Nest Material Research Articles

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.

Early experience alters developmental trajectory of central oxytocin systems involved in hypothalamic-pituitary-adrenal axis regulation in Long-Evans rats

Oxytocin is important for postnatal developmental experiences for mothers, infants, and transactions between them. Oxytocin is also implicated in adult affiliative behaviors, including social buffering of stress. There is evidence for connections between early life experience and adult oxytocin system functioning, but effects of early experience on behavioral, endocrine, and neurophysiological outcomes related to adult social buffering are not well explored. We use a limited bedding and nesting (LBN) material paradigm as an environmental disruption of early experiences and assessed central oxytocin systems in brain regions related to hypothalamic-pituitary-adrenal (HPA) axis regulation (paraventricular nucleus of the hypothalamus, amygdala, hippocampus). We also assessed developmentally-appropriate social behaviors and HPA reactivity during social buffering testing in adulthood. LBN litters had larger huddles and more pups visible compared to control litters during the first two weeks of life. LBN also altered the developmental trajectory of oxytocin-expressing cells and oxytocin receptor cells, with increases in oxytocin receptor cells at P15 in LBN pups. By adulthood, LBN females had more and LBN males had fewer oxytocin and oxytocin receptor cells in these areas compared to sex-matched controls. Adult LBN females, but not LBN males, had behavioral changes during social interaction and social buffering testing. The sex-specific effects of early experience on central oxytocin systems and social behavior may contribute to female resilience to early life adversity.

A comparative study of the fauna associated with nest mounds of native and introduced populations of the red wood ant Formica paralugubris

In the second half of the twentieth century, many red wood ant populations were transferred from the Alps to the Apennines as biological control agents. Since the introduction involved the relocation of entire nest mounds, it is presumable that the associated fauna was also relocated. While the introduction of these ants has raised several concerns about their ecological impact, there has been no attempt to investigate the introduction of other nest-associated species. In this study, we collected samples of soil and nest material from three populations of the red wood ant Formica paralugubris, one Alpine native and two imported into the Apennines. We aimed to confirm that nest mounds are hotspots for soil fauna, detect the occurrence of new myrmecophilous species, and compare the nest-associated fauna among sites, to test the hypothesis of mass species relocation. We focused our analyses mainly on two taxa, springtails and oribatid mites, two highly representative groups of the mesofauna inhabiting nest mounds. The results showed higher richness and diversity in nests than soil for oribatids but not for springtails. We found 17 myrmecophilous oribatid species, but only two springtail species. Finally, native and imported sites shared only a few oribatid and springtail species, suggesting that massive relocation did not occur with nest transplants or it was likely limited. Additionally, we found some species never before collected in Italy.

Effects of Chemical and Auditory Cues of Hoopoes (Upupa epops) in Repellence and Attraction of Blood-Feeding Flies

Research on the mechanisms involved in host location by parasites is of paramount importance and may aid in developing protective measures against them. This topic attains far-reaching repercussions for human and animal welfare regarding parasites transmitting vector-borne pathogens, such as blood-feeding flies. Very few studies have evaluated the effect of bird-derived cues on attraction of vectors in field conditions. We here explored the attraction of different groups of blood-feeding flies (mosquitoes, blackflies and biting midges) to auditory cues produced by begging hoopoe (Upupa epops) nestlings, and to three chemical cues derived from hoopoe nestlings or nests (uropygial secretion, symbiotic bacteria isolated from the secretion, and nest material) in the field. We deployed insect traps baited with the different stimuli at the beginning and at the end of the hoopoe breeding-season in four different habitats. Abundance of blood-feeding flies varied depending on habitat and sampling period. Begging auditory cues of nestling hoopoes did not affect abundance of flies. However, chemical stimuli affected abundance of mosquitoes, which were less abundant in traps baited with bacteria or with nest material than in control traps. Abundance of biting midges in traps also depended on the chemical stimulus but in interaction with sampling period or habitat. Fewer biting midges were collected in traps baited with bacteria and with secretion in the habitats where abundance of biting midges is higher. Our results suggest that uropygial secretion of hoopoes, and symbiotic bacteria living in this secretion, may repel blood-feeding flies from their nests.

