Ibis最新文献

Parental care in birds encompasses many behaviours, from selecting nest-sites and supplying eggs with nutrients to incubation and offspring provisioning. Unlike the early stages, where offspring are passive receivers of care, chicks actively solicit care after hatching. This may lead to either parent–offspring conflict or coadaptation, or both, if there is genetic variance in both parental provisioning and offspring begging. However, given that parental provisioning is highly responsive to brood size and age, its genetic determination is questioned. In this study, we used a multigenerational pedigree and 11 years of provisioning data to dissect the variation in this trait in the Collared Flycatcher Ficedula albicollis, and to examine whether offspring provisioning changes as parents age. We found that the parental provisioning rate was weakly repeatable (r = 0.088–0.213) and heritable (h² = 0.052–0.158). Higher values were obtained when calculated based on within-individual averages rather than individual measurements, and after adjusting for fixed effects. Older parents provisioned offspring at a lower frequency than younger ones. An additive genetic component in provisioning indicates potential for the evolution of parental care, parent–offspring coadaptation and indirect genetic effects on offspring traits. Future studies employing new tracking technologies, including accelerometers, radars and radio-frequency identification readers, may help to determine whether senescence or increased experience causes the lower rate of offspring provisioning observed in older parents.

Understanding the impact of anthropogenic threats, such as light pollution, on biodiversity is necessary to establish effective guidelines to protect diminishing wildlife. In this study, we examined the effect of artificial light at night (ALAN) on the roosting behaviour of Chimney Swifts Chaetura pelagica, a highly threatened migratory bird species that lives commensally with humans, where it often breeds and roosts in artificial structures such as chimneys. Although Chimney Swifts are known to use time of sunset in combination with temperature, wind and season to coordinate roost entry, we predicted that high ALAN exposure would override these natural cues and lead to a delayed entry compared with sites with less light pollution. To test this, we examined the effects of ALAN on the start and end times of entry to 21 roosting sites located along a light pollution gradient in New Jersey and the New York Metropolitan area. We found that ALAN was a significant predictor of roosting entry time, with birds entering later in sites with more light pollution. While Chimney Swifts initiated roosting earlier in the summer months compared with the autumn, this effect was absent in areas with high light pollution. These findings highlight the need to determine the causes and consequences of light pollution effects.

In many bird species, nestling begging signals play a key role in the interaction between parents and their offspring during development. The information conveyed by begging calls can be disrupted by anthropogenic noise, which is one of the major threats to biodiversity in increasingly urbanized landscapes. Here, we describe the developmental change in acoustic structure of begging calls in nestling Eurasian Blue Tits Cyanistes caeruleus; begging calls are pure-tone, low-frequency, soft calls during the first days of development and gradually turn into white-noise, hiss-like, powerful calls of broadband frequency. This strong developmental variation highlights the importance of an extended sampling scheme in developmental studies. Furthermore, we pinpoint two phases where begging calls could be most vulnerable to masking by anthropogenic noise. First, during early development, begging calls are very soft and low-pitched, closer to high-intensity noise bands of traffic noise. Secondly, around day 11, begging calls show reduced tonality, which implies higher degradation, and relatively low amplitude, which implies reduced signal range. We encourage future research to describe acoustic development of begging calls in other species, to provide a robust foundation that will make noise mitigation policies more effective.

Nomadic species can rely on unpredictable resources making them challenging to understand and, consequently, to conserve. Here, we present knowledge advancement for a nomadic predator, the Short-eared Owl Asio flammeus, by tracking individuals from a wide latitudinal range inclusive of most breeding populations in western Europe (Iceland, Scotland and Spain). Tracked owls showed pronounced plasticity in both inter- and intra-individual behaviour. Distances between sequential breeding areas of individual owls ranged from 41 to 4216 km, with similar low fidelity to areas used at other times of year. Owls spent most (> 60%) of their time occupying home-ranges (including breeding) and least (< 10%) undertaking long-distance movements. The propensity for long-distance movements was least for the most geographically isolated population, Iceland. Annual survival rates of 47% were lower than expected for an owl of comparable body mass with mortality concentrated during long-distance displacements and immediately after breeding. Extensive, nomadic travel to find areas where large broods might be reared may incur carry-over costs that lower survival. Conservation planning and assessment for nomadic species and their habitats must acknowledge the uncertainties associated with nomadism at scales from local to international.

