Timing Of Breeding Research Articles

Is it beneficial to be a city dweller? Impact of urban conditions on red fox reproduction

AbstractVarious species inhabit cities around the world, and numerous changes in their biology can be observed. Among them, changes in the time of reproduction or productivity are often recorded in urban populations. Firstly, we compared selected reproductive features (i.e., litter size and time of breeding) of two red fox (Vulpes vulpes) populations, one living in the city of Warsaw and the other inhabiting a forest‐field mosaic in Central Poland. Secondly, we investigated fox reproductive and social behaviour in an extensive camera trap study in Warsaw (2018–2021). By means of generalized linear mixed effects models, we identified which factors (fox social group size, share of natural food, and level of urbanization, created by using principal components analysis for habitat and landscape variables) affected the reproduction and/or social group size of urban foxes. We found that urban foxes started breeding about 2 weeks earlier than their rural counterparts and produced bigger litters (3.98 vs. 3.48 cubs). Opposite to rural foxes where only pairs of adult foxes were reported, in the urban population, social groups were observed with a mean number of 2.37 individuals. Interestingly, none of the studied factors affected group size or litter size in urban foxes, while breeding time was influenced by the level of urbanization and share of natural food. Earlier reproduction in urban areas is fairly frequently observed and may be attributed to altered environmental conditions in urban habitats, while higher productivity is probably a consequence of higher food availability.

Impact of Feed Bunk Space on the Prevalence of Torsion and Foreleg Distal Asymmetry in Holstein Cows.

Leg torsion and distal asymmetry (LTDA) among cows reared on intensive farms in the Comarca Lagunera region of northern Mexico may be indicative of underlying health concerns. To ascertain whether the incidence of LTDA is associated with trough measurements and with productive, reproductive, and disease variables, the prevalence of LTDA was determined in lactating dairy cows. The data were derived from two intensive dairy farms in northern Mexico (G60: 2043 cows in 13 pens with 142.0 m of linear feed bunk space and 65.0 m of pen depth; G100: 2227 cows in 12 pens with 215.0 m of linear feed bunk space and 49.0 m of pen depth). The cows were observed over the course of a week to identify any macroscopic lesions indicative of LTDA. Cows exhibiting lesions were assigned a value of "1", while those without lesions were assigned a value of "0". Furthermore, data regarding other limb diseases (LDs) were collected and subjected to analysis. A comparison was conducted to ascertain the impact of reproductive, productive, and feed bunk size variables on the prevalence of LTDA and other LDs. To ascertain the prevalence of LTDA and LDs, a chi-squared test was employed. The prevalence of LTDA was found to be 27.6% (G60: 31.4%, G100: 22.4%). No association was identified between LTDA and the variables included in the study. However, a correlation was identified between LDs and the following variables: total width, distance from the edge, width from the feed bunk to the tramp, and the presence of a manure crust on the walls. Principal component analysis (PCA) was conducted to examine the correlation between LDs and various factors at the farm and pen levels. The findings indicated that the distance from the feed bunk to the trough, the presence of manure crusts on the walls, and the breeding time were associated with LDs in G100, as well as in three of the twelve pens (302, 306, and 308) within G100. The findings suggest that the prevalence of LDs is associated with an increase in the width of the feed bunk and the width of the manure crust on the walls, particularly in pregnant cows. The results permit the conclusion that LTDA and LDs are associated with the measurements of the feed bunks, the absence of manure cleaning of the feed bunks, and gestation. This association gives rise to significant health issues for Holstein cows on these farms, with more than one in four cows affected. To reduce the prevalence of LTDA in lactating dairy cows, it is recommended that the standard measurements for feed bunk design be adhered to. This will reduce the prevalence of LTDA and LDs, promote the cleaning protocols to avoid the accumulation of manure crusts, and facilitate close monitoring of pregnant cows, thereby alleviating the impacts of these foot pathologies on animal welfare.

