Avian incubation behaviors respond to the thermal environment, and this is best studied in relation to average thermal conditions. Although climate change models predict increases in environmental thermal variation, how thermal variability shapes incubation behaviors of birds is not as well explored as responses to average conditions. We examined the relationship between nesting behaviors and temperature in Eastern Bluebirds (Sialia sialis) and Tree Swallows (Tachycineta bicolor) and found that they were time dependent. We also found that incubation behaviors respond independently to average temperature and thermal variation. The rate of temperature change and average temperature experienced just prior to an off-bout reduced individual off-bout length in the mornings but not the afternoons. Patterns of incubation at the scale of the incubation period reflected these decision-level patterns, as incubation constancy, or percentage of time spent on the nest, increased with increasing mean temperature and thermal variation. On the daily scale, increasing thermal variation led to increased daily investment in Eastern Bluebirds. Our findings suggest a complex dynamic between behavior and environmental temperature that is shaped by thermal characteristics present as incubation decisions are made and by general thermal patterns experienced over the entire incubation period.

Nest boxes are widely used for Sialia sialis (Eastern Bluebird), yet the influence of box design on occupancy and reproductive success remains contested. We monitored 60 nest boxes in rural south-central Florida to compare 3 common designs constructed from wood and plastic. Bluebirds showed a strong preference for wooden boxes, in contrast to previous findings from urban sites. This discrepancy may reflect differences in prior experience, with urban populations more accustomed to nesting in plastic tubes on buildings, whereas rural populations more often use natural tree cavities and wooden fence posts. Only 2 of 20 plastic boxes were occupied, limiting our ability to evaluate their effects on reproductive performance. Nevertheless, our results align with prior studies indicating that common nest-box materials do not significantly affect reproductive success.

Measuring embryonic development inside the egg can provide useful information for research on the breeding biology of birds. Because embryo heart rate is correlated with oxygen consumption, it provides a way to quantify embryo metabolism as a proxy for development. However, it can be difficult to non-invasively measure embryo heart rate in the field. We used a relatively new technology, the Buddy digital egg monitor, to measure the heart rates of Eastern Bluebird (Sialia sialis) embryos. We wanted to determine how well this machine would work for field studies and to test whether embryo age, external egg temperature, or clutch size were correlated with embryo heart rate. We found that heart rate significantly increased as the age of the embryo increased and as the external temperature of the egg increased. However, there was no relationship between heart rate and clutch size, suggesting that even females with larger clutches are able to maintain their nest temperature at a level that supports embryo development to produce viable young. Although we were able to obtain useful data that addressed our study questions, using this monitor presented some challenges. We frequently could not obtain a heart rate reading when the embryo was moving too much (36% of readings) and sometimes no heart rate was detected (33% of readings), even in eggs that did eventually hatch. Overall, we found that this device has the potential to be useful in a wide variety of field studies, but that researchers should be prepared for an approximately two-thirds decrease in sample size due to unsuccessful measurements, as well as potential bias introduced by the failure to obtain a reading from moving embryos.

Abstract Diet can be an important health factor that links fitness to an individual’s ecology. The gut microbiome responds to diet changes and plays an important role in host physiology. Dietary interventions are known to impact gut microbiome composition, but long-term effects and to what extent these impacts vary among individuals at different life-history stages are unclear. To address this question, we performed a supplemental feeding experiment by providing live mealworms (Tenebrio molitor) to Sialia sialis (Eastern Bluebird) during the chick-rearing period. We produced 16S metabarcoding data to quantify gut microbiome diversity from fecal samples of adults and nestlings collected during our experimental period, and again 1 year later when the individuals returned to breed at the study site. Food supplementation was associated with shifts in gut microbiome composition for adults, but not early (8-day-old) or late stage (15-day-old) nestlings. In particular, one bacterium in the genus Staphylococcus was more abundant in food-supplemented adults. Nestling gut microbiomes were similar among nest mates, and differed between the sexes during early development, but sex differences disappeared before fledging (nest departure). Microbiome richness was higher in female nestlings, but not related to chick maturity. We did not observe any effects of the previous year’s diet treatment among returning breeders. Humans commonly provide mealworms for S. sialis in order to attract them to their property and to help them achieve nutritional requirements. Our results suggest this practice has limited, short-term effects on gut microbiome diversity that differ among individuals of different life-history stages.

