Demographic drivers of reproductive failure in a threatened bird: insights from a decade of data

Hatching failure affects up to 77% of eggs laid by threatened bird species, yet the true prevalence and drivers of egg fertilization failure versus embryo mortality as underlying mechanisms of hatching failure are unknown. Here, using ten years of data comprising 4,371 eggs laid by a population of a threatened bird, the hihi (Notiomystis cincta), we investigate the relative importance of infertility and embryo death as drivers of hatching failure and explore population-level factors associated with them. We show that of the 1,438 eggs that failed to hatch (33% of laid eggs) between 2010 and 2020, 83% failed due to embryo mortality, with the majority failing in the early stages of embryonic development. In the most comprehensive estimates of infertility rates in a wild bird population to date, we find that fertilization failure accounts for around 17% of hatching failure overall and is more prevalent in years where the population is smaller and more male biased. Male embryos are more likely to die during early development than females, but we find no overall effect of sex on the successful development of embryos. Offspring fathered by within-pair males have significantly higher inbreeding levels than extra-pair offspring; however, we find no effect of inbreeding nor extra-pair paternity on embryo mortality. Accurately distinguishing between infertility and embryo mortality in this study provides unique insight into the underlying causes of reproductive failure over a long-term scale and reveals the complex risks of small population sizes to the reproduction of threatened species

Early‐life telomere length predicts life‐history strategy and reproductive senescence in a threatened wild songbird

Telomeres are well known for their associations with lifespan and ageing across diverse taxa. Early-life telomere length can be influenced by developmental conditions and has been shown positively affect lifetime reproductive success in a limited number of studies. Whether these effects are caused by a change in lifespan, reproductive rate or perhaps most importantly reproductive senescence is unclear. Using long-term data on female breeding success from a threatened songbird (the hihi, Notiomystis cincta), we show that the early-life telomere length of individuals predicts the presence and rate of future senescence of key reproductive traits: clutch size and hatching success. In contrast, senescence of fledging success is not associated with early-life telomere length, which may be due to the added influence of biparental care at this stage. Early-life telomere length does not predict lifespan or lifetime reproductive success in this species. Females may therefore change their reproductive allocation strategy depending on their early developmental conditions, which we hypothesise are reflected in their early-life telomere length. Our results offer new insights on the role that telomeres play in reproductive senescence and individual fitness and suggest telomere length can be used as a predictor for future life history in threatened species

Genetic structure of captive and free-ranging okapi (Okapia johnstoni) with implications for management

Breeding programs for endangered species increasingly use molecular genetics to inform their management strategies. Molecular approaches can be useful for investigating relatedness, resolving pedigree uncertainties, and for estimating genetic diversity in captive and wild populations. Genetic data can also be used to evaluate the representation of wild population genomes within captive population gene-pools. Maintaining a captive population that is genetically representative of its wild counterpart offers a means of conserving the original evolutionary potential of a species. Okapi, an even-toed ungulate, endemic to the Democratic Republic of Congo, have recently been reclassified as Endangered by the IUCN. We carried out a genetic assessment of the ex-situ okapi (Okapia johnstoni) population, alongside an investigation into the genetic structure of wild populations across their geographic range. We found that while levels of nuclear (12 microsatellite loci) genetic variation in the wild, founder and captive okapi populations were similar, mitochondrial (833 bp of Cyt b, CR, tRNA-Thr and tRNA-Pro) variation within captive okapi was considerably reduced compared to the wild, with 16 % lower haplotype diversity. Further, both nuclear and mitochondrial alleles present in captivity provided only partial representation of those present in the wild. Thirty mitochondrial haplotypes found in the wild were not found in captivity, and two haplotypes found in captivity were not found in the wild, and the patterns of genetic variation at microsatellite loci in our captive samples were considerably different to those of the wild samples. Our study highlights the importance of genetic characterisation of captive populations, even for well-managed ex-situ breeding programs with detailed studbooks. We recommend that the captive US population should be further genetically characterised to guide management of translocations between European and US captive population

Conservation in the maelstrom of Covid‐19 – a call to action to solve the challenges, exploit opportunities and prepare for the next pandemic

As we sit in the vortex of the Covid‐19 outbreak, individual energies are focused on staying safe and juggling the personal, social and financial impacts of the pandemic and political responses to it. These impacts are profoundly re‐shaping our lives, with many commentators suggesting that ‘normality’ will be permanently redefined for all sectors of society. The future is not clear because the maelstrom is so intense that it is unlikely that the dust will settle any time soon. This pandemic will be one of the major game changers for humanity in the 21st century. The conservation impacts are set to be huge, and this is an understatement. It is remarkable how little past attention has been given to identifying the conservation impacts of human responses to pandemics and preparing for these, especially given considerable investment in global biodiversity and conservation‐focused horizon scanning exercises over the last decade (e.g. Sutherland et al., 2020). Conservation scientists, practitioners and policy‐makers must urgently address this lack of preparation and innovate solutions to confront the challenges arising from the radically altered economics, attitudes and behaviours imposed by Covid‐19. Our job is to think creatively and collaboratively with other sectors of society to ensure that recent progress in implementing effective conservation and protection of nature is not lost. We must also insist that conservationists contribute to re‐shaping the future post‐Covid‐19 world, to ensure that potential benefits to nature conservation and protection are realized. We identify three broad challenges and a diverse set of potential positive developments that require urgent attention and strategy development. We cannot afford to sit back and wait to see what happens as the new world emerges, or to be unprepared when the next pandemic hits

Changes in social groups across reintroductions and effects on post-release survival

