National and regional patterns of habitat association with foraging Barn Swallows Hirundo rustica in the UK

Capsule Barn Swallows showed a consistent association with cattle across the UK, but certain landscape features, particularly mixed field types and tall trees, were also important.

Aim To provide nationally representative data on habitat selection in foraging Barn Swallows.

Method Observers carried out four timed point counts within an allocated 2-km square(s). Point counts were at least 500 m apart and considered as independent sample points. Each point count covered 100 m radius and was visited twice during the summer. An index of foraging activity was derived from the number of foraging passes made by Barn Swallows within ten minutes. The maximum count of Swallows present was also recorded. Habitat data included the presence or absence of landscape features and buildings and the proportion of area covered by particular crop and boundary types within the 100 m count radius.

Results Cattle were the single most important and most consistent variable associated with foraging Barn Swallows, in every UK region. Horses were also important in the southeast. Grassland was only important if livestock were present. Foraging pass rates were higher where count circles contained a mixture of grass and arable fields rather than just one or the other. There was a general positive relationship between foraging pass rates and the presence of tall trees in boundaries, and this was significant in the arable eastern region of the UK, where their relative importance of concentrating prey may be more acute.

Conclusion Historical changes in the distribution and availability of habitat features associated with foraging Barn Swallows are consistent with regional differences in population change for this species in the UK. These patterns of association are discussed in terms of changes in land use, the widespread loss of mixed farming and simplifications to landscape complexity.     

Partitioning the effects of livestock farming on the diet of an aerial insectivorous passerine,the Barn Swallow Hirundo rustica

Capsule The presence of farm animals increases the amount of larger insect prey (mainly large Diptera and Coleoptera) and decreases the proportion of smaller prey (Hymenoptera).

Aims To determine the relationships between presence of farm animals and diversity of diet of nestling Barn Swallows from 52 colonies located at sites with and without livestock.

Methods Diet was determined on the basis of faecal analysis. We used two approaches to quantify livestock based on their spatial distribution – a breeding site-focused approach and a village-focused approach.

Results Our results show a relationship between the presence of livestock and the size, number and composition of insect prey detected in the diet of nestling Barn Swallows. The results from the two approaches we used in our study were broadly consistent, although effects varied according to the number and types of animal being raised. The presence of domestic animals increases the amount of larger prey (mainly larger Diptera and Coleoptera) and decreases the proportion of smaller prey (Hymenoptera species). The effect of individual livestock species, mainly pigs and poultry alone, was considerably higher than the effects of pooling livestock species from Principal Component Analysis.

Conclusion Our results imply that Barn Swallows were foraging beyond the immediate area of the farm buildings in which they nest, suggest considerable adaptability in the species' diet and further emphasize the ecological role that livestock play in providing a source of prey of a required size rather specific identity. Furthermore, a statistically significant positive effect of average mass of prey (which is a direct consequence of the presence of cattle at a breeding site) on colony size suggests that livestock farming provides a more profitable prey community, which may ultimately increase local populations of Barn Swallow.     

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

Capsule: 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.     

Leaving on migration: estimating departure dates of Barn Swallows Hirundo rustica from summer roosts using a capture–mark–recapture approach

Capsule Capture–mark–recapture data can be used to predict departure dates of Barn Swallows Hirundo rustica from summer roosts.

Aims To investigate how long Barn Swallows remain at their breeding grounds before migration by estimating departure dates.

Methods A capture–mark–recapture approach was applied to an extensive data set (65?303 ringed and 710 recaptured birds) from two summer roosts. Multiple-day constancy models were used to estimate apparent survival, which was subsequently translated to residence time.

Results The longest intervals between ringing and recapturing were between 66 and 67 days; estimated mean minimum durations were between 16.3 and 18.5 days. Apparent survival was high over most of the summer, indicating that there is little emigration during this period and was followed by a sharp departure-related decline in late August and September. Expected residence time, derived from apparent survival estimates, declined linearly from about 80 days in early July to less than 10 days in September. Estimated departure dates were highly consistent between years and occurred in late September.

Conclusions Barn Swallows stay much longer at post-breeding roost sites than is necessary to build up their fat reserves for migration. We suggest that the birds are likely to derive a number of benefits from such a prolonged stay that are not directly related to preparation for migration; for example, minimizing predation risk by foraging in familiar areas, and gathering information on the quality of future breeding sites.     

