Nest Lining Research Articles

Modeling and tests of nested transmission lines for current adding on a four-stage linear transformer driver.

Linear transformer driver (LTD) technology allows a pulsed-power generator to be transportable due to its salient features in compactness and modular design. To further reduce the footprint of an MA-class pulsed-power generator, nested transmission lines were designed and tested for current adding in a four-stage gas-insulated LTD module. The current adder assembly contained two modules that were charged in opposite polarities. Each module held two LTD cavities that shared a common electrode of the nested transmission line with deionized water insulation. Post-hole convolutes were installed for the aggregation of the output current of different modules. More specifically, numerical simulations were conducted to calculate the nested line inductance, which revealed that the total system inductance was ∼10 nH in the nested geometry. Experimentally, testing on the four-stage LTD prototype showed that the LTD module can deliver a 1.2 MA current peak with a rise time of 140ns to a short circuit load under the charging voltage of ±50kV, which validated the applicability of using nested lines for current adding in an MA-class LTD module.

Who stole my nest? Weaver nests used as nest lining

Birds stealing nest material from a neighbour’s nest is well known, but stealing entire nests is less well known. This has been reported nine times for raptors and waterbirds taking the domed nests of weaverbirds. Three waterbird species and five raptor species are involved. Nests of four weaver species were identified. Three records were from Kwa-Zulu Natal in South Africa, and the rest from elsewhere in Africa. Weaver nests included green nests, but most were old nests, and at least one occupied nest (with eggs). Since green nests were not the norm, the weaver nests were probably taken as a source of plant material, rather than for any specific benefit relating to weaver nests.

Insulation of Common Chaffinch Fringilla coelebs Nests is Largely Driven by Animal-Derived Materials in the Cup Lining

Incubation of eggs and nestlings is energetically costly and may be affected by the amount of thermal insulation the surrounding nest provides. In many small passerine species, animal-derived materials, i.e., feathers and hair, are often used in the nest lining where, presumably, their lower thermal conductance offers better insulation. A previous study that involved partial deconstruction of thrush nests revealed that different parts of the nest confer different levels of insulation. The present study examined the insulatory values of Common Chaffinch Fringilla coelebs nests because of the high proportion of animal-derived materials in their cup lining but not the outer nest. Insulatory values and cooling rates of temperature loggers inside the cup were determined for whole nests and then only the cup lining. There were no significant relationships between nest measurements and measures of thermal insulation. However, removal of the outer nest wall reduced the insulatory value by around 10% despite the cup lining being less than half the thickness of the complete nest wall and the cup lining being only a third of the total nest mass. Differential placement of animal-derived materials within the cup lining of Common Chaffinch nests means that the birds seem to be able to confer a high level of insulation without expending too much energy searching for a large mass of particular nest materials.

Lining the nest with more feathers increases offspring recruitment probability: Selection on an extended phenotype in the blue tit.

Birds, among various other taxa, construct nests. Nests form an extended phenotype of the individual building it. Nests are used to extend control over the conditions in which offspring develop, and are therefore commonly considered to be shaped by selection. Nevertheless, scarcely any scientific evidence exist that nest composition is under selection. Here, we demonstrate with data from over 400 blue tit (Cyanistes caeruleus) nests collected over 8 years that a higher proportion of feathers in the nest lining is positively associated with the probability of offspring to recruit as a breeding adult later in life. Strikingly, the extended phenotype (nest) was associated stronger with recruitment probability than phenotypic traits that have typically been considered important in selection (laying date, and female size and condition). Our findings suggest that the choice of nest material could be a maternal behavior with potential lifelong effects on her offspring.

