Clutch Size Research Articles

Light pollution affects activity differentially across breeding stages in an urban exploiter: an experiment in the house sparrow (Passer domesticus)

Artificial Light At Night (ALAN) is a major urban perturbation, which can have detrimental effects on wildlife. Recent urban planning has led to an increased use of white light emission diodes (LEDs) in cities. However, little is known about the effects of this type of ALAN on wild vertebrates, especially during reproduction. We designed an experiment to test the impact of ALAN on the activity rhythms (daily time of first activity (TFA) and time of last activity (TLA)) of captive House sparrows (Passer domesticus) during several reproductive stages (from pre-breeding to post-breeding). We also tested the impact of ALAN on reproductive performance (laying date, clutch size, hatching and fledging success). Experimental birds were active earlier in the morning (earlier TFA) relative to controls although experimental and control birds did not differ in their TLA. The effect of ALAN on TFA was apparent during specific stages only (pre-breeding and chick-rearing stages), suggesting that sparrows actively adjust their activity in response to ALAN only during specific periods. This impact of ALAN on activity did not persist through the whole breeding season, suggesting that sparrows may habituate to ALAN. Alternatively, they may not be able to sustain a long-term increased activity in response to ALAN because of sleep deprivation and related physiological costs. Finally, we did not find any impact of ALAN on the reproductive performance of captive house sparrows held under optimal conditions. This suggests that ALAN may not be dramatically detrimental to the reproduction of this urban exploiter, at least when food availability is not constraining.

Filling latitudinal gaps in Tachycineta swallows: reproductive strategies in a South American species

ABSTRACT Chilean swallows (Tachycineta leucopyga) are the southernmost swallows in the Tachycineta genus, breeding from central Chile to southern Chile and Argentina. Studies focused on a population breeding at 54°S in Tierra del Fuego, revealed differences in life-history traits compared to their Northern Hemisphere congeners, such as smaller clutch size, and greater male nest attendance during the incubation period. To assess the consistency of these patterns for the species, we studied breeding biology and parental care of Chilean swallows in Northwestern Argentine Patagonia (41°S). If austral population breeding traits reflect species traits, we predict smaller clutch size, higher female reproductive investment, and similar nest attendance by both sexes during incubation compared to Tachycineta species breeding at similar Northern Hemisphere latitudes. We also anticipate negative correlation between clutch size, egg size, and breeding success with laying date, as observed in Tachycineta species, including Chilean swallows. Surprisingly, clutch and egg sizes did not differ between northern and southern Patagonian populations. We did not find evidence of a negative relationship between clutch or egg size and laying date. Male nest attendance during incubation was variable and low, but their nestlings feeding rates equalled those of females. These findings suggest that Chilean swallows adopt diverse reproductive strategies across regions. This may help this species adapt to different environments and climates, ranging from the shorter breeding seasons and lower summer mean temperatures of Tierra del Fuego to the longer breeding seasons and higher seasonal and daily thermal amplitudes in continental north Andean Patagonia.

Breeding parameters of a Great Tit (Parus major) population on the island of Cyprus compared to other Mediterranean populations

Many studies on the Great Tit, Parus major, have been conducted within the Mediterranean Basin, especially on its reproductive biology, forest habitat interactions, and nutritional resources. However, to date no detailed scientific research on these issues has been conducted on the island of Cyprus with a general paucity in research on this topic from the Eastern Mediterranean. Island species, through reduced gene flow and general isolation often evolve reproductive differences from their mainland relatives. As Cyprus is the third largest island in the Mediterranean and the most easterly positioned it provides an ideal opportunity compare the breeding biology of this island population with those from the wider Mediterranean region. This study aimed to gather some baseline reproductive data for Great Tits breeding in Cyprus. This data was then used to compare the reproductive outputs of Cypriot Great Tits from the sub species Parus major aphrodite with other Mediterranean island populations. This study was performed over a 3-year period during the breeding seasons of 2016-2018 in four evergreen forest areas. Mean clutch size was 7.7 eggs and hatching success 76.0%. The mean weight of the young was 16.3 g and mean tarsus length 18.7 mm. Significant differences were found between the years of the study, both in mean clutch size (p<0.0001) and the day of the first egg (p<0.0001), with 2016 producing the largest clutches and clutches being laid earlier than the subsequent two years. The start of the breeding season of the Great Tit was considerably earlier in Cyprus compared to other Mediterranean regions.