Obligate avian brood parasites lay their eggs in other bird species' nests, leaving these hosts to rear the parasitic young. To eliminate or reduce the costs of parasitism, many hosts have evolved the ability to recognize and reject parasitic eggs, and most use eggshell color for recognition; however, color discrimination should be more challenging in the low‐light conditions facing cavity‐nesting hosts. Therefore, we hypothesized that instead of color, cavity‐nesting birds could rely on perceived differences in brightness (i.e. luminance) and on light levels in their nests for egg recognition. Specifically, we expected that rejection rates would be higher when foreign eggs are lighter or darker than the hosts' own eggs or when nest light levels are higher. To investigate this hypothesis, we experimentally altered the luminance of 413 similarly colored (blue) experimental model eggs and added these experimental eggs to the nests of cavity‐nesting eastern bluebirds Sialia sialis that typically lay immaculate blue eggs. Contrary to our expectations, neither the perceived luminance of the eggs nor the amount of light in the nest cavity predicted host responses. Therefore, it is unlikely that bluebirds base their antiparasitic decisions on perceived differences in eggshell luminance. Our work provides a foundation for future studies that can inform us about how cavity‐nesting birds perceive salient visual stimuli in the dim light conditions of their nests.

Eggshell recognition in parental birds is vital for nest management, defense against brood parasitism, optimal embryonic development and minimizing disease and predation risks. This process relies on acceptance thresholds balancing the risk of rejecting own eggs against the benefit of excluding foreign ones, following signal detection theory. We investigated the role of object shape in egg rejection decisions among three host species of the obligate brood parasitic brown-headed cowbird (Molothrus ater), each with a varying known response to parasitic eggs. Following previous studies on the American robin (Turdus migratorius; a robust cowbird-egg rejecter), we presented Eastern bluebirds (Sialia sialis; moderate rejecter) and red-winged blackbirds (Agelaius phoeniceus; an accepter) with 3D-printed blue model eggs varying in width or angularity. To examine the shape-color interaction, we also presented Eastern bluebirds with these series in two colors and maculation: light blue (bluebird mimetic) and white with speckles (more cowbird-like). Both American robins and Eastern bluebirds were less likely to accept blue models as their width decreased. For the blue angularity series, acceptance decreased significantly with increased angularity for the red-winged blackbird, as has been previously seen in the American robin, but not for the Eastern bluebird. For bluebirds with the white-maculated models, these patterns remained but statistical significance reversed: acceptance did not decrease significantly with width, but did decrease significantly with angularity. These results suggest that egg shape variation influences antiparasitic egg rejection behaviors, is modulated by shell color and maculation patterns, and varies among different host species, highlighting the complexity of behavioral defense cues against brood parasitism.

ABSTRACTExposure of avian mothers to stressful conditions permanently alters offspring behavior and physiology. Yet, the effects of maternal stress on the development of offspring immunity in birds remain unclear, particularly in wild species. We injected Eastern bluebird (Sialia sialis) eggs with either a corticosterone or control solution, then measured the impacts on nestling morphology and two measures of immunity, bactericidal capacity and swelling responses to phytohemagglutinin. Nestlings from corticosterone‐treated eggs had lower condition indices at hatch but quickly caught up to their control counterparts by Day 5 posthatch and until fledging. Corticosterone‐exposed nestlings also mounted smaller swelling responses to phytohemagglutinin, whereas there were no effects on bactericidal capacity. These results indicate that maternal stress can impact offspring immunocompetence, fitness prospects, and potentially their ability to fend off parasites and pathogens.