EFFECTS OF A HAEMATOPHAGOUS MITE ON THE BARN SWALLOW (HIRUNDO RUSTICA): A TEST OF THE HAMILTON AND ZUK HYPOTHESIS

I tested three assumptions of the Hamilton and Zuk hypothesis (1982), which suggests that the extravagant male plumage of many bird species allows females to choose mates that are resistant to the parasites exploiting the host population at a given time. By choosing such males as mates, females will rear offspring carrying the genes for resistance. I tested three necessary conditions for the Hamilton and Zuk model: (1) whether parasites affect the fitness of their hosts; (2) whether there is heritable variation in parasite resistance, and (3) whether the expression of the sexual ornament varies with parasite burden. The haematophagous mite Ornithonyssus bursa (Macronyssidae, Gamasida) sucks blood from their Barn Swallow (Hirundo rustica) hosts. Experimental manipulation of mite loads and partial cross-fostering experiments on Barn Swallows, where half of the nestlings in the brood were exchanged with nestlings from another nest, shows that parasite burdens and origin, but not rearing conditions, of Bam Swallow nestlings, affected their adult tarsus length and maximum body weight shortly before fledging. Mite loads of adult Barn Swallows at spring arrival were more similar to mite loads of their own offspring, whether reared in their own or in foster nests inoculated with mites, than to loads of foster offspring. Parent Barn Swallows with long tail ornaments had offspring with smaller mite loads in the partial cross-fostering experiments. The amount of increase in male tail ornaments from one year to another was negatively related to experimentally manipulated mite loads of Barn Swallow nests during the preceding breeding season. In conclusion, the three assumptions of the hypothesis were supported by the experimental tests.     

A new species of parasitic mites of the genus Syringophiloidus Kethley 1970 (Acari: Syringophilidae) from the barn swallow Hirundo rustica Linnaeus, 1758

A new quill mite species Syringophiloidus hirundinis (Acari: Syringophilidae) is described from the Barn Swallow Hirundo rustica. The species Syringophiloidus hirundinis had a prevalence of 17.1% in the two outermost tail feathers (N = 208 adult Barn Swallows) during the breeding season of the Barn Swallow host. Intensity of infestation was 9.7 adult mites per pair of infested tail feathers. The sex ratio was highly biased towards females, with only 7.5% of all individuals being males (20:3).     

大杜鹃对家燕的巢寄生

了解杜鹃(Cuculus spp.)对不同宿主鸟类的巢寄生,是研究杜鹃与其宿主之间协同进化的重要基础资料。大杜鹃(Cuculus canorus)和家燕(Hirundo rustica)分布遍及全国,且为同域分布,但两者之间的寄生现象尚未有过系统调查。2012年和2014年4~8月,对繁殖于吉林市昌邑区桦皮厂镇(34°58′44.18″N,126°13′26.83″E,海拔184 m)和海南岛的家燕种群进行调查,结果表明,吉林市昌邑区桦皮厂镇家燕种群的寄生率为2.4%(1/42),而在海南岛所调查的1 719个家燕巢未发现杜鹃寄生现象。同时在网络上搜集家燕巢寄生的报道案例,共记录到13巢家燕被大杜鹃寄生繁殖,均发生在北方的家燕种群。     

Breeding ecology of Yellow Wagtails Motacilla flava in an arable landscape dominated by autumn-sown crops

Capsule Yellow Wagtails successfully raised two consecutive broods in landscapes dominated by autumn-sown crops and did not require spring crops or fallow plots for later nesting.

Aims To assess whether arable landscapes dominated by winter cropping provide habitats that allow Yellow Wagtails to raise two successful broods. To assess the utility of spring cultivated agri-environment fallow plots as a nesting and foraging habitat for Yellow Wagtails.

Methods Nesting success and foraging behaviour of Yellow Wagtails was monitored on lowland arable farmland dominated by winter cropping during two successive breeding seasons.

Results Yellow Wagtails successfully raised first and second broods mainly in winter cereals, with later nests being more successful. Some nests were initiated in bean fields where egg-stage failure rates were high, probably as a consequence of depredation. Fallow plots were not used for nesting but, along with other areas of sparse vegetation, were regularly used for foraging.

Conclusions Yellow Wagtails breeding at relatively low densities achieved high rates of reproductive success in a landscape dominated by winter cereals and with few spring-sown crops. This study suggests that spring-sown crops may not be necessary for Yellow Wagtails to rear two successful broods each summer within arable landscapes.     