Long-term monitoring of dwarf eggs in clutches of Yellow-legged Gulls (Larus michahellis) breeding in a western Mediterranean colony

AbstractThe present study provides data on clutches with dwarf eggs from a large sampling in a colony of Yellow-legged Gulls (Larus michahellis) over 31 years. Their occurrence was very low, with a global percentage of 0.26%. Significant variations were not detected among periods of 10 or 11 years. In all the cases, only one dwarf egg was found per clutch. Mean volume of dwarf eggs was 34% of that of non-dwarf eggs. Their content was mostly albumen and a very reduced quantity of yolk, and they were infertile. Several results of the study (the laying order of the dwarf eggs, their mean clutch size and the mean size of the non-dwarf eggs from clutches with dwarf eggs) support the hypotheses that runt eggs occur from a temporary disturbance to the reproductive tract.

Sexual dimorphism and reproductive biology of commercially harvested oriental rat snakes (Ptyas mucosa: Colubridae) from West Java

Large (&gt;3 m) slender-bodied rat snakes are abundant in agroecosystems of southern Asia and are heavily exploited for their skins and meat. We examined 216 specimens killed at commercial facilities in Cirebon, West Java, to quantify morphological and reproductive traits and evaluate harvest sustainability by comparing this sample to one taken 25 years previously. The snakes we examined were mostly adults, and mostly male. Females were less heavy-bodied than males of the same body length, matured at a larger size than males, but attained smaller maximum sizes. Reproduction and energy (fatbody) storage was seasonal in both sexes, with females containing oviductal eggs primarily during the annual wet season. Clutch size averaged 12.6 eggs and increased with maternal body size. Comparison of the two samples taken 25 years apart revealed strong similarity in sex ratio, the numerical preponderance of adults, body sizes at sexual maturation and mean adult body sizes, sexual dimorphism in body length and mass, reproductive seasonality in females, mean fecundity, and the relationship between fecundity and maternal body size. That consistency suggests that commercial harvesting over the intervening period has not affected the biological traits of rat snake populations, consistent with a sustainable level of offtake.

Androgen and glucocorticoid profiles throughout extended uniparental paternal care in the eastern hellbender salamander (Cryptobranchus a. alleganiensis)

The behavioral endocrinology associated with reproduction and uniparental male care has been studied in teleosts, but little is known about hormonal correlates of uniparental male care in other ectotherms. To address this gap, we are the first to document the seasonal steroid endocrinology of uniparental male hellbender salamanders during the transition from pre-breeding to nest initiation, and through the subsequent eight months of paternal care. In doing so, we investigated the correlates of nest fate and clutch size, exploring hellbenders’ alignment with several endocrinological patterns observed in uniparental male fish. Understanding the endocrinology of hellbender paternal care is also vital from a conservation perspective because high rates of nest failure were recently identified as a factor causing population declines in this imperiled species. We corroborated previous findings demonstrating testosterone and dihydrotestosterone (DHT) to be the primary androgens in hellbender reproduction, and that cortisol circulates as the most abundant glucocorticoid. However, we were unable to identify a prolactin or a “prolactin-like” peptide in circulation prior to or during parental care. We observed ∼ 80 % declines in both primary androgens during the transition from pre-breeding to nest initiation, and again as paternal care progressed past its first month. In the days immediately following nest initiation, testosterone and DHT trended higher in successful individuals, but did not differ with males’ clutch size. We did not observe meaningful seasonality in baseline glucocorticoids associated with breeding or nesting. In contrast, stress-induced glucocorticoids were highest at pre-breeding and through the first two months of care, before declining during the latter-most periods of care as larvae approach emergence from the nest. Neither baseline nor stress-induced glucocorticoids varied significantly with either nest fate or clutch size. Both stress-induced cortisol and corticosterone were positively correlated with total length, a proxy for age in adult hellbenders. This is consistent with age-related patterns in some vertebrates, but the first such pattern observed in a wild amphibian population. Generally, we found that nesting hellbenders adhere to some but not all of the endocrinological patterns observed in uniparental male teleosts prior to and during parental care.