Anthropogenic noise pollution disrupts wildlife behavior, physiology, and demography yet species characterized as urban adapters, such as the Eastern Bluebird (<em>Sialia sialis</em>), willingly breed in urban areas. Hypothesizing that noise levels could disrupt incubation behavior, we examined the effect of (a) chronic traffic and (b) episodic construction noises on nest attendance (males, females) and in-nest incubation behaviors (females) in Eastern Bluebird pairs. We used photos taken at nest boxes placed along an anthropogenic noise gradient on the University of Florida campus to identify key behaviors. Nest boxes were in quiet (< 70dB) or traffic noise-exposed areas (> 70dB) and some boxes in each category received additional intermittent playback of construction noises. We used Chi² tests, Mahalanobis distances, and confusion matrices to ascertain whether treatments distinctly altered a suite of nest attendance behaviors exhibited by pairs. Playback significantly increased the frequency of peeking and poking from the nest hole by females; males spent more time atop nest boxes in traffic noise-exposed sites; and males spent almost no time on quiet boxes exposed to playback. Findings are consistent with current understanding that anthropogenic noise, especially intermittent loud bursts, disrupts incubation stage behaviors in birds, reducing incubation constancy and, in turn, hatching success.

Sialia sialis (Eastern Bluebird), a secondary cavity nester, often nests in anthropogenic structures, particularly nest boxes established throughout its range. We describe 3 observations of Eastern Bluebird nests at 2 photovoltaic (PV) solar facilities in eastern New York. At one facility, we observed an open-cup nest on the PV steel support structure, while at another, we observed 2 nests within structures mimicking cavities. At least 2 nests were likely successful. To our knowledge, these are the first documented occurrences of Eastern Bluebird nests within PV solar facilities in the northeastern US. Although further research is needed to determine if successful nesting in PV solar facilities is widespread, our observations suggest that Eastern Bluebirds can nest successfully within these facilities.

Abstract Extreme cold events, which have become more frequent, can revert the direction of long-term responses to climate change. In 2021, record snowstorms swept the United States, causing wildlife die-offs that may have been associated with rapid natural selection. Our objective was to determine whether the snowstorms caused natural selection in Eastern Bluebirds (Sialia sialis). To test which mechanism most influenced their survival, we measured the morphology and coloration of fatalities and survivors at three sites. Survival was associated with a longer tarsus and with a wider, longer, and deeper beak, in support of the starvation and thermal endurance hypotheses. Additionally, bluebirds with more-ornamented plumage were less likely to have survived, perhaps because of an early energy investment in mate and site acquisition. As bluebirds encounter increasingly warm summer conditions, the longer extremities favored during the snowstorms may continue to be favored through their thermoregulatory benefits. However, the dull plumage coloration favored by natural selection during the snowstorms may be opposed by sexual selection benefits of more-ornamented plumage. Overall, responses to extreme events are difficult to predict from responses to long-term climate change, and responses to one event, such as the 2021 snowstorms, may not predict responses to a future extreme event.

