Timing Of Breeding Research Articles

Delayed egg-laying in Red-backed Shrike Lanius collurio in relation to increased rainfall in east-central Poland

Climate change has affected the breeding parameters of many animal species. In birds, most studies have focused on the effects of temperature on clutch phenology and clutch size. The long-term influence of other weather factors, including rainfall, on breeding parameters have been analysed much less often. Based on a 23-year dataset and 308 broods, we documented shifts in the timing of breeding, clutch size and mean egg volume in a long-distance migrant, the Red-backed Shrike Lanius collurio, from a central European population. We found a 5-day shift towards delayed breeding, but no differences in brood size or egg volume during those 23 years. The GLM analysis showed that the mean May temperature had a positive influence on the clutch initiation date, whereas the number of days with rain delayed laying. During the period 1999–2021, there was no change in the mean May temperature, but total precipitation and the number of days with rain in May increased. Thus, delayed nesting in this population was probably due to the increase in rainfall during this period. Our results provide a rare example of delayed nesting in birds in recent years. Predicted changes in the climate make it difficult to assess the long-term impact of global warming on the viability of Red-backed Shrike populations in east-central Poland.

Rapid formation of new migration route and breeding area by Arctic geese

Many Arctic-breeding animals are at risk from local extirpation associated with habitat constriction and alterations in phenology in their Arctic environment as a result of rapid global warming.1 Migratory species face additional increasing anthropogenic pressures along their migratory routes such as habitat destruction, droughts, creation of barriers, and overexploitation.2,3 Such species can only persist if they adjust their migration, timing of breeding, and range.4 Here, we document both the abrupt (∼10 years) formation of a new migration route and a disjunct breeding population of the pink-footed goose (Anser brachyrhynchus) on Novaya Zemlya, Russia, almost 1,000km away from the original breeding grounds in Svalbard. The population has grown to 3,000-4,000 birds, explained by intrinsic growth and continued immigration from the original route. The colonization was enabled by recent warming on Novaya Zemlya. We propose that social behavior of geese, resulting in cultural transmission of migration behavior among conspecifics as well as in mixed-species flocks, is key to this fast development and acts as a mechanism enabling ecological rescue in a rapidly changing world.

Nanoplastics induce more severe multigenerational life-history trait changes and metabolic responses in marine rotifer Brachionus plicatilis: Comparison with microplastics

Micro/nanoplastics (MPs/NPs) have attracted global attention for their potential adverse impacts on marine ecosystems. This study investigated the impacts of MPs/NPs (70 nm, 500 nm, and 2 µm) on population growth and life-history traits of marine rotifer (Brachionus plicatilis), and further explored the differences from the aspects of nutrient accumulation and metabolomic profiles. The results showed that 200 and 2000 µg/L 70 nm NPs significantly suppressed population growth, and negatively affected life span, the first spawning and breeding time, and fecundity in F0–F2 generation rotifers. Whereas 500 nm NPs and 2 µm MPs showed no effect on population growth 200 µg/L and only changed the life-history traits at the highest concentration. Moreover, 70 nm NPs were more easily accumulated in the rotifers and reduced food ingestion and nutrient accumulation, which caused more severe disruption on purine-pyrimidine metabolism, tricarboxylic acid cycle, and protein synthesis pathway compared to 500 nm NPs. Thus, the smaller the size of the plastic particles, the stronger the toxicity to the rotifers. This study provided new insights into the toxicity of MPs/NPs on marine zooplankton and proposed that metabolomics was powerful to explore the toxicity mechanisms of MPs/NPs.

Insights into Transcriptomic Differences in Ovaries between Lambs and Adult Sheep after Superovulation Treatment

Superovulation technology shows a great potential for shortening breeding time. Using the juvenile superovulation technology, juvenile animals can generate more follicles than adult animals. By sequencing using high-throughput methods, we studied and described differentially expressed (DE) long non-coding RNA (lncRNAs) and messenger RNAs (mRNAs) in the ovaries of young and adult sheep. Herein, 242 DE lncRNAs and 3150 DE mRNAs were screened. Through GO and KEGG analyses, we obtained genes related to ovarian/follicle development and ovulation in DE mRNAs, including OaFSHR, OaLHCGR, OaLDLR, OaZP3, OaSCARB1, and OaPDGFRA; through lncRNA-mRNA correlation analysis, we found that genes associated with ovarian/follicle development or ovulation include: XR_003585520.1, MSTRG.15652.1, XR_003588840.1, and their paired genes PDGFC, LRP5, and LRP1. We observed a synergistic effect between PDGFR and LRP1. PDGFR may play a leading role compared with LRP1. The induced LHCGR in lambs is higher than in adult sheep, showing more sensitivity to LH. The release of the oocytes was stimulated. Among the three lncRNAs, we found that XR_003588840.1 was significantly different and might perform a regulatory role in ovarian/follicle growth or ovulation.

