A Comparison of Homing Behavior in Feral and Homing Pigeons

The social system of 4 adult Chinese hamsters was analysed under semi-natural conditions in a large enclosure. In all trials the home ranges overlapped, but were patterned in a different way and patrolled in turn. ♂♂ were inferior and less aggressive than ♀♀ and had to change their nest site more frequently. The observed social organization is based on a dominance order influenced by home range site and by activity.     

Does Familiarity with the Release Site Influence the Initial Orientation of Homing Pigeons? Experiments with Clock-shifted Birds

Experiments were performed to test whether the familiarity with the release site plays a role in the initial orientation of homing pigeons. Repeated releases of 6 h clock-shifted birds from the same site during the shifting time produced an improvement of their initial orientation: the shift effect decreased progressively. Since in subsequent releases from unfamiliar sites the shift effect reappears, the course correction observed at the familiar site is attributable to local stimuli and not to a general recalibration of the sun compass.     

Superparamagnetic Magnetite in the Upper Beak Tissue of Homing Pigeons

Homing pigeons have been subject of various studies trying to detect magnetic material which might be involved in magnetic field perception. Here we focus on the upper-beak skin of homing pigeons, a region that has previously been shown to contain nerves sensitive to changes of the ambient magnetic field. We localized Fe³⁺ concentrations in the subcutis and identified the material by transmission electronmicroscopy (TEM) as aggregates of magnetite nanocrystals (with grain sizes between 1 and 5 nm). The particles form clusters of 1–3 m diameter, which are arranged in distinct coherent elongated structures, associated with nervous tissue and located between fat cells. Complementary low-temperature magnetic measurements confirm the microscopic observations of fine-grained superparamagnetic particles in the tissue. Neither electron-microscopic nor magnetic measurements revealed any single-domain magnetite in the upper-beak skin tissue.     

无数候鸟命之所依

达里湖位于亚洲东部主要候鸟类迁徙路线的中间位置,而且周边数十万平方公里普遍干旱,如此广阔的湿地对于众多候鸟来说,有着重要的价值。夜宿离湖边有一两公里的达里湖宾馆,等安静下来,房间里能听到叽叽呱呱的声音,仿佛夏夜蛙鸣。推开向湖的窗户,清晰响亮的鸣声迎面扑来。原来是湖边的鸟儿在上演“大合唱”,歌声洪亮高越,此起彼伏,交织成一片,和草原夜空中密集而闪耀的星星相映成趣。我这才想起白天在离湖边一百多米的管护小屋里,值班人员曾说起     

Occurrence of Yeasts in Cloacae of Migratory Birds

Several species of yeast have been reported as pathogens in humans based on increases in immunodeficiency syndromes and as a result of immunosuppressant chemotherapy in cancer treatment. Domestic and wild birds are known to act as carriers of human pathogenic fungi. To gain additional information on the yeasts present in the cloacae of some species of migratory birds, 421 wild birds (24.39% out of 1726 birds caught in Romania, Hungary and Bulgaria) were sampled with the permission of the local judicial authority. The state of conservation of the birds (i.e. post-mortem alterations, colour of the mucosae etc.), along with their age and sex were determined. Samples were collected directly from the cloacae and cultured, and colonies were identified in each positive sample. Yeasts were isolated from 15.7% of the animals sampled, with the highest percentage found in coots (Fulica atra −58.8%) and the lowest in quails (Coturnix coturnix −1.7%). A total of 131 isolates belonging to 15 species of yeast were identified. Rhodotorula rubra was the yeast with the highest number of isolates (28.2%), followed by Cryptococcus albidus (18.4%), Candida albicans (9.2%), Trichosporon cutaneum (8.4%), Candida guilliermondii (6.1%), Candida tropicalis (6.1%) and other species. The present study represents the first survey on the occurrence of yeasts in the cloacae of migratory birds. The prevalence and species of yeasts isolated is discussed on the basis of the ecology, diet, and habitat of the birds.     