Nest-type associated microclimatic conditions as potential drivers of ectoparasite infestations in African penguin nests.

Nest design and characteristics can influence the microclimatic conditions in the nest. Nest-dwelling ectoparasites are sensitive to temperature and moisture and as such the conditions in the nest can influence parasite infestations. The endangered African penguin (Spheniscus demersus) breeds in different nest types and as yet little is known with regard to the microclimate and parasite infestation within these nests. This study characterized the microclimatic conditions in natural open, natural covered (with vegetation) and artificial nests, and assessed the relationship between nest characteristics (type, age, distance from the coast, orientation and entrance opening) and in-nest ectoparasite infestations and the health of African penguins in Stony Point, South Africa. Penguins (50 adults and 192 chicks) and their nests (n = 308) were sampled in 2016 and 2017. Soil temperature was higher in artificial than in natural nests, and soil and nest material moisture was lower in artificial and natural covered nests than natural open. Ectoparasite infestations were higher under warmer and drier conditions, in artificial nests and nests near the coastline. Penguin (adult and chick) body mass and chick body condition were lower in warmer nests and total plasma protein (in adults and checks) was lower in drier nests. Given the potential adverse effects of ectoparasites on host species, it is recommended that conservation agencies implement a monitoring programme to assess the ectoparasite infestation in artificial nests across multiple colonies. This information will facilitate a more holistic penguin conservation management plan that may prevent further detrimental effects on this endangered penguin species.

Autoclaving Nest-Material Remains Influences the Probability of Ectoparasitism of Nestling Hoopoes (Upupa epops).

Simple SummaryMicroorganisms may have direct negative effects on their animal hosts and cause diseases, but some others provide animals with protection against infections, parasites, and even predators. However, parasites or predators might take their cue from odors produced by bacteria, even those from protecting microorganisms, which could turn net benefits of bacteria that are a priori considered beneficial into a neutral or even negative outcome. This possibility has scarcely been studied in wildlife populations; we manipulated the bacterial community of nest-material of hoopoes and detected a negative effect in terms of the intensity of parasitism by blood-sucking flies that nestlings suffer. We also detected a positive link between the bacterial density of the nest-materials and the intensity of ectoparasitism, which further points at the importance of the bacteria determining the level of parasitism. Blood-sucking ectoparasites are also disease vectors, affecting both humans and livestock, and considering the role of the bacterial environment might help to establish new transmission control protocols.Nest bacterial environment influences avian reproduction directly because it might include pathogenic- or antibiotic-producing bacteria or indirectly because predators or ectoparasites can use volatile compounds from nest bacterial metabolism to detect nests of their avian hosts. Hoopoes (Upupa epops) do not build nests. They rather reuse holes or nest-boxes that contain remains of nest-materials from previous breeding seasons. Interestingly, it has been recently described that the nest’s bacterial environment partly affects the uropygial gland microbiota of hoopoe females and eggshells. Blood-sucking ectoparasites use chemical cues to find host nests, so we experimentally tested the hypothetical effects of microorganisms inhabiting nest-material remains before reproduction regarding the intensity of ectoparasitism suffered by 8-day-old nestling hoopoes. In accordance with the hypothesis, nestlings hatched in nest-boxes with autoclaved nest-material remains from the previous reproductive seasons suffered less from ectoparasites than those hatched in the control nest-boxes with nonautoclaved nest-material. Moreover, we found a positive association between the bacterial density of nest-material during the nestling phase and ectoparasitism intensity that was only apparent in nest-boxes with autoclaved nest-material. However, contrary to our expectations, nest bacterial load was positively associated with fledgling success. These results suggest a link between the community of microorganisms of nest-material remains and the intensity of ectoparasitism, and, on the other hand, that the nest bacterial environment during reproduction is related to fledging success. Here, we discuss possible mechanisms explaining the experimental and correlative results, including the possibility that the experimental autoclaving of nest material affected the microbiota of females and nestlings’ secretion and/or nest volatiles that attracted ectoparasites, therefore indirectly affecting both the nest bacterial environment at the nestling stage and fledging success.