Abstract Grassland bird populations are declining steeply, reflecting the degradation and loss of native grassland habitats. To assess how grazing management affects declining grassland bird populations, we compared breeding avifaunal communities in adaptive multi‐paddock (AMP) grazed and continuously grazed (CG) pastures in the Southeastern United States. AMP grazing involves alternating very short grazing periods at high animal densities with prolonged recovery periods across many small paddocks. Both the AMP and CG paddocks attracted obligate grassland birds during the breeding season; however, AMP‐grazed paddocks supported significantly higher detection of four obligate grassland breeding bird species. We used distance sampling techniques to account for differences in detectability for each species. The resulting densities for the grassland guild and Eastern Meadowlark as a species both revealed significantly higher densities within the AMP versus CG paddocks. Despite significantly more unadjusted detections of confirmed breeding ecotonal species, such as Blue Grosbeak, Eastern Bluebird, Brown Thrasher, Yellow‐breasted Chat, Eastern Towhee, Loggerhead Shrike, and Field Sparrow in AMP versus CG paddocks, no significant difference was found in the ecotonal guild after adjusting densities using effective detection radii. The CG paddocks supported fewer obligate grassland and ecotonal birds, with some exceptions (e.g., higher adjusted density of Eastern Bluebirds in CG) but supported comparable overall bird species richness. AMP grazing practices offer a viable strategy for increasing the diversity and abundance of obligate grassland and ecotonal breeding birds within existing cattle‐grazed landscapes in the Southeastern United States.

ABSTRACTGut microbiota regulate multiple aspects of host health, including metabolism and the development of the immune system. However, we still know relatively little about how the gut microbiota influences host responses to parasitism in wild organisms, particularly whether host‐microbiota interactions contribute to variation in parasitism across host species. The goal of this study was to determine the role of gut microbiota in shaping how birds respond to nest parasites and investigate whether this relationship varies between host species. Both eastern bluebirds (Sialia sialis) and tree swallows (Tachycineta bicolor) are parasitized by blow flies (Protocalliphora sialia), for which larval flies feed on nestlings' blood. We experimentally manipulated the gut microbiota of nestling bluebirds and tree swallows by dosing nestlings with an oral antibiotic or sterile water as a control. We then quantified nestling physiology (haemoglobin, glucose, parasite‐specific IgY antibody levels), body morphometrics, and survival until fledging, as well as blow fly abundance and size. An experimental disruption of nestling gut microbiota increased parasite abundance in tree swallows, but decreased parasite abundance in bluebirds, which suggests that the disruption has opposing effects on resistance across host species. Furthermore, experimental treatment delayed parasite development and had variable effects on nestling body morphometrics and physiology across the two host species. Together, these results suggest that gut microbiota contribute to host differences in resistance to blow flies and can influence host–parasite interactions.

Research Highlight: Knutie, S., Bahouth, R., Bertone, M., Webb, C., Mehta, M., Nahom, M., Barta, R., Ghai, S., Love, A., Horan, S., Soldo, A., Cochrane, E., Bartholomew, J., Cowan, E., Bjerke, H., Balenger, S., Butler, M., Cornell, A., Kennedy, A., Rolland, V., Schultz, E., Stanback, M., Taff, C., Albery, G. (2024). Understanding spatiotemporal effects of food supplementation on host-parasite interactions using community-based science. Journal of Animal Ecology. https://doi.org/10.1111/1365-2656.14155. Wildlife have become increasingly dependent on anthropogenic food supplementation, resulting in altered nutritional intake and inter- and intraspecific interactions. Subsequently, supplemental feeding can affect both the immunological function of individuals and transmission dynamics among individuals and species. The magnitude of the effect supplemental feeding has on disease is likely to vary across time and space with the nutritional demands of hosts. However, the broad temporal or spatial scale effects of supplementation are poorly understood. Recently, Knutie etal. (2024) introduced their citizen science program, the Nest Parasite Community Project, a broadscale coordinated effort by scientists and the public to monitor box nesting wild birds and their ectoparasites across the eastern United States. The authors amassed an impressive 4-year data set with hundreds of nests spanning the entire US breeding range of Eastern bluebirds (Sialia sialis). In the first study to come from the project, the authors demonstrate that the effects of food supplementation on host-parasite interactions vary across time and space and do not consistently influence host-parasite outcomes, highlighting that host-parasite interactions are often context dependent and influenced by many environmental factors (e.g. weather and habitat quality). The authors also found that supplemental feeding increases host fitness, regardless of parasitism. The study provides strong evidence that citizen science projects can help broaden our understanding of how human food sources influence wildlife disease in various environmental contexts.

