Breeding Events Research Articles

Genetic evidence for polyandry in the threatened green and golden bell frog.

Identifying which species exhibit polyandry may lead to further insights into evolutionary biology and social behaviour. However, confirming polyandry can be difficult. High-resolution genetics provides a useful means to gain evidence. Although the threatened Pelodryadid frog, the green and golden bell frog Litoria aurea, has been subject to numerous ecological studies, there is uncertainty surrounding its reproductive ecology. Polyandry has not been formally identified in L. aurea or any species within the Pelodryadidae family. We aimed to identify if there was genetic evidence of polyandry in a population occurring in a wetland complex on Kooragang Island, New South Wales. To accomplish this, we collected genetic samples of tadpoles within the same size cohort about 20-30days after explosive breeding events. Genotypes of 14 females, nine males and 70 tadpoles were analysed with COLONY (1988 single nucleotide polymorphisms after filtering) to identify parentage, full-siblings and half-siblings. We found support for the hypothesis that L. aurea is polyandrous. Based on previous observations of multi-male matings and the narrow time periods that breeding occurred in, it is likely this species exhibits simultaneous polyandry. We discuss these results in regards to behavioural adaptive processes and avenues for further research.

Parental Care System and Brood Size Drive Sex Difference in Reproductive Allocation: An Experimental Study on Burying Beetles

Life-history theory predicts that increased resource allocation in current reproduction comes at the cost of survival and future reproductive fitness. In taxa with biparental care, each parent can adjust investment on current reproduction according to changes in their partner’s effort, but these adjustments may be different for males and females as they may have different reproductive strategies. Numerous theoretical and empirical studies have proposed the mechanism underlying such adjustments. In addition, the value of the brood or litter (brood size) has also been suggested to affect the amount of care through manipulation of brood size. While the two conditions have been studied independently, the impact of their interplay on potential sex-dependent future reproductive performance remains largely unknown. In this study, we simultaneously manipulated both care system (removal of either parent vs. no removal) and brood size in a burying beetle (Nicrophorus vespilloides) to understand their joint effect on reproductive allocation and trade-off between current and future reproduction. Our results show that males compensated for mate loss by significantly increasing the level of care regardless of brood size, while females exhibited such compensation only for small brood size. Additionally, with an increase in allocation to current reproduction, males showed decreased parental investment during the subsequent breeding event as a pair. These findings imply a dual influence of parental care system and brood size on allocation in current reproduction. Moreover, the impact of such adjustments on sex-dependent differences in future reproduction (parental care, larvae number, and average larval mass at dispersal) is also demonstrated. Our findings enhance the understanding of sex roles in parental investment and highlight their importance as drivers of reproductive allocation.

Ten Years on: Have Large Carnivore Reintroductions to the Eastern Cape Province, South Africa, Worked?

Large (>15 kg) carnivores, namely lions (Panthera leo), leopards (Panthera pardus), cheetahs (Acinonyx jubatus), African wild dogs (Lycaon pictus), spotted (Crocuta crocuta) and brown hyaenas (Parahyaena brunnea), have been reintroduced to 16 private- and state-owned reserves in the Eastern Cape Province, South Africa. Objectives behind these reintroductions ranged from ecotourism, ecological restoration, to species conservation. We reassessed the reintroductions' objectives and updated their outcomes a decade after the initial assessment. Ecotourism and ecological restoration were the most common objectives for the reintroduction of top predators to these reserves. With one exception, these reintroductions were successful in meeting their specific objectives, as only African wild dogs have failed to re-establish in the province. Assessments for leopards and brown hyaenas were inconclusive due to a lack of monitoring data. Causes of objective- and species-specific failures in some reserves included founding same-sex populations, lack of breeding events and changes in reserve management objectives. Long-term monitoring is essential in managing and assessing the success of conservation actions, including reintroductions of threatened species. Our review demonstrates this by highlighting changed outcomes for populations and identifying new challenges that have arisen in the landscape. In the modern parlance of conservation marketing, the multi-species reintroductions that occurred within the Eastern Cape represent successful rewilding within the province.