Assessing wild turkey productivity before and after a 14-day delay in the start date of the spring hunting season in Tennessee.

Ten state wildlife management agencies in the United States, including six within the Southeast, have delayed their spring wild turkey (Meleagris gallopavo) hunting seasons since 2017 by five or more days to address concerns related to the potential effects of hunting on wild turkey seasonal productivity. One hypothesis posits that if the spring hunting season is too early, there may be insufficient time for males to breed hens before being harvested, thus leading to reduced seasonal productivity. We conducted an experiment to determine whether delaying the wild turkey hunting season by 2 weeks in south-middle Tennessee would affect various reproductive rates. In 2021 and 2022, the Tennessee Fish and Wildlife Commission experimentally delayed the spring hunting season to open 14 days later than the traditional date (the Saturday closest to 1 April) in Giles, Lawrence, and Wayne counties. We monitored reproductive rates from 2017 to 2022 in these three counties as well as two adjacent counties, Bedford and Maury, that were not delayed. We used a Before-After-Control-Impact design to analyze the proportion of hens nesting, clutch size, hatchability, nest success, poult survival and hen survival with linear mixed-effect models and AIC model selection to detect relationships between the 14-day delay and reproductive parameters. We detected no relationship (p > .05) between the 14-day delay and any individual reproductive parameter. In addition, recruitment (hen poults per hen that survived until the next breeding season) was very low (<0.5) and did not increase because of the 14-day delay. The traditional Tennessee start date had been in place since 1986 while the turkey harvest increased markedly until about 2006 and more recently stabilized. Our data indicate that moving the start of the hunting season from a period just prior to peak nest initiation to 2 weeks later, to coincide with a period just prior to peak nest incubation initiation, resulted in no change to productivity or populations in wild turkey flocks in south-middle Tennessee.

Taxonomic inflation as a conservation trap for inbred populations.

Conservation is prioritized based on accepted taxa. As a consequence, a conservation incentive exists to emphasize inter-population differences to define taxa, potentially leading to taxonomic inflation. But stressing the uniqueness of threatened populations has the side effect of hindering conservation actions that promote inter-population gene flow, such as genetic rescue. These actions may be of critical importance for severely inbred populations involved in extinction vortices, for which an inflated taxonomy can become a conservation trap. Here, we exemplify this scenario with the western capercaillie (Tetrao urogallus, Phasianidae) population in the Cantabrian Mountains, described and legally listed as a subspecies not supported by recent molecular data. The Cantabrian capercaillie population is Critically Endangered after a long-lasting decline and a recent demographic collapse. It shows clear signs of inbreeding depression, including striking clutch size decreases as well as reduced hatchability and chick survival. This critical situation could be alleviated through a genetic rescue, but this possibility is hindered by inertias rooted in the putative uniqueness of the Cantabrian capercaillie. It had been previously argued that poor taxonomy could hamper conservation, through the oblivion of populations deserving, but not having, a taxonomic status. We show that taxonomic inflation can also become an obstacle for effective conservation.

