Ibis最新文献

Large-scale releases of domesticated, game-farm Mallards Anas platyrhynchos to supplement wild populations have resulted in widespread introgressive hybridization that changed the genetic constitution of wild populations in eastern North America. The resulting gene flow is well documented between game-farm and wild Mallards, but the mechanistic consequences from such interactions remain unknown in North America. We provide the first study to characterize and investigate potential differences in morphology between genetically known, wild and game-farm Mallards in North America. We used nine morphological measurements to discriminate between wild and game-farm Mallards with 96% accuracy. Compared with their wild counterparts, game-farm Mallards had longer bodies and tarsi, shorter heads and wings, and shorter, wider and taller bills. The nail on the end of the bill of game-farm Mallards was longer, and game-farm Mallard bills had a greater lamellae:bill length ratio than wild Mallards. Differences in body morphologies between wild and game-farm Mallards are consistent with an artificial, terrestrial life whereby game-farm Mallards are fed pelleted foods, resulting in artificial selection for a more ‘goose-like’ bill. We posit that: (1) game-farm Mallards have diverged from their wild ancestral traits of flying and filter feeding towards becoming optimized to run and peck for food; (2) game-farm morphological traits optimized over the last 400 years in domestic environments are likely to be maladaptive in the wild; and (3) the introgression of such traits into wild populations is likely to reduce fitness. Understanding the effects of game-farm Mallard introgression requires analysis of various game-farm × wild hybrid generations to determine how domestically derived traits persist or diminish with each generation.

Seabirds are important sentinels of climate and ecosystem change, but many breeding populations are difficult to monitor because of the remoteness and inaccessibility of their colonies, and the sometimes cryptic nature of their nests and burrows. Large-scale monitoring of seabird populations at sea can also be used to estimate population trends and inform conservation efforts. However, although modern survey techniques can be used to estimate absolute abundance, many older survey methodologies have recorded only relative, and possibly biased, abundance. These approaches are exemplified in the western North Atlantic, where seabirds have been surveyed at sea using modern methods (Eastern Canada Seabirds at Sea, or ECSAS) since 2006, but under the simpler PIROP (Programme intégré de recherches sur les oiseaux pélagiques) protocol from 1965 to 1992. Methodological differences between these survey types limit our understanding of long-term trends in seabird populations, both in the western North Atlantic and elsewhere. Hence, we conducted simultaneous surveys using both methods from 2014 to 2021 and used advances in model-based distance sampling to allow comparison across these longer-term datasets. We validated our methodology by comparing population trends of Northern Gannets Morus bassanus using the at-sea data and breeding colony surveys. The trend in abundance at sea (2.69% increase annually) was similar to that at breeding colonies (2.91% increase annually), suggesting that our combined approach can be used to estimate seabird population changes robustly across the period spanned by the two survey programmes. We envision that analyses using similar combined survey methods could reveal decadal population trends and changes in conservation status of many seabird species that currently lack such information because of the absence of colony counts.

As a field, ecology has historically misunderstood or overlooked female organisms, or assumed that they are ‘similar enough’ to males. The typical unit of study for ecology research stops at the species level, but that can be too coarse and can obscure important intraspecific differences. Projecting the results of studies based on only half of the population (i.e. males) onto females can be misleading, if not dangerous, as female birds differ from males in key aspects of their biology. Birds are widespread and can be sexed more often than most other taxa; yet although it uses them as model organisms, current ornithological research is disproportionately based on male birds. We review some fields pertinent to ecology and conservation and highlight biases and key research gaps. We find that, counter to ‘traditional’ assumptions, reproductive roles are balanced between sexes across many, but not all, species. In addition, female birds sing, tend to be more dispersive than males, have lower survival, often use different habitats – which has implications for conservation – and may be affected by climate change differently. We call for ornithologists to study sexes separately because the lack of attention to these differences has real-world conservation implications. Potential solutions include training observers to recognize female traits, using more field methods that increase the detection of female birds (e.g. catching birds during the migration season, using DNA to determine sex), broadening geographical regions of study and recruiting a diverse group of scientists to help equalize the field of ornithological research.

Stable isotope analysis has been used extensively in migratory bird studies to provide ecological insights that may otherwise be difficult to obtain. However, an understanding of moult is critical for appropriate feather sampling, and here we make the first assessment of its relevance for examining the non-breeding ecology of the Alpine Swift Tachymarptis melba, a long-distance Afro-Palaearctic migrant. We sampled three feather types from birds found dead after their return from migration and investigated variability in δ¹³C, δ¹⁵N and δ²H within and among feathers and between age classes. We found isotopic evidence supporting an interrupted primary moult in adults, with the innermost primary of adults (known to be moulted on the breeding grounds) significantly depleted in ¹³C and ²H compared with either the outermost primary or outermost tail feather, both of which were representative of sub-Saharan non-breeding areas. In contrast, the absence of significant differences in immature birds suggests the probable existence of a non-migratory strategy within this age class. These isotopic insights into moult and life history highlight the potential for stable isotope analysis as a tool for investigating non-breeding strategies in the Alpine Swift.