Nest ornaments and feather composition form an extended phenotype syndrome in a wild bird

Many species throughout the animal kingdom construct nests for reproduction. A nest is an extended phenotype—a non-bodily attribute—of the individual building it. In some bird species, including our study population of blue tits (Cyanistes caeruleus), conspicuous feathers or other material are placed on top of the nest. These so-called nest ornaments do not contribute to nest insulation, but are hypothesised to have a signalling function. Here, we apply the concept of behavioural syndromes, with focus on between-individual variation (repeatability) and between-individual correlations, to the study of avian nest construction. We find that nest ornamentation is a moderately repeatable trait in female blue tits, which suggests it is an extended phenotype of the female. Furthermore, the tendency to ornament the nest covaries across females with another aspect of her extended phenotype, the composition of the nest lining material, and these two traits thus form an extended phenotype syndrome. Assuming the correlation is reflected on a genetic level, it implies that nest ornamentation and composition of the nest lining do not evolve in isolation; one aspect may be an evolutionary by-product of selection on the other aspect and their overall flexibility to respond to change is reduced.Significance statementThe avian nest is an extended phenotype (a non-bodily attribute) of its builder with potentially multiple functions in terms of insulation and signalling. In particular, many bird species’ nests contain nest ornaments, feathers or other materials that are placed on top of the nest and that stand out from the nest material due to their colour and/or size. We quantified between-individual variation (repeatability) of nest ornamentation behaviour in a wild population of blue tits and between-individual covariation (syndrome) of nest ornamentation to other features of nest construction. We find that nest ornamentation is a repeatable trait limited to females in our study population. The tendency to ornament the nest covaries across females with another aspect of her extended nest phenotype, the composition of the nest lining material. These correlated traits thus form an extended phenotype syndrome. It hence becomes crucial to recognise that a study of a single aspect of nest construction in isolation captures only a part of the complexity, as one aspect may have evolved as a correlated response of selection on the other aspect. Moreover, such a syndrome implies limited flexibility in the range of adaptive response.

Great variability in nest lining size: support for thermoregulation but not for anti-predatory adaptation hypothesis

Nest lining is a key component in nests of many bird species. Among ground-nesting birds with open nests, it usually consists of dry sticks and stalks creating a thermoregulatory insulating layer for the eggs. However, a bigger nest lining can attract predators and increase nest mortality. The factors influencing behavioural plasticity in birds facing the trade-off between nest lining thermoregulation and conspicuousness for predators have remained poorly understood. The Northern Lapwing Vanellus vanellus, a visibly incubating shorebird with an active nest defence against potential predators, demonstrates great variability in the size of nest lining and, at the same time, is subject to a high frequency of nest predation. We analysed the variability of nest-lining size across time and space in 915 measurements of 601 lapwing nests in South Bohemia, Czech Republic, during 2010–2015. We show that lapwing nests placed closer to small water pools with generally cooler microclimates had bigger nest lining. The size of nest linings also reflected the availability of nest lining material in the vicinity of the nest. On the other hand, there was no effect of nest position within the breeding association and distance to the nearest perch as a possible stand for predators on nest lining size. Furthermore, nest lining size did not predict nest predation rate. Our findings suggest that lapwings adjust the size of their nest lining to local microclimate conditions rather than potential predation risk which is in concordance with the thermoregulation hypothesis of the nest size in birds.

Increased egg–nest visual contrast does not induce egg ejection in the eastern phoebe (Sayornis phoebe), an accepter host of the brood parasitic brown-headed cowbird (Molothrus ater).

Hosts of obligate brood parasitic birds can offset the costs of parasitism by rejecting foreign eggs. Like the vast majority of brown-headed cowbird (Molothrus ater) hosts, the eastern phoebe (Sayornis phoebe) paradoxically incurs substantial fitness costs by accepting cowbird parasitism. We investigated whether acceptance of brown-headed cowbird eggs may be mediated via lack of recognition due to crypsis in eastern phoebe nests, and whether egg-rejection behavior could be induced by manipulating egg-nest visual contrast as a means of facilitating parasitic egg detection in an artificial parasitism experiment. We found that brown-headed cowbird eggs have significantly lower achromatic, but not chromatic, visual contrast against the natural nest lining relative to phoebe eggs, suggesting that cowbird eggs may be cryptic in the low ambient light environments of natural or artificial covered ledges where eastern phoebes tend to nest. We also found that despite successfully increasing egg-nest visual contrast in our treatment, eastern phoebes did not reject model parasitic eggs. Our findings are consistent with previous work showing that increased egg-nest visual contrasts do not increase parasitic egg discriminability and rejection in hosts of avian brood parasites. Because sensory modeling showed that eastern phoebes were predicted to be able to visually perceive natural and experimental parasitism events, these hosts are suggested to lack the cognitive flexibility necessary to reject dissimilar eggs in their nests. Future work should determine whether this and other accepter species can be made to reject parasitism by using a more diverse array of artificial egg stimuli. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Stimulus Preceding Negativity in Trauma Survivors to Negatively Valenced Pictures

