental period. Yet, despite facingTn 50°C (as measured in the bottom of the nest cup below the nestlings), the highest nestlingTbrecorded was 43.8°C with nestlings showing evidence of controlled facultative hyperthermia without any increased nestling mortality in heated nests. However, body mass gain was lower in these nestlings compared to nestlings from control nest‐boxes. Contrary to our prediction, a larger proportion of nestlings from heated nest‐boxes were recaptured during their first winter, or subsequently recruited into the breeding population as first‐ or second‐year breeders. This result should, however, be treated with caution because of low recapture rates. This study highlights the importance of the thermal environment during nestling development, and its role in shaping both growth patterns and possibly also apparent survival.

Predation on artificial and natural nests in the lowland rainforest of Papua New Guinea

ABSTRACTCapsule: Although survival of nests was similar between forest fragments and continuous forest, the range of predators differed. Artificial nests provide an under-estimate of nest predation by snakes.Aims: To estimate the natural nest predation rate in continuous primary forest, compare it with predation rates in forest fragments. To assess the reliability of nest survival rates determined by the use of artificial nests with clay eggs and identify the main nest predators.Methods: We observed survival of natural nests during the incubation period in continuous primary forest in Papua New Guinea. Some nests were monitored with infrared cameras. We also used artificial nests deployed with clay eggs to identify predators.Results: There was a predation rate of 50% for natural nests and snakes were major predators of nest contents. Clutch daily survival rates (DSRs) differed among nest types. The DSR of artificial nests (0.977) was not significantly different to that of natural cup nests (0.969). Survival rates of artificial nests were similar in forest fragments and continuous forest. Forest fragments had, however, a higher proportion of avian predators than continuous forest.Conclusion: Although, we observed similar survival rates in artificial and natural nests, the composition of nest predators was different between natural and artificial nests. Artificial nests were not suitable for estimating the real predation caused by reptiles. Nevertheless, we find that participation of avian nest predators can be estimated correctly with the use of artificial nests.

Birds adopting weaver nests for breeding in Africa

Weavers build domed, long-lasting nests that may also be adopted by other species for breeding, probably reducing the energetic costs of nest building to varying degrees. In an extensive literature search, 57 species were found to have at least one record of adopting a weaver nest. There is one known obligate nest user, the Pygmy Falcon Polihierax semitorquatus. Four species were classed as near obligate nest adopters. Four species were listed as common, 10 as occasional, and 38 species as rare nest adopters. Other than the falcon and lovebirds Agapornis species, these nest adopters are passerines. Of the 57 species of nest adopters, 35 species had confirmed eggs and/or chicks found in the weaver nests. Most nest adopter species were in the Estrildidae family (20 species), with three estrildids classed as near obligates. This was followed by the Muscicapidae family, species that build cup nests. By building their cup nests inside weaver nests, there is likely protection from adverse weather and predators. Overall, there appeared to be a large diversity of nest adopter species for the traditional savanna living weavers (Ploceus, Bubalornis, Anaplectes, Plocepasser and Philetairus).

Effect of air movement on the thermal insulation of avian nests

ABSTRACTCapsule: Air movement over a nest increases the rate of cooling within the nest cup but the walls provide good thermal insulation.Aims: This study compared nests of six bird species of the families Fringillidae and Motacillidae to investigate the insulative properties in still and moving air treatments. It was hypothesized that differences in nest size and moving air would differ between species and would have a significant effect on insulatory values of the nests.Methods: Nest dimensions were measured for a total of 35 nests from six species. Thermal properties of the nests were recorded using temperature loggers within nests placed in a wind tunnel under still and moving air conditions.Results: Insulatory values and internal nest cooling rates were significantly increased by moving air. There was no significant difference between species for the thermal properties of nests but nest mass correlated with greater insulatory values and a lower rate of cooling within the nest cup. Nest wall thickness had no significant effect on the thermal characteristics of the nests.Conclusion: The use of a constructed nest mitigated the effects of air movement but the differences between species reflected difference in nest mass rather than wall thickness.