Highly Pathogenic H5N1 Influenza Virus Infection in Migratory Birds

H5N1avianinfluenza virus(AIV)has emerged as a pathogenic entityfor a variety of species,including humans,inre-cent years.Here we report an outbreak among migratory birds on Lake Qinghaihu,China,in May and June2005,inwhich more than a thousand birds were affected.Pancreatic necrosis and abnormal neurological symptoms were the majorclinical features.Sequencing of the complete genomes of four H5N1AIVstrains revealedthemto be reassortants relatedto a peregrine falconisolate from Hong Kong an…     

Acuity of a Cryptochrome and Vision-Based Magnetoreception System in Birds

The magnetic compass of birds is embedded in the visual system and it has been hypothesized that the primary sensory mechanism is based on a radical pair reaction. Previous models of magnetoreception have assumed that the radical pair-forming molecules are rigidly fixed in space, and this assumption has been a major objection to the suggested hypothesis. In this article, we investigate theoretically how much disorder is permitted for the radical pair-forming, protein-based magnetic compass in the eye to remain functional. Our study shows that only one rotational degree of freedom of the radical pair-forming protein needs to be partially constrained, while the other two rotational degrees of freedom do not impact the magnetoreceptive properties of the protein. The result implies that any membrane-associated protein is sufficiently restricted in its motion to function as a radical pair-based magnetoreceptor. We relate our theoretical findings to the cryptochromes, currently considered the likeliest candidate to furnish radical pair-based magnetoreception.     

沈阳周边重要生态保护地春季迁徙鸟类多样性调查

2014年3月21日—5月9日,采用样线法与定点观察法对沈阳市周边26个重要生态保护地春季迁徙期鸟类多样性进行了调查。共记录鸟类16目40科94种。其中,国家Ⅰ级重点保护鸟类2种;国家Ⅱ级重点保护鸟类4种。居留型组成以夏候鸟和旅鸟为主,共占记录鸟类物种总数的77.7%。区系组成以古北界种为主,占74.5%。生态型中鸣禽最多,占36.2%。不同调查样地的鸟类组成与多样性指数存在较大差异,水库湿地鸟类数量最多;湿地公园物种丰富度最高;森林生态系统鸟类多样性较高;沙地生境鸟类多样性较低。调查发现部分生态保护地存在人为干扰程度较大、生态破坏严重、生境类型高度单一等生态问题。针对相应的生态保护地应进一步加强生态环境治理,为鸟类生存提供良好的栖息环境。     

The Orientational Consequences of Flocking Behaviour in Homing Pigeons,Columba livia

Two experiments are described which investigate the orientational consequences of flocking in homing pigeons Columba livia. Previous experiments have shown that homing pigeons placed inside a clear-sided release box for 5 min before release from a familiar site have enhanced ground homing speed compared with those placed in an opaque-sided box. It is assumed that previewing the surrounding landscape allows for faster homing since a bird denied this information must accumulate the knowledge on release. In experiment 1, using the same technique developed in these experiments but releasing the birds in pairs we showed that within familiar areas, homing pigeons can exploit a partner that has acquired more information, allowing them to home more quickly. In experiment 2 we attempted to test three potential strategies which may occur during homing flights. The results do not conclusively distinguish between these three mechanisms but suggest that orientation of the pairs of birds is most likely to have resulted from a compromise of individual tendencies, or from following the best homer, but not from following a ‘governing leader’. The consequence of these mechanisms is discussed.     

Evolutionary Divergence in Brain Size between Migratory and Resident Birds

Despite important recent progress in our understanding of brain evolution, controversy remains regarding the evolutionary forces that have driven its enormous diversification in size. Here, we report that in passerine birds, migratory species tend to have brains that are substantially smaller (relative to body size) than those of resident species, confirming and generalizing previous studies. Phylogenetic reconstructions based on Bayesian Markov chain methods suggest an evolutionary scenario in which some large brained tropical passerines that invaded more seasonal regions evolved migratory behavior and migration itself selected for smaller brain size. Selection for smaller brains in migratory birds may arise from the energetic and developmental costs associated with a highly mobile life cycle, a possibility that is supported by a path analysis. Nevertheless, an important fraction (over 68%) of the correlation between brain mass and migratory distance comes from a direct effect of migration on brain size, perhaps reflecting costs associated with cognitive functions that have become less necessary in migratory species. Overall, our results highlight the importance of retrospective analyses in identifying selective pressures that have shaped brain evolution, and indicate that when it comes to the brain, larger is not always better.     