Development of the control system for Artificial Reproduction of Fish Populations Based on a Complex of Neroendocrinological research and Biotech Innovations

The participation of the hypothalamic-hypophysial neurosecretory system (HHNS) in fish reproduction using light, electron microscopy and immunocytochemistry was established by ecologo-histophysiological studies for the first time in the world literature. At the beginning of passing fish migrations a violation of the HHNS basic osmoregulative function, causing habitat change is revealed. Simultaneously the HHNS causes the neurotropic effect on the central nervous system (CNS) arousal in the form of a dominant state of "Migration impulse." At the beginning of spawning, HHNS also initiates spawning behavior and completes it by participating in the body's protective-adaptive reactions to natural physiological stress. The functional role of the HHNS in fish reproduction is to initiate energy-intensive (reproductive) processes of migratory and spawning behaviors and to complete spawning by suppressing the hyperactivity of target glands, which ensures the body's transition to energy-saving plastic exchange. The analysis of the key role of the HHNS in the integration of fish reproduction by the self-regulation principle has allowed the development of a constructive working scheme. New biotech methods of managing breeding time, rates of survival and growth of valuable fish species were developed on this basis. They are presented in the form of 10 inventions. To stimulate sex maturation, drugs of isolated anterior and posterior pituitary lobes were developed and introduced in sturgeon industry, increasing the extent of their fish-breeding use by 15% and saving the pituitary up to 40%. To delay puberty, a method of industrial fish breeders reservation in the critical salinity habitat of 4-8%, both in seawater and in table salt solutions has been developed. On this basis, a full-system method of sturgeon and salmon fish populations reproduction, covering all stages of farm biotechnology has been developed. It is carried out by mass breeders reservation in sea cages, obtaining there offspring and, after the river fish-farm growing youngs to their readiness for migration, the final cultivation them in sea cages gardens till large life-resistant youngs. For the implementation of the proposed industrial biotechnology and year-round fish farming a new installation of recirculating aquaculture systems (RAS) hatcheries and farms was developed by means of the off-season underground conditioning of fish cultivation habitat and by the principle of natural-industrial engineering ecology. Due to the general aim ‒ increasing the efficiency biotechnology of reproduction and logical relationships, all developments are integrated into the system of biotech management of fish population reproduction.

Four decades of phenology in an alpine amphibian: trends, stasis, and climatic drivers

Strong phenological shifts in response to changes in climatic conditions have been reported for many species, including amphibians, which are expected to breed earlier. Phenological shifts in breeding are observed in a wide number of amphibian populations, but less is known about populations living at high elevations, which are predicted to be more sensitive to climate change than lowland populations. The goal of this study is to assess the main factors determining the timing of breeding in an alpine population of the common toad (Bufo bufo) and to describe the observed shifts in its breeding phenology. We modelled the effect of environmental variables on the start and peak dates of the breeding season using 39 years of individual-based data. In addition, we investigated the effect of the lunar cycle, as well as the individual variation in breeding phenology. Finally, to assess the individual heterogeneity in the timing of breeding, we calculated the repeatability of the timing of arrival at the breeding site. Breeding advanced to earlier dates in the first years of the study but the trend continued only until the mid 1990s, and stabilised afterwards. Overall, toads are now breeding on average around 30 days earlier than at the start of the study period. High temperatures and low snow cover in winter and spring, as well as reduced spring precipitation were all associated with earlier breeding. Additionally, we found evidence of males arriving on average before females at the breeding site but no clear and strong effect of the lunar cycle. We only found weak evidence of among-individual variation in shifts in the breeding phenology, as well as a low repeatability of arrival timing. Our findings show that the observed changes in breeding phenology are strongly associated with the environmental conditions. These results contribute to filling a knowledge gap on the effects of climate change on alpine amphibian populations. Moreover, we show that changes in phenology, especially in the mountains, can be hard to predict as local microclimatic conditions do not necessarily reflect the observed global climatic trends.

