家燕营巢特征及其对城市环境的适应性

城市面积在全球范围内迅速扩张,一些鸟类种群通过改变营巢特征,在与自然生境截然不同的城市中筑巢繁殖。但目前城市环境对于鸟类营巢影响的研究较缺乏。为了解鸟类营巢对城市环境的适应,于2016、2019年在黑龙江哈尔滨的城市与乡村环境,分别测量家燕（Hirundo rustica）巢（如,大小及形状）及巢址特征等（如,距地面和屋顶距离）参数,以探究：（1）家燕巢特征在乡村及城市生境是否存在差异？（2）家燕巢特征在年际间是否存在变化？并为城市家燕种群的保护提供理论依据及合理建议。研究采用Kruskal-Wallis秩和检验以及Wilcoxon秩和检验比较分析所测量的巢特征参数在城乡之间、年际间的差异,并对组间参数进行线性判别分析（LDA,Linear Discriminant Analysis）。结果发现,城乡间具有显著差异：（1）与乡村相比,城市巢距离屋顶更远,距地相对更近（P<0.05）;（2）城市巢更浅（P<0.05）;（3）从2016到2019年,城市和乡村巢都变得更深,半径更大（P<0.05）。根据这些发现,推测城市楼房建筑的楼道为家燕繁殖提供了相对更为封闭、安全的环境,旧巢及较为丰富的支撑物为家燕提供了适宜的巢址,有可能节省亲鸟在营巢上的繁殖投入;但同时应当警惕门窗关闭、资源受限、人为干扰等不利因素可能造成的生态陷阱。     

Recognition of a new generic‐level swallow taxon from central Africa

The forest swallow Petrochelidon fuliginosa is a little‐known species endemic to lowland forests in central Africa; for lack of access to high‐quality genetic material, the species has been omitted from all previous molecular phylogenetic studies of the swallows. The species is currently placed in the genus Petrochelidon, within the ‘mud‐nester’ clade of swallows, yet its plumage, morphology, and nesting behavior do not align well with those of other major swallow lineages. As a consequence, upon securing recent specimens and high‐quality tissue samples, we sequenced DNA from two mitochondrial genes and one nuclear marker to place this species in the swallow phylogenetic tree. Our results placed the forest swallow firmly within the ‘mud nester’ clade, but outside of the clade corresponding to Petrochelidon. This outcome led us to document and describe formally a distinct, generic‐level lineage of swallow endemic to the Lower Guinean forest region of central Africa.     

The fossil birds of Henderson Island, Pitcairn Group: natural turnover and human impact, a synopsis

Recent studies of island biotas have suggested that the impact of man on indigenous flora and fauna is much greater than previously suspected. This impact resulted in the introduction of many new species and the extinction of many unique life-forms. Henderson Island, in the Pitcairn Group, has been found to be an excellent laboratory for the study of natural faunal turnover and the impact of people on the natural environment. This was principally due to the island's remote location and its limestone structure, which resulted in the excellent preservation of fossil remains. During the Sir Peter Scott Commemorative Expedition to the Pitcairn Islands, extensive excavations were undertaken resulting in the collection of 42213 bird bones. It was possible to identify 31%. Of the 31 taxa identified, four seabirds appear to be vagrants, a surprisingly high number illustrating that the uncritical evaluation of fossil bird lists from other islands risks over-estimating the number of indigenous species. As a result of the arrival of Polynesian people during the first half of this millennium, half of Henderson's endemic landbirds became extinct, as did most of the small ground-nesting seabirds. The lower sea level during cold stages creates many temporary limestone 'high' islands. This results in many 'former-atolls' developing geological and ecological similarity to Henderson. Hence lower sea-level greatly facilitates the movement of flora and fauna between currently isolated oceanic 'high' islands.     

Predation by ants controls swallow bug (Hemiptera: Cimicidae: Oeciacus vicarius) infestations

The swallow bug (Oeciacus vicarius) is the only known vector for Buggy Creek virus (BCRV), an alphavirus that circulates in cliff swallows (Petrochelidon pyrrhonota) and house sparrows (Passer domesticus) in North America. We discovered ants (Crematogaster lineolata and Formica spp.) preying on swallow bugs at cliff swallow colonies in western Nebraska, U.S.A. Ants reduced the numbers of visible bugs on active swallow nests by 74‐90%, relative to nests in the same colony without ants. Ant predation on bugs had no effect on the reproductive success of cliff swallows inhabiting the nests where ants foraged. Ants represent an effective and presumably benign way of controlling swallow bugs at nests in some colonies. They may constitute an alternative to insecticide use at sites where ecologists wish to remove the effects of swallow bugs on cliff swallows or house sparrows. By reducing bug numbers, ant presence may also lessen BCRV transmission at the spatial foci (bird colony sites) where epizootics occur. The effect of ants on swallow bugs should be accounted for in studying variation among sites in vector abundance.     