Low Repeatability of Breeding Events Reflects Flexibility in Reproductive Timing in the Pied Flycatcher Ficedula hypoleuca in Spain

Individual flexibility in breeding time is essential to respond to unpredictable changes in environmental conditions. Repeatability quantifies the consistency of the expression of phenotypes over time due to differences between individuals. Here, we estimate the repeatability of breeding date (laying date of first egg), hatching date and timing of pre-breeding events in a population of Pied Flycatchers Ficedula hypoleuca monitored over three decades in central Spain. We found low repeatabilities of breeding and hatching dates (respectively, R = 0.135 and R = 0) and among-year fluctuations (R = 0.276 and R = 0.218) in the expression of these traits. Repeatabilities of mating dates and of the interval between mating and egg laying were also very low (respectively R = 0.053 and R = 0) and among years (respectively R = 0.218 and R = 0.172), suggesting that Pied Flycatcher females are flexible to adjust their breeding schedule to current breeding conditions. We interpret the low consistency of traits related to breeding phenology as strong support for female phenotypic plasticity in breeding timing and the potential of such traits to respond to changing environmental conditions.—Le Vaillant, J., Potti, J., Camacho, C., Canal, D. & Martínez-Padilla, J. (2022). Low repeatability of breeding events reflects flexibility in reproductive timing in the Pied Flycatcher Ficedula hypoleuca in Spain. Ardeola, 69: 21-39.

Rainfall driven and wild-bird mediated avian influenza virus outbreaks in Australian poultry

Globally, outbreaks of Avian Influenza Virus (AIV) in poultry continue to burden economies and endanger human, livestock and wildlife health. Wild waterbirds are often identified as possible sources for poultry infection. Therefore, it is important to understand the ecological and environmental factors that directly influence infection dynamics in wild birds, as these factors may thereby indirectly affect outbreaks in poultry. In Australia, where large parts of the country experience erratic rainfall patterns, intense rainfalls lead to wild waterfowl breeding events at temporary wetlands and increased proportions of immunologically naïve juvenile birds. It is hypothesized that after breeding, when the temporary wetlands dry, increasing densities of immunologically naïve waterbirds returning to permanent water bodies might strongly contribute to AIV prevalence in wild waterfowl in Australia. Since rainfall has been implicated as an important environmental driver in AIV dynamics in wild waterbirds in southeast Australia and wild waterbirds are identified globally to have a role in virus spillover into poultry, we hypothesise that rainfall events have an indirect effect on AIV outbreaks in poultry in southeast Australia. In this study we investigated this hypothesis by examining the correlation between the timing of AIV outbreaks in poultry in and near the Murray-Darling basin in relation to temporal patterns in regional rainfall since 1970. Our findings support our hypothesis and suggest that the risk of AIV outbreaks in poultry increases after a period of high rainfall, with peak AIV risk two years after the onset of the high-rainfall period. This is presumably triggered by increased rates of waterbird breeding and consequent higher proportions of immunologically naïve juvenile waterbirds entering the population directly after major rainfall events, which subsequently aggregate near permanent water bodies when the landscape dries out.

The Nrf2a pathway impacts zebrafish offspring development with maternal preconception exposure to perfluorobutanesulfonic acid

Since the voluntary phaseout of perfluorooctanesulfonic acid (PFOS), smaller congeners, such as perfluorobutanesulfonic acid (PFBS) have served as industrial replacements and been detected in contaminated aquifers. This study sought to examine the effects of a maternal preconception PFBS exposure on the development of eggs and healthy offspring. Adult female zebrafish received a one-week waterborne exposure of 0.08, 0.14, and 0.25 mg/L PFBS. After which, females were bred with non-exposed males and embryos collected over 5 successful breeding events. PFBS concentrations were detected in levels ranging from 99 to 253 pg/embryo in the first collection but were below the limit of quantitation by fourth and fifth clutches. Therefore, data were subsequently binned into early collection embryos in which PFBS was detected and late collections, in which PFBS was below quantitation. In the early collection, embryo 24 h survival was significantly reduced. In the late collection, embryo development was impacted with unique patterns emerging between Nrf2a wildtype and mutant larvae. Additionally, the impact of nutrient loading into the embryos was assessed through measurement of fatty acid profiles, total cholesterol, and triglyceride content. There were no clear dose-dependent effects, but again unique patterns were observed between the genotypes. Preconception PFBS exposures were found to alter egg and embryo development, which is mediated by direct toxicant loading in the eggs, nutrient loading into eggs, and the function of Nrf2a. These findings provide insight into the reproductive and developmental effects of PFBS and identify maternal preconception as a novel critical window of exposure.

