Apus Apus Research Articles

Behavior of Common Swift Apus apus and House Martin Delichon urbicum towards a flying dummy

We tested for airborne epimeletic (care-giving) behaviour in Common Swift Apus apus towards young swifts during their first flight. Tests were performed where colonies of Common Swift and Western House Martin Delichon urbicum co-occur. Three variants of a flying dummy were used; two with pointed wings of which one entirely black (1) and one with partly white body (2). The third was black with broad wings (3). Reactions were documented on film. Swifts and martins had opposite reactions to dummies 1 and 2. As we anticipated, martins seemed supportive in a test with dummy 2 and seemed to “guide” the dummy epimeletically. However, a swift approached dummy 2 in a support-like attempt, but deviated after a close look. In a test with dummy 3, swifts acted highly hostilely. We discuss reasons for these outcomes and the importance of dummy appearance. We illustrate the flight paths of the dummy, swifts and martins with trajectories, and the behaviour of the Western House Martin is shown in stepwise larger magnification stills of a video.

Phenological changes in arrival and breeding in common swifts (Apus apus) in central Israel

Phenological changes in arrival and breeding in common swifts (Apus apus) in central Israel

Anthropogenic debris as nest material in three swift species: New insights into the interactions of atmospheric pollution with wildlife

Plastic pollution has become a global concern, affecting many species around the world. While well-documented for marine ecosystems, the impact of plastic pollution on terrestrial ecosystems is comparatively limited. In fact, only recently have some studies begun to explore the occurrence, pathways, and impacts of plastic in the atmosphere and on terrestrial species. Here, we assess the presence of synthetic material in nests of three swift species breeding in the Western Palearctic: the common swift (Apus apus), the pallid swift (Apus pallidus), and the alpine swift (Tachymarptis melba). Using data from 487 nests spanning 25 colonies and seven European countries, we show that 36.5 % of the examined nests contained anthropogenic materials, mainly plastic debris. Notably, Pallid swifts' nests, with 85 % of the total nests examined with plastic, rank among birds with the highest plastic content in nests. We also demonstrate that the probability of finding plastic in the nest increased substantially with the human footprint of the landscape. Last, we recorded four cases of swifts entangled in their own nest, a low proportion compared to other species studied previously. Our study provides compelling evidence that plastic pollution may also be considered a concern for other terrestrial species, particularly for birds with highly aerial lifestyles, such as other swifts. The correlation with the human footprint suggests that areas with higher human activity contribute more significantly. Moreover, the entanglement cases, although low, indicate a threat to bird health and welfare. To our knowledge, our study is the first to report a direct interaction between floating plastic debris in the atmosphere and any species. Understanding this interaction is key, not only due to the lack of research on the topic, but also because it highlights that plastic pollution is a multifaceted environmental issue affecting various ecosystem categories, and the broader implications of atmospheric plastic circulation on wildlife and ecosystems health.

Microfibers in the Diet of a Highly Aerial Bird, the Common Swift Apus apus.

Microplastic pollution is a pervasive global issue affecting various ecosystems. Despite the escalating production and well-documented contamination in both aquatic and terrestrial environments, the research focused on airborne microplastics and their interaction with terrestrial birds remains limited. In this study, we collected fecal sacs from Common swifts (Apus apus) to investigate their diet and to evaluate the potential ingestion of microplastics by both adults and nestlings. The diet was mainly composed of Hymenoptera and Coleoptera and did not differ among sexes and age classes. The 33% of nestlings' and 52% of adults' fecal sacs contained anthropogenic items, the totality of which was in the shape form of fibers. The 19.4% of the anthropogenic items were chemically characterized as microplastics, either polyethylene terephthalate (PET; two microfibers) or cellophane (four microfibers). Airborne anthropogenic items, including microplastic, might be passively ingested during the Common swift aerial feeding. In addition, our findings suggest that these ingested microparticles have the potential to be transferred to the offspring through food. While further research is essential to elucidate the pathways of microplastic ingestion, our results reinforce the evidence of the transfer of anthropogenic items from the atmosphere to the biota.