Reintroductions, essential to many conservation programmes, disrupt both abiotic and social environments. Despite growing recognition that social connections in animals might alter survival (e.g. social transmission of foraging skills, or transmission of disease), there has thus far been little focus on the consequences of social disruption during reintroductions. Here we investigate if moving familiar social groups may help a threatened species to adjust to its new environment and increase post-release survival. For a reintroduction of 40 juvenile hihi Notiomystis cincta (a threatened New Zealand passerine), we observed social groups before and after translocation to a new site and used social network analysis to study three levels of social change: overall group structure, network associations and individual sociality. We also tested alternate translocation strategies where birds were kept temporarily in aviaries in either a familiar group, or where their prior association was mixed. Although social structure remained similar among juveniles that remained at the source site, we detected significant changes in translocated birds at both the group- and individual- level post-release. However, our holding treatments did not affect these social bonds so we remain unable to maintain or manipulate social groups during translocation. Crucially, there was a small tendency for translocated juveniles that gained more associates during re-assortment of social groups to be more likely to survive their first year post-release. We suggest that prior sociality may not be important during translocations, but rather individuals that are most able to adapt and form associations at a new site are most likely to be the surviving founders of reintroduced populations.Peer reviewe

Genetic variance in fitness indicates rapid contemporary adaptive evolution in wild animals

The rate of adaptive evolution, the contribution of selection to genetic changes that increase mean fitness, is determined by the additive genetic variance in individual relative fitness. To date, there are few robust estimates of this parameter for natural populations, and it is therefore unclear whether adaptive evolution can play a meaningful role in short-term population dynamics. We developed and applied quantitative genetic methods to long-term datasets from 19 wild bird and mammal populations and found that, while estimates vary between populations, additive genetic variance in relative fitness is often substantial and, on average, twice that of previous estimates. We show that these rates of contemporary adaptive evolution can affect population dynamics and hence that natural selection has the potential to partly mitigate effects of current environmental change

Parasites as drivers and passengers of human-mediated biological invasions

We provide an overview of the current state of knowledge of parasites in biological invasions by alien species. Parasites have frequently been invoked as drivers of invasions, but have received less attention as invasion passengers. The evidence to date that parasites drive invasions by hosts is weak: while there is abundant evidence that parasites have effects in the context of alien invasions, there is little evidence to suggest that parasites have differential effects on alien species that succeed versus fail in the invasion process. Particular case studies are suggestive but not yet informative about general effects. What evidence there is for parasites as aliens suggests that the same kind of factors determine their success as for non-parasites. Thus, availability is likely to be an important determinant of the probability of translocation. Establishment and spread are likely to depend on propagule pressure and on the environment being suitable (all necessary hosts and vectors are present); the likelihood of both of these dependencies being favourable will be affected by traits relating to parasite life history and demography. The added complication for the success of parasites as aliens is that often this will depend on the success of their hosts. We discuss how these conclusions help us to understand the likely effects of parasites on the success of establishing host populations (alien or native)

Carotenoids, colour and conservation in an endangered passerine, the hihi or stitchbird (Notiomystis cincta)

Carotenoids are essential dietary components utilized not only in pigmentation but also as immuno-stimulants and antioxidants. Reduced availability can have consequences on individual health and survival, thus making carotenoids a good indicator of environmental stress. We compared carotenoid profiles and plumage colour characteristics of an endangered passerine species in New Zealand, between its remnant island source population and two reintroduced island populations. Circulating carotenoids were predominantly lutein (mean of 82.2%) and zeaxanthin (mean of 14.8%), and these were the major carotenoids present as yellow pigments in the males' plumage. There were clear differences in total carotenoid concentrations and plumage colour among the three populations. Circulating carotenoid concentration was significantly higher in one of the reintroduced populations, and the yellow plumage of males was significantly higher in both reintroduced populations in comparison with the remnant population (reflected as a significant increase in hue). Understanding how these differences arise may be of importance to this species given the health benefits carotenoids impart and our ability to select plant species containing these compounds or artificially supplement the

Investigation of mortalities associated with Salmonella spp. infection in wildlife on Tiritiri Matangi Island in the Hauraki Gulf of New Zealand

CASE HISTORY: Salmonellosis was suspected as the cause of death in eight wild animals on Tiritiri Matangi Island, in the Hauraki Gulf of New Zealand, between November and September 2011, including three hihi (Notiomystis cincta), a tuatara (Sphenodon punctatus), a masked lapwing (Vanellus miles novaehollandiae), and a saddleback (Philesturnus carunculatus). An outbreak investigation to identify the source and distribution of infection was undertaken over the summer of 2011–2012. CLINICAL AND LABORATORY FINDINGS: Surveillance of five species of forest bird (n=165) in December 2011 returned a single positive result for Salmonella spp. Environmental sampling of 35 key water sources and hihi supplementary feeding stations conducted in December 2011 and March 2012 returned isolates of S. enterica subspecies houtenae and S. enterica serovar Saintpaul from a stream, a dam and a supplementary feeding station. The same serotypes were identified in tissue samples collected from post mortem specimens of the affected birds, and their similarity was confirmed by pulsed-field gel electrophoresis. DIAGNOSIS: Mortality in wildlife associated with infection with S. enterica subspecies houtenae and S. enterica serovar Saintpaul. CLINICAL RELEVANCE: This is the first detection of these Salmonella spp. from wild birds in New Zealand. Our study highlights how active surveillance in response to observed disease emergence (here mortalities) can provide important insight for risk assessment and management within populations of endangered species and inform risk assessment in translocation planning