Morphometric variation and deteriorating food availability both explain seasonally declining reproductive success of Dicrurus hottentottus (Hair-crested Drongo)

Abstract Seasonally declining reproductive performance in avian populations may be attributed to high-quality individuals breeding earlier than low-quality individuals (the quality hypothesis), to deteriorating environmental conditions (the date hypothesis), or both. By comparing the reproductive performance among different perennial pairs, and the same perennial pairs across different years, we tested the influence of timing of breeding on reproductive performance in Dicrurus hottentottus (Hair-crested Drongo) from 2010 to 2022. Breeding pairs that typically laid earlier relative to the population mean (i.e., early-breeding pairs) exhibited a significantly higher fledging rate compared to breeding pairs that often bred later relative to the population mean (i.e., late-breeding pairs). For a given pair, the fledging rate of early-breeding pairs increased when they bred later compared to other years, while the fledging rates of late-breeding pairs were significantly lower in years when they bred later than usual. We found that male morphological traits were associated with both the timing of breeding and the feeding rate. Pairs with long-billed (indicator of high quality) males bred earlier than pairs with short-billed males, and pairs with larger males (indicator of high quality) had a higher feeding rate than pairs with smaller males. Female age had reversed effects on the timing of breeding and fledging rate: older females tended to breed earlier than younger females; but there was a sharp decline in fledging rate after 7 years of age in late-breeding pairs. Finally, our results showed that the feeding rate and the amount of invertebrate biomass decreased with laying date, indicating deteriorating feeding conditions later in the breeding season. Overall, our findings support both the quality hypothesis and the date hypothesis. Low-quality D. hottentottus are likely to be most adversely affected by the phenological mismatches induced by climate change, which, in turn, may affect population dynamics through reduced fecundity.

Arrival-breeding interval is flexible in a songbird and is not constrained by migration carry-over effects.

As spring phenology advances with climate change, so too must the timing of life cycle events. Breeding at the right time is critical in many species as it maximizes fitness. For long-distance migratory birds, flexibility in the duration of the arrival-breeding interval (pre-breeding period) may allow populations to adjust their timing of breeding. However, whether first egg-lay dates are flexible to local environmental conditions after arrival, and if they are constrained by the time needed to replenish energy lost during migration, remains unclear. We investigated the regional flexibility of the arrival-breeding interval in an avian migrant, the purple martin, Progne subis, across their breeding range. We evaluated whether the duration of the arrival-breeding interval was flexible to temperature and precipitation at breeding sites, and if timing was limited by migration rate and stopover duration. We also tested if longer interval durations were associated with higher fledging success. To address our hypotheses, we used a combination of migration tracking, weather and breeding data collected from four regions across eastern North America (26.1° N to 52.4° N latitude). We found the arrival-breeding interval to be shortest in the north and longest in the south. Across all regions, warmer temperatures encountered at breeding grounds were associated with shorter intervals, and faster migration rates led to longer intervals. The length of the interval was not influenced by precipitation or stopover duration. Finally, longer intervals were not associated with higher fledge success. Currently, the longer arrival-breeding intervals in this study system, on average 28.3 days, may provide both early and late-arriving birds with ample time for recovery so birds can lay eggs according to temperature. Any negative effects of faster migration may have been buffered by longer arrival-breeding intervals, as interval length did not determine fledge success. With ongoing climate change, further research is needed to examine if arrival-breeding intervals become constrained by migration timing, which may limit opportunities for migrants to match the timing of breeding with key resources.