Consequences of Climate Change-Induced Habitat Conversions on Red Wood Ants in a Central European Mountain: A Case Study.

Simple SummaryThe red wood ants are considered to be one of the main ecosystem engineers and keystone species of the habitats in which they exist. Most of the species from this species group inhabit coniferous forests, which, due to the consequences of anthropogenic climate change, are continuously cut down. Therefore, the main habitat of these important species is rapidly disappearing. We investigated the consequences of the absence of conifers (clear-cut area and deciduous forest) on one of the members of this species group, namely Formica polyctena. We have found that compared with the mixed-coniferous forest stand, the absence of coniferous species resulted in significant changes in the colony and nest structure of F. polyctena. In addition, the colony size was also smaller in these sites. These changes suggest that although F. polyctena is able to survive in suboptimal habitats, still their population decline is expected and urges conservation managers to apply necessary action plans for their protection.The consequences of anthropogenic climate change are one of the major concerns of conservation biology. A cascade of negative effects is expected to affect various ecosystems, one of which is Central European coniferous forests and their unique biota. These coniferous forests are the primary habitat of many forest specialist species such as red wood ants. Climate change-induced rising of temperature allows trees to skip winter hibernation, making them more vulnerable to storms that cause wind felling, and in turn, promotes bark beetle infestations that results in unscheduled clear-cuttings. Red wood ants can also be exposed to such habitat changes. We investigated the effects of bark beetle-induced clear-cutting and the absence of coniferous trees on colonies of Formica polyctena, including a mixed-coniferous forest as a reference. Our aim was to investigate how these habitat features affect the nest characteristics and nesting habits of F. polyctena. Our results indicate that, in the absence of conifers, F. polyctena tend to use different alternatives for nest material, colony structure, and food sources. However, the vitality of F. polyctena colonies significantly decreased (smaller nest mound volumes). Our study highlights the ecological flexibility of this forest specialist and its potential to survive under extreme conditions.

Red-legged cormorant uses plastic as nest material in an artificial breeding colony of Atacama Desert coast

Plastic debris affects the survival of numerous marine species such as seabirds. Several studies have report ingestion and entanglement of seabird species in plastic debris but just few describe plastic presence in nests. Here we report the first evidence of a novel artificial nesting colony of red-legged cormorant (Phalacrocorax gaimardi) using plastic as nesting material in two major seaport structures in Northern Chile. We sampled 18 abandoned nests and determined that overall nests contained plastic: industrial polypropylene bulk bags (35%), plastic bags (33%) and fishing gear (10%). Plastic types differ among seaports, ENAEX (National Company of Explosives) seaport located near the main city contained plastic bags as predominant material while GNL (Liquid Natural Gas Company) seaport located near the industrial area contained bulkbag fibers. Further research should analyze debris in beaches nearby the nesting colony in order to assess whether red-legged cormorants have any plastic preference or if they use the most available in the nature.

A parasite reduction conservation intervention does not improve fledging success or most condition metrics for Purple Martins

AbstractEastern Purple Martins (Progne subis subis) have an unusually close relationship with humans, as they nest exclusively in man-made nest boxes. Current conservation policy directly promotes further interaction with this species by advocating regular replacement of nest materials during the nestling phase to reduce ectoparasite load and increase nestling fitness. We conducted the first test of the efficacy of this recommendation and found that it was partially effective in reducing parasite abundance, but had no effect on nestling fledging success, body mass, leukocyte count, or triglyceride or uric acid concentration. We found a small but significant increase in nestling hematocrit associated with nest material replacement, implying that parasites may induce nestling anemia. Contrary to our expectations, we also found elevated heterophil/lymphocyte ratios in nestlings with replacements, possibly indicating elevated physiological stress associated with nest replacements. Based on our results, we do not recommend nest material replacements to combat routine parasite infestations.