Parasite populations are never evenly distributed among the hosts they infect. Avian nest ectoparasites, such as mites, are no exception, as their distribution across the landscape is highly aggregated. It remains unclear if this pattern is driven by differences in transmission events alone, or if the environment that parasites inhabit after transmission also plays a role. Here, we experimentally examined the influence of the post-transmission microclimate, nest characteristics, and host condition on ectoparasite population growth in a bird-ectoparasite system. We infested barn swallow (Hirundo rustica erythrogaster) nests with a standardized number of Northern Fowl Mites (Ornithonyssus sylvarium) and analyzed both biotic (nestling mass, wing length, number of other arthropods present in the nest, and brood size) and abiotic (temperature, humidity, nest lining, nest dimensions, and substrate upon which the nest was built) predictors of mite population growth. Our results suggest that mite populations were most successful, in terms of growth, in nests with higher temperatures, lower humidity, few other arthropods, and hosts in good condition. We also found that nests built on wooden substrates support larger populations of mites than those constructed on metal or concrete. These findings lend insight into the factors that drive large-scale patterns of ectoparasite distributions.

Microclimate and host body condition influence mite population growth in a wild bird-ectoparasite system.

Parasite populations are never evenly distributed among the hosts they infect. Avian nest ectoparasites, such as mites, are no exception, as their distribution across the landscape is highly aggregated. It remains unclear if this pattern is driven by differences in transmission events alone, or if the environment that parasites inhabit after transmission also plays a role. Here, we experimentally examined the influence of the post-transmission microclimate, nest characteristics, and host condition on ectoparasite population growth in a bird-ectoparasite system. We infested barn swallow (Hirundo rustica erythrogaster) nests with a standardized number of Northern Fowl Mites (Ornithonyssus sylvarium) and analyzed both biotic (nestling mass, wing length, number of other arthropods present in the nest, and brood size) and abiotic (temperature, humidity, nest lining, nest dimensions, and substrate upon which the nest was built) predictors of mite population growth. Our results suggest that mite populations were most successful, in terms of growth, in nests with higher temperatures, lower humidity, few other arthropods, and hosts in good condition. We also found that nests built on wooden substrates support larger populations of mites than those constructed on metal or concrete. These findings lend insight into the factors that drive large-scale patterns of ectoparasite distributions.

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.

Arrival date and microorganisms in barn swallows

Migration between breeding sites and winter quarters constitute a major life history strategy in birds. The benefits of such migrations must at least equal the costs for such behavior to evolve and be maintained. We tested whether there was a relationship between abundance and diversity of microorganisms on nest lining feathers and timing of arrival by barn swallows Hirundo rustica. Nest lining feathers are chosen and transported by adult barn swallows to their nests just before and during egg laying, at a time when barn swallows have arrived weeks earlier, implying that any heterogeneity in abundance and diversity of microorganisms on feathers in nests must arise from feather preferences. There was a negative relationship between arrival date and the total number of fledglings showing that early arrival is advantageous. The arrival date of adult barn swallows was significantly positively correlated with the abundance of specific bacteria (Bacillus licheniformis) and positively correlated with the abundance of the fungus Trichoderma reesei and negatively correlated with the abundance of the fungus Mucor circinelloides. Moreover, we found a significant positive relationship between arrival date and mean total number of bacterial colonies in TSA medium. There was a significant negative relationship between arrival date and mean total number of bacterial colonies in FMA medium, and Simpson's diversity index of the abundance of bacteria in FMA medium. Such heterogeneity may arise from some microorganisms being beneficial, others detrimental and yet others benign and of no significant importance. In contrast, there was no significant relationship between arrival date and age of individuals. These findings are consistent with the hypothesis that early arriving barn swallows differ in abundance and diversity of microorganisms from late arriving conspecifics, and that they choose feathers for their nests that differ in terms of microorganisms from those chosen by late arrival individuals.