VETERINARY ETHOLOGY APPLIED TO A DAIRY GOAT HERD: CLASS REPORT

Environmental stress on farm animals is a limiting factor for all livestock farming. In this sense, the action of professionals, such as veterinarians is essential to outline the best management and the best actions to develop with livestock in a region. In this manner the results from the study performed by Furtado (2007) presented information on the behavior of dairy goats that favor new evaluations. The influence of the environment on the behavioral parameters of dairy goats was observed in Lajes do Cabugi, Rio Grande do Norte, on a dairy goat production farm. Ethology is a science that favors the understanding of the adaptation of animals (i.e. behavior) to the environment in which they are found. Therefore, this knowledge field helps the veterinarian in the clinical assessment of animals’ health and well-being, promoting animal aid to achieve greater productivity, which is one of the objectives of the animals' actions professionals. Through research carried out in a brief bibliographical-secondary survey, the objective of this study is to evaluate the recorded ethogram of a goat herd, which had been exposed at two different times of breeding. The environmental variations recorded at the beginning and end of the experiment (June and September 2007) were, respectively: i) ambient temperature 25.82ºC and 25.88 ºC; ii) relative humidity 67.48% and 66.64%. The outcome obtained with ethogram was that the animals had many more episodes of lying under the shade in August compared to June, as well as grazing in the shade, brooding in the shade, standing still in the shade and walking. These results show that the herd spent much more energy to maintain homeostasis under heat stress (FURTADO; SILVA; TELES, 2018; GAIA et al., 2019). It was concluded that the herd must be relocated in terms of access to nutritional supplementation with hay and concentrates, have access to more shaded areas and promote relocation in grazing and stabling hours, with the aim of preventing pathologies linked to heat stress, as well as having a better quality of life and animal well-being.

429 Maternal rate of gain and one-carbon metabolites supplementation alters the gene expression profile of fetal brain during early gestation in beef heifers

Abstract Maternal nutritional plane during pregnancy may leave lifelong impacts on offspring in beef cattle. Given that, we hypothesized that the supplementation of one-carbon metabolites (OCM) during pregnancy would mitigate the negative effects of maternal rate of gain through brain gene expression regulation in early developing bovine fetuses. The objective of this study was to evaluate the effects of OCM supplementation and maternal rate of gain on gene expression in the developing fetal brain in gestating beef heifers. Herein, Angus crossbred heifers (n = 72, body weight = 406 ± 33 kg) were randomly assigned to 2 × 2 factorial arrangement of treatments with two levels of maternal rate of gain (CON, 0.60 kg/d; and RES, -0.23 kg/d) each with or without OCM supplementation (+OCM, and -OCM). Heifers were fed individually and were bred using female-sexed semen from a single sire. The OCM supplementation included rumen-protected choline (44.4 g/d) and methionine (7.4 g/d) in corn carrier fed daily and weekly injections of folate (320 mg) and vitamin B12 (20 mg). The -OCM heifers received the corn carrier and saline injections. The treatments started at the time of breeding and continued until d 63 of gestation when pregnant heifers (n = 29) were slaughtered to collect fetal brain tissues for RNA sequencing. The fetal brain phenotypic data were analyzed using MIXED procedures of SAS, indicating that restricted nutrition affected the fetal right hemisphere weight (P < 0.05), and there was a strong tendency for overall fetal brain weight (0.05 < P < 0.1) to be affected as well. Brain transcriptomics data were analyzed using STAR aligner and a total of 177 differentially expressed genes (DEGs, FDR < 0.05) were identified across all treatment comparisons using DESeq2. Most of the DEGs were either isoforms of spliceosomal non-coding RNAs or micro-RNAs (miRNAs) associated with biological processes (FDR < 0.1) like mRNA processing, cellular nitrogen metabolism, lipid metabolism, and post-transcriptional gene silencing. The key miRNAs upregulated in the brain tissue of restricted fetuses without OCM supplementation, bta-mir-2375, bta-mir-876, and bta-mir-196a-1, were found to be associated with early embryogenesis and essential cellular regulatory processes. Conversely, in restricted fetuses with OCM supplementation, upregulated miRNAs such as bta-mir-216b, bta-mir-2285dd, and bta-mir-1298 were linked to early embryonic development, muscular development, and lipid metabolism in cattle. Both phenotypic and transcriptomics data here revealed that the maternal rate of gain altered fetal brain development, with differences seemingly compensated by OCM supplementation. USDA is an equal opportunity provider and employer.