First report of Newly Identified Ornithodoros Species in the Republic of Korea.

Ticks and tick-borne diseases are important issues worldwide because of their effects on animal and human health. The genus Ornithodoros, which is included in the family Argasidae, is typically associated with wild animals, including seabirds. In this study, samples from the nests of seabirds and surrounding soil were collected to investigate Ornithodoros spp. from 9 uninhabited islands in the western, eastern, and southern parts of Korea from April 2017 to October 2018. The islands are known as the breeding places of migratory and resident birds. Ticks were collected from soil and nest material of seabirds using a Tullgren funnel and identified using 16S rRNA and the cytochrome c oxidase 1 gene (COI), and host animals of soft ticks were identified using the mitochondrial DNA cytochrome b gene by a polymerase chain reaction. In the sequence identity of the 16S rRNA gene fragment of Ornithodoros sp., Ornithodoros sawaii was identified as the closest homologous sequence, and the new Ornithodoros sp. was newly identified. We found that the newly identified Ornithodoros sp. in the Republic of Korea was located in uninhabited islands used as breeding places by the black-tailed gull, Larus crassirostris.

Exploring the Genetic Background of the Differences in Nest-Building Behavior in European Rabbit.

Simple SummaryThe rabbit is one of the genetically most diverse farm animals, where domestication has resulted in a change primarily in the genes responsible for behavior. The elements of intensive production technology (e.g., nursing, change of nest material) can have a significant effect on maternal behavior. Its individual variability is evident in the timing of nest building and nest composition. As a result that the hormone progesterone strongly influences the steps of nest building, we investigated the association of genetic mutations in the progesterone receptor gene with nest-building behavior in wild-type rabbit does. In addition to the already described point mutations in domesticated lines, we detected a new mutation in our wild type rabbits. However, the timing of nest building (hay carrying) was related to an already described point mutation. The heritability of this trait was low, but it confirms the genetic determination of the behavior besides the environmental factors. One of the genotypes was responsible for the two days earlier initiation of the hay carrying behavior. The early initiation of this process allows animals to construct a high-quality nest resulting in better survival of the offsprings in nature.Once a day, nursing and absentee mothering make the wild rabbit (Oryctolagus cuniculus) an ideal model animal for measuring differences in maternal behavior. Behavioral events and their hormonal regulation leading to parturition are well documented; however, the genetic background behind individual differences in this complex process is unknown. Decreased progesterone hormone level and the reduction of progesterone receptor activity are crucial to initiating the collection of nest material. The progesterone receptor gene is a likely candidate affecting nest-building behavior. In addition to several known point mutations in the progesterone receptor gene of the European wild rabbit, we have found a new mutation in the promoter region of the gene at 2682 T > C. Although this new single nucleotide polymorphism (SNP) was not involved in the formation of the nest-building behavior, an SNP (2464G > A) already described in the promoter region showed an association with individual differences in the initiation of hay carrying. The distribution of this SNP delivered an opposite result compared to domestic rabbits. Genotype (GG) with high uterine capacity was most frequent; the hereditary value of the trait was h2 = 0.10. Thus, progesterone receptor gene polymorphism may manifest in individual differences affecting breeding success in this species.