Does the female seahorse still prefer her mating partner after a period of separation?

For species showing sexual monogamy, once one male and one female form a mating pair bond, they will be faithful to each other in subsequent breeding events. However, if their pair bond is broken for some reason, do they continue to prefer their partner when they come together again for mating? In other words, can the broken pair bond of sexually monogamous species be repaired? This is an interesting question but not yet well answered. To address this question, in the present study we used the lined seahorse (Hippocampus erectus), a typical sexually monogamous species, to study the partner preference of a female individual who experienced a complete separation followed by a reunion with her partner. Our main findings are as follows: (i) The female seahorse no longer prefers her partner after a separation, whether it is a former partner or a recent partner. No preference for partner-males may indicate that the broken pair bond cannot be repaired. (ii) The female seahorse maintains sexual fidelity to her partner in the absence of separation. However, once the health of her partner decreases, the female will switch mate, and her courtship with the new partner can take place during the pregnancy of her original partner. The first finding may provide insight into whether monogamous species still have an opportunity to reselect a new partner in the future to correct their poor choice once they have mated with a low-quality partner. The answer is that they can still gain an opportunity as long as the pair bonds with their current partners are broken. The second finding may reveal the conditions and timing at which a female seahorse switches her mate. These findings help us better understand the mating system of the seahorse H. erectus.

Identifying a limiting factor in the population dynamics of a threatened amphibian: The influence of extended female maturation on operational sex ratio

AbstractUnderstanding amphibian population dynamics is integral to mitigating severe declines that are occurring due to threats such as habitat removal and chytrid‐induced disease. Few studies have focused on sex‐specific population dynamics, despite the potential for these processes to alter colonisation and population turn‐over in newly created habitats. Here, we investigate sex‐specific population dynamics in the threatened green and golden bell frog (Litoria aurea) using intensive capture‐recapture methods in a newly created wetland complex and control sites. As hypothesised, females took longer to reach maturity compared to males. The length of female maturation was 3.9 times greater than that of males (428.68 days ± 107.6 SD and 110.16 days ± 20.59 SD, respectively). This resulted in a one‐year delay in female population size increase compared to the male population. The operational sex ratio (OSR) in the second year of monitoring in the created wetlands had the most disproportionate male bias out of any year and any site (12/1 male/female, male proportion = 0.92 ± 0.89–0.94 95% CI). In the third year, the OSR had become less male biased (2.6/1, male proportion = 0.72 ± 65–0.78 95% CI), likely attributed to the maturing of the females produced in the first year breeding events. We did not find any evidence that survival or detection probability influenced the observed OSRs in the created wetlands. Based on survival rates of each sex, we estimate that males are 77 times more likely to reach sexual maturity compared to females. We postulate that the combination of chytrid‐induced disease and sex‐biased maturation rates may be a driver of declines, especially in populations with limited recruitment. We encourage future research into investigating sex‐specific population dynamics of amphibians, especially relating to reintroduction ecology and disease.

More Than Just a Trend: Integrating Population Viability Models to Improve Conservation Management of Colonial Waterbirds.

Waterbird populations in eastern Australia have been declining over the past 35 years primarily due to water resource development and resultant changes to natural river flows and flooding. To mitigate these impacts there is an increased allocation of water for the environment, including waterbird populations. We used population viability models to identify the frequency of breeding events required to reverse the trend and achieve long-term species' management objectives. We found that the population size of straw-necked ibis was primarily dictated by the frequency of large breeding events and to a lesser extent by adult annual survival and the frequency of small breeding events. We identified combinations of small and large breeding events over the next 10 years required for increased population growth. We also assessed the likelihood of current water management policies increasing populations and thereby reversing the decline in eastern Australia's waterbird populations.