Polyembryony and morpho-genetic characterisation of zygotic seedlings through microsatellite markers in ten polyembryonic citrus rootstocks

Morpho-genetic characterisation of zygotic and nucellar seedlings of 10 citrus rootstocks was carried out to know the degree of polyembryony. 'Volkameriana' rootstock had maximum fruit and seed weight. Polyembryony, number of embryos per seed and clutch size was highest in 'Katazamir'. However, the seeds of 'Schaoub' took minimum days to germinate while 'Cleopatra' took maximum days. Significant positive correlation was observed between percent polyembryony and average number of embryos per seed, seed weight and number of seeds per fruit. Twenty SSR primers were utilised for detection of zygotic seedling from all rootstocks. None of the individual primers used in this study were able to consistently identify zygotic seedlings in all rootstocks tested. The maximum (26.7%) zygotic seedlings were identified in 'Katazamir' and minimum (5.0%) in 'X-639' rootstocks. There was not a significant correlation between seedling height and zygotic and nucellar seedlings, identified with SSR markers. Therefore, seedling height cannot be taken as a criteria to identify the nucellar and zygotic seedlings.

Breeding by Barn Owls Tyto alba in artificial nest hollows established for an endangered black cockatoo in the northern wheatbelt of Western Australia

ABSTRACT Barn Owls Tyto alba were recorded breeding in natural nest hollows in a Wandoo Eucalyptus wandoo woodland in the northern wheatbelt of Western Australia infrequently and at low densities during the period 1969-2022. During a record cropping season in 2022, Barn Owls were first recorded nesting successfully in natural hollows and in artificial nest hollows designed for use by Carnaby’s Cockatoos. The large clutch sizes (5-7) and complete fledging success observed in three artificial nest hollows was likely facilitated by a large House Mouse Mus musculus population associated with the record cropping season experienced at the study site.

Variation in reproductive traits associated with different host plants in the subsocial bug Elasmucha putoni (Hemiptera: Acanthosomatidae)

ABSTRACTHost plants are an important selective factor for the evolution of reproductive traits in herbivorous insects. Among different host plants, offspring will be exposed to different environmental conditions, and parents are expected to allocate reproductive resources adaptively to their offspring according to such environmental heterogeneity. Elasmucha putoni Scott (Hemiptera: Acanthosomatidae) is a bivoltine shield bug showing maternal care. We examined the variation in reproductive traits, that is, egg size, clutch size and the trade‐off between them, between two generations of a population and two populations of the same (later) generation, which differ in their host plants. Controlling for female body size, a significant difference was detected in egg size, but not in clutch size between the earlier generation on Morus australis and the later one on Euptelea polyandra or Rosa multiflora. Moreover, there was no difference in the two traits between the populations (one using E. polyandra and another using R. multiflora) of the same generation. A significant trade‐off between egg size and clutch size was detected in the earlier generation on M. australis but not in the later generation on E. polyandra or R. multiflora. This is the first study indicating variable reproductive allocation according to different host plants in herbivorous insects with maternal care.

Biparental Care in a Generalist Raptor, the Chimango Caracara in Central Argentina

ABSTRACT The allocation of parental care behaviors between the sexes may be influenced by the species’ mating system, degree of sexual size dimorphism, and predictability of food resources. Biparental care (i.e., both parents contributing to raising young) has been documented in raptors, including those with minimal sexual size dimorphism and/or whose food resources are unpredictable in time (e.g., scavengers). The Chimango Caracara (Milvago chimango) is a common raptor with slight sexual size dimorphism and a scavenging lifestyle. During two breeding seasons, we performed focal observations at nests in a Chimango Caracara colony in central Argentina to assess the division of labor between the sexes. For males and females separately, we measured the time spent incubating and brooding, and the food delivery rate to nestlings; then we used GLMMs to assess various factors that may influence these behaviors, including parental sex, time of day, clutch or brood size, and nestlings’ age. We used GLMMs to test the influence of time spent brooding and food delivery rate (both parents combined for these variables) on nest success and productivity. Although both sexes contributed to all parental care activities, females spent more time incubating and brooding than males. Brooding time decreased as nestlings aged. Food delivery rate did not differ between the sexes. Food delivery rate was higher during the middle of nestlings’ development but declined thereafter. Nest success and productivity were higher at nests with higher food delivery rates. Adults spent more time incubating and brooding during morning and midday, and food delivery rate was higher during the afternoon.