ЗООТЕХНИЧЕСКИЕ ПОКАЗАТЕЛИ ПОДСТИЛОЧНОГО МАТЕРИАЛА ИЗ ХВОЙНОЙ ДРЕВЕСНОЙ СТРУЖКИ

At present, poultry farms are faced with the urgent task of choosing high-quality nesting material to provide floor birds with a soft, dry and warm bed. This is usually done by covering the floor of the house with a nesting material that changes at the end of the growing cycle or as it becomes dirty and wet. The introduction of industrial technologies for growing poultry in agriculture, characterized by a high intensity of poultry production, makes increased demands on the nesting materials functional properties. We have conducted a study and made an analysis of the main zootechnical requirements of coniferous wood chips for nesting materials: mass fraction of moisture, maximum moisture capacity, thermal conductivity coefficient, and dust formation indicators. Three samples of coniferous wood chips with dimensions of 5-40 mm, 2-5 mm, and 0.5- 1.5 mm were selected for the study at the “OOO Omega enterprise”, Mari El Republic, on the basis of which optimal samples were determined as a nesting material, both for industrial livestock and domestic animals. According to the data obtained as a result of research, coniferous wood chips will reduce unsanitary conditions of keeping animals and birds, and will also facilitate the fight against pathogens of infectious and invasive diseases.

Notes on the Distribution and The Lekking and Nesting Behaviors of the Mexican Hermit (Phaethornis mexicanus griseoventer) in West-Central Mexico

The Mexican Hermit (Phaethornis mexicanus) is endemic to west-central Mexico, with 2 recognized subspecies, P. mexicanus mexicanus and P. mexicanus griseoventer. This hummingbird forms leks, where males are territory holders and females visit them to choose a mate. Only the female provides parental care to the progeny. We observed P. mexicanus griseoventer leks over different breeding seasons at 3 sites in the understory of tropical dry forest and subtropical moist lowland forests. The displays of males consisted of monosyllabic calls from perched individuals and, when a female appeared nearby, slow-speed tail movements and hover flying in front of that female. The females visited the leks and moved around, perching in the territories of different males. In addition, we monitored one nest from egg-laying to fledging of the young in Hacienda Las Tres Carmelitas. We also characterized the nest site and the materials used in nest construction. For 20 d in July and August, the female incubated 2 eggs and hatched 2 chicks. The young left the nest 31 d after hatching. We inferred that the Mexican Hermit moves between the cloud forest (790 m asl) and the pine-oak forest (1080 m asl) to obtain nest material and food. Our observations of lekking and nesting behavior suggest that breeding in P. m. griseoventer extends from February (leks) to at least mid-October (nesting).

Substrates for the Production of Passiflora setácea cv. BRS Pérola do Cerrado Seedlings

ABSTRACT The substrate is essential to ensure suitable conditions for the growth of Passiflora setacea seedlings. Thus, a study was conducted to investigate the effect of alternative substrates formulated with bee nest and termite mound materials on the growth of P. setacea cv. BRS Pérola do Cerrado seedlings. Six substrate combinations formulated from different proportions (v:v) of bee nest material (BNM) and termite mound material (TMM) or commercial substrate were tested considering the randomized block design with four replicates. The following substrates were used: S1 = BNM100%; S2 = BNM75% + TMM25%; S3 = BNM50% + TMM50%; S4 = BNM25% + TMM75%; S5 = TMM100%; and S6 = commercial substrate (Click Mudas®). The plant height, stem diameter, root length, root dry matter (RDM), shoot dry matter (SDM), total dry matter (TDM), and morphological indices were measured. Passiflora setacea seedlings have better development with the use of substrates S1, S2, and S3, with greater emphasis on the substrate S1. The substrate S1 (100% BNM) should be recommended for the production of P. setacea cv. BRS Pérola do Cerrado seedlings, for improving plant development and providing higher quality seedlings.