Structural colors particularly of the angle-independent category stemming from wavelength-dependent light scattering have aroused increasing interest due to their considerable applications spanning displays and sensors to detection. Nevertheless, these colors would be heavily altered and even disappear during practical applications, which is related with the variation of refractive index mismatch by liquid wetting/infiltrating. Inspired by bird feathers, we propose a simple deposition toward the coating with angle-independent structural color and superamphiphobicity. The coating is composed of ∼200 nm-sized channel-type structures between hollow silica and air nanostructures, exhibiting a robust sapphire blue color independent of intense liquid intrusion, which duplicates the characteristics of the back feather of Eastern Bluebird. A high color saturation and superamphiphobicity of the biomimetic coating are optimized by manipulating the coating parameters or adding black substances. Excellent durability under harsh conditions endows the coating with long-term service life in various extreme environments.

Supplemental feeding can increase the overall health of animals but also can have variable effects on how animals defend themselves against parasites. However, the spatiotemporal effects of food supplementation on host-parasite interactions remain poorly understood, likely because large-scale, coordinated efforts to investigate them are difficult. Here, we introduce the Nest Parasite Community Science Project, which is a community-based science project that coordinates studies with bird nest box 'stewards' from the public and scientific community. This project was established to understand broad ecological patterns between hosts and their parasites. The goal of this study was to determine the effect of food supplementation on eastern bluebirds (Sialia sialis) and their nest parasite community across the geographic range of the bluebirds from 2018 to 2021. We received 674 nests from 69 stewards in 26 states in the eastern United States. Nest box stewards reported whether or not they provided mealworms or suet near nesting bluebirds, then they followed the nesting success of the birds (number of eggs laid and hatched, proportion that hatched, number and proportion of nestlings that successfully fledged). We then identified and quantified parasites in the nests. Overall, we found that food supplementation increased fledging success. The most common nest parasite taxon was the parasitic blow fly (Protocalliphora sialia), but a few nests contained fleas (Ceratophyllus idius, C. gallinae and Orchopeas leucopus) and mites (Dermanyssus spp. and Ornithonyssus spp.). Blow flies were primarily found at northern latitudes, where food supplementation affected blow fly prevalence. However, the direction of this effect varied substantially in direction and magnitude across years. More stewards fed bluebirds at southern latitudes than at northern latitudes, which contradicts the findings of other community-based science projects. Overall, food supplementation of birds was associated with increased host fitness but did not appear to play a consistent role in defence against these parasites across all years. Our study demonstrates the importance of coordinated studies across years and locations to understand the effects of environmental heterogeneity, including human-based food supplementation, on host-parasite dynamics.

Abstract Songbirds incidentally ingest soil contaminated with lead and several species in the Southeast Missouri Lead Mining District have a negative relationship between soil lead concentration and reproduction. We used an individual-based model (IBM) to simulate nesting processes throughout the breeding season to estimate annual productivity for 5 songbirds in relation to soil-lead concentration. We modeled daily nest survival and number fledged in relation to soil lead and incorporated these relationships into the IBM using a Bayesian approach that fully captured parameter uncertainty and process variation. The proportion of the posterior distribution for the effect of soil lead on daily nest survival was mostly negative for Pipilo erythrophthalmus (Eastern Towhee), Passerina cyanea (Indigo Bunting), Cardinalis cardinalis (Northern Cardinal), Sialia sialis (Eastern Bluebird; f = 0.972, 0.990, 0.741, 0.581, respectively), and slightly positive for Spizella pusilla (Field Sparrow; f = 0.680). The proportion of the posterior distribution for the effect of soil lead on the number fledged from successful nests was mostly negative for S. pusilla, P. erythrophthalmus, and C. cardinalis (f = 0.867, 0.585, 0.508, respectively) and positive for P. cyanea and S. sialis (f = 0.773, 0.744). Simulated annual productivity decreased by 0.04–1.47 young/female/year among species across the range of soil lead concentrations, with the greatest declines for P. erythrophthalmus and P. cyanea. The probability of fledging one or more young changed from 51% to 15% for P. erythrophthalmus, 57% to 23% for P. cyanea, 60% to 48% for C. cardinalis, 94% to 84% for S. sialis, and 57% to 64% for S. pusilla as soil-lead concentration around a nest increased from 20 to 4,000 ppm. Most nest failures were the result of predation; therefore, we suggest lead may have affected birds’ behavior at the nest, or affected nest site quality, which resulted in higher nest predation.