52 Differences in body composition measurements for developing Angus heifers

Abstract The profitability of beef cow-calf operations relies on the reproductive ability of females to calve at 2 yr of age and provide a calf each subsequent year for her lifetime. The management of replacement heifers could affect her ability to conceive early, calve, and rebreed. Common management practices use heifer body weight (BW) (and body condition score (BCS) as indicators of puberty onset but do not indicate body composition and fat deposition. The objective of this study was to use ultrasound measurements of carcass traits to compare the effect of different diet management practices on muscle development and fat deposition of post-weaning heifers. The heifers placed on a higher energy diet are expected to have greater mean carcass trait measurements than the lower energy diet heifers. A total of 124 purebred Angus heifers from the Iowa State University McNay Memorial Research and Demonstration Farm were used for this study. Two diets were administered in this study. One group of heifers (G1; n = 61) was developed on a low-energy roughage diet to reach a target BW of 55% of mature BW at the time of breeding. The second group (G2; n = 63) was developed on a grain diet to reach the target BW of 65% mature BW at breeding. Body weight and ultrasound measurements for backfat (BFAT), ribeye area (REA), and intramuscular fat (IMF) were collected over three time points (0-d, 55-d, and 123-d) during the study to quantify the development of body composition characteristics. The initial measurements were collected 1 wk post-weaning. Significant mean differences between the two groups were observed for BW, BFAT, and REA at 55-d (P = 0.027, P = 0.008, and P < 0.0001, respectively), and 123-d (P < 0.001). The mean differences for BW, BFAT, and REA at 123-d between G1 and G2 were 30.98 kg, 0.10 cm, and 7.81 cm2, respectively No significant difference was found between the groups for IMF measurements at 55-d (P = 0.927) or 123-d (P = 0.169). This suggests IMF is not significantly influenced by diet during the early, post-weaning heifer developmental stage. Although further research is needed, the results from this study suggest the development of weight, BFAT, and REA in early post-weaning beef heifers is influenced by the energy concentration of the diet.

348 Repeat breeding syndrome: Dexamethasone decreases the prevalence of anti-sperm antibodies in dairy cows

Abstract Cows that require greater than two inseminations to conceive are diagnosed with repeat breeding syndrome (RBS). Anti-sperm antibodies (ASA) in serum are in greater abundance among individuals exhibiting fertility challenges. In humans, treatment with glucocorticoids has been shown to decrease the prevalence of ASA and improve fertility. Therefore, the purpose of this study was to determine the impact of dexamethasone on ASA and pregnancy outcomes in RBS cattle. Holstein multiparous cows (n = 18) diagnosed as having RBS were randomly allotted to one of three treatment groups: Control (C; n = 6), low dexamethasone (LD; n = 6) and high dexamethasone (HD; n = 6). Intramuscular injections of saline (C), 0.05 mg/kg of BW of dexamethasone (LD), or 0.10 mg/kg of BW of dexamethasone (HD) were administered daily starting 4 d prior to insemination (d 0) through insemination (d 4). All treatment volumes were standardized with saline to achieve the same treatment level. Blood was collected on d 0, 4, 8 and 18, with serum extracted on d 0 through 8. Additionally, milk weights were recorded until d 34. For breeding, cows were synchronized using the Double Ovsynch protocol and only one insemination was conducted at the time of breeding. The MIXED procedure in SAS was used to determine the relationship of treatment with the repeated measures of ASA abundance and milk yield. Additionally, a non-parametric chi-square analysis was conducted in SAS using PROC GENMOD to determine the relationship of treatment with immune cell count and pregnancy outcomes. Day, Treatment and Treatment × Day were designated as fixed effects, and a protected post hoc analysis was conducted to account for multiple comparisons. Anti-sperm antibodies tended to decrease (P ≤ 0.082) as dexamethasone increased compared with C, however, there was no Treatment × Day interaction. Daily milk yields for both LD and HD decreased (P < 0.002) compared with C cows, but there was no interaction with day. Though there was an effect for Treatment × Day (P ≤ 0.002) for white blood cell count, percentage lymphocytes, eosinophils, and neutrophils, there was no effect of treatment (P ≥ 0.181). Therefore, interaction differences were largely driven by day (P < 0.001). Surprisingly, there was a trend (P = 0.069) for an increase in pregnancy rates for C cows compared with LD and HD cows. In fact, one-half of the C cows achieved pregnancy compared with just one cow for LD and HD treatments. Overall, dosage of dexamethasone did not differ for ASA or pregnancy outcomes. However, dexamethasone did decrease ASA but did not increase pregnancy rates. Based on these results, we suggest that alternative treatment measures should be explored to improve pregnancy rates in RBS cows.