Substrate and structure of ground nests have fitness consequences for an alpine songbird

Songbird nests are an important life‐history component with multiple functions, including the creation of a suitable microclimate for offspring development. Thus, functional nest characteristics may influence fitness correlates, such as nestling size traits, and may co‐vary with prevailing environmental conditions. We investigated among‐ and within‐female variation in nest substrate, lining and decoration structures with associated fitness consequences (hatching success, nestling size traits, nest survival) across two breeding seasons for an alpine population of Horned Lark Eremophila alpestris. We combined these observations with explicit measures of nest temperature to address the influence of nest characteristics on microclimate. Nests in heather substrate had the coldest microclimates compared with grass and bare‐ground substrate, but also the greatest nest survival rates (68% versus 37–44% in other substrates), indicating the potential for substrate use decisions to reflect a trade‐off between microclimate and nest survival in response to prevailing weather and predation risk conditions. Furthermore, nest lining and nest decoration patterns indicated some support for a thermoregulatory function. Nests that were lined with willow (Salix sp.) seed‐down were associated with larger, heavier nestlings and the use of down lining decreased in frequency as the season warmed up. Nest decoration placed in front of the nest (e.g. stones or dirt clumps varying in mass from 5.3 to 186.6 g) was positively associated with warmer nest microclimates. Females demonstrated high phenotypic flexibility, as 61–94% of the observed variance in nest characteristics was explained by within‐female rather than among‐female differences. Such flexible nesting behaviour suggests the capacity to adjust to changing environmental conditions to maintain vital fitness correlates such as nest survival and nestling size development.

The Nest and Eggs of the Rufous Mourner (Rhytipterna h. holerythra)

ABSTRACT We provide the first description of nest architecture and composition, adult construction behavior, and egg characteristics for the genus Rhytipterna. We provide these data for a nest of the Rufous Mourner (Rhytipterna h. holerythra) found under construction and followed through clutch completion and subsequent failure at La Selva Biological Station, Heredia, Costa Rica. Given the historically labile taxonomic placement of the genus Rhytipterna, our observations provide important additional lines of evidence further supporting its affinity to Myiarchus within the Tyrannidae. We highlight our record of the incorporation of shed reptile skins in the nest lining, only the second instance of this nest character within Tyrannidae outside of the genus Myiarchus. The phylogenetic distribution of this specialized nesting trait suggests the possibility of a single origin near the base of the subclade Tyranninae. Received 29 August 2016. Accepted 30 November 2016.

An experimental demonstration that house finches add cigarette butts in response to ectoparasites

Urban species encounter resources that are uncommon in nature, such as materials found in city waste. Many studies have shown that these can be harmful to wildlife. In Mexico City, house finches bring cigarette butts to their nests, which reduces the amount of ectoparasites, but also induces genotoxic damage in chicks and parents. Yet, the reason for this behaviour is unknown. One possibility is that birds extract the cellulose fibres from discarded butts simply because they resemble feathers. Alternatively, disassembled cigarette butts may be brought to the nests because they repel ectoparasites. Here we tested the latter hypothesis by assessing whether house finches Carpodacus mexicanus increase the amount of cigarette butts in their nests in response to a raise in ectoparasite load. When present, fibres from butts are concentrated in the nest lining. By taking it away, we simultaneously removed most of the butt material and collected the bulk of the tick population infesting each nest, as these parasites cluster in the lining. We removed the bedding of nests when chicks had recently hatched, and randomly assigned each nests to one of the following treatments: 1) addition of live ticks, 2) addition of dead ticks and 3) simulation of tick addition. Females in the live ticks’ treatment added more butt fibres to their nests than parents in control treatments. Additionally, the amount of butt fibres in the original lining also predicted the amount of fibres added after the manipulation. It seems that the tendency to bring to the nest cigarette butts is at least partially a response to current, and perhaps also past, parasite load.