Variation in nuptial color in relation to sex, individual quality and mating success in the sex-role reversed Phalaropus fulicarius (Red Phalarope)

Abstract In most bird species, males are more ornamented and compete for females, who contribute more to offspring care. In a minority of species this pattern is reversed, with more colorful females competing for mates and males taking care of parental duties. In such sex-role reversed species, the links between colorful ornamentation, individual quality and mating success are not well established. Phalaropus fulicarius (Red Phalarope) is a colorful sex-role reversed migratory shorebird with regular social polyandry, in which both sexes show considerable color variation. Here, we describe sex differences in color and quantify associations between color variation and indicators of quality and mating success in both sexes. Using a large sample of photos collected across three consecutive years on the Arctic breeding grounds, we scored color variation for four body parts (bill, crown, cheek and breast), and analyzed scores separately and combined into an overall color score. Females were more colorful and larger than males, and individuals could be unambiguously sexed by crown color. Nevertheless, there was substantial variation within sexes and some overlap between males and females in bill, cheek, breast, and overall color scores. Assortative mating by color was only found for the bill. Color variation did not correlate with plasma testosterone levels, except for male cheek color. Females in better body condition had yellower bills and higher overall color scores, while early-arriving birds had higher breast and overall scores. Phalaropus fulicarius that bred locally were heavier than those that did not, but they did not have higher color scores. Female color variation did not predict the probability of local social polyandry nor variation in clutch size, and male coloration did not predict the probability of nest predation. In conclusion, P. fulicarius color variation showed modest correlations with individual quality and was unrelated to variation in local reproductive success.

Species-Specific Seasonal Shifts in Reproductive Allocation in the Southern Grass Lizard, Takydromus sexlineatus (Lacertidae).

We designed a common garden design to collect data on female reproductive traits from three populations of the southern grass lizard Takydromus sexlineatus, testing the hypothesis that a species-specific pattern of seasonal shifts in reproductive allocation should be shared by geographically separated populations. Of the seven examined traits, six differed among populations, with four of the six also differing among successive clutches. Females grew longer during the breeding season and produced more eggs in the first clutch than in the subsequent clutches; egg size was unchanged throughout the breeding season. After removing the influence of female size or postpartum body mass we found the following. First, postpartum body mass, clutch mass, and relative clutch mass were greater in the Wuzhishan population than in the Shaoguan and Zhaoqing populations. Second, egg size was greatest in the Wuzhishan population and smallest in the Zhaoqing population. Third, clutch size was greatest in the Wuzhishan population and smallest in the Shaoguan population. Females did not trade-off egg size against number within each population × clutch combination. Our study validates the hypothesis tested, supports the conventional view that reproductive output is highly linked to maternal body size in lizards, and follows the classic prediction that females with different amounts of resources to invest in reproduction should give priority to adjusting the total number rather than size of their offspring.

Breeding biology of the Ochre-breasted pipit (Anthus nattereri), with notes on its conservation in the Upper Rio Grande Grasslands, south-eastern Brazil

ABSTRACT The Ochre-breasted pipit Anthus nattereri is a terrestrial bird restricted to natural grasslands of south-eastern South America. The species is globally Vulnerable to extinction and its natural history is still poorly known. We investigated the breeding biology of Ochre-breasted pipits, commenting on its habitat use and the potential impacts of local grasslands management practices with fire on the species’ conservation. Fieldwork took place mainly between January and December 2016 in the Upper Rio Grande Grasslands, south-eastern Brazil. Five nests of the species were found between September and November, one of them recently destroyed by fire. Nests were cup shaped and placed on the ground, being built with dry grasses, resembling the pattern documented for other species of Anthus. The eggs were covered with brownish spots and dots to a variable extent and the background colour ranged from greyish white to brownish white. The egg colour pattern also fell within the known range of variation for congeneric species, as did the clutch size (two to three eggs) observed in tropical species of Anthus. Ochre-breasted pipits tended to occupy nesting sites with higher and denser grass cover (eg small patches of vegetation that survived the last fire event) when compared to non-nest sites located in adjacent recently burned areas, which potentially suggests a preference for such habitat attributes. Although the Ochre-breasted pipit is relatively common in the study area, the highest temporal incidence of fire coincides with its breeding season, which can directly impact the local population through the burning of nests and the elimination of suitable nesting sites. Thus, it is important to conduct long-term studies to evaluate the impact of different fire regimes on the reproductive performance of Ochre-breasted pipits, thus allowing the design of better ecosystem management practices to guarantee its conservation.