An assessment of seasonal bait uptake by individual grey squirrels to develop a delivery system for oral contraceptives.

Globally, human-wildlife conflicts continue to increase, owing to human population growth and expansion. Many of these conflicts concern the impacts of invasive non-native species. In the UK, the invasive, non-native grey squirrel Sciurus carolinensis negatively affects tree health and has caused the decline of the native red squirrel Sciurus vulgaris. Oral contraceptives are being developed to manage the impacts of the grey squirrel. To be effective, contraceptives will need to be deployed at a landscape scale, and will require a delivery system that is practical and economically viable. Understanding grey squirrel feeding behaviour is important so that delivery methods can be designed so that a sufficient number oftarget individuals receive an effective contraceptive dose at a time of year that will ensure their infertility throughout peak times of breeding. The main aims of this study were to assess how sex, season, squirrel density and bait point density influenced; (1) the probability of a squirrel visiting a feeder and (2) the amount of bait consumed from feeders. Field trials were conducted on six woodland populations of squirrels in three seasons, with four days of bait deployment via purpose-designed squirrel-specific bait hoppers with integrated PIT-tag readers. It was possible to deliver multiple doses on most days to most male and female grey squirrels, with bait deployment more likely to be effective in spring, immediately before the second annual peak in squirrel breeding, followed by winter, immediately before the first peak in breeding. The results from this study could be used to design methods for delivering oral contraceptive baits to grey squirrels in the future and the methods used could be applied to other small mammal species and other bait delivery systems. © 2024 Crown copyright and The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. This article is published with the permission of the Controller of HMSO and the King's Printer for Scotland.

It is good to be average: Ecological correlates of breeding phenology in an Arctic seabird, Alle alle (Dovekie)

Abstract Recognizing the deviation in an animal’s behavior from a population mean is not only necessary to understand the evolution and stability of the whole system but also to predict the future of a population in a changing environment. Arctic seabirds are expected to exhibit high synchronization in timing of breeding at the population level, due to highly seasonal and harsh environmental conditions. Nevertheless, even in such a highly synchronized system, there are always some earlier and later breeders, and the drivers of inter-pair variation remain largely unknown. Using an 8-year dataset on Alle alle (Dovekie), a small Arctic seabird, we examined potential drivers of breeding phenology. We found that A. alle pairs were quite repeatable in their phenology, and preserved their phenological status, with their chicks hatching consistently before, during, or after the population median date for hatching, despite that the calendar position of the median shifted between years. This would suggest that timing of breeding is associated with some pair characteristics, either via properties of the nest and/or some partner’s traits. However, breeding phenology of the pair was not dependent on nest location, pair bond duration or morphological similarity of the partners. Importantly, timing of breeding was negatively associated with chick growth rate, indicating fitness consequences of phenology. A simulation in our study further suggests that the chance of fledgling survival in the context of predation may be the highest for the chicks that hatched during the peak of the hatching period. While our results suggest that the timing of the breeding is important for the reproductive outcome, further research is required to determine the drivers of the consistent breeding phenology within A. alle pairs.