Extreme use of feathers for nest construction by the Chilean Swallow (Tachycineta leucopyga) in the sub-Antarctic forests of southern Chile

Nesting birds commonly incorporate feathers into nest linings given their insulation properties. Although use of feathers is common among swallows, here we provide the first recording of nests built almost completely with feathers (57–60% of total nests mass), by the Chilean Swallow (Tachycineta leucopyga) in southern Chile. Low temperatures or a high availability of feathers near the nesting sites could have elicited this response in the breeding birds, but further observations are needed to determine the frequency of the extreme use of feathers in this species, and the proximate causes promoting such behavior.

Mammal hair in nests of four cavity-nesting songbirds: occurrence, diversity and seasonality

ABSTRACTCapsule: The diversity of mammal hair found in nest linings varied between bird species and with season.Aims: We examined mammal species composition in the guard hair material of four cavity-nesting songbirds, focusing on their numbers and occurrence, nest predation and seasonality.Methods: We surveyed 219 nests of four cavity-nesting songbirds breeding in a Central European woodland and identified hairs from 28 mammal species.Results: Roe Deer Capreolus capreolus hair was the most commonly used hair type in the nests of all four songbird species. This was especially the case in Blue Tit Cyanistes caeruleus nests, which may suggest a preference for Roe Deer hair. The greatest diversity of hairs was found in the nests of Great Tits Parus major, while the lowest was found in the Collared Flycatcher Ficedula albicollis. In flycatchers, 59% of females used only plant material for nest construction. Interestingly, we found a strong seasonal effect in hair use. Flycatcher nests that were initiated early in the season were more likely to contain mammal hair than those initiated later in the season. Similar, albeit weaker, negative seasonal effect was detected in Great and Blue Tit nests. There were no significant effects of any potential anti-predatory functions of mammalian hair in nests.Conclusion: Our study showed a clear prevalence of Roe Deer in the hair material of all bird species and certain preferences of birds for particular mammal species. When the aim is to detect a wide range of mammal species, for example, during biodiversity surveys, we advise to consider sampling effort and to focus on early breeding birds.

Effects of Nest Characteristics on Reproductive Performance in Blue TitsCyanistes Caeruleusand Great TitsParus major

A major function of birds’ nests is to protect eggs and offspring against temperature fluctuations. Reproductive performance was found to be closely related to nest characteristics in some species. We present results concerning nest attributes and their impact on breeding characteristics in Blue Tits ( Cyanistes caeruleus) and Great Tits ( Parus major) in central Poland over a three year period, 2012-2014, in an urban parkland and a deciduous forest. In Blue Tits, hatching success was positively affected by the nest lining mass. Clutch size was associated with the lining mass and nest mass, and the number of hatchlings was associated with both the nest mass and lining mass. In Great Tits, hatching success was positively affected by the lining mass and fledging success was positively affected by the nest depth and nest mass. Also, clutch size tended to be related to the nest depth and the number of hatchlings was associated with the lining mass. We found that Blue Tit nests were deeper and heavier than Great Tit nests. There were no differences in nest depth and nest mass between two habitats for both tit species. We conclude that there is a relationship between better quality nests and better breeding performance in both Great Tits and Blue Tits.

