Ibis最新文献

Museum collections of birds are a key source of data on the colours of ‘soft parts’, e.g. legs, feet, bill (maxilla, mandible), wattles, periocular skin and, our focus here, the iris of the eye. However, subjective descriptions of soft parts' colours have long plagued their use, whether in research or in illustrations of birds. We document a case where reasonable doubt about the accuracy of iris colour recorded more than 50 years ago in several taxonomically important series of specimens of the Australian Spinifex Pigeon Geophaps plumifera is probably unresolvable. This doubt clouds the downstream use of the specimens in a complete understanding of geographical and temporal variation, and taxonomy. We discuss how ornithologists may apply methods now readily available that will enable more rigorous recording of soft parts' colours, despite many valid limitations. This especially applies in situations where existing knowledge dictates care, such as in already known zones of taxonomic intergradation or when colours known to be unusual and unexpected are seen.

During 2021 and 2022 High Pathogenicity Avian Influenza (HPAI) killed thousands of wild birds across Europe and North America, suggesting a change in infection dynamics and a shift to new hosts, including seabirds. Northern Gannets Morus bassanus appeared to be especially severely impacted, but a detailed account of the data available is required to help understand how the HPAI virus (HPAIV) spread across the meta-population, and the ensuing demographic consequences. Accordingly, we analyse information on confirmed and suspected HPAIV outbreaks across most North Atlantic Gannet colonies and, for the largest colony (Bass Rock, UK), provide impacts on population size, breeding success, and preliminary results on apparent adult survival and serology. Unusually high numbers of dead Gannets were first noted at colonies in Iceland during April 2022. Outbreaks in May occurred in many Scottish colonies, followed by colonies in Canada, Germany and Norway. By the end of June, outbreaks had occurred in colonies in Canada and the English Channel. Outbreaks in 12 UK and Ireland colonies appeared to follow a clockwise pattern with the last infected colonies recorded in late August/September. Unusually high mortality was recorded at 40 colonies (75% of global total colonies). Dead birds testing positive for HPAIV H5N1 were associated with 58% of these colonies. At Bass Rock, the number of occupied nest-sites decreased by at least 71%, breeding success declined by c. 66% compared with the long-term UK mean and the resighting of marked individuals suggested that apparent adult survival between 2021 and 2022 could have been substantially lower than the preceding 10-year average. Serological investigation detected antibodies specific to H5 in apparently healthy birds, indicating that some Gannets recover from HPAIV infection. Further, most of these recovered birds had black irises, suggestive of a phenotypic indicator of previous infection. Untangling the impacts of HPAIV infection from other challenges faced by seabirds is key to establishing effective conservation strategies for threatened seabird populations as the likelihood of further epizootics increases, due to increasing habitat loss and the industrialization of poultry production.

The rate and magnitude of contemporary changes in natural systems is unprecedented in the Earth's history. Studies of wild birds have been critically important in helping us understand and address these environmental changes. Avian collections provide a potentially unique perspective on change through time, but their role in environmental change research is limited by the availability of collections data. Here we describe how avian collections might be unlocked to enable environmental change research, and discuss the opportunities and constraints associated with this. We use the concept of the extended specimen to describe the types of data that could be unlocked from basic data for discoverability to enhanced data that might be directly applied to environmental change questions. We illustrate the type of environmental change research these data might support. We argue that data creation and access is currently limited by funding for digitization, a rather patchy understanding of the needs of the research community and less than adequate data-sharing by institutions and researchers. We develop a blueprint for addressing these issues which includes (1) improvements in sharing the data we are already creating and (2) building a better case for digitization at scale. As one of the largest avian collections in the world, the Natural History Museum, UK, is committed to unlocking our collections, but we will need input and support from the avian research community to do so.

When waders gather in mixed-species flocks to feed on benthic prey, differences in morphological traits, foraging strategies and prey selection may allow different species to optimize their energy intake while reducing competition. As the effect of the fine-scale spatial distribution of resources on energy intake is unknown, we simulated the foraging performance of two types of waders with contrasting body plans and foraging strategies in a variety of virtual mudflats with different horizontal and vertical prey distribution patterns. Although larger, longer-billed individuals had higher energy intake rates, smaller individuals with shorter bills maintained higher prey capture rates by relocating if prey was insufficiently available. Shorter-billed individuals struggled more to meet their energetic demands because they selected smaller prey items and had a more limited capacity to metabolize energy from food. Being able to catch larger, high-quality prey offered a competitive advantage for longer-billed individuals, which could be a driving force for the evolutionary lengthening of bills in waders. Interestingly, their performance was more affected by the horizontal than by the vertical prey distribution. Quantifying prey distributions may help explain how some wader species can co-occur in the field and why some wetland areas are unattractive as foraging areas. The work confirms that the foraging performance of larger, longer-billed birds is not limited by bill size per se, but by the energetic trade-offs associated with the ability to catch larger prey items more efficiently, increased handling times and higher absolute energy costs. These trade-offs may become particularly important in landscapes where prey is scarce and spatially patchy.