Fishing Enclosure as a Simple Approach to Stimulate Spawning Success of Tenualosa ilisha (Hamilton, 1822) in Bangladesh

The study was intended to assess the impact of fishing enclosure during the peak breeding time of hilsa, Tenualosa ilisha on its breeding success. During the last peak breeding season of hilsa (October 4-25, 2021) a comprehensive investigation was attempt to evaluate the impact of fishing enclosure by “MV Rupali Ilish” research vessel, speedboat and experimental fishing net were deployed to demeanor a rigorous investigation in and around the spawning grounds areas (about 7,000 sq km, including Moulvirchar, Monpura, Dhalchar and Kalirchar). Additionally, data were also assumed from landing stations (via terrestrial cruises) near the spawning ground areas and other hilsa prone region of Bangladesh. The percentage of spent hilsa (locally called pite) and oozing hilsa were monitored following a standard protocol. Among all the hilsa captured in and around the spawning grounds, the proportion of male and female were 16-41% and 85-97%, respectively of the total catch, suggesting a male and female sex ratio (1:2.3). The rate of breeding success in 2021 was 51.76% i.e., 51.7% hilsa successfully participated in the breeding process which was 103.52% higher than the base year (2001-02). The approximate number of fertilized eggs in 2021 was 7,86,314 kg. Increased production of hilsa eggs and jatka indicated a positive impact of twenty-two days fishing enclosure. Percentages of gravid and oozing hilsa were also found higher compared to previous years. Due to the prohibition of all types of fishing, the percentage of female hilsa in the breeding areas increased up to 83.96%. Overall, twenty-two days fishing enclosure was found very effective for successful spawning of hilsa.

Assessing the breeding phenology of a threatened frog species using eDNA and automatic acoustic monitoring.

Climate change has driven shifts in breeding phenology of many amphibians, causing phenological mismatches (e.g., predator-prey interactions), and potentially population declines. Collecting data with high spatiotemporal sensitivity on hibernation emergence and breeding times can inform conservation best practices. However, monitoring the phenology of amphibians can be challenging because of their cryptic nature over much of their life cycle. Moreover, most salamanders and caecilians do not produce conspicuous breeding calls like frogs and toads do, presenting additional monitoring challenges. In this study, we designed and evaluated the performance of an environmental DNA (eDNA) droplet digital PCR (ddPCR) assay as a non-invasive tool to assess the breeding phenology of a Western Chorus Frog population (Pseudacris maculata mitotype) in Eastern Ontario and compared eDNA detection patterns to hourly automatic acoustic monitoring. For two eDNA samples with strong PCR inhibition, we tested three methods to diminish the effect of inhibitors: diluting eDNA samples, adding bovine serum albumin to PCR reactions, and purifying eDNA using a commercial clean-up kit. We recorded the first male calling when the focal marsh was still largely frozen. Chorus frog eDNA was detected on April 6th, 6 days after acoustic monitoring revealed this first calling male, but only 2 days after males attained higher chorus activity. eDNA signals were detected at more sampling locales within the marsh and eDNA concentrations increased as more males participated in the chorus, suggesting that eDNA may be a reasonable proxy for calling assemblage size. Internal positive control revealed strong inhibition in some samples, limiting detection probability and quantification accuracy in ddPCR. We found diluting samples was the most effective in reducing inhibition and improving eDNA quantification. Altogether, our results showed that eDNA ddPCR signals lagged behind male chorusing by a few days; thus, acoustic monitoring is preferable if the desire is to document the onset of male chorusing. However, eDNA may be an effective, non-invasive monitoring tool for amphibians that do not call and may provide a useful complement to automated acoustic recording. We found inhibition patterns were heterogeneous across time and space and we demonstrate that an internal positive control should always be included to assess inhibition for eDNA ddPCR signal interpretations.