Habitat associations and breeding success of the Chaffinch Fringilla coelebs

Capsule Population trends for Chaffinch on farmland are unlikely to be explained by their preference for non-crop habitats alone.

Aims To investigate the importance of non-cropped habitats for Chaffinch territory distribution, breeding success and foraging habitat selection in Scottish farmland.

Methods Territory distribution, nesting success and foraging behaviour of adults feeding chicks at the nest were recorded and related to habitat composition on two Scottish lowland farms.

Results Higher Chaffinch territory densities were associated with the presence of hedgerows, trees and grass leys, whereas lower densities were found adjacent to winter Barley. Nests were predominantly located in conifer trees and hedgerows. Trees were selected preferentially for foraging. Poor breeding success was detected in nests associated with cereal crops and wider field margins. Farmland in Scotland supported much lower territory densities than in England.

Conclusion Chaffinches rely predominantly on non-cropped habitats for territory establishment, nesting and foraging habitats. Differences in habitat composition between England and Scotland may explain differences in territory densities. However, the Chaffinch's preference for non-crop habitats is unlikely to explain its population trends alone. Immigration from other habitats and/or a decrease in inter-specific competition for resources may also have contributed to the increase in the national farmland Chaffinch population.     

Breeding Barn Swallows Hirundo rustica on organic and conventional arable farms in the Netherlands

Populations of farmland birds are under pressure as a result of agricultural intensification. It has been proposed that less intensive approaches to farming, such as organic farming methods, may halt these population declines. In addition, organic farmers may have a more positive attitude towards nature and the environment which can possibly also have positive effects on the populations of breeding birds. We have compared the attitude of conventional and organic farmers towards the presence of Barn Swallows Hirundo rustica and the abundance of breeding Barn Swallows on organic and conventional arable farms in the Netherlands. We found that the abundance of breeding Barn Swallows did not differ between these two types of farms an that both organic and conventional farmers had a positive attitude towards the presence of Barn Swallows on their farms. Our results show that organic farming does not attract more Barn Swallows. However, agricultural intensification could have resulted in lower breeding success and, consequently, population declines, although there may be other contributory factors as well.     

Diet of nestling Barn Swallows <Emphasis Type="Italic">Hirundo rustica</Emphasis> in rural areas of Poland

Analysis of faecal sacs of nestling Barn Swallows Hirundo rustica from 52 breeding colonies located within fifteen spatially-separated villages in Poland has revealed that the basic component of the diet was Coleoptera (56.1% of all identified prey items), followed by Hymenoptera (24.1%), Diptera (16.1%) and Hemiptera (3.3%). The average mass of all prey items with known weight amounted to 3.40 mg (95% CL, 3.16–3.63 mg; median=0.49 mg) dry weight. Coleopterans associated with dung and manure jointly made up 23.5% of the number and 24.3% of the total biomass of all representatives of the order. Statistically significant negative relationships between the average weight of prey and number of prey found in 52 analyzed breeding sites suggest a particular need for Barn Swallows to find larger-bodied prey rather than to exploit the local abundance of smaller prey. The high percentage of Coleoptera in the diet of nestling Barn Swallows probably results from extensive or traditional farm management based on rules of organic farming in agricultural areas of central Europe, mainly commonly used organic fertilizers, and suggests the importance of these insects as a more easily accessible and larger-bodied prey in comparison to some small Diptera or Hymenoptera. We believe that a large number of randomly collected faecal samples from tens of breeding sites allow us to precisely describe variation in the diet of the Barn Swallow. Our work has great importance for documenting of the food composition of the Barn Swallow in traditional European countrysides, i.e. under environmental and agricultural conditions which, as a result of transformations of the system of farming, ceased to exist in the western and northern part of this continent.     

Nocturnal foraging habitats of French and bluestriped grunts,Haemulon flavolineatum and H. sciurus,at Tobacco Caye,Belize

Synopsis Nocturnal foraging habitats of Haemulon flavolineatum and H. sciurus were investigated in the backreef habitat around Tobacco Caye, Belize. Grunts leave the reef at dusk to forage in the grass beds and sand flats surrounding the reef. The hypothesis that French and bluestriped grunts use separate foraging habitats was examined by following tagged fishes from their diurnal territories or schooling sites to nocturnal foraging grounds. The tag consisted of a small, glowing Cyalume light stick sutured to the dorsal musculature of the fish, next to the first dorsal fin. Surveys of foraging habitats were done to support the tracking study. Large quadrats (225 m²) were set out over the sand flats and grass beds during the day. The numbers of French and bluestriped grunts feeding in each habitat were counted one hour after dark. Foraging French grunts used sand flats, whereas bluestriped grunts usually fed in grass beds. Repeated sightings of two French grunts and one bluestriped grunt in the same individual night-time locations support the hypothesis that nocturnal foraging sites may be used repeatedly by the same individuals.     