Potential drivers of differences in breeding phenology as a component of life history strategies among coexisting species

Abstract Breeding phenology can have strong demographic consequences. Yet, the reasons why coexisting animal species differ in breeding phenology have received little attention. We tested selection pressures that underlie life history variation, such as age‐specific mortality, diet, and body size to explain breeding phenology of 16 coexisting songbird species in arid shrubland in South Africa. The average start and end dates for the earliest and latest species differed by 1.5 months, with a gradient among remaining species. Nest predation risk generally increased through the season, although species differed in seasonal patterns. Species with lower annual adult mortality, greater seasonal increases in nest predation, and greater nest predation rates had earlier start and stop dates, thereby reducing demographic risks. Species with higher adult mortality had larger brood sizes that require more food and they bred later when food was more abundant. Evolved timing of breeding thereby reflected risk management and food availability related to longevity and brood size. These factors may place unrecognized constraints on within‐species responses to climate change. Given the importance of phenology for fitness, phenology should be integrated as a core life history trait in future theory, and evolutionary constraints need to be considered in responses to climate change. Read the free Plain Language Summary for this article on the Journal blog.

A review of MPTP-induced parkinsonism in adult zebrafish to explore pharmacological interventions for human Parkinson's disease.

Novel work in adult zebrafish, Danio rerio, to recapitulate human neurodegenerative disease has proven useful in both pharmaceutical development and research on genetic disease. Due to high genetic homology to humans, affordable husbandry, relatively quick life cycle breeding times, and robust embryo production, zebrafish offer a promising model to test pharmaceutical performance in a high throughput, in vivo setting. Currently, most research in zebrafish models of Parkinson's disease induces the disease in larval or embryonic stage organisms due to ease of administration, with advancement through developmental stages taking only a matter of days. The use of early-stage organisms limits the usability of zebrafish as models for adult disease and specifically age-related neurodegenerative conditions. Recently, researchers have sought to extend the usability of zebrafish into models for Parkinson's disease. Specifically, 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has emerged as a prodrug that upon injection well-encompasses the biochemical mechanisms and symptomology associated with Parkinson's disease. By utilizing MPTP in an adult zebrafish model, advancements in Parkinson's disease research may be achieved. This paper highlights the recent research on this model, comparing it to the human form of Parkinson's disease.

An efficient AAV vector system of Rec2 serotype for intravenous injection to study metabolism in brown adipocytes in vivo

ObjectiveRecombinant adeno-associated virus (rAAV) vectors are powerful tools for the sustained expression of proteins in vivo and have been successfully used for mechanistic studies in mice. A major challenge associated with this method is to obtain tissue specificity and high expression levels without need of local virus administration. MethodsTo achieve this goal for brown adipose tissue (BAT), we developed a rAAV vector for intravenous bolus injection, which includes an expression cassette comprising an uncoupling protein-1 enhancer-promoter for transcription in brown adipocytes and miR122 target sequences for suppression of expression in the liver, combined with packaging in serotype Rec2 capsid protein. To test tissue specificity, we used a version of this vector expressing Cre recombinase to transduce mice with floxed alleles to knock out MLXIPL (ChREBP) or tdTomato-Cre reporter mice. ResultsWe demonstrated efficient Cre-dependent recombination in interscapular BAT and variable effects in minor BAT depots, but little or no efficacy in white adipose tissues, liver and other organs. Direct overexpression of glucose transporter SLC2A1 (GLUT1) using the rAAV vector in wild type mice resulted in increased glucose uptake and glucose-dependent gene expression in BAT, indicating usefulness of this vector to increase the function even of abundant proteins. ConclusionTaken together, we describe a novel brown adipocyte-specific rAAV method to express proteins for loss-of-function and gain-of-function metabolic studies. The approach will enable researchers to access brown fat swiftly, reduce animal breeding time and costs, as well as enable the creation of new transgenic mouse models combining multiple transgenes.

Multi-dimensional niche differentiation of two sympatric breeding secondary cave-nesting birds in Northeast China using DNA metabarcoding.