Low‐temperature nights delay the timing of breeding in a wild songbird

Global climate change has posed widespread challenges to the ecological process critical to the fitness of many wild organisms, such as reproductive phenology. Many bird species have advanced their reproductive phenology in response to the increases in spring temperatures. However, the mechanism of how climate influences the timing of breeding is still often unclear in many species. We explored the relationship between the timing of breeding and spring temperatures based on 14 years of data on hair‐crested drongos Dicrurus hottentottus in the wild. By applying a ‘sliding window' approach, we aimed to identify the time window and weather variable that best explains the timing of breeding at both population and individual levels. We found that the more nights with a minimum temperature below 17°C, around three weeks earlier than the peak reproduction, delayed the breeding time. Low night temperatures may force females to allocate more energy to thermoregulation and therefore physiologically constrain egg‐laying. Although annual minimum and maximum temperatures have increased over the study period, the timing of breeding showed no trend as there was no change in the number of low‐temperature nights in the relevant period across years. The repeatability of the laying date for individual females (R = 0.211) and across the years (R = 0.270) were low indicating that drongos were flexible in adjusting their breeding phenology to environmental variation. These results suggest an effect of low night temperature on avian breeding phenology. This effect may apply commonly across bird species considering shared physiological constraints.

Novel SNP Markers and Their Application in Low-Cyanide Cassava (Manihot esculenta crantz) Breeding Program

The major flaw of cassava is its indigenous cyanide. Traditional breeding program for diminishing cyanide in cassava take a long waiting time for harvesting cassava tubers to assess cyanide content. Genetic markers are useful for selection of good agricultural traits, which also applied in low-cyanide cassava breeding programs by detecting gene associate with cyanide content in cassava. Therefore, the objective of this study was to develop SNP markers to detect low cyanide trait in cassava. Genotype analysis was carried out using Genotyping by Sequencing (GBS) technology assembling with phenotype analysis. Then, the SNP markers associated with cyanide content were found. Afterward, the primers of SNP marker associated with cyanide content 2 positions were developed using tetra-primer ARMS-PCR techniques. S16_640082 and S16_735381 SNP markers on chromosome 16 showed potential ability of the selection of cassava varieties with cyanide content less than 250 mg HCN/kg fresh weight. The selection accuracy of S16_640082 and S16_735381 SNP markers was 73.33 and 76.64 %, respectively. These markers could be used in marker assisted selection (MAS) in cassava seedling. It substantially reduces cassava breeding programs cost and time. HIGHLIGHTS The major flaw of cassava is its indigenous cyanide. Up to our knowledge, there is rarely report on SNP marker related to cyanide content in Thai cassava population By performing genome wide association mapping (GWAS) to characterize the genome position related to HCN, 2 novel SNP markers associated with cyanide content were found The primers to detect the SNP markers were developed using tetra-primer ARMS-PCR techniques The markers showed ability of the selection of cassava varieties with cyanide content less than 250 mg HCN/kg fresh weight GRAPHICAL ABSTRACT

Effects of dam construction on the reproduction of the Yellow River carp (Cyprinus carpio) in lower reaches of the Yellow River, China

The construction of dams changes the natural flow of rivers, affects the integrity of river ecosystems, and causes a series of ecological and environmental problems, such as habitat fragmentation and reduction in fish resources. This study took a section of the Yellow River in China from the Xiaolangdi Dam to Gaocun as the research area. The Yellow River carp (Cyprinus carpio) was selected as an indicator species for its economic value. A habitat suitability model for the Yellow River carp coupled with a one-dimensional hydrodynamic model was built. It was used to simulate dynamic changes in the reproductive habitat suitability of the Yellow River carp before and after the construction of the Xiaolangdi Dam. We demonstrated the spatial distribution of the carp’s spawning reaches before and after the Xiaolangdi Dam construction and investigated its influence on the spawning activity and larval development of the species accordingly. The results apparently showed that the construction and operation of the Xiaolangdi Dam delayed the breeding time of the Yellow River carp and decreased its quality by 5.28%. In particular, the larval fish development was greatly affected by the dam, with the quality being reduced by 8.95%. Furthermore, the habitat suitability of the spawning reaches slightly decreased as the extent of spawning reaches decreased by 16.23%, and several spawning reaches were lost entirely. This study shed light on the response of the Yellow River carp to hydrological and physical changes in the period 1980–1990 before the construction of the Xiaolangdi Dam and 2006–2018 after the construction. Thus, it is a valuable reference for the ecological scheduling of discharges of the Xiaolangdi Dam.