Nesting success of birds from Brazilian Atlantic Forest fragments

Several aspects of the ecology of tropical birds remain unresolved both descriptively and experimentally, in spite of the high diversity of birds and the high deforestation rates. Here, I evaluate, apparently for the first time, nesting success and predation levels of open and closed-cupped nesting birds in an avian community from Atlantic Forest fragments in southeastern Brazil. The monitoring of 257 nests of more than 22 species from 1995 to 1999 revealed that overall apparent nest success (42.4%) was in the upper range for tropical species. Daily survival rates (DSR) for 18 species ranged from 0.900–0.987. Total average survival probability was 55.9 for open cup and 60.1% for closed nests. There was no evidence for an edge effect on the success of either open cup or closed nests. Against predictions, apparent success of closed nests (43.6%) did not differ from open cup nests (38.1%). However, there were differences in apparent success within three types of closed nests. Closed nests higher above the ground had greater apparent nest success than lower nests, but this pattern did not occur for open cup nests. This study demonstrates that some patterns of nesting success might not hold for all Neotropical sites, especially disturbed ones.

Effect of Nest Characteristics on Thermal Properties, Clutch Size, and Reproductive Performance for an Open-Cup Nesting Songbird

Maintaining avian eggs and young at optimum temperatures for development can increase hatching success and nestling condition, but this maintenance requires parental energetic demands. Bird nests, which often provide a structure to safely hold the eggs and nestlings and protect them from predators, can additionally be designed to help maintain eggs’ optimum temperatures by minimising heat loss, especially in climates where eggs cool rapidly when unattended. We collected and measured Prairie Warbler ( Setophaga discolor) nests in western Massachusetts, U.S. in 2009 and conducted a climate-controlled, nest-cooling experiment to determine how nest characteristics affect thermal properties for small, open-cup nesting birds. We then assessed if nests with better insulation properties resulted in any fitness benefits, and also tested if nest structural characteristics affected birds’ fitness. We found that nest characteristics influenced their thermal properties, with thicker, heavier, and larger nests having slower cooling rates and higher predicted equilibrium egg temperatures. Both nest cup depth and clutch size significantly declined over the breeding season, and we observed a trend, although non-significant, that nests with shallower cups had smaller clutches. Contrary to studies on cavity-nesting birds, we found no significant effects of nest thermal properties or nest structure on hatching and fledging success, nestling condition, brood parasitism, or nest survival. Prairie Warblers in our study site may already be adapted to build nests within a range that maximises their fitness. Furthermore, studies have shown that open-cup nests of other species are relatively thicker and more insulated in colder environments at higher latitudes than our study. Instead of building nests to solely minimise heat loss, open-cup nesting birds in temperate climates may also be driven by opposing selection pressures when building their nests, such as to prevent nestlings from overheating during hot days.

First description of the nest, egg, and nestling of Multicolored Tanager (Chlorochrysa nitidissima)

ABSTRACT The genus Chlorochrysa, with three species: C. phoenicotis, C. calliparaea, and C. nitidissima, is distributed throughout the Andes from Colombia to northern Bolivia inhabiting mossy cloud forests between 900–2400 m. We describe for the first time the reproductive biology of the C. nitidissima and the use of different nesting sites. This study was conducted at three sites located on the eastern slope of the Western Cordillera in Colombia. The shallow cup nests were built with small thin sticks and dry bamboo leaves, placed inside hanging mossy clumps located on horizontal branches or inside abandoned dome-shaped songbird nests. We report a clutch size of one white, oval egg with brown spots, which measured 21.45 × 15.0 mm and weighted 2.3 g (n = 2). The average nestling period was 23 days, and the nestling growth rate (K) was, on average, 0.29. Finally, these results could be used to implement plans for the conservation of this endemic and critical endangered species.