The influence of mist and rain on the reproductive success of the Blue Swallow Hirundo atrocaerulea (1995–96)

Evans, S.W. & Bouwman, H. 2000. The influence of mist and rain on the reproductive success of the Blue Swallow Hirundo atrocaerulea. Ostrich 71 (1 & 2): 83–86.

Due to the locality of the Blue Swallow Natural Heritage Site it appears that the birds have no alternative but to forage in the mist. The birds cease foraging as soon as it starts raining. Eight eggs failed to hatch after a week in which rainfall occurred for 60% and mist for 85% of the time. Later in the season a further six eggs failed to hatch after a week in which rainfall occurred for 18% and mist occurred for 65% of the time. The only mortality of two nestling Blue Swallows occurred at the end of a week in which rainfall occurred for 65% and mist was recorded for 85% of the time. At a nest containing three eggs, during the presence of mist (16°C wet/19°C dry) the female Blue Swallow spent a mean of 52 min h^?1 foraging and therefore only a mean of 8 min h^?1 incubating. In the absence of mist (21°C wet/26°C dry) the female Blue Swallow spent a mean of 25 min h^?1 foraging and therefore 35 min h^?1 incubating. Rainfall did not occur during the monitoring of this nest. It appears that the mist greatly reduces the foraging efficiency of the birds and that rainfall duration impacts on the birds by limiting the available foraging time.     

Diet breadth and overlap in three sympatric aerial insectivorous birds at the same location

Capsule We found significant differences in the composition and diversity of diet among House Martins, Barn Swallows and Swifts breeding in the same village in Poland.

Aims To evaluate the character and extent of diversity, specialization and overlap of diet between trophically similar nestlings of three species of aerial feeding birds breeding at the same location and differing considerably in foraging height.

Methods Diet was determined based on faecal analysis. Differences in composition and diversity of diet and food niche overlap were assessed through multivariate analysis of variance (manova), Shannon Diversity Index and the Pianka index. Diet specialization was measured by application of the Berger–Parker index of dominance.

Results manova indicated significant differences in diet composition among all three species. House Martins showed the most diverse diet, Swallows were intermediate and Swifts least diverse. Average body mass of all prey found in the diet of Swifts was nearly three times smaller than in Swallows and two times smaller than in House Martins.

Conclusion Our findings show that these three species consume the same types of insect prey, but they take different proportions, and hence biomass, of the major prey groups. House Martins had the widest niche and greatest overlap.     

Inter-specific nest re-use by Barn Swallows Hirundo rustica

Capsule: Reports of inter-specific nest re-use by Barn Swallows Hirundo rustica in Europe and North America are reviewed. Inter-specific nest re-use was rare but appeared opportunistic, possibly functioning as a time-saving mechanism or as a result of limited nest sites.     

Nest and foraging‐site selection in Yellowhammers Emberiza citrinella: implications for chick provisioning

Capsule Vegetation structure and invertebrate abundance interact to influence both foraging sites and nestling provisioning rate; when invertebrate availability is low, adults may take greater risks to provide food for their young.

Aims To investigate nesting and foraging ecology in a declining farmland bird whose fledging success is influenced by the availability of invertebrate prey suitable for feeding to offspring, and where perceived predation risk during foraging can be mediated by vegetation structure.

Methods Provisioning rates of adult Yellowhammers feeding nestlings were measured at nests on arable farmland. Foraging sites were compared with control sites of both the same and different microhabitats; provisioning rate was related to habitat features of foraging‐sites.

Results Foraging sites had low vegetation density, probably enhancing detection of predators, or high invertebrate abundance at high vegetation density. Parental provisioning rate decreased with increasing vegetation cover at foraging sites with high invertebrate abundance; conversely, where invertebrate abundance was low, provisioning rate increased with increasing vegetation cover.

Conclusions Vegetation structure at foraging sites suggests that a trade‐off between predator detection and prey availability influences foraging site selection in Yellowhammers. Associations between parental provisioning rate and vegetation variables suggest that where invertebrate abundance is high birds increase time spent scanning for predators at higher vegetation densities; however, when prey are scarce, adults may take more risks to provide food for their young.     