Swift sampling of farmland aerial invertebrates offers insights into foraging behaviour in an aerial insectivore

The common swift Apus apus is an obligate aerial, migratory, insectivorous bird, that has experienced significant declines in the UK since the 1990s. Reductions in the availability of prey during their summer breeding season in the UK are likely to be a key factor in this decline. This short communication aims to contribute new insights into the current foraging behaviours of adult swifts feeding their nestlings, as a means of provoking new conversation and stimulating further work. Food bolus samples are small ball‐like structures containing the insect prey that is regurgitated to nestlings. Boluses from adult swifts provisioning their nestlings were collected incidentally at a breeding colony in Suffolk, UK. These were taxonomically identified and compared to corresponding daily insect catches from a nearby Rothamsted Insect Survey suction trap operating within the foraging area of common swifts. There was a distinction between the contents of the bolus samples and the suction‐trap samples, whereby larger‐bodied aerial invertebrates appeared in greater numbers in bolus samples. This was evidenced by the relatively high numbers of agriculturally important species, pollen beetles, and cabbage stem flea beetles in bolus samples compared to low numbers in suction traps. Smaller invertebrates such as aphids (Aphididae), parasitoid wasps (Hymenoptera), and thrips (Thysanoptera) were not frequent in the bolus samples, relative to the high numbers identified from the suction‐trap catch. These results are discussed in relation to swifts providing a pest suppression service, potential impacts of pesticides, and how selective foraging may both buffer and facilitate the challenges swifts face in a modern agricultural landscape.

Dynamics оf Nesting Ornithofauna Structure оf Tiraspol City’s Resident Area

43 species of nesting birds were registered of Tiraspol City’s resident area in 1999–2019. The total density was about 1995,7–2361 pairs/km2 . House Sparrow, Rock Dove, Tree Sparrow and Common Swift were the dominants. Crested Lark, Willow Warbler and Wood Warbler disappeared from nesting ornithofauna of resident area. Common Kestrel, Common Woodpigeon, Eurasian Scops-owl, Robin, Blackbird, Song Thrush, Blue Tit and Eurasian Nuthatch for 20 years were appeared. A signifi cant increase in abundance was noted in populations of Rock Dove, Long-eared Owl, Common Swift, Eurasian Golden Oriole, Rook and Tree Sparrow. There was a decrease in the number in the populations of Chiffchaff, Northern Wheatear, Black Redstart, House Sparrow and Chaffi nch. The majority of birds nesting in the resident area belong to the Transpalearctic type of the fauna, to the desert-mountains landscape-genetic faunistic complex, to the sklerophilnai ecological group and phytophagan trophic group.

Evaluating the effects of moonlight on the vertical flight profiles of three western palaearctic swifts.

Recent studies have suggested the presence of moonlight mediated behaviour in avian aerial insectivores, such as swifts. Here, we use the combined analysis of state-of-the-art activity logger data across three swift species, the common, pallid and alpine swifts, to quantify flight height and activity in responses to moonlight-driven crepuscular and nocturnal light conditions. Our results show a significant response in flight heights to moonlight illuminance for common and pallid swifts, i.e. when moon illuminance increased flight height also increased, while a moonlight-driven response is absent in alpine swifts. We show a weak relationship between night-time illuminance-driven responses and twilight ascending behaviour, suggesting a decoupling of both crepuscular and night-time behaviour. We suggest that swifts optimize their flight behaviour to adapt to favourable night-time light conditions, driven by light-responsive and size-dependent vertical insect stratification and weather conditions.

Crossing Worlds in Buildings

Holes in the houses of Brussels, as in other buildings across Europe, have long been the preferred nesting sites of the common swift (Apus apus), a bird famous for its fast flight and for spending most of its life on the wing. For several decades, however, urban construction and renovation has led to the destruction of swifts’ breeding sites, contributing significantly to their disappearance, and have prompted amateur naturalists to spatial interventions in ways that they hope the birds will accept. This essay explores this form of care that is forging a new path through the more-than-human city. It starts with an account of how swifts “story” the cavities they inhabit, and then describes the engagement of a devoted swift caretaker with the birds’ astute knowledge of buildings and their meaningful worlds. Moving across sites in Brussels, the essay articulates how an attentiveness takes shape between swifts, their storied-places, and the human caretakers who learn about them, as well as the tensions and contradictions that arise. Such a care practice involves noticing and experiential learning, it requires conveying importance to unfamiliar interlocutors, and leads both to the reactivation of architectural heritages and pleasure at aesthetic encounters with the birds. In some cases, the employment of nest boxes and other technologies may also risk greenwashing ecologically harmful operations. Caring for swifts, the essay concludes, involves a reciprocal co-becoming at specific architectural interfaces, through attentive and imaginative practices. These modes of attention and of imagination enable material interventions in buildings with a fuller appreciation of swifts’ storied worlds.

Tuta absoluta-Specific DNA in Domestic and Synanthropic Vertebrate Insectivore Feces.