A significant body of evidence indicates that climate change is influencing many aspects of avian ecology. Yet, how climate change is affecting, and is expected to influence some aspects of the breeding ecology of cavity-nesting birds remains uncertain. To explore the potential linkage between timing of first clutch, and the influence of ambient temperature on hatching success, we used Eastern Bluebird (Sialia sialis) nest records over a nine-year period from Alabama, USA. We investigated changes to annual clutch initiation dates, as well as variability in hatching success associated with ambient air temperatures during the incubation period. Using a simple linear model, we observed earlier annual egg laying dates over the nine years of this study with a difference of 24 days between earliest egg-laying date of the season. Daily temperature minima increased 2 °C across the nine-year time frame of this study. These data also indicate that Eastern Bluebird hatching success was the highest when mean ambient air temperature during incubation was between 19 °C and 24 °C (78%, as opposed to 69% and 68% above and below this temperature range, respectively). Our findings of increasing maxima, earlier maxima each year, and the lower minima of temperatures within our study area could expand the breadth of temperatures experienced by nesting Eastern Bluebirds possibly exposing them to temperatures outside of what promotes nesting success. These findings with a cavity-nesting bird highlight an optimal range of ambient temperatures associated with highest hatching success, conditions likely to be affected by climate change.

Many species of birds incorporate feathers into their cavity nests. The Fear of Feathers Hypothesis proposes that a major benefit of incorporating feathers into cavity nests is to trick other birds into thinking that a predation event occurred in the cavity. Evidence has been provided supporting this hypothesis for cavity-nesting species in three families with very different ecologies: the Tree Swallow (<em>Tachycineta bicolor</em>) of North America and the Pied Flycatcher (<em>Ficedula hypoleuca</em>) and the Blue Tit (<em>Cyanistes caeruleus</em>), both of Eurasia. In 2023, I tested whether the presence of feathers in nest boxes in North Carolina (USA) affected the eventual nest site choice of 3 species of cavity-nesters belonging to different families. Specifically, I added white feathers to 192 (of 388) nest boxes. The remaining 196 nest boxes received wood chips/shavings. If Eastern Bluebirds (<em>Sialia sialis</em>), Carolina Chickadees (<em>Poecile carolinensis</em>), and Tree Swallows are dissuaded more than temporarily by the presence of feathers in potential nest cavities, one would expect to find at least one of two patterns. First, because I positioned nest boxes without feathers within 200 m of nest boxes with feathers, I expected that all 3 species would gravitate toward the nest boxes without feathers, even if they nested successfully the previous year in a box that was assigned to the feather treatment. Second, in the event that most nest boxes ultimately contained nests, I predicted that the first egg date (FED) of nests in nest boxes with feathers to be, on average, later in the spring than the FED of nests in nest boxes without feathers. I hypothesized that such a delay would result from either an initial “fear of feathers” or the earlier breeding of higher quality birds that successfully avoided nest boxes containing feathers. I found neither pattern for bluebirds, chickadees, or Tree Swallows. Although it has been found that the negative effect of feathers was short lived, all things being equal, one would expect one of the above trends to be observed. My results suggest that the addition of feathers to nest cavities does not act in a long-term manner to dissuade or delay breeding by birds living in southeastern North America.