Factors Affecting Wetland Use by Spring Migrating Ducks in the Southern Prairie Pothole Region

ABSTRACTThere is increasing recognition of the importance of wetlands in the prairie pothole region (PPR) of the northern United States for stopover habitat for spring‐migrating waterfowl. The quality and quantity of stopover habitat found near breeding areas can affect speed and success of migration and subsequent breeding events. Conservation and management of wetlands in the region has traditionally focused narrowly on reproductive phases of the life cycle, and little to no research has examined how ducks use a diversity of available wetlands in the region during migration. We conducted weekly surveys on 1,061 wetlands during spring 2018 and 2019 to examine factors affecting duck use of wetlands in the intensively modified southern PPR landscape of Iowa, USA, for wetland restoration and conservation strategies. We compared wetland types, which included farmed, seasonal, and semi‐permanent wetlands, and lakes. The highest duck use per unit area occurred on semi‐permanent wetlands, followed by seasonal, and then farmed wetlands, and lakes. Ducks were highly clustered in our study, with 75% of all use‐days occurring on only 37 wetlands comprising 41% of all wetland area surveyed. We used hurdle models to examine how local and landscape factors measured within and around wetlands influenced duck use during spring migration. Multiple factors related to duck use at local and landscape scales, such as wetland area, vegetation abundance, and number of wetlands in the surrounding landscape. Among semi‐permanent wetlands, local factors within wetlands were more important than landscape factors in determining duck use. Collectively, our findings suggest semi‐permanent wetlands within the PPR play a key role in transitioning birds from wintering areas to breeding areas and that management of semi‐permanent wetlands should promote interspersion of emergent vegetation and open water and growth of submersed aquatic plants to improve their function for migrants. © 2021 The Authors. The Journal of Wildlife Management published by Wiley Periodicals LLC on behalf of The Wildlife Society.

Nesting attempts and success of Arctic-breeding geese can be derived with high precision from accelerometry and GPS-tracking

Sensors, such as accelerometers, in tracking devices allow for detailed bio-logging to understand animal behaviour, even in remote places where direct observation is difficult. To study breeding in birds remotely, one needs to understand how to recognise a breeding event from tracking data, and ideally validate this by direct observation. We tagged 49 adult female pink-footed geese (Anser brachyrhynchus) with transmitter neckbands in Finland in spring of 2018 and 2019, and in Svalbard in summer 2018, and validated inferences from tracking by field observations of nesting sites and family status in 2018–2020 (54 spring–summer tracks). We estimated nesting locations by taking the median coordinates of GPS-fixes at which the goose was motionless (overall dynamic body acceleration, ODBA < 1) on days with a daily median ODBA < 1, which approached the real nesting locations closely (within 1.6–3.7 m, n = 6). The start of nesting was defined as the first day on which the goose spent > 75% of time within 50 m of the nest, because nest site attendances steeply increased within one day to above this threshold. Nesting duration (number of consecutive days with > 75% nest site attendance) ranged between 3 and 44 days (n = 28), but was 30–34 days in confirmed successful nests (n = 9). The prolonged nesting of 39–44 days (n = 3) suggested incubation on unhatchable egg(s). Nest losses before hatching time occurred mostly in day 3–10 and 23–29 of nesting, periods with an increased frequency of nest site recesses. As alternative method, allowing for non-simultaneous GPS and accelerometer data, we show that nesting days were classified with 98.6% success by two general characteristics of breeding: low body motion (daily median ODBA) and low geographic mobility (daily SD of latitude). Median coordinates on nesting days approached real nest sites closely (within 0.8–3.6 m, n = 6). When considering only geographic mobility (allowing for GPS data only) nesting locations were similarly accurate, but some short nesting attempts were undetected and non-breeding tracks misclassified. We show that nesting attempts, as short as 3 days, and nesting success can be detected remotely with good precision using GPS-tracking and accelerometry. Our method may be generalised to other (precocial) bird species with similar incubation behaviour.

A RETROSPECTIVE STUDY OF DYSTOCIA IN EASTERN INDIGO SNAKES (DRYMARCHON COUPERI).