Survival estimates are critical components of avian ecology. In well-intentioned efforts to maximize the utility of one's research, survival estimates often derive from data that were not originally collected for survival assessments, and such post hoc analyses may include unintentional biases. We estimated the survival of Whimbrels captured and marked at two breeding sites in Alaska using divergent data streams that in isolation were subject to methodological biases. Although both capture sites were chosen to study the migration ecology of Alaska-breeding Whimbrels, maximizing the conservation value of the data we collected was obviously desirable. We used multi-year telemetry information to infer survival from one site (Colville River) and mark–resight techniques to estimate survival from a second site (Kanuti River). At Colville River, we could not feasibly include a control group of birds to assess potential survival effects of externally mounted transmitters, and at Kanuti River we were unable to account accurately for potential emigration events because we used resightings alone. We integrated these datasets in a Bayesian hierarchical framework, an approach that permitted insights across sites that moderated methodological biases within sites. Using telemetry enabled us to detect permanent emigration events from breeding sites in two of 10 birds, results that informed estimates for birds without tracking devices. These datasets yielded point estimates of true survival of Whimbrels from Colville River equipped with solar-powered satellite transmitters that were higher (0.83) than true survival estimates of Whimbrels from Kanuti River marked with leg flags alone (0.74) or equipped with surgically implanted satellite transmitters (0.50), but the 95% credible intervals on these estimates overlapped across groups. For species such as Whimbrels that are difficult and costly to study, combining information from disparate data streams allowed us to derive novel demographic estimates, an approach with clear application to other similar studies.

Advancing breeding phenology is a commonly observed response to climate warming among bird species, potentially in response to shifts in the phenology of key resources. However, for migratory birds breeding at high latitudes, their capacity to breed earlier may be constrained by the time available between arrival on the breeding grounds and nesting, especially for later-arriving individuals. This may have consequences for productivity, as early laying is often linked to higher breeding success, particularly in such seasonal environments. We investigated how migratory arrival timing influences subsequent timing of breeding, in particular whether the time between arrival and laying (arrival–laying gap) varies with arrival date, and if later-arriving individuals are able to catch up with early-arriving conspecifics. We tracked individual Icelandic Black-tailed Godwit Limosa limosa islandica with GPS and PTT tags for one to two complete breeding seasons between 2013 and 2022. After arrival in Iceland, most Godwits visited their breeding territory within 5 days, though this interval was longer for earlier-arriving birds. The total gap between arrival and laying was also longer for earlier-arriving birds, such that laying date did not vary significantly with arrival date. These results suggest that, despite individual consistency in migratory phenology, subsequent timing of nesting is probably influenced by other factors, such as mate arrival timing and/or annual variation in environmental conditions. Regular pre-nesting visits to the breeding territory may indicate that Godwits are able to monitor such factors closely and to nest early when conditions allow, but a larger sample of individuals and years is needed to assess whether early-arriving individuals contribute disproportionately to population-level advances in breeding phenology. Widespread tracking with high temporal and spatial resolution helps improve our understanding of phenological variation during the breeding season and its consequences for productivity and variation in juvenile phenology.

Nest-site selection is the principal way in which secondary cavity-nesting species mitigate the negative effects of factors such as predation, parasitism and exposure on reproductive success. Large-bodied secondary cavity-nesting birds rely on large cavities in mature trees that are often absent or reduced in anthropogenically disturbed forests. Hence, the availability of high-quality nest-sites may be limited for these species, potentially reducing reproductive success. The aim of this study was to investigate nest-site selection and the effect of nest-site features on reproductive success in the critically endangered Great Green Macaw Ara ambiguus in northern Costa Rica. We show that Great Green Macaws select nest-sites according to the characteristics of the cavity and the tree in which they are located. Moreover, reproductive success is a function of certain cavity features. However, the availability of high-quality cavities, those with features associated with higher reproductive success, is potentially limited. By studying nest-site selection and productivity together, we have identified that the availability of high-quality cavities could potentially limit the future recovery of the critically endangered Great Green Macaw.

Measuring seasonal productivity is difficult in multi-brooded species without labour-intensive ringing studies. Individual-based (IB) models have been used to estimate seasonal productivity with no direct knowledge of number of nesting attempts, but they are often based on simplified re-nesting probability (φ_R) step-functions instead of observed or more biologically plausible ones. We present a new, open-source IB seasonal productivity model parameterized from studies of Black Redstart Phoenicurus ochruros and Yellowhammer Emberiza citrinella. We examined how the φ_R function shape (empirical versus simplified) influenced (1) model performance, (2) re-nesting compensation and (3) population-level predictions of a simulated management intervention. Population-level predictions were made only for Yellowhammer as we had more detailed demographic data, such as survival rates, available. Pattern-oriented modelling revealed that IB models produced realistic within-population distributions of breeding parameters, and those specified with an observed or empirically derived φ_R function generally outperformed those specified with simpler step functions. Strength of re-nesting compensation differed depending on the φ_R function used. For Yellowhammers, type of φ_R function in IB models marginally influenced population-level predictions of a simulated management intervention (potential population growth rate increased between 23% and 29% relative to no management intervention). In contrast, a simple deterministic productivity model, which did not simulate re-nesting compensation, predicted a 41% increase in potential population growth. At a population level, choice of φ_R function may have less influence on IB model predictions, but choice of model itself (IB versus deterministic) may have substantial impact. We discuss how more biologically plausible φ_R functions might either be observed directly, derived from nest data, or estimated from proxy information such as moult or brood patch changes.