Among avian species, particularly those with altricial young, life-history strategies are characterized by a ‘slow’ pace-of-life at lower latitudes, where relatively low annual investments in reproduction are traded-off for increased survival. Evidence for this pattern in precocial species, however, is equivocal, and questions about ecological drivers of latitudinal variation in reproduction remain. To better understand spatial variation in pace-of-life and related reproductive traits across bird species and to test a hypothesis that might explain observed spatial patterns, we analysed breeding data from closely related Canada Geese Branta canadensis and Cackling Geese Branta hutchinsii, hereafter Canada-type geese, comprising eight sub-species from 16 sites across a broad gradient of latitude (32°N to 69°N) and season length. Unlike the pattern reported for many altricial species, Canada-type geese did not show reduced annual fecundity at lower latitudes, and instead this reduced reproductive investment was at higher latitudes. For three of five reproductive traits, the relative influence of growing season length (GSL; an index of the time available to breed) was greater than that of latitude. A shorter GSL resulted in later nest initiations, shorter pre-laying intervals and higher seasonal rates of clutch size decline. Our results suggest that these and other species of geese are able to circumvent nutritional and temporal constraints imposed by shorter GSL by storing and using nutrient reserves for egg laying and incubation. Relative flexibility in reproductive traits may permit Canada-type geese to accommodate predicted increases in climatic variability, compared to species with more rigid reproductive strategies.

We combined data from two independent Danish citizen science time-series to describe changes in (1) abundance and (2) distribution of 12 wintering populations of geese and swans and tested the hypothesis that increases in national abundance since 2003 correlated with an expansion into formerly unoccupied winter farmland habitat. Five populations showed significant increases in national abundance, two declined and the remainder showed no significant trend over the same period; nine populations (including the five nationally increasing and two nationally declining) showed significantly positive correlations between annual abundance and distribution range size, including one stable population and one showing only local expansion. These results support our prediction that the five key increasing goose and swan populations benefiting from farmland exploitation are showing the greatest correlation between changes in abundance and wintering range in Denmark. This implies that continued growth in abundance in these populations will lead to continued expansion in their ranges, which will not only increase the potential for agricultural conflict with increasing abundance, but importantly also the geographical extent of such conflicts.

The Hoopoe Starling Fregilupus varius is an extinct species of the Sturnidae that was endemic to Réunion Island in the Indian Ocean. The species rapidly disappeared in the middle of the 19th century, primarily because of overexploitation by humans. We generated an approximately 11× coverage genome to reconstruct the demographic history of the Hoopoe Starling and compared these results with the demographic histories of other starlings and myna species. Our analyses confirmed the close affinities of the Hoopoe Starling with the genera Sturnia, Leucopsar and Sturnornis, and revealed that it went through a strong population bottleneck during its evolutionary history, but that its effective population size was not particularly low when compared with other extinct or critically endangered species of birds.

Some probiotics including lactobacilli, colonize host animal cells by targeting glycosaminoglycans (GAGs), such as heparin, located in the extracellular matrix. Recent studies have shown that several lactic acid bacteria degrade GAGs. Here we show the structure/function relationship of Lacticaseibacillus rhamnosus 4-deoxy-L-threo-5-hexosulose-uronate ketol-isomerase (KduI) crucial for metabolism of unsaturated glucuronic acid produced through degradation of GAGs. Crystal structures of ligand-free and bound KduIs were determined by X-ray crystallography and the enzyme was found to consist of six identical subunits and adopt a β-helix as a basic scaffold. Ligands structurally similar to the substrate were bound to the cleft of each enzyme subunit. Several residues located in the cleft interacted with ligands through hydrogen bonds and/or C-C contacts. In addition to substrate analogs, a metal ion coordinated to four residues, His198, His200, Glu205, and His248, in the cleft, and the enzyme activity was significantly inhibited by a chelator, ethylenediaminetetraacetic acid. Site-directed mutants in Arg163, Ile165, Thr184, Thr194, His200, Arg203, Tyr207, Met262, and Tyr269 in the cleft exhibited little enzyme activity, indicating that these residues and the metal ion constituted an active site in the cleft. This is the first report on the active site structure of KduI based on the ligand-bound complex.

The Nicobar Bulbul Ixos nicobariensis is an endemic species found across the central Nicobar Islands whose systematic position has been debated for many decades. Its current placement in the genus Ixos is tentative and is based on morphological similarities and geographical affinities to other members of the genus. We used mitochondrial and nuclear markers to examine its phylogenetic relationship to other members of Ixos and Hypsipetes. Our results indicate that the Nicobar Bulbul is sister to members of the genus Hypsipetes, and not Ixos. We further discuss the origin of this species based on the results of our study.