Medical and husbandry records of eastern indigo snakes (EIS) (Drymarchon couperi) housed at the Orianne Center for Indigo Conservation (OCIC) were reviewed to determine risk factors for developing dystocia. Thirty-four cases of dystocia were identified out of 104 successful breeding events between 2010 and 2020. The number of breeding events, age, body weight, housing, and selected blood parameters were reviewed for the female EIS successfully bred at OCIC between 2010 and 2020. Categorical data were evaluated with chi-square and the Fisher exact test, and the continuous data were evaluated using analysis of variance. Differences in data were considered statistically significant when P < 0.05. There was a significant difference seen between EIS that developed dystocia (EISd) and EIS that did not (EISn) for breeding events, with the virgin breeding event having more EISd than any other breeding event. Risk analysis of the data revealed that EIS were 9.28 times more likely to develop dystocia during the virgin breeding event than on subsequent breeding events. Age and housing were not significantly different between EISd and EISn for each breeding event, but body weight was, as EIS weighing less than 1.5 kg were found to be 4.43 times more likely to develop dystocia. There was also a significant difference between EISd and EISn in plasma sodium, calcium, ionized calcium, glucose, and albumin. When compared to EISn, EISd had lower plasma sodium, calcium, ionized calcium, and albumin and higher plasma glucose. There were also significant differences in the white blood cell differential count, as EISd had lower basophils and monocytes when compared to EISn. The majority of EISd were managed surgically, and retained eggs were more likely to be located within the right oviduct. This retrospective study is the first to evaluate potential causes of dystocia in EIS.

Confirmation Bias Perpetuates Century-Old Ecological Misconception: Evidence Against ‘Secretive’ Behavior of Eastern Spadefoots

Despite a 1944 publication questioning the misconception that Eastern Spadefoots (Scaphiopus holbrookii) and other Scaphiopodidae are ‘secretive’ outside of rain-induced migration and breeding aggregations, confirmation bias has perpetuated this fallacy. As a result, S. holbrookii is one of the least studied frogs in the United States. Amassing a large postmetamorphic dataset, we examined the misconception that S. holbrookii are secretive outside of breeding aggregates or optimal environmental conditions. Using eyeshine spotlighting, we conducted transect, mark–recapture, and haphazard spotlighting surveys in Virginia and Rhode Island forests. Although no breeding events or migration occurred during this study, we detected thousands of postmetamorphic S. holbrookii in Virginia and dozens in Rhode Island, the majority of which were subadults—a demographic category severely overlooked in the literature. These results are in direct contradiction with historical surveys of our sites. Spotlighting was an efficient method of detecting S. holbrookii eyeshine in forests, which were easily differentiated from arthropod eyeshine. Minimal effort was needed to detect the presence of S. holbrookii in Virginia and Rhode Island, even though both states have different climates and S. holbrookii densities. We also discovered a previously undetected population in Rhode Island. Scaphiopus holbrookii of all postmetamorphic size classes emerged regularly from burrows, even with no precipitation. We discuss how confirmation bias and lack of appropriate field methods for nonbreeding life history stages has fueled the misconception that S. holbrookii are difficult to find outside of optimal weather conditions, which has hindered progress studying the ecology and conservation of this species.

Unraveling a genetic roadmap for improved taste in the domesticated apple

Although taste is an important aspect of fruit quality, an understanding of its genetic control remains elusive in apple and other fruit crops. In this study, we conducted genomic sequence analysis of 497 Malus accessions and revealed erosion of genetic diversity caused by apple breeding and possible independent domestication events of dessert and cider apples. Signatures of selection for fruit acidity and size, but not for fruit sugar content, were detected during the processes of both domestication and improvement. Furthermore, we found that single mutations in major genes affecting fruit taste, including Ma1, MdTDT, and MdSOT2, dramatically decrease malate, citrate, and sorbitol accumulation, respectively, and correspond to important domestication events. Interestingly, Ma1 was identified to have pleiotropic effects on both organic acid content and sugar:acid ratio, suggesting that it plays a vital role in determining fruit taste. Fruit taste is unlikely to have been negatively affected by linkage drag associated with selection for larger fruit that resulted from the pyramiding of multiple genes with minor effects on fruit size. Collectively, our study provides new insights into the genetic basis of fruit quality and its evolutionary roadmap during apple domestication, pinpointing several candidate genes for genetic manipulation of fruit taste in apple.