Integrating stable isotopes,parasite, and ring‐reencounter data to quantify migratory connectivity—A case study with Barn Swallows breeding in Switzerland,Germany, Sweden,and Finland

Ecosystems around the world are connected by seasonal migration. The migrant animals themselves are influenced by migratory connectivity through effects on the individual and the population level. Measuring migratory connectivity is notoriously difficult due to the simple requirement of data conveying information about the nonbreeding distribution of many individuals from several breeding populations. Explicit integration of data derived from different methods increases the precision and the reliability of parameter estimates. We combine ring‐reencounter, stable isotope, and blood parasite data of Barn Swallows Hirundo rustica in a single integrated model to estimate migratory connectivity for three large scale breeding populations across a latitudinal gradient from Central Europe to Scandinavia. To this end, we integrated a non‐Markovian multistate mark‐recovery model for the ring‐reencounter data with normal and binomial mixture models for the stable isotope and parasite data. The integration of different data sources within a mark‐recapture modeling framework enables the most precise quantification of migratory connectivity on the given broad spatial scale. The results show that northern‐breeding populations and Southern Africa as well as southern‐breeding populations and Western–Central Africa are more strongly connected through Barn Swallow migration than central European breeding populations with any of the African wintering areas. The nonbreeding distribution of Barn Swallows from central European breeding populations seems to be a mixture of those populations breeding further north and south, indicating a migratory divide.     

Temporal and spatial patterns of flight and body feather molt of Bank,Barn, and Cliff swallows in North and South America

Molt is energetically demanding and various molt strategies (i.e., molt series, duration, intensity, timing, and location) have evolved to reduce the negative fitness consequences of this process. As such, molt varies considerably among species. Identifying where and when specific feathers are molted is also crucial to inform species‐specific studies using stable isotope markers to assign individuals to geographical regions where they molt. Using museum specimens, we examined the molt of three species of migratory swallows in the Americas: Bank Swallows (Riparia riparia), Barn Swallows (Hirundo rustica), and Cliff Swallows (Petrochelidon pyrrhonota). All three species have one primary and two secondary molt series. Bank and Cliff swallows had one rectrix molt series, and Barn Swallows molted the outer rectrix (R6) separately from the inner five rectrices (R1‐5). All three species have a relatively long flight feather molt duration (i.e., 140–183 days) and low molt intensity. Barn Swallows initiated flight feather molt in the fall, about 2 months later than Bank and Cliff swallows. Barn Swallows likely delay molt because of constraints associated with double brooding. For all three species, molt started with the primaries and inner secondaries and was closely followed by the rectrices and, finally, the outer secondaries. For those that began and then interrupted molt either in breeding areas or during fall migration, the first feathers molted were predominantly S8 and P1. All three species underwent body molt throughout the year, but most individuals molted their body plumage in wintering areas. We recommend that the most appropriate feathers for stable isotope research examining migratory connectivity and habitat use are either R2‐R4 or S2‐S4.     

Wildflower areas within revitalized agricultural matrices boost small mammal populations but not breeding Barn Owls

Agro-ecosystems have recently experienced dramatic losses of biodiversity due to more intensive production methods. In order to increase species diversity, agri-environment schemes provide subsidies to farmers who devote a fraction of their land to ecological compensation areas (ECAs). Several studies have shown that invertebrate biodiversity is actually higher in ECAs than in nearby intensively cultivated farmland. It remains poorly understood, however, to what extent ECAs also favour vertebrates, such as small mammals and their predators, which would contribute to restoring functional food chains within revitalised agricultural matrices. We studied small mammal populations among eight habitat types—including wildflower areas, a specific ECA in Switzerland—and habitat selection (radiotracking) by the Barn Owl Tyto alba, one of their principal predators. Our prediction was that habitats with higher abundances of small mammals would be more visited by foraging Barn Owls during the period of chicks’ provisioning. Small mammal abundance tended to be higher in wildflower areas than in any other habitat type. Barn Owls, however, preferred to forage in cereal fields and grassland. They avoided all types of crops other than cereals, as well as wildflower areas, which suggests that they do not select their hunting habitat primarily with respect to prey density. Instead of prey abundance, prey accessibility may play a more crucial role: wildflower areas have a dense vegetation cover, which may impede access to prey for foraging owls. The exploitation of wildflower areas by the owls might be enhanced by creating open foraging corridors within or around wildflower areas. Wildflower areas managed in that way might contribute to restore functional links in food webs within agro-ecosystems.