The ecology of greenhouse pests generally involves parasitoid or predatory insects. However, we investigated whether the leaf miner Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae) is part of the diet of domestic and synanthropic vertebrate animals, such as birds, reptiles, and mammals, and that take part in an ecosystem that contains a high density of tomato greenhouses. Feces from domesticated partridges, common quails, and chickens, as well as from wild lizards were collected within tomato greenhouses, and fecal pellets from bats, swallows, common swifts, and house martins living in the vicinity of tomato greenhouses were collected outside. The efficiencies of three different DNA extraction methods were compared on bird, reptile, and mammal stool samples, and the DNA extracts were analyzed using probe real-time PCR for the presence of T. absoluta DNA. The results showed that bats fed on the pest, which was also part of the diet of several bird species: partridges and common quails kept within tomato greenhouses and swallows and common swifts living outside but in the vicinity of tomato greenhouses. In addition, fecal samples of three lizard species living near tomato crops also tested positive for T. absoluta DNA. The results suggest that aerial foraging bats and insectivorous birds are part of ecosystems that involve leaf miners and tomato greenhouses.

Slight sexual dimorphism in tail-fork depth of Common Swifts Apus apus

ABSTRACT For two new data sets from the Netherlands, we show that male Common Swifts have deeper tail forks than females. Although this hints at sexual selection, with a degree of masculine extravagance at work, the male dimensions are closer to the design rules for an aerodynamically optimal swift than are those of females.

Distribution and characteristics of urban nesting sites of sympatric swifts

Distribution and nest locations of Common and Pallid Swifts are compared in two towns located in the Mediterranean zone, Bastia in Corsica and Nice on the French Riviera. Our goal is to evaluate whether nesting site selection by swifts on urban settings differs between the two locations. First, we noted an avoidance in the distribution between the two swifts in both towns. Secondly, our results show that Common and Pallid Swifts use different nesting sites to breed in Bastia, whereas the same structures are used by the two species in Nice. Requirement of each species differs between the two localities, suggesting that nesting site use is more locality dependent than species dependent.

Molecular investigation on infection by haemosporidians in three Western Palearctic species of swift (Apodidae) and their ectoparasitic louse flies.

Swifts (Apodidae) are an unusual group of birds that spend most of their lives in flight, landing only when breeding. Although this aerial lifestyle greatly reduces their likelihood of being bitten by vectors and infected by vector-born parasites, swifts can still be heavily infested during breeding by nest-based vectors such as louse flies (Hippoboscidae). Here, we investigated host, vector, and vector-borne parasite relationships in the three most widespread swift species in the Western Palearctic (WP): common swifts (Apus apus), pallid swifts (A. pallidus), and alpine swifts (Tachymarptis melba), their nest-based louse flies (Crataerina pallida and C. melbae) and avian haemosporidians (genera Haemoproteus, Plasmodium, and Leucocytozoon). Studies of haemosporidian infections in Apodidae remain limited, with clear evidence of infection found to date in just four Neotropical and one Australasian species. The possible role of louse flies in transmitting haemosporidian infections has never been tested in swifts. We assessed the occurrence of haemosporidian infection by PCR screenings of DNA from blood samples from 34 common swifts and 44 pallid swifts from Italy, and 45 alpine swifts from Switzerland. We also screened 20 ectoparasitic louse flies present on 20 birds and identified them by both morphological features and cytochrome oxidase subunit 1 (COI) barcodes. Our results provide no evidence of haemosporidian infection in the 123 swifts tested or in the two louse fly species we identified. Our findings are consistent with available knowledge showing no haemosporidian occurrence in WP swift species and that the most likely infection route for these highly aerial species (via louse fly ectoparasites during nesting) is unlikely.

Drink safely: common swifts (Apus apus) dissipate mechanical energy to decrease flight speed before touch-and-go drinking.

Flight is an efficient way of transport over a unit of distance, but it can be very costly over each unit of time, and reducing flight energy expenditure is a major selective pressure in birds. The common swift (Apus apus) is one of the most aerial bird species, performing most behaviours in flight: foraging, sleeping and also drinking by regularly descending to various waterbodies and skimming over the surface. An energy-saving way to perform such touch-and-go drinking would be to strive to conserve mechanical energy, by transforming potential energy to kinetic energy during the gliding descent, touching water at high speed, and regaining height with minimal muscular work. Using 3D optical tracking, we recorded 163 swift drinking trajectories, over three waterbodies near Rennes, France. Contrary to the energy conservation hypothesis, we show that swifts approaching a waterbody with a higher mechanical energy (higher height and/or speed 5 s before contact) do not reach the water at higher speeds, but do brake, i.e. dissipate mechanical energy to lose both height and speed. Braking seems to be linked with sharp turns and the use of headwind to some extent, but finer turns and postural adjustments, beyond the resolving power of our tracking data, could also be involved. We hypothesize that this surprisingly costly behaviour results from a trade-off between energy expenditure and safety, because approaching a water surface requires fine motor control, and high speed increases the risk of falling into the water, which would have serious energetic and survival costs for a swift.