The Effect of Floods on Nest Survival Probability of Common Sandpiper Actitis hypoleucos Breeding in the Riverbed of a Large Lowland European River

The natural valleys of large rivers provide suitable nesting and foraging sites for many bird species. In this study, we assess the effects of water fluctuations during the breeding season on Common Sandpipers’ nest survival on a semi-natural section of the Vistula River, and evaluate which tactics this species can adopt to minimise the effects on a long-term scale. Birds can avoid losses due to flooding by adjusting the timing of nesting to avoid the occurrence of extreme water conditions, and/or by choosing a safe nesting location. We found that nest location is a direct response to periodic high water, and the threat of flooding seems to be one of the important determinants of Common Sandpiper nest placement. The choice of nest location is not random, as 70% of pairs nested above a height that provides an 80% chance of avoiding flooding of the nest. For the lowest-lying nests found in this study, nesting success was reduced up to 92% because of inundation. Birds choose more elevated places, even during the second half of the season when the threat of flooding is lower. Their preference for nesting above a certain height does not change over the breeding season, which corresponds to the very small impact of the date of first egg laying on breeding success. Those who breed earlier in the season have a slightly higher risk of being flooded, but nesting in more elevated places reduces this risk much more than shifting the time of breeding.

Determinants of departure to natal dispersal across an elevational gradient in a long-lived raptor species.

Attributes of natal habitat often affect early stages of natal dispersal. Thus, environmental gradients at mountain slopes are expected to result in gradients of dispersal behavior and to drive elevational differences in dispersal distances and settlement behavior. However, covariation of environmental factors across elevational gradients complicates the identification of mechanisms underlying the elevational patterns in dispersal behavior. Assuming a decreasing food availability with elevation,we conducted a food supplementation experiment of red kite (Milvus milvus) broods across an elevational gradient toward the upper range margin and we GPS-tagged nestlings to assess their start of dispersal. While considering timing of breeding and breeding density across elevation, this allowed disentangling effects of elevational food gradients from co-varying environmental gradients on the age at departure from the natal home range. We found an effect of food supplementation on age at departure, but no elevational gradient in the effect of food supplementation. Similarly, we found an effect of breeding density on departure age without an underlying elevational gradient. Supplementary-fed juveniles and females in high breeding densities departed at younger age than control juveniles and males in low breeding densities. We only found an elevational gradient in the timing of breeding. Late hatched juveniles, and thus individuals at high elevation, departed at earlier age compared to early hatched juveniles. We conclude that favorable natal food conditions, allow for a young departure age of juvenile red kites. We show that the elevational delay in breeding is compensated by premature departure resulting in an elevational gradient in departure age. Thus, elevational differences in dispersal behaviour likely arise due to climatic factors affecting timing of breeding. However, the results also suggest that spatial differences in food availability and breeding density affect dispersal behavior and that their large-scale gradients within the distributional range might result in differential natal dispersal patterns.

Timing of breeding as a determinant of nest success of the vulnerable Chestnut Seedeater (Sporophila cinnamomea) in grasslands of southern South America

The breeding traits of Sporophila seedeaters have been relatively well studied in recent years; nevertheless, a group of ten species in the genus, known as southern capuchinos, remain understudied. That is the case with Chestnut Seedeater (Sporophila cinnamomea), a species vulnerable to extinction, which breeds in the grasslands of southeast South America and, after reproduction, migrates towards the Cerrado region in central Brazil. Here, we investigated breeding ecology and calculated average clutch size, productivity, the sex ratio of nestlings, and estimated nest success. Then we tested (1) whether there is a relationship between the number of active nests and environmental variables, (2) whether the nestling sex ratio deviates from the 1:1 ratio, (3) whether clutch size varies between breeding seasons, and (4) whether the nest success is related to starting date, nest age, plant support, nest height from the ground, and clutch size. During two breeding seasons (October–March 2018–2020), we monitored 98 nests. We generated survival models with five interacting covariates to assess the survival of the nests. We recorded the entire breeding period for Chestnut Seedeater, which was estimated to be 4.6 months, similar to other migratory seedeaters. Clutch size did not differ between breeding seasons. The sex ratio of nestlings was not significantly different from the 1:1 ratio. Nest success was 31%, and predation was the leading cause of unsuccessful nests (83%). The daily survival rate was 0.95 ​± ​0.01. The main predictor of nest survival was the covariate starting date. These findings, added to other aspects of the species' natural history described here, may help illuminate the ecology and behavior of Chestnut Seedeater and other southern endangered capuchinos, and grassland-dependent species of South America.