Incorporation of anthropogenic debris into double-crested cormorant nests, Toronto, Ontario

Prior research suggested using double-crested cormorants (Phalacrocorax auritus) as an indicator species to track anthropogenic debris in inland aquatic environments such as the Great Lakes. In this study, we sampled cormorant nests on the ground (n = 50) for the presence and type of debris at the Leslie Street Spit, a human built peninsula in Toronto, Ontario. We also compared the proportion of debris type to the Great Canadian Shoreline Cleanup data (2011–2018) for this site. All of the nests sampled had anthropogenic debris present, including plastic items, metal bars and clothing (average ± SD: 28.7 ± 22.0 g debris per nest). Out of four broad categories of debris type (plastic, building materials, miscellaneous and mixed materials), plastic had the highest proportion for nests (53.6%) and shoreline cleanup (63.9%), though plastic type differed. Nests (32.4%) had proportionally more building materials specific to the site, such as electrical wires compared to the shoreline cleanup data (4.7%). Because the Leslie Street Spit is a human-constructed site and cormorants accessed local construction material for their nests, the site should not be used to track changes in debris over time. We recommend that other ground-nesting colonies be used to: monitor changes in debris type and quantity; determine the proportion of nest material from terrestrial and aquatic environments; and estimate the distance cormorants will travel to gather nest material.

Habitat Selection of Skylarks During the Breeding Season on the Volcanic Slope of Mt. Tarumae

The Eurasian Skylark, Alauda arvensis, is a passerine bird that mainly breeds in open habitats, such as lowland grasslands and farmlands. However, recent studies have shown that they form breeding territories on volcanic and alpine slopes in central/northern Japan. During the 2018 breeding season, we investigated the density and habitat selection of Skylarks on the volcanic slopes above timber line, of Mt. Tarumae, Hokkaido. Our results showed that there were 27 Skylark territories in the study area, with a density of 7.26 territories per square kilometer. This spatial arrangement was dense around the eastern slope. Skylarks favored habitats with a low vegetation height. The quantity of short plant species, i.e. Carex oxyandra and Arcterica nana was larger in territories than in randomly selected points. C. oxyandra plays important roles not only in forming low vegetation, but also in available and limited nest material in their breeding territories on the volcanic slopes. These results suggest that Skylarks occupy areas of low vegetation with C. oxyandra, as there are limited resources available for nest materials within the breeding territories that are on the volcanic slope above a timber line.

Neural Circuits Underlying Nest Building in Male Zebra Finches.

Nest building consists of a series of motor actions, which are concomitant with activity in regions of the anterior motor pathway, the social behavior network, and the reward circuity in nest building adult male zebra finches (Taeniopygia guttata). It is not clear, however, whether this activity is due to nest building, collection, and/or manipulation of nest material. To identify which areas of the brain are specifically involved, we used immunohistochemistry to quantify the immediate early gene c-Fos in male zebra finches that were nest building (Building), birds given a nest box but could interact only with tied down nest material (Fixed), and birds that were not given a nest box or nest material (Control). We investigated the following brain regions: the anterior motor pathway (anterior ventral mesopallium [AMV], AN, anterior striatum [ASt]), areas of the social behavior network (bed nucleus of the stria terminalis, dorsomedial subdivision [BSTmd], lateral septum [LS]), the dopaminergic reward circuitry (ventral tegmental area), and the cerebellum. We found that there was greater Fos immunoreactivity expression in the BSTmd, LS, and AMV with increased material deposition; in LS, AMV ASt, and Folium VI with increased material carrying; in LS, AMV, and ASt with increased nest material tucking; and in LS and all folia (except Folium VIII) with increased tugging at tied down material. These data confirm a functional role for areas of the anterior motor pathway, social behavior network, and the cerebellum in nest material collection and manipulation by birds.