Open cup nests evolved from roofed nests in the early passerines.

The architectural diversity of nests in the passerine birds (order Passeriformes) is thought to have played an important role in the adaptive radiation of this group, which now comprises more than half of avian species and occupies nearly all terrestrial ecosystems. Here, we present an extensive survey and ancestral state reconstruction of nest design across the passerines, focusing on early Australian lineages and including members of nearly all passerine families worldwide. Most passerines build open cup-shaped nests, whereas a minority build more elaborate domed structures with roofs. We provide strong evidence that, despite their relative rarity today, domed nests were constructed by the common ancestor of all modern passerines. Open cup nests evolved from enclosed domes at least four times independently during early passerine evolution, at least three of which occurred on the Australian continent, yielding several primarily cup-nesting clades that are now widespread and numerically dominant among passerines. Our results show that the ubiquitous and relatively simple cup-shaped nests of many birds today evolved multiple times convergently, suggesting adaptive benefits over earlier roofed designs.

Enclosed nests may provide greater thermal than nest predation benefits compared with open nests across latitudes

Summary Nest structure is thought to provide benefits that have fitness consequences for several taxa. Traditionally, reduced nest predation has been considered the primary benefit underlying evolution of nest structure, whereas thermal benefits have been considered a secondary or even non‐existent factor. Yet, the relative roles of these factors on nest structures remain largely unexplored. Enclosed nests have a constructed or natural roof connected to sides that allow a restricted opening or tube entrance that provides cover in all directions except the entrance, whereas open nests are cups or platforms that are open above. We show that construction of enclosed nests is more common among songbirds (Passeriformes) in tropical and southern hemisphere regions than in north temperate regions. This geographic pattern may reflect selection from predation risk, under long‐standing assumptions that nest predation rates are higher in southern regions and that enclosed nests reduce predation risk compared with open cup nests. We therefore compared nest predation rates between enclosed vs. open nests in 114 songbird species that do not nest in tree holes among five communities of coexisting birds, and for 205 non‐hole‐nesting species from the literature, across northern temperate, tropical, and southern hemisphere regions. Among coexisting species, enclosed nests had lower nest predation rates than open nests in two south temperate sites, but not in either of two tropical sites or a north temperate site. Nest predation did not differ between nest types at any latitude based on literature data. Among 319 species from both our field studies and the literature, enclosed nests did not show consistent benefits of reduced predation and, in fact, predation was not consistently higher in the tropics, contrary to long‐standing perspectives. Thermal benefits of enclosed nests were indicated based on three indirect results. First, species that built enclosed nests were smaller than species using open nests both among coexisting species and among species from the literature. Smaller species lose heat fastest and thereby may gain important thermal benefits from reduced convective cooling. Second, eggs were warmed by parents for less time in species with enclosed nests, as can be expected if egg cooling rates are slower. Finally, species using enclosed nests exhibited enhanced growth of mass and wings compared with species using open nests, suggesting reduced thermoregulatory costs allowed increased energy for growth. Enclosed nests may therefore provide more consistent thermal than nest predation benefits, counter to long‐standing perspectives. A lay summary is available for this article.

The common redstart as a suitable model to study cuckoo-host coevolution in a unique ecological context.