Impact of cold and wet weather on Common Swifts Apus apus (with comments)

This note describes the effects of a cold and wet weather event on the Common Swifts Apus apus.

No "carry-over" effects of tracking devices on return rate and parameters determining reproductive success in once and repeatedly tagged common swifts (Apus apus), a long-distance migratory bird.

To understand life-history strategies in migratory bird species, we should focus on migration behaviour and possible carry-over effects on both population and individual level. Tracking devices are useful tools to directly investigate migration behaviour. With increased use of tracking devices, questions arise towards animal welfare and possible negative effects of logger on birds. Several studies were conducted to address this question in birds that were tagged and tracked for one complete non-breeding season including migration but with mixed results. To detect individual-based decisions regarding migration strategy, we need to track the same individuals several times. So far, there are no studies investigating effects of repeatedly tagging on reproduction and life-history traits in individual migratory birds, especially in small birds. We used long-term data of 85 tagged common swifts (Apus apus), a long-distance migratory bird, of a breeding colony in Germany to test whether carrying a geolocator or GPS logger once or repeatedly during non-breeding season affected return rate, apparent survival, and parameters determining reproductive success. Additionally, we checked for individual differences in arrival date and breeding parameters when the same individuals were tagged and when they were not tagged in different years. Further, we calculated the individual repeatability in arrival at the breeding colony and date of egg laying in repeatedly tagged swifts. Once and repeatedly tagged birds returned to the colony at a similar rate as non-logger birds and arrived earlier than non-logger birds. We found no effect of logger-type on return rate in logger birds. We detected no differences in apparent survival, time lag to clutch initiation, date of clutch initiation, clutch size, number of chicks and fledglings between logger and non-logger birds. We found neither an effect of loggers nor of logger-types on the arrival date and breeding parameter on individual-level. Arrival date was highly repeatableand date of clutch initiation was moderately repeatable within repeatedly tagged individuals.

Demography of Common Swifts (Apus apus) breeding in the UK associated with local weather but not aphid biomass

In common with many other insectivorous birds, the Common Swift Apus apus is undergoing population declines, with an estimated 57% reduction in abundance between 1995 and 2017 in the UK. The ultimate drivers of this decline are poorly understood but links have been drawn to reductions in the abundance and availability of insect prey, as well as loss of nesting sites. The aim of this study is to improve understanding of the demographic and environmental drivers of Swift decline in Great Britain, with a particular focus on weather and aphid biomass. We explore spatio‐temporal trends in the biomass of aphids, an important source of food for these aerial feeders, from a network of 17 suction‐traps, each 12.2 m in length. We then use data from national nest recording and ringing schemes to describe temporal trends in, and covariates of, Swift breeding success and annual survival. Demographic data are sparse prior to the mid‐1990s but show stable adult survival, a reduction in first‐year survival and an increase in nest failure rate since the mid‐1970s. Despite marked declines in aphid biomass across much of southern and eastern England during this period, we find no association between aphid biomass and Swift demography. Weather was a stronger correlate of variation in Swift demography, with increased precipitation associated with smaller brood size, higher nest failure rate and lower first‐year survival. Our data suggest that falling first‐year survival, partly linked to wetter summers, may be the most likely demographic driver of population decline. Given that the only convincing correlates of Swift demography were weather‐related, we suggest it would be precautionary for conservation efforts to continue to focus on ensuring that safe and productive nesting sites are in sufficient supply. Further research to identify habitats and land management practices which provide foraging resources, particularly during periods of inclement weather, is required, and future demographic modelling exercises would benefit from increased nest recording and ringing efforts.