Understanding sociality and behavior change associated with a nesting event in a captive flock of great white pelicans

Zoo-housed pelicans are commonplace, but their breeding record is poor and little research is published on the activity patterns, as potential predictors of nesting, of captive flocks. Existing literature shows that comparative research can provide useful information for husbandry and conservation planning for pelican populations. The opportunity arose to investigate the time-activity budget and social network of a breeding flock of captive great white pelicans. Three chicks were hatched in June and July 2016 and one in March 2017. Data on state behaviors, space use, and association preferences were collected around these nesting events, from October 2016 to February 2017 and July to October 2017. Results suggest that pre-nesting periods were associated with heightened flock-wide vigilance, suggesting that vigilance may be a precursor for courtship or nesting activity. Social network analysis revealed nonrandom associations between birds and a social structure across the flock, in which subadults seemed to associate more with each other than with adult birds. A limited visitor effect was noted; whilst no overall behavior change was apparent with different numbers of visitors, pelicans did widen their enclosure usage with increased visitor presence. These data are relevant to those attempting to breed this pelican, who wish to know more about the daily behavior patterns of this species across the season and physiological state, and who wish to understand pelican social structure, which is useful to the planning and implementation of bird moves or changes to the social environment of the flock. Further extending such research to include uninterrupted observation over a successful breeding event is recommended.

Rapid population increase of the threatened Australian amphibian Litoria aurea in response to wetlands constructed as a refuge from chytrid-induced disease and introduced fish

Amphibians have declined due to multiple impacts including invasive fish and the disease chytridiomycosis caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd). Wetland restoration can be used to increase amphibian populations. However the design of created wetlands must account for threats such as Bd and introduced fish. There have been no attempts on a landscape level to manage these threats with habitat design. Here we monitored the green and golden bell frog (Litoria aurea) in 2.6 ha of constructed wetlands designed to enhance breeding and increase survival through passive mitigation of Bd and exotic fish. We compared the fecundity, adult population sizes, introduced fish occupancy, Bd prevalence and survival rates of frogs in created wetlands (CW) to three control sites to determine if and why the habitat design was successful. Monitoring involved weekly capture-recapture during the austral spring and summer for three L. aurea breeding seasons. We hypothesised that (1) if the CWs were successful in passively limiting fish colonisation, a larger number of breeding events would be detected compared to control sites which are known to be widely colonised by introduced fish. (2) If the wetlands were successful in passively mitigating Bd, then we would observe an equal or greater survival rate and equal to or lower Bd prevalence compared to control wetlands. We observed a 3.3-fold increase in adult population size in CW from season 1 to 2, and the population increased further in season 3.We found strong support for hypothesis (1) and weak support for (2). Based on these results, we conclude that this design was beneficial shortly after their formation primarily due to fish exclusion, but further study is required to determine if these benefits extend long-term. Future amphibian restoration studies are needed to improve the design of wetlands to enhance suppression of Bd.

Socioecological conditions predict degu social instability and provide limited cues to forecast subsequent breeding conditions

Permanent changes in group membership may result in detrimental fitness effects on both group residents and immigrants. Factors associated with this form of social instability are rarely documented. We used a 15-year dataset on degus, a social and short-lived species, to test the hypothesis that physical condition and socioecological factors experienced during breeding are associated with social instability in terms of group individual membership (hypothesis 1). We also tested the hypothesis that these factors represent potential cues for individuals to predict social instability conditions during subsequent breeding (i.e., exhibiting autocorrelation) (hypothesis 2). Social instability in degu group membership was ubiquitous. Social instability increased with increasing ectoparasite load but decreased with increasing food abundance, increasing degu density, increasing mean minimum temperature, and increasing number of female group members. Of these conditions, degu density during winter exhibited autocorrelation. Finally, overall predictability of ecological conditions varied from low to high within a 5–6-year period. These findings indicate that socioecological conditions experienced by the breeding adults and their developing offspring predict within-year social instability (hypothesis 1) and provide some limited cues to individuals to predict similar conditions during the subsequent breeding event (hypothesis 2). Permanent changes in the adult composition of social groups (social instability) can have significant impacts on the fitness of group members. Determining the ecological and social conditions associated with social instability and whether individuals can anticipate social instability in adulthood can inform socioecological theory. In the communally rearing rodent, Octodon degus, social instability during breeding is ubiquitous and impacts the fitness of adult males and females differently. We determined that social instability in degu groups during breeding is associated with local ecological conditions (ambient temperature, ectoparasite loads, abundance of food, population density) and the social environment (number of adult females). Of the ecological variables, only population density exhibited autocorrelation. These results are important because they imply limited ecological cues available for the offspring to anticipate social instability conditions as adults.