Experimental shifts in egg–nest contrasts do not alter egg rejection responses in an avian host–brood parasite system

Obligate brood parasitic birds exploit their hosts to provide care for unrelated young in the nest. Potential hosts can reduce the cost of parasitism by rejecting foreign eggs from the nest. Observational, comparative, and experimental studies have concluded that most hosts use the coloration and patterning of eggshells to discriminate between own and foreign eggs in the nest. However, an alternative hypothesis is that birds use the colour contrasts between eggshells and the nest lining to identify parasitic eggs (egg-nest contrast hypothesis). In support of this hypothesis, we found that the avian perceivable chromatic contrasts between dyed eggs and unmanipulated nest linings significantly and negatively covaried with the rejection rates of different dyed eggs of the great reed warbler Acrocephalus arundinaceus, a frequently parasitized host of the common cuckoo Cuculus canorus. To experimentally test whether egg-nest contrasts influence rejection, we reciprocally dyed both eggs and the nest lining of this host species with one of two colours: orange and green. Contrary to the egg-nest contrast hypothesis, host rejection patterns in response to dyed eggs were not altered by dyeing nests, relative to unmanipulated control eggs and nests. In turn, experimental egg colour was the only significant predictor of egg rejection rate. Our results demonstrate that egg-nest contrast is a collateral, not a causal factor in egg rejection, and confirm the conclusions of previous studies that hosts can rely on the parasitic egg's appearance itself to recognize the foreign egg in the nest.

The role of egg-nest contrast in the rejection of brood parasitic eggs

Hosts of avian brood parasites can avoid the reproductive costs of raising genetically unrelated offspring by rejecting parasitic eggs. The perceptual cues and controls mediating parasitic egg discrimination and ejection are well studied: hosts are thought to use differences in egg color, brightness, maculation, size and shape to discriminate between their own and foreign eggs. Most theories of brood parasitism implicitly assume that the primary criteria to which hosts attend when discriminating eggs are differences between the eggs themselves. However, this assumption is confounded by the degree to which chromatic and achromatic characteristics of the nest lining co-vary with egg coloration, so that egg-nest contrast per se might be the recognition cue driving parasitic egg detection. Here, we systematically tested whether and how egg-nest contrast itself contributes to foreign egg discrimination. In an artificial parasitism experiment, we independently manipulated egg color and nest lining color of the egg-ejector American robin (Turdus migratorius), a host of the obligate brood parasitic brown-headed cowbird (Molothrus ater). We hypothesized that the degree of contrast between foreign eggs and the nest background would affect host egg rejection behavior. We predicted that experimentally decreasing egg-nest chromatic and achromatic contrast (i.e. rendering parasitic eggs more cryptic against the nest lining) would decrease rejection rates, while increasing egg-nest contrast would increase rejection rates. In contrast to our predictions, egg-nest contrast was not a significant predictor of egg ejection patterns. Instead, egg color significantly predicted responses to parasitism. We conclude that egg-egg differences are the primary drivers of egg rejection in this system. Future studies should test for the effects of egg-nest contrast per se in predicting parasitic egg recognition in other host-parasite systems, including those hosts building enclosed nests and those parasites laying cryptic eggs, as an alternative to hypothesized effects of egg-egg contrast.

Applying the multilayer level set approach to explore the thermal surface characteristics of hot mix asphalt

The surface temperature of hot mix asphalt (HMA) in the field is an important indicator of whether it is under the appropriate conditions for installation and satisfies the installation specifications. Traditionally, field engineers examine the temperature of HMA by employing a metal thermometer, penetrating the HMA at random locations to measure the temperature. However, a non-contact thermal infrared camera effectively provides a reasonable correlation between the surface temperature readings and the internal mat temperature. In this paper, an image segmentation method is proposed and employed to analyze collected thermal images of HMA in order to extract the surface temperature information without contacting the HMA. Based on the minimization of energy, the multilayer level set approach implicitly presents the regional boundaries as several nested level lines. The segmented results can be used to extract the temperature information in order to establish the relationships between the recorded temperature and time. These relationships can be utilized to monitor the cool-down phenomena of HMA to control the quality of HMA installation.