The leading-edge vortex over a swift-like high-aspect-ratio wing with nonlinear swept-back geometry

The leading-edge vortex (LEV) is a common flow structure that forms over wings at high angles of attack. Over the years, LEVs were exploited for augmenting the lift of man-made slender delta wings aircraft. However, recent observations suggested that natural flyers with high-aspect-ratio (high-AR) wings, such as the common swift (Apus apus), can also generate LEVs while gliding. We hypothesize that the planform shape and nonlinear sweep (increasing towards the wingtip) enable the formation and control of such LEVs. In this paper, we investigate whether a stationary LEV can form over a nonlinear swept-back high-AR wing inspired by the swift’s wing shape and evaluate its characteristics and potential aerodynamic benefit. Particle image velocimetry (PIV) measurements were performed in a water flume on a high-AR swept-back wing inspired by the swift wing. Experiments were performed at four spanwise sections and a range of angles of attack for a chord-based Reynolds number of . Stationary LEV structures were identified across the wingspan by utilizing the proper orthogonal decomposition (POD) method for angles of attack of 5∘–15∘. The size and circulation of the stationary LEV were found to grow towards the wingtip in a nonlinear manner due to shear layer feeding and spanwise transport of mass and vorticity within the LEV, thus confirming that nonlinear high-AR swept-back wings can generate stationary LEVs. Our results suggest that the common swift can generate stationary LEVs over its swept-back wings to glide slower and at a higher rate of descent, with the LEVs potentially supporting up to 60% of its weight.

A 30,000-km journey by Apus apus pekinensis tracks arid lands between northern China and south-western Africa

BackgroundAs a widely distributed and aerial migratory bird, the Common Swift (Apus apus) flies over a wide geographic range in Eurasia and Africa during migration. Although some studies have revealed the migration routes and phenology of European populations, A. a. apus (from hereon the nominate apus), the route used by its East Asian counterpart A. a. pekinensis (from hereon pekinensis) remained a mystery.MethodsUsing light level geolocators, we studied the migration of adult pekinensis breeding in Beijing from 2014 to 2018, and analysed full annual tracks obtained from 25 individuals. In addition, we used the mean monthly precipitation to assess the seasonal variations in humidity for the distribution ranges of the nominate apus and pekinensis. This environmental variable is considered to be critically relevant to their migratory phenology and food resource abundance.ResultsOur results show that the swifts perform a round-trip journey of ca 30,000 km each year, representing a detour of 26% in autumn and 15% in spring compared to the shortest route between the breeding site in Beijing and wintering areas in semi-arid south-western Africa. Compared to the nominate apus, pekinensis experiences drier conditions for longer periods of time. Remarkably, individuals from our study population tracked arid habitat along the entire migration corridor leading from a breeding site in Beijing to at least central Africa. In Africa, they explored more arid habitats during non-breeding than the nominate apus.ConclusionsThe migration route followed by pekinensis breeding in Beijing might suggest an adaptation to semi-arid habitat and dry climatic zones during non-breeding periods, and provides a piece of correlative evidence indicating the historical range expansion of the subspecies. This study highlights that the Common Swift may prove invaluable as a model species for studies of migration route formation and population divergence.

House Sparrows (Passer domesticus) do not make good neighbours: Interspecific clutch destruction of Common Swifts (Apus apus)

Abstract Following extensive renovation of urban areas of central Israel, and in the framework of a research project of supplying nest-boxes for urban breeding birds, especially Common Swifts Apus apus, we documented interspecific nest destruction by House Sparrows Passer domesticus. In two separate incidents the House Sparrows entered the nest chamber of the swifts and removed the eggs by puncturing them. In one, the incident occurred early enough in the breeding season and allowed the Common Swift pair to renest and successfully fledge two young.

Cryptic hybridization between Common (Apus apus) and Pallid (A. pallidus) Swifts

Artificial structures, and particularly in urban settings, attract species showing similar ecological niches and provide nest‐sites for cavity‐breeding species. It is, however, unknown whether this proximity creates opportunities for hybridization and gene flow across related species. We investigated whether two colonial species, the Common Swift Apus apus and the Pallid Swift Apus pallidus, are experiencing gene flow by genotyping individuals that breed in sympatry in the town of Bastia (Corsica, France). We compared them with individuals sampled in colonies where a single species is breeding, in the Mediterranean region and in Switzerland. Our results provided evidence of gene flow between the two species and showed that introgression was not limited to sympatric urban colonies. Gene flow was asymmetrical, with more Pallid Swifts than Common Swifts showing evidence of mixed ancestry. Several individuals were assessed as late‐generation hybrids, suggesting that introgression between the two species was associated with their range expansion since the Last Glacial Maximum. However, we also identified individuals that exhibit the characteristics of recent‐generation hybrids, particularly in Bastia. This result suggests that hybridization between the two species is an ongoing and underestimated phenomenon, with a single observation of a mixed pair in the literature, and may be favoured by close proximity in urban colonies.