Positive early-late life-history trait correlations in elephant seals.

Correlations between early- and late-life performance are a major prediction of life-history theory. Negative early-late correlations can emerge because biological processes are optimized for early but not late life (e.g., rapid development may accelerate the onset of senescence; "developmental theory of aging") or because allocation to early-life performance comes at a cost in terms of late-life performance (as in the disposable soma theory). But variation in genetic and environmental challenges that each individual has to cope with during early life may also lead to positive early-late life-history trait correlations (the "fixed heterogeneity" or "individual quality" hypothesis). We analyzed individual life-history trajectories of 7,420 known-age female southern elephant seals (Mirounga leonina) monitored over 36yr to determine how actuarial senescence (a proxy for late-life performance) correlate with age at first reproduction (a proxy for early-life performance). As some breeding events may not be detected in this field study, we used a custom "multievent" hierarchical model to estimate the age at first reproduction and correlate it to other life-history traits. The probability of first reproduction was 0.34 at age 3, with most females breeding for the first time at age 4, and comparatively few at older ages. Females with an early age of first reproduction outperformed delayed breeders in all aspects we considered (survival, rate of senescence, net reproductive output) but one: early breeders appeared to have an onset of actuarial senescence 1 yr earlier compared to late breeders. Genetics and environmental conditions during early life likely explain the positive correlation between early- and late-life performance. Our results provide the first evidence of actuarial senescence in female southern elephant seals.

Assessment of the status and trends in abundance of a coastal pinniped, the Australian sea lion Neophoca cinerea

Australian sea lions Neophoca cinerea are endemic to Australia, with their contemporary distribution restricted to South Australia (SA) and Western Australia (WA). Monitoring of the species has proved challenging due to prolonged breeding events that occur non-annually and asynchronously across their range. The most recent available data from 80 extant breeding sites (48 in SA, 32 in WA) enabled us to estimate the species-wide pup abundance to be 2739, with 82% (2246) in SA and 18% (493) in WA, mostly based on surveys conducted between 2014 and 2019. We evaluated 1776 individual site-surveys undertaken between 1970 and 2019 and identified admissible time-series data from 30 breeding sites, which revealed that pup abundance declined on average by 2.0% yr-1 (range 9.9% decline to 1.7% growth yr-1). The overall reduction in pup abundance over 3 generations (42.3 yr) was estimated to be 64%, with over 98% of Monte Carlo simulations producing a decline &gt;50% over a 3-generation period, providing strong evidence that the species meets IUCN ‘Endangered’ criteria (decline ≥50% and ≤80%). The population is much smaller than previously estimated and is declining. There is a strong cline in regional abundances (increasing from west to east), with marked within-region heterogeneity in breeding site pup abundances and trends. Results from this study should improve consistency in the assessment of the species and create greater certainty among stakeholders about its conservation status. To facilitate species management and recovery, we prioritise key data gaps and identify factors to improve population monitoring.

Trends in Black Swift (Cypseloides niger) breeding phenology, productivity, and nest success in southwest Colorado, 1996–2017

This study presents breeding phenology, fledgling production, and nest success for the Black Swift (Cypseloides niger) over a 22 year period at the Box Canyon colony, Ouray, Colorado, USA. Data were collected annually from 1996 to 2017 by direct observation from arrival of the birds at the nesting colony until all adults and fledglings departed. We documented dates of first arrival, laying, incubation onset, hatching, and fledging, and determined the intervals from arrival to laying, laying to incubation, length of incubation, and length of the nestling period in each year. Breeding events followed each other closely and showed little chronological change throughout the study. We identified a negative trend in the number of nest attempts and fledged Black Swift chicks over time but found no relationship between these 2 trends and the environmental factors of summer temperature, summer precipitation, or tourist visitation. The Mayfield estimate of nest success for all nest attempts was 77.5%. There was unexplained annual variation in nest success, but the trend in nest success remained static, with no correlation between nest success and temperature, precipitation, or tourist visitation. This study represents the largest dataset and longest-duration investigation into the breeding phenology and nest success of the Black Swift.