A methodology for image-based measurement of plate movement in disengaged wet clutches

The drag loss behavior of a disengaged wet clutch is influenced, among other things, by the movement of the plates. Therefore, knowledge about the plate movement is essential for investigating and optimizing the drag loss behavior. This paper presents a methodology for image-based measurement of plate movement in disengaged wet clutches. A drag torque test rig is equipped with a camera to create the image series. The oil displacement from the measuring zone is crucial to obtain permanent optical access to the clutch pack. The rough plate positions are determined by segmentation using thresholding and template matching. Using the Canny edge detector significantly improves the accuracy of the position evaluation. The plate positions are finally converted into a metric unit based on the real plate thicknesses. The clearances are calculated from the determined positions of two adjacent plates. In the ideal case, an evaluation accuracy in the range of a few micrometers can be achieved. The image evaluation methodology is universally applicable to different clutch sizes, friction systems, plate types, and plate numbers. The methodology enables researchers to generate fundamental knowledge and derive design guidelines based on this, for example. In the development phase, it can also be used to optimize the design and operating parameters.

Phylogenetic analysis of viviparity, matrotrophy, and other reproductive patterns in chondrichthyan fishes.

The reproductive diversity of extant cartilaginous fishes (class Chondrichthyes) is extraordinarily broad, reflecting more than 400 million years of evolutionary history. Among their many notable reproductive specialisations are viviparity (live-bearing reproduction) and matrotrophy (maternal provision of nutrients during gestation). However, attempts to understand the evolution of these traits have yielded highly discrepant conclusions. Here, we compile and analyse the current knowledge on the evolution of reproductive diversity in Chondrichthyes with particular foci on the frequency, phylogenetic distribution, and directionality of evolutionary changes in their modes of reproduction. To characterise the evolutionary transformations, we amassed the largest empirical data set of reproductive parameters to date covering nearly 800 extant species and analysed it via a comprehensive molecular-based phylogeny. Our phylogenetic reconstructions indicated that the ancestral pattern for Chondrichthyes is 'short single oviparity' (as found in extant holocephalans) in which females lay successive clutches (broods) of one or two eggs. Viviparity has originated at least 12 times, with 10 origins among sharks, one in batoids, and (based on published evidence) another potential origin in a fossil holocephalan. Substantial matrotrophy has evolved at least six times, including one origin of placentotrophy, three separate origins of oophagy (egg ingestion), and two origins of histotrophy (uptake of uterine secretions). In two clades, placentation was replaced by histotrophy. Unlike past reconstructions, our analysis reveals no evidence that viviparity has ever reverted to oviparity in this group. Both viviparity and matrotrophy have arisen by a variety of evolutionary sequences. In addition, the ancestral pattern of oviparity has given rise to three distinct egg-laying patterns that increased clutch (brood) size and/or involved deposition of eggs at advanced stages of development. Geologically, the ancestral oviparous pattern arose in the Paleozoic. Most origins of viviparity and matrotrophy date to the Mesozoic, while a few that are represented at low taxonomic levels are of Cenozoic origin. Coupled with other recent work, this review points the way towards an emerging consensus on reproductive evolution in chondrichthyans while offering a basis for future functional and evolutionary analyses. This review also contributes to conservation efforts by highlighting taxa whose reproductive specialisations reflect distinctive evolutionary trajectories and that deserve special protection and further investigation.