Expression of the Dentin Matrix Protein 1 Gene in Birds

The emergence of jawed vertebrates was predicated on the appearance of several innovations, including tooth formation. The development of teeth requires the participation of several specialized genes, in particular, those necessary for the formation of hard tissues—dentin, enamel, and cementum. Some vertebrates, most conspicuously birds, secondarily lost the tooth-forming ability. To determine the fate of some of the tooth-forming genes in the birds, we tested a domestic fowl cDNA library for the expression of the dentin matrix protein 1 (DMP1) gene. The library was prepared from the poly(A⁺) RNA isolated from the jaws of 11- to 13-day-old embryos and the testing was carried out by the polymerase chain reaction with degenerate primers designed on the basis of the available mammalian and reptile sequences. A chicken homologue of the DMP1 gene identified by this approach was shown to be expressed in the jaws and long bones, the same two tissues as in mammals. The chicken DMP1 gene has an exon/intron organization similar to that of its mammalian and reptile counterparts. The chicken gene contains three short highly conserved segments, the rest of the gene being poorly alignable or not alignable with its mammalian or reptilian homologues. The distribution of similarities and dissimilarities along the gene is indicative of a mode of evolution in which only short segments are kept constant, while the rest of the gene is relatively free to vary as long as the proportion of certain amino acid residues is retained in the encoded polypeptide. The DMP1 gene may have been retained in birds because of its involvement in bone formation. Received: 5 April 1999 / Accepted: 9 August 1999     

Pineal Body and Magnetic Sensitivity: Homing in Pinealectomized Pigeons under Overcast Skies

Since birds use the earth's magnetic field for compass orientation when astronomical cues are lacking and it has recently been suggested that the pineal body is part of their magnetic compass, test releases have been performed in overcast conditions with pigeons deprived of the pineal body. On the whole, both experimental and control birds were capable of homeward orientation, though the bearings of experimental were rather more scattered. No differences in homing speed or success were recorded. Thus, the pineal body does not appear to play an important role in the homing of pigeons.     

候鸟迁徙过程中"雄性早现"的六种假说及未来研究热点

"雄性早现"(protandry)是指雄性相对于雌性更早进入繁殖状态或更早到达繁殖地的现象.该文针对候鸟的雄性比雌性在春季时更早到达繁殖地这一现象,介绍了雄性早现的6种假说,即等级优势(rank advantage)假说、敏感性(susceptibility)假说、限制性(constraint)假说、交配机会(mate opportunity)假说、等待代价(waiting cost)假说和配偶选择(mate choice)假说,并通过近年来的研究证据阐述了上述假说对解释候鸟雄性早现的适用性.此外,对鸟类雄性早现未来研究中可能的热点问题做了展望.     

The Effects of Zinc Sulphate Anosmia on Homing Pigeons,Columba livia,in a Homing and a Non-homing Experiment

There is debate over whether homing pigeons, Columba livia, use olfactory information as part of their navigational map. Antagonists of the theory argue that homing deficits noted in anosmic pigeons may be due to a non-specific impairment in general information processing. In Experiment I, we present data from a modest investigation describing the typical navigational deficits that occur following zinc sulphate-mediated anosmia. Our results are consistent with previous experiments that noted impairments in homing performance from unfamiliar locations of anosmic pigeons. Experiment II is a critical experiment that involved a spatial working memory paradigm; this paradigm consisted of testing zinc sulphate-treated birds in a forced-choice alternation task in a T-maze. This experiment allowed us to determine whether anosmic pigeons were impaired in memory performance, a robust measure of general information processing. There were no differences between the last day of training and a subsequent-test day when pigeons received an intranasal injection of zinc sulphate. This experiment suggests that zinc sulphate anosmia does not impair general information processing, supporting the hypothesis that homing pigeons use olfactory cues when homing from unfamiliar locations.     