Niche theory predicts that ecologically similar sympatric species should show differentiation in at least one of the main niche dimensions (time, space, and/or food). Here, we combined observations of breeding timing, nest site selection, and diet (the latter determined using DNA metabarcoding) to analyze the niche overlap and differentiation between two sympatric secondary cavity-nesting birds, the Japanese Tit Parus minor and the Yellow-rumped Flycatcher Ficedula zanthopygia. The results showed that (1) there were significant differences in the first egg laying date, length of the egg laying period, incubation date, and hatching date between tits and flycatchers, and the breeding time of flycatchers peaked later (about 30 days) than that of tits; (2) the two species had a large overlap in nest site selection, although the canopy coverage and shrub density of flycatchers were significantly higher than those of tits; and (3) the niche overlap in diet was minimal, with both species heavily relying on Lepidoptera (39.6% and 63.7% for tits and flycatchers, respectively), but with flycatchers consuming significantly higher percentages of Lepidoptera, Diptera, and Coleoptera than tits. The results indicate that these two sympatric secondary cavity-nesting species have significant niche differentiation in breeding time and diet, but little differentiation in nest site selection.

Relative breeding timing and reproductive success of a resident montane bird species.

Wild populations appear to synchronize their reproductive phenology based on numerous environmental and ecological factors; yet, there is still individual variation in the timing of reproduction within populations and such variation may be associated with fitness consequences. For example, many studies have documented a seasonal decline in reproductive fitness, but breeding timing may have varying consequences across different environments. Using 11 years of data, we investigated the relationship between relative breeding timing and reproductive success in resident mountain chickadees (Poecile gambeli) across two elevational bands in the Sierra Nevada mountains, USA. Chickadees that synchronized breeding with the majority of the population ('peak' of breeding) did not have the highest breeding success. Instead, birds that bred early performed best at high elevation, while at low elevation early and peak nests performed similarly. At both elevations, late nests consistently performed the worst. Overall, breeding success decreased with increasing relative timing at both high and low elevations, but the relationship between breeding success and timing differed among years. Our results suggest that in mountain chickadees, earlier breeding is associated with higher reproductive success, especially at high elevations, while late breeding is consistently associated with lower reproductive success at both elevations.

Breeding records of 325 bird species from Peru over 21 years based on citizen science data

AbstractBreeding is a key component of the life history of birds. Documenting diverse aspects of their breeding biology provides valuable natural history data that can be used to address questions of evolutionary, ecological, or conservation significance. Despite its importance, this information is scarce for most Neotropical species. We compiled 1180 breeding records corresponding to 325 bird species for the period 2000–2021, through an in‐depth review of photo or video records from Peru, sourced from Macaulay Library and iNaturalist platforms. We determined the geographical distribution of the breeding records, described patterns of activity and nesting behavior (i.e., host plant preference and clutch size), and explored the timing of breeding. Our study represents one of the few efforts to provide nationwide data on breeding birds in the Neotropical region. We also offer broad taxonomic coverage for further studies interested in testing hypotheses on the variation of reproductive traits and timing at both local and regional scales. The complete data set for this abstract published in the Data Article section of the journal is available in electronic format in MetaCat in JaLTER at http://db.cger.nies.go.jp/JaLTER/metacat/metacat/ERDP-2024-07.1/jalter-en.

Whole-genome sequencing of a worldwide collection of sugarcane cultivars (Saccharum spp.) reveals the genetic basis of cultivar improvement.

Sugarcane is the main source of sugar worldwide, and 80% of the sucrose production comes from sugarcane. However, the genetic differentiation and basis of agronomic traits remain obscure. Here, we sequenced the whole-genome of 219 elite worldwide sugarcane cultivar accessions. A total of approximately 6 million high-quality genome-wide single nucleotide polymorphisms (SNPs) were detected. A genome-wide association study identified a total of 2198 SNPs that were significantly associated with sucrose content, stalk number, plant height, stalk diameter, cane yield, and sugar yield. We observed homozygous tendency of favor alleles of these loci, and over 80% of cultivar accessions carried the favor alleles of the SNPs or haplotypes associated with sucrose content. Gene introgression analysis showed that the number of chromosome segments from Saccharum spontaneum decreased with the breeding time of cultivars, while those from S. officinarum increased in recent cultivars. A series of selection signatures were identified in sugarcane improvement procession, of which 104 were simultaneously associated with agronomic traits and 45 of them were mainly associated with sucrose content. We further proposed that as per sugarcane transgenic experiments, ShN/AINV3.1 plays a positive role in increasing stalk number, plant height, and stalk diameter. These findings provide comprehensive resources for understanding the genetic basis of agronomic traits and will be beneficial to germplasm innovation, screening molecular markers, and future sugarcane cultivar improvement.