A two-step Bayesian network approach to identify key SNPs associated to multiple phenotypic traits in four purebred laying hen lines.

When purebred laying hen chicks hatch, they remain at a rearing farm until approximately 17 weeks of age, after which they are transferred to a laying farm. Chicks or pullets are removed from the flocks during these 17 weeks if they display any rearing abnormality. The aim of this study was to investigate associations between single nucleotide polymorphisms (SNPs) and rearing success of 4 purebred White Leghorns layer lines by implementing a Bayesian network approach. Phenotypic traits and SNPs of four purebred genetic White Leghorn layer lines were available for 23,000 rearing batches obtained between 2010 and 2020. Associations between incubation traits (clutch size, embryo mortality), rearing traits (genetic line, first week mortality, rearing abnormalities, natural death, rearing success, pullet flock age, and season) and SNPs were analyzed, using a two-step Bayesian Network (BN) approach. Furthermore, the SNPs were connected to their corresponding genes, which were further explored in bioinformatics databases. BN analysis revealed a total of 28 SNPs associated with some of the traits: ten SNPs were associated with clutch size, another 10 with rearing abnormalities, a single SNP with natural death, and seven SNPs with first week mortality. Exploration via bioinformatics databases showed that one of the SNPs (ENAH) had a protein predicted network composed of 11 other proteins. The major hub of this SNP was CDC42 protein, which has a role in egg production and reproduction. The results highlight the power of BNs in knowledge discovery and how their application in complex biological systems can help getting a deeper understanding of functionality underlying genetic variation of rearing success in laying hens. Improved welfare and production might result from the identified SNPs. Selecting for these SNPs through breeding could reduce stress and increase livability during rearing.

Responses in the breeding parameters of the collared flycatcher to the changing climate

Global climate change involves various aspects of climate, including precipitation changes and declining surface wind speeds, but studies investigating biological responses have often focused on the impacts of rising temperatures. Additionally, related long-term studies on bird reproduction tend to concentrate on breeding onset, even though other aspects of breeding could also be sensitive to the diverse weather aspects. This study aimed to explore how multiple aspects of breeding (breeding onset, hatching delay, breeding season length, clutch size, fledgling number) were associated with different weather components. We used an almost four-decade-long dataset to investigate the various aspects of breeding parameters of a collared flycatcher (Ficedula albicollis) population in the Carpathian Basin. Analyses revealed some considerable associations, for example, breeding seasons lengthened with the amount of daily precipitation, and clutch size increased with the number of cool days. Parallel and opposing changes in the correlated pairs of breeding and weather parameters were also observed. The phenological mismatch between prey availability and breeding time slightly increased, and fledgling number strongly decreased with increasing mistiming. Our results highlighted the intricate interplay between climate change and the reproductive patterns of migratory birds, emphasizing the need for a holistic approach. The results also underscored the potential threats posed by climate change to bird populations and the importance of adaptive responses to changing environmental conditions.

The effect of nesting habitat on reproductive output of the Barn Swallow (Hirundo rustica). A comparative study of populations from atypical and typical nesting habitats in western Poland

The aim of this study was to discover if atypical nesting places such as abandoned second world war bomb shelters and conditions occurring within, can constitute suitable and good quality alternative habitat for the Barn Swallow. To answer this question, the time of breeding, clutch size and the mean survival probability of nest contents were compared between swallows nesting in shelters and in farm outbuildings – typical nesting habitat. The study showed that bunkers do constitute a suitable and relatively good quality alternative habitat for the Barn Swallow but they are poorer nesting places than pigsties or cowsheds. Mean survival rate of nest contents (eggs/nestlings) was higher in farm outbuildings than in bunkers, but only differences in the first broods were recorded. The results are most probably the effect of different conditions occurring in the two kinds of nesting habitat, especially at the beginning of the breeding season, when the unfavourable weather conditions can negatively influence breeding swallows to a higher degree in bunkers than in outbuildings.