Because plumage coloration is frequently involved in sexual selection, for both male and female mate choice, birds with aberrant plumage should have fewer mating opportunities and thus lower reproductive output. Here we report an Eastern Bluebird (Sialia sialis) female with a brown phenotype that raised a brood of four chicks to fledging. The brown female and her mate were only related to their social offspring to the second degree and one of the offspring was a half-sibling. We propose four family tree scenarios and discuss their implications (e.g., extra-pair paternity, conspecific brood parasitism). Regardless of the tree, the brown female was able to find a mate, which may have been facilitated by the bottleneck created by the severe snowstorms in February 2021.

Noise pollution can degrade the behavioral, physiological, and psychological health of humans and other creatures. We used breeding pairs of Eastern Bluebirds (Sialia sialis) to assess behavioral and reproductive responses to both chronic roadway noise and experimental intermittent playbacks of construction noise. Active nests in boxes placed near and far from large roads were randomly assigned as treatments or controls for experimental playbacks during incubation. Using temperature signatures from iButtons placed within nest cups we quantified certain female incubation behaviors (# and length of bouts, # of small temperature fluctuations, and total warming minutes per day) and hatching success was recorded for 40 nests in spring of 2019. Nests in quiet areas that received no additional playback treatments of construction noise had markedly higher nest success than any exposed to noise. Nests exposed to chronic traffic noise only, and quiet nests that received 3-4 days of construction noise had the lowest hatching success. Females in traffic-quiet nests increased restlessness (small temperature fluctuations) and experienced decreasing hatching success as the number of days of construction noise playback increased. Thus, birds choosing either quiet or noisy boxes had contrasting responses to bouts of construction noise. Other female incubation behaviors we could detect were unaffected by noise but changed in expected ways with seasonal progression. In sum, both types of noise can decrease hatch rate, but with intermittent noise this is likely due to female restlessness, or too many small drops in temperature to maintain optimal embryo development. RÉSUMÉ. La pollution sonore peut avoir un effet négatif sur la santé comportementale, physiologique et psychologique d'humains et d'autres créatures. Nous avons examiné les réactions comportementales et reproductives de couples nicheurs de Merlebleu de l'Est (Sialia sialis) face au bruit routier chronique et à la diffusion intermittente expérimentale de bruits de construction. Des nids actifs dans des nichoirs installés près ou loin de grandes routes ont été assignés au hasard comme traitements ou contrôles pour la diffusion d'enregistrements pendant l'incubation. Au moyen de signatures de température d'iButtons placés dans les coupelles de nids, nous avons quantifié certains comportements d'incubation des femelles (# et durée des épisodes, # de petites fluctuations de température et durée totale d'incubation par jour) et noté le succès d'éclosion de 40 nids au printemps 2019. Les nids situés dans les lieux calmes n'ayant reçu aucune diffusion de bruits de construction ont eu un succès de nidification nettement plus élevé que les nids exposés au bruit. Les nids exposés au bruit routier chronique seulement et les nids calmes mais ayant subi 3-4 jours de diffusion de bruits de construction ont eu le succès d'éclosion le plus faible. Les femelles de nids situés en lieux calmes ont augmenté leur agitation (petites fluctuations de température) et ont connu une diminution du succès d'éclosion au fur et à mesure que le nombre de jours avec diffusion de bruits de construction augmentait. Ainsi, les oiseaux choisissant des nids en lieux calmes ou bruyants ont eu des réactions différentes aux bruits de construction. D'autres comportements d'incubation des femelles que nous avons pu détecter n'ont pas été affectés par le bruit mais ont changé de manière attendue avec la progression saisonnière. En résumé, les deux types de bruits peuvent contribuer à diminuer le taux d'éclosion; dans le cas d'un bruit intermittent, l'agitation des femelles est probablement en cause ou le trop grand nombre de petites baisses de température pour permettre de maintenir un développement embryonnaire optimal.