BackgroundCo-evolutionary arms-races result in spatio-temporally dynamic relationships between interacting species, e.g., brood parasites and their avian hosts. However, majority of avian co-evolutionary studies are limited to “snap-shots” of a single breeding season in an open-nesting host. In a long-term study (11 breeding seasons), we explored a unique system between the brood parasitic common cuckoo (Cuculus canorus) and its host, the common redstart (Phoenicurus phoenicurus) which is exceptional among all cuckoo hosts due to being a cavity nester. Conditions in cavities are different from open nests, e.g., lower risks of predation, more favourable microclimate, increased risks of unsuccessful eviction of host offspring by the cuckoo nestling. Different conditions in cavities thus can be expected to shape parasite-host coevolution differently from what is typically studied in open nesting hosts.ResultsIn our highly parasitised nest-box population (32.5%, n = 569 nests) only 35.7% of cuckoo eggs were laid into the nest cup and incubated by redstarts. Host nests shifted availability to later into the breeding season from 2006 to 2016 and cuckoos followed this trend by also shifting their timing of parasitism. Although previous studies revealed that redstarts selectively eject experimental non-mimetic eggs (desertion was not a specific response to foreign eggs), the hosts never ejected naturally-laid cuckoo eggs or cuckoo eggs cross-fostered into naturally non-parasitised nests. We solve the long-standing debate about the origin of cuckoo eggs found on the nest rim: we gained the first direct video-recording evidence that eggs found on the nest rim were mislaid by parasites and not ejected by hosts. Naturally-parasitised nests were deserted more often (18.6%) than control non-parasitized nests (5.6%) or nests artificially parasitised by us (1.4%). This suggests that the sight of the laying cuckoo female is the primary cue that triggers egg rejection (by desertion) in this host. Review of data from this and other study sites (10 populations, n = 853 experiments) demonstrates high variability in rejection rates and shows that populations facing higher parasitism rates reject parasitic eggs with higher frequencies. Surprisingly, cuckoo chicks either growing solitarily or with redstart chicks did not differ in their fledging success.ConclusionsWe suggest that the redstart is an ideal model system to study the flexibility and limits of brood parasite-host co-evolution in an extreme ecological setting.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0835-5) contains supplementary material, which is available to authorized users.

How does The Bird-nest Incubation Unit Work?

The bird-nest incubation unit was proposed as a means of explaining the functionality of incubation in most avian species where the egg is in direct contact with the incubator. Subsequent work resulted in revision of this idea to suggest that large birds act as incubators and the nest is a location for incubation; by contrast, in small species the interaction between the bird and its nest played a key role in ensuring efficiency of incubation. This paper briefly reviews what we know about the incubation environment within nests and considers how small birds can contact-incubate eggs whilst ensuring appropriate levels of respiratory gas exchange. A hypothesis is proposed that the incubating bird does not ‘sit tight’ on its nest to maintain egg temperature at a minimal energy expenditure but, rather, it allows warmed air to escape from the nest cup. This convection flow draws air into the cup from the nest walls, providing oxygen for developing eggs and diluting carbon dioxide that they produce. Evidence supporting this idea of an ‘open’ nest during incubation is presented. Further experimentation is required to understand the environment within the nest cup better and this paper presents a hypothesis that can be tested in future studies. Investigations of how nests interact with their immediate environment should no longer be biased towards the effects of temperature on nest dimensions or composition. Instead, they should address all of the environmental factors that could affect the composition and function of a bird nest.

Effect of nestbox type on the breeding performance of two secondary hole-nesting passerines

The use of nestboxes to study secondary cavity nesting avian species has greatly improved the knowledge related to many fields of environmental sciences. The aim of this study has been to compare the breeding performance of Great Tits (Parus major) and Blue Tits (Cyanistes caeruleus) in two types of nestboxes that differ with regard to their shape and thermal properties. Both nestbox types were placed in the same area to avoid confounding factors. There were significant differences between the extreme values of temperature and relative humidity obtained for the two nestbox types, and this was also the case in their daily patterns. Secondary hole-nesting birds appear to prefer breeding in woodcrete nestboxes. Nest predation was, however, significantly greater in woodcrete nestboxes. The nest height was significantly higher in woodcrete nestboxes, as was the danger distance between the nest cup and the entrance hole, which could account for the fact that Great Tits prefer this type of nestbox. The laying date was earlier in woodcrete boxes, but nestbox type did not influence clutch size. However, the eggs of both species were significantly smaller in woodcrete boxes. Breeding success was worse in woodcrete nestboxes. Nestbox type also affected the incubation pattern in both species, and attentiveness was significantly diminished in woodcrete nestboxes. This study reinforces the idea that the type of nestbox used in avian studies is not a trivial issue and may have strong biological effects on avian populations. It is important to take this into account when nestboxes are used as management measures for bird conservation.