Genetic Diversity of Newcastle Disease Virus in Wild Birds and Pigeons in West Africa

In West and Central Africa, virulent Newcastle disease virus (NDV) strains of the recently identified genotypes XIV, XVII, and XVIII are enzootic in poultry, representing a considerable threat to the sector. The increasing number of reports of virulent strains in wild birds at least in other parts of the world raised the question of a potential role of wild birds in the spread of virulent NDV in sub-Saharan Africa as well. We investigated 1,723 asymptomatic birds sampled at live-bird markets and sites important for wild-bird conservation in Nigeria and 19 sick or dead wild birds in Côte d''Ivoire for NDV class I and II. Typical avirulent wild-type genotype I strains were found in wild waterfowl in wetlands in northeastern Nigeria. They were unrelated to vaccine strains, and the involvement of inter- or intracontinental migratory birds in their circulation in the region is suggested. Phylogenetic analyses also revealed that genotype VI strains found in pigeons, including some putative new subgenotype VIh and VIi strains, were introduced on multiple separate occasions in Nigeria. A single virulent genotype XVIII strain was found in a dead wild bird in Côte d''Ivoire, probably as a result of spillover from sick poultry. In conclusion, screening of wild birds and pigeons for NDV revealed the presence a variety of virulent and avirulent strains in West Africa but did not provide strong evidence that wild birds play an important role in the spread of virulent strains in the region.     

virF-Positive Yersinia pseudotuberculosis and Yersinia enterocolitica Found in Migratory Birds in Sweden

During spring and autumn migrations, 468 fecal samples from 57 different species of migratory birds were collected in Sweden. In total, Yersinia spp. were isolated from 12.8% of collected samples. The most commonly found species was Yersinia enterocolitica, which was isolated from 5.6% of all collected samples, followed by Y. intermedia (3.8%), Y. frederiksenii (3.0%), Y. kristensenii (0.9%), Y. pseudotuberculosis (0.6%), and Y. rohdei (0.4%). The pathogenic, virF-positive Y. pseudotuberculosis strains were recovered from three thrushes. These strains belonged to the same bioserotype, 1/O:2, but had two different profiles as determined by pulsed-field gel electrophoresis with NotI and SpeI enzymes. In addition, 10 Y. enterocolitica strains, all from barnacle geese, belonged to bioserotype 3/O:3, which is associated with human disease. Two of the strains were pathogenic, carrying the virF gene on their plasmids. All pathogenic Y. pseudotuberculosis and Y. enterocolitica strains were recovered during the spring, and as the birds were caught during active migration they likely became infected at an earlier stage of the migration, thus potentially transporting these bacterial pathogens over long geographical distances.     

Seasonally Changing Cryptochrome 1b Expression in the Retinal Ganglion Cells of a Migrating Passerine Bird

Cryptochromes, blue-light absorbing proteins involved in the circadian clock, have been proposed to be the receptor molecules of the avian magnetic compass. In birds, several cryptochromes occur: Cryptochrome 2, Cryptochrome 4 and two splice products of Cryptochrome 1, Cry1a and Cry1b. With an antibody not distinguishing between the two splice products, Cryptochrome 1 had been detected in the retinal ganglion cells of garden warblers during migration. A recent study located Cry1a in the outer segments of UV/V-cones in the retina of domestic chickens and European robins, another migratory species. Here we report the presence of cryptochrome 1b (eCry1b) in retinal ganglion cells and displaced ganglion cells of European Robins, Erithacus rubecula. Immuno-histochemistry at the light microscopic and electron microscopic level showed eCry1b in the cell plasma, free in the cytosol as well as bound to membranes. This is supported by immuno-blotting. However, this applies only to robins in the migratory state. After the end of the migratory phase, the amount of eCry1b was markedly reduced and hardly detectable. In robins, the amount of eCry1b in the retinal ganglion cells varies with season: it appears to be strongly expressed only during the migratory period when the birds show nocturnal migratory restlessness. Since the avian magnetic compass does not seem to be restricted to the migratory phase, this seasonal variation makes a role of eCry1b in magnetoreception rather unlikely. Rather, it could be involved in physiological processes controlling migratory restlessness and thus enabling birds to perform their nocturnal flights.