Investigating the intestinal microbiome and its interactions with the host is crucial for understanding the adaptation mechanisms, functional dynamics and co-evolution of these microbiomes in wild birds. This review examines how gut microbiomes interact with their avian hosts, focusing on the establishment of gut microbiomes, the dynamic changes occurring throughout different life stages and the factors that influence microbial variations. It also explores the evolutionary relationship between birds and their microbial symbionts, and identifies key areas for future research on avian gut microbes to advance wildlife microbiology.

The emergence of Highly Pathogenic Avian Influenza (HPAI) H5N1 in wild bird populations in 2020 changed the landscape of this disease for seabird populations, including Northern Gannets Morus bassanus. In 2023, we photographed the three Northern Gannet colonies in Newfoundland and Labrador, Canada (Funk Island, Baccalieu Island and Cape St Mary's), following an HPAI outbreak in 2022 and documented an overall 43% decline in apparently occupied sites (AOS) from the last population survey in 2018. During the photo analyses, we assigned immature birds present in the core breeding area to one of four age categories according to their plumage characteristics, and estimated that 9% (inter-colony variance ranging from 7 to 14%) of all AOS in 2023 hosted at least one immature bird, an increase compared with rates of 2% or less before the outbreak. Further, 16% of all immature birds present in the core breeding area showed evidence of breeding and were probably 2- and 3-year-old birds. Our results support the social competition theory whereby a higher proportion of immature and/or younger immature birds occupying an AOS within the core breeding area is observed following significant reductions in numbers of established breeders, suggesting the presence of a pool of immature birds capable of recruiting into the Newfoundland Northern Gannet breeding population and help its recovery.

Aapa mires are distinctive base-enriched northern peatland systems, often with pronounced flark-string (deep-pool) surface features. Aapa mires are used by specialist breeding migratory waterbirds (particularly Broad-billed Sandpiper Calidris falcinellus, Jack Snipe Lymnocryptes minimus, Taiga Bean Goose Anser fabalis and Pintail Anas acuta) and support high densities of other nesting wader species (Wood Sandpiper Tringa glareola, Spotted Redshank Tringa erythropus, Ruff Calidris pugnax, Common Snipe Gallinago gallinago, Curlew Numenius arquata and Whimbrel Numenius phaeopus) compared with other peatland landforms. Remote sensing, palynology and peat stratigraphy studies confirm rapid and massive loss of aapa mires through recent drainage, but now also through climate change. Botanists report that recent warming has caused enhanced successional expansions in ombrotrophic raised mire vegetation to engulf aapa mires, destroying their unique surface and nutrient characteristics. As the waterbird species associated with aapa mires cannot survive on acidic base-poor raised mire systems, this ecological change places their populations in jeopardy. While acknowledging the need to reduce climate change through other means, these changes prioritize the need for international cooperation to extend and improve site-safeguarding of intact aapa mires and restoration of damaged aapa mires, as well as effective conservation of affected avian species throughout their full annual cycle to safeguard them, aapa mires and their associated bird communities for future generations. The case regarding aapa mires highlights the need to establish new mechanisms to create cohesive networks of protected areas for special habitats that are of disproportional importance to key avian populations and other wetland species that may not be adequately represented in current site-safeguard networks.

Plumage coloration is an important trait for communication signalling and camouflage, enabling birds to provide cues of health condition and avoid predators. Such coloration can differ among body regions, with some regions presenting conspicuous coloration, while others are more discreet. Plumage coloration can also be associated with species' life-history traits, such as diet, habitat and nest type. Despite the relevance to ecology and evolution of bird plumage coloration, little is known regarding the relationship between the coloration of ventral and dorsal regions of bird species, especially in the Atlantic Forest, a global hotspot of biodiversity. Here we assessed plumage brightness and saturation of the dorsal and ventral regions of Atlantic Forest birds, and analysed the differences in coloration and colour variability between the regions. We also tested whether sex dichromatism, nest type, diet, habitat and foraging stratum preference are related to plumage coloration. We found that dorsal regions tend to be darker, more achromatic and less variable across species when compared to ventral regions. Additionally, plumage coloration of bird species incubating in open nests is brighter than in birds from closed nests, while species with sexual dichromatism tend to present darker ventral regions. Our results bring new insights into the role of plumage coloration in Atlantic Forest bird ecology, suggesting that different evolutionary forces may act in different body regions.