Smaller distance between nest contents and cavity entrance increases risk of ectoparasitism in cavity‐nesting birds

Determining costs associated with nest‐building behaviour and nest characteristics is of prime importance to understand the evolution of such extended phenotypic traits. We explored a cost of nest building experimentally to determine whether large nests attracted more ectoparasites. This cost may be especially important to cavity‐nesting species where larger nests likely reduce the distance between nest contents and the cavity entrance, making the host nest more vulnerable to ectoparasite detection. We manipulated the amount of nest material and the distance between nest and cavity entrance and estimated the abundance of ectoparasites (Carnus hemapterus flies) before and after manipulation in nests of spotless starlings Sturnus unicolor breeding in nest boxes. Nest size was enlarged and elevated in a first group of nests by adding nest material to the base of the nest (enlarged nests); a second group of nests was elevated with a piece of plastic but without adding nest material (elevated nests); a third group of nests was not manipulated (control nests). Number of flies per nest increased significantly in enlarged and elevated nests compared to control nests. Moreover, distance to cavity entrance after manipulation was negatively associated with the increase in the number of flies per nest (i.e. nests closer to the entrance had more parasites). Thus, nest size, through its effect on distance between nest and cavity entrance, affected fly abundance. Cues produced by nest contents located closer to the cavity entrance may be detected more readily by ectoparasitic flies searching for hosts. These results suggest a novel constraint for the evolution of nest size in cavity‐nesting birds.

Gaps and Runs in Nest Cavity Occupancy: Cavity “Destroyers” and “Cleaners” Affect Reuse by Secondary Cavity Nesting Vertebrates

Many animals require tree cavities for breeding and these sites may be reused by a diversity of secondary nesters over a timespan of decades. It is unknown whether the reuse of holes changes their desirability as nest sites. We hypothesized that some species, cavity degraded the quality of holes by filling them with coarse nest material or waste whereas other species, cavity cleaners, might prolong the use of a hole by removing debris or enlarging the hole. Using data gathered during 22 years from a field study in central British Colombia, we analyzed long-term patterns of occupancy in relation to their sequential use by bird and mammal species, grouped by traits. Patterns of occupancy were variable with 49% of 875 large-sized holes (excavated by northern flickers Colaptes auratus and pileated woodpeckers Dryocopus pileatus) and 19% of 672 smaller-sized holes incorporating runs of sequential use that lasted up to 18 years. But 11-25% of cavities also had gaps of 3-13 years between occupancies. Mammals, raptors and European starlings, consistent with the hypothesis they were destroyers, occupied cavities as terminal users and before gaps more often than expected by chance. The pattern of occupancy by northern flickers was random in relation to gaps or prior use by other species so, although flickers did not target old holes to clean, neither did they avoid them. Small cavities that were renovated by flickers into larger cavities had double the reuse rate. Runs of occupancy that involved only cavity-destroying species were shorter than runs that involved periodic use by flickers, suggesting the woodpecker, through its cleaning and renovation, prolonged the use of such holes.

Characterization of anthropogenic materials on yellow-legged gull (Larus michahellis) nests breeding in natural and urban sites along the coast of Portugal.

Anthropogenic materials are a persistent pressure on ecosystems, affecting many species. Seabirds can collect these materials to construct their nests, which may modify nest characteristics and cause entanglement of chicks and adults, with possible consequences on breeding success. The incorporation of anthropogenic materials in nests of seabird species that breed in both natural and urban environments, such as gulls, is poorly known. Here, we characterize and compare anthropogenic materials incorporated in yellow-legged gull (Larus michahellis) nests from two natural and two urban breeding sites across their Portuguese breeding range and during 2 consecutive years. Anthropogenic materials were found in 2.6% and 15.4% of gull nests from natural locations and in 47.6% and 95.7% of nests from urban breeding sites. No differences were found on hatching success between urban and natural breeding colonies. A significantly higher number of anthropogenic materials were found in the largest and more populated urban breeding colony, which on average included items of a greater mass but smaller size than items from the other three colonies. The higher incorporation of anthropogenic materials in urban locations could be a consequence of a lower access to natural nest construction materials and higher availability of anthropogenic debris. The quantity and diversity of anthropogenic materials incorporated in gull nests from urban locations indicate a need for improved debris management in urban settlements.