Divergent patterns of impact of environmental conditions on life history traits in two populations of a long-distance migratory bird

Some areas have experienced recent dramatic warming due to climate change, while others have shown no change at all, or even recent cooling. We predicted that patterns of selection on life history would differ between southern and northern European populations of a long-distance migratory bird, the barn swallow Hirundo rustica, because global patterns of weather as reflected by large-scale weather phenomena such as the North Atlantic Oscillation (NAO) and the El Niño-Southern Oscillation (ENSO) have different effects on environmental conditions in different parts of the world frequented during the annual cycle. We investigated relationships between mean arrival date, dispersal rate and yearling survival rate among years, using two long-term population studies in Spain and Denmark. We found evidence of a difference in the effects of normalized difference vegetation index in North and West Africa on mean arrival date of male barn swallows, with the effect differing significantly between populations. Second, there was a significant interaction between ENSO and population on dispersal rate, showing that conditions in Africa during winter differentially affected dispersal in the two populations. Finally, the NAO index in winter had an effect on yearling survival that differed between populations. These findings highlight the divergent patterns of response to climate change among populations, and they suggest that climate change can differentially affect important life history traits with potential implications for maintenance of viable populations and gene flow among populations.     

DNA damage in barn swallows (Hirundo rustica) from the Chernobyl region detected by use of the comet assay

We investigated levels of DNA damage in blood cells of barn swallows (Hirundo rustica) inhabiting the Chernobyl region to evaluate whether chronic exposure to low-level radioactive contamination continues to induce genetic damage in free-living populations of animals. Blood samples were obtained from barn swallows collected at sites with different background levels of radiation, including a relatively uncontaminated area. The extent of DNA damage was evaluated using the alkaline (pH = 12.1) comet assay, a robust and sensitive electrophoresis-based technique widely employed in research ranging from biomonitoring to clinical studies. We found that levels of DNA damage, as indexed by the extent of DNA migration, were increased in barn swallows living in areas surrounding Chernobyl when compared to swallows sampled at low-level sites. The results we obtained are consistent with previous findings on this same species, which showed that swallows breeding in areas heavily contaminated with radionuclides have increased mutation rates, higher oxidative stress and incidence of morphological aberrations and tumors. Overall, these results indicate that chronic exposure to radioactive contaminants, even 20 years after the accident at the Chernobyl nuclear power plant, continues to induce DNA damage in cells of free-living animals.     

Habitat preference, escape behavior, and cues used by feather mites to avoid molting wing feathers

We analyzed the pattern of distribution and the effect of moltingon the escape behavior of feather mites on the wing feathersduring the nonmolting and molting season of the barn swallowHirundo rustica. Feather mites showed consistent preferencefor the second outermost primary, with a steady decrease inproximal distance and avoidance of the outermost primary. Severalexplanations are suggested to explain this unusual distribution.Further, analyzing the escape behavior of feather mites on moltingprimaries, we show that mites avoid the feathers destined tobe dropped next on molting barn swallows, and in the case ofthe outermost primary, mites use the "last moment" strategy,namely, leaving feathers shortly before it is dropped. Next,we performed an experiment in which we simulated shedding feathersor feathers about to be shed on nonmolting barn swallows, inorder to test cues used by feather mites in avoiding moltingprimaries. Both the vibration of the incised feather and thegap of the pulled feather induced mites to leave primaries situateddistally, at two-feathers distance from the manipulated primary,related to the control group. Our results show that feathermites have the ability to perceive the signal produced by thefeather that will drop next and by the gap of the missing feather.It remains to be demonstrated, whether feather mites have theability to perceive the vibration of the feather per se or theyperceive the altered airflow caused by the vibrating feathers.     

Intranasal concentrations of orally administered flavors

The odorants emanating from the oral cavity during eating and drinking reach the olfactory mucosa via the pharynx (retronasal olfaction). It is unclear which variables influence the perception of intraorally applied substances. The aim of the present study was to determine the temporal profiles of volatile odor concentrations at different locations in the nasal cavity during consumption of liquid and solid custard samples using proton transfer reaction mass spectrometry. Intranasal odor concentrations were measured at least twice in nine subjects (six female, three male) at four nasal positions during the consumption of liquid and solid custards. The low-viscosity custard was swallowed earlier than the more solid one. The compounds were found to reach the nose in different concentrations. Largest maximal amplitudes were measured in the nasopharynx, whereas lowest concentrations were found in the region of the olfactory cleft. In addition, different odorants reached the different regions in the nasal cavity in varying concentrations, indicated by a significant interaction between factors "position" and "compound". Furthermore, the compounds were found to reach the positions within the nasal cavity with different latencies. These results indicate that different volatile flavor compounds exhibit different temporal and spatial profiles in terms of their intranasal distribution.