Seasonality of breeding by Chukar Partridge Alectoris chukar on Robben Island

Eight records suggest that the timing of breeding of the introduced Chukar Partridge Alectoris chukar on Robben Island can tentatively be described as from September to November.

How interacting anthropogenic pressures alter the plasticity of breeding time in two common songbirds.

Phenological adjustment is the first line of adaptive response of vertebrates when seasonality is disrupted by climate change. The prevailing response is to reproduce earlier in warmer springs, but habitat changes, such as forest degradation, are expected to affect phenological plasticity, for example, due to loss of reliability of environmental cues used by organisms to time reproduction. Relying on a two-decade, country-level capture-based monitoring of common songbirds' reproduction, we investigated how habitat anthropization, here characterized by the rural-urban and forest-farmland gradients, affected the average phenology and plasticity to local temperature in two common species, the great tit Parus major and the blue tit Cyanistes caeruleus. We built a hierarchical model that simultaneously estimated fledging phenology and its response to spring temperatures based on the changes in the proportion of juveniles captured over the breeding season. Both species fledge earlier in warmer sites (blue tit: 2.94 days/°C, great tit: 3.83 days/°C), in warmer springs (blue tit: 2.49 days/°C, great tit: 2.75 days/°C) and in most urbanized habitats (4 days for blue tit and 2 days for great tit). The slope of the reaction norm of fledging phenology to spring temperature varied across sites in both species, but this variation was explained by habitat anthropization only in the deciduous forest specialist, the blue tit. In this species, the responses to spring temperature were shallower in agricultural landscapes and slightly steeper in more urban areas. Habitat anthropization did not explain variation in the slope of the reaction norm in the habitat-generalist species (great tit), for which mean fledgling phenology and plasticity were correlated (i.e., steeper response in later sites). The effects of habitat change on phenological reaction norms provide another way through which combined environmental degradations may threaten populations' persistence, to an extent depending on species and on the changes in their prey phenology and abundance.

Nest survival of Crested Lark (Galerida cristata) in intensively used habitats in Central Poland

Breeding success of birds depends on survival during two critical stages of the reproductive period: First, egg laying and incubation, and then nestling and fledgling. This essential element of avian life history mirrors an evolutionary adaptation of parents to existing environmental conditions. The main factors that determine nest survival involve weather, predation and sibling competition. Despite numerous studies documenting their impact on breeding success, only a few have analysed the issue with regard to ground-nesting birds and estimated their survival functions. Therefore, we decided to examine nest survival probability of the Crested Lark (Galerida cristata) in a population that occupies newly established roadside habitats in Central Poland. The analysis is based on 141 nests monitored between 2018 and 2022. We found that the mean survival probability of the whole nesting period was 0.376, and it was higher during the egg stage (0.836) than during the nestling period (0.392). The Cox proportional hazards model shows that nest survival in the nestling stage is mainly affected by the time of breeding and the distance from the road edge, and also by mean temperature of the whole nesting period. In other words, the probability of a brood failure in the nestling stage decreases as the breeding season advances, whereas it increases among nests located closer to the road edge. Furthermore, during the whole nesting period, nest failure decreases as the temperature rises. Our study suggests that the Crested Lark, being a multi-brood and thermophilic species inhabiting temperate regions, may benefit more if its nesting attempts begin later during the season when breeding conditions become more favourable. However, we also take into consideration a hypothesis that nesting in grassy habitats near road edges may prove to be an ecological trap, attracting high densities of nesting birds but leading to their low nest success.