Facultative Nest Modification by Rock Wrens (Salpinctes obsoletus)

Dynamic nest-construction behaviours suggest that nest structures can be facultatively adjusted in response to environmental conditions. This is particularly true when nest builders create environmental structures that are supplemental to the nest itself, because these structures can be adapted to nest site conditions. Rock Wrens ( Salpinctes obsoletus) mechanically alter their nest environments by amending rock-based cavities with stones, which are placed below their soft nest cups and often occlude cavity entrances, and extending out of nest cavities. We measured stones and cavity dimensions in 68 Rock Wren nests to quantify stone form and functional variability in stone use. Nests in our study contained stones with a consistent, flat shape, suggesting that Rock Wrens were selective when choosing stones for use around nests. We found significant positive correlations between the size of the nest cavity entrance, the amount of stones placed in nests, and the occlusion rates of the nest cavity entrances. Our data suggest that Rock Wrens place stones around their nests using selective, goal-directed behaviour with the objective of approaching an optimal cavity entrance size. Stone use at nests reflects high behavioural flexibility, and can be considered tool use during nest construction.

Cuckoo parasitism in a cavity nesting host: near absent egg‐rejection in a northern redstart population under heavy apparent (but low effective) brood parasitism

Brood parasite – host systems continue to offer insights into species coevolution. A notable system is the redstartPhoenicurus phoenicurusparasitized by the ‘redstart‐cuckoo’Cuculus canorusgens. Redstarts are the only regular cuckoo hosts that breed in cavities, which challenges adult cuckoos in egg laying and cuckoo chicks in host eviction. We investigated parasitism in this system and found high overall parasitism rates (31.1% of 360 redstart nests), but also that only 33.1% of parasitism events (49 of 148 eggs) were successful in laying eggs into redstart nest cups. The majority of cuckoo eggs were mislaid and found on the rim of the nest; outside the nest cup. All available evidence suggests these eggs were not ejected by hosts. The effective parasitism rate was therefore only 12.8% of redstart nests. Redstarts responded to natural parasitism by deserting their nests in 13.0% of cases, compared to desertion rates of 2.8% for non‐parasitized nests. Our egg parasitism experiments found low rates (12.2%) of rejection of artificial non‐mimetic cuckoo eggs. Artificial mimetic and real cuckoo eggs added to nests were rejected at even lower rates, and were always rejected via desertion. Under natural conditions, only 21 cuckoo chicks fledged of 150 cuckoo eggs laid. Adding to this low success, is that cuckoo chicks are sometimes unable to evict all host young, and were more likely to die as a result compared to cuckoo chicks reared alone. This low success seems to be mainly due to the cavity nesting strategy of the redstart which is a challenging obstacle for the cuckoo. The redstart‐cuckoo system appears to be a fruitful model system and we suggest much more emphasis should be placed on frontline defences such as nest site selection strategies when investigating brood parasite–host coevolution.

Successful shared breeding in an artificial nest-box by Common Swift Apus apus and Common Redstart Phoenicurus phoenicurus

During the spring 2015, a pair of Common Redstarts Phoenicurus phoenicurus successfully raised a five-chick brood in an artificial nest-box designed for and occupied by a pair of Common Swifts Apus apus in southern Sweden. The breeding was monitored by a nest-box camera, which recorded close interactions between the two species. The Common Redstarts initiated the breeding first and had young in the nest when the Common Swifts arrived and initiated breeding by laying their eggs in a nearby nest cup. The breeding overlapped by 15 days between the second and the fourth week of June when all five of the nestlings of the Common Redstart fledged. The Common Swifts raised two young which fledged in early August.