Ultrasonography assisted estrus detection improves the submission rate in prostaglandin treated sub-estrus Murrah buffaloes

Sub-estrus is a condition in buffalo in which the ovarian picture and uterine changes suggest the presence of estrus and cyclicity, despite the absence of behavioural symptoms. The current study describes the effects of ultrasonography (USG)-aided estrus detection on submission and conception rate in sub-estrus Murrah buffaloes after a single shot of prostaglandin (PG) treatment. The study included 67 sub-estrus buffaloes between 2020 and 2021. The teaser bull was used to detect estrus, and the diameter of the pre-ovulatory follicle (POF) and corpus luteum (CL) was measured using transrectal USG. A single PG treatment induced behavioural estrus in 43.28% buffaloes (Gr. 1), while estrus were detected in 35.8% of sub-estrus buffaloes using sonographic examination (Gr. 2) that were otherwise remained undetected. The overall submission rate was 79.1 percent. The first-service conception rate was higher in Gr. 1 (55.2 vs. 33.3%), compared to Gr. 2. The CL diameter at pre-treatment was significantly larger in Gr. 1 buffaloes than in Gr.2 buffaloes. However, the POF diameter was comparable during induced estrus. Furthermore, the time elapsed between induction and breeding in both groups was comparable. Furthermore, the CL size at pre-treatment, POF size at estrus, and time elapsed to breeding had no effect on conception. Thus, the use of USG improves the submission rate in PG administered sub-estrus buffaloes, resulting in a 45.3% overall first service conception rate. However, breeding time must be optimised in order to improve the conception rate and efficient reproductive management in sub-estrus buffaloes in the field.

Correlational analysis of anuclear cell index and serum progesterone concentration for predicting the optimum time of breeding in subfertile bitches

Twenty bitches with previous history of subfertility presented for breeding management at University Veterinary Hospital, Kokkalai were selected for the study. The stage of oestrous cycle was determined and breeding scheduled based predominantly on anuclear cell index (ACI) and serum progesterone assay, after giving due weightage to behaviour and clinical signs. First mating was considered as day 0 and the second as day 3. The mean ACI of the bitches under study was 56.4 ± 1.53 per cent and the mean serum progesterone levels was recorded as 2.82± 0.16 ng/mL three days prior to breeding (day 3). Since, ACI had highly positive correlation with serum progesterone level (Pearson’s correlation coefficient being 0.880) in subfertile bitches three days prior to first breeding, it could be inferred that, when the mean ACI reached more than 55 per cent, serum progesterone levels reach values corresponding to presumably the day of LH surge and by considering both the variables, the day of ovulation could be predicted. Hence, the correlation analysis of ACI and progesterone assay can be considered as reliable method to schedule optimum breeding time in subfertile bitches.

In vivo embryo development in bitches inseminated laparoscopically after ovulation time estimated based on a single progesterone determination.

Logistic and economical limitations are often the causes of dog owners not accurately monitoring the estrous cycle and the optimal insemination time. The aim of this study was to evaluate in vivo early embryonic development in bitches, after the analysis of sequential vaginal cytologies associated to single progesterone measurement and single laparoscopic insemination with high quality semen (fresh and with high spermatozoa concentration) or low-quality semen (frozen/thawed and with low spermatozoa concentration) at 48 h post- ovulation time predicted on a single progesterone measurement. Ten bitches were inseminated with 250 x 106 fresh spermatozoa (80% motility), and ten with 80 x 106 frozen/thawed spermatozoa (60% motility) in the cranial part of each uterine horn. Seven days later, ovariohysterectomy was performed and the oviducts and uterine horns and body were flushed to recover embryos and unfertilized oocytes. In 80% of the bitches inseminated with fresh and 50% of bitches inseminated with frozen/thawed semen, embryos at 2 to 8 cells stage were recovered mostly from the, oviducts. This study indicates that pregnancies can be obtained with a single laparoscopic intrauterine insemination after single serum progesterone measurement, although with a low number of embryos. This result should be taken into account in case economic or logistic restrictions that affect the possibility of owners to plan an accurate monitoring of the optimal breeding time using fresh and frozen semen.

Assessing nitrogen dynamics model and the role of artificial lagoon in effluent loading of shrimp farms in Gomishan wetland, southern Caspian Sea

Shrimp farming increases the nutrients, especially nitrogen in the water resources reducing water quality. This study was conducted to evaluate the nitrogen dynamics in white shrimp (Litopenaeus vannamei) farms and the role of artificial lagoon (24 ha) in reducing nitrogen levels in Gomishan coastal wetland, the eastern Caspian Sea. The results indicated that at the end of the 4-month breeding period, the amounts of nitrogen and phosphorus introduced into Gomishan wetland were calculated as to 220.157 and 39 tons, respectively in a breeding area covering 830 hectares. Nitrogen values (based on nitrate) calculated based on the relationship between the basin and the discharge of the outlet channel of the site at the time of complete emptying of the farms, were calculated to be approximately 121.8 tons per breeding time that it had an important role in eliminating about 45% of nutrient pollution and reducing the concentration of dissolved nitrogen. Moreover, nitrogen isotopic trace was observed in shrimp samples, in similar levels in the samples of both shrimp pond and lagoon, which emphasizes the role of feeding from natural food, especially benthic fauna. Overall, due to the decline of Caspian Sea water level, Gomishan coastal wetland is drying, and the output of shrimp farms is currenly the only source supplying water for the wetland. Hence, appropriate management strategies could minimize the amounts of nutrients into the natural water whilst aiding wetland’s survaival.

Photoperiod and rainfall are associated with seasonal shifts in social structure in a songbird

Abstract Seasonally breeding animals often exhibit different social structures during non-breeding and breeding periods that coincide with seasonal environmental variation and resource abundance. However, we know little about the environmental factors associated with when seasonal shifts in social structure occur. This lack of knowledge contrasts with our well-defined knowledge of the environmental cues that trigger a shift to breeding physiology in seasonally breeding species. Here, we identified some of the main environmental factors associated with seasonal shifts in social structure and initiation of breeding in the red-backed fairywren (Malurus melanocephalus), an Australian songbird. Social network analyses revealed that social groups, which are highly territorial during the breeding season, interact in social “communities” on larger home ranges during the non-breeding season. Encounter rates among non-breeding groups were related to photoperiod and rainfall, with shifting photoperiod and increased rainfall associated with a shift toward territorial breeding social structure characterized by reductions in home range size and fewer encounters among non-breeding social groups. Similarly, onset of breeding was highly seasonal and was also associated with non-breeding season rainfall, with greater rainfall leading to earlier breeding. These findings reveal that for some species, the environmental factors associated with the timing of shifts in social structure across seasonal boundaries can be similar to those that determine timing of breeding. This study increases our understanding of the environmental factors associated with seasonal variation in social structure and how the timing of these shifts may respond to changing climates.

Variation in breeding phenology in response to climate change in two passerine species

Increasingly warmer springs have caused phenological shifts in both plants and animals. In birds, it is well established that mean laying date has advanced to match the earlier food peak. We know less about changes in the distribution of egg-laying dates within a population and the environmental variables that determine this variation. This could be an important component of how populations respond to climate change. We, therefore, used laying date and environmental data from 39 years (1983–2021) to determine how climate change affected laying date variation in blue tits (Cyanistes caeruleus) and marsh tits (Poecile palustris), two sympatric passerines with different life histories. Both species advanced mean laying date (0.19–0.24 days per year) and mean laying date showed a negative relationship with maximum spring temperature in both blue and marsh tits. In springs with no clear temperature increase during the critical time window (the time-window in which mean laying date was most sensitive to temperature) start of breeding in blue tits was distributed over a longer part of the season. However, there was no such pattern in marsh tits. Our findings suggest that temperature change, and not necessarily absolute temperature, can shape the variation in breeding phenology in a species-specific manner, possibly linked to variation in life-history strategies. This is an important consideration when predicting how climate change affects timing of breeding within a population.