鸟类磁感受的生物物理机制研究进展

行为学实验表明,许多鸟类能够感受到地磁信息,并利用地磁信息完成迁徙或归巢。地磁场信息能提供可靠导航信息,磁力线可提供罗盘信息,而磁场强度和倾角可提供位置信息。文章介绍了鸟类磁感受机制的两种重要假说——基于磁铁矿的磁感受假说和化学磁感受假说,阐明了两种假说的理论原理及实验证据,对地磁信息传导神经通路与处理脑区做了评述,并展望了其发展方向。     

鸟类迁徙导航定位机制与人工设施的影响

简要介绍了鸟类迁徙导航定位机制的各种学说及机制,分析了人工设施对鸟类迁徙导航和定位的影响概况,提出了降低人工设施对鸟类影响的保护措施。     

动物地磁导航机制研究进展

地磁场是地球重要的物理场,它不仅能保护地球生物免受太阳风及其他宇宙射线的伤害,阻挡地球生命赖以生存的大气圈和水圈被剥蚀,为地球生物提供一个温和的生存进化环境,而且其强度、偏角和倾角能为动物迁徙提供定位导航参考。目前,行为学研究已经发现许多鸟类、爬行类、两栖类、哺乳类等动物都能够利用地磁场导航。动物感知地磁场的磁感受器(magnetoreceptor)、磁信息的感知机制和信号传递通路一直是动物地磁导航研究的焦点和难点,但目前对它们的了解并不十分清楚。基于国内外学者最近的研究成果,本文首先介绍三种主要的磁感知机制及其相应的证据:电磁感应、基于光受体的磁感知及基于磁铁矿纳米颗粒的磁感知。其次,总结鸟类基于光受体和磁铁矿纳米颗粒的磁感知神经通路和相应的磁信息响应脑区:(1)眼睛视网膜上光依赖的磁感受器——隐花色素通过视觉通路与大脑联系获取准确方向信息;(2)上喙或内耳中的磁铁矿纳米颗粒磁感受器,通过三叉神经或内耳听壶传入神经将感知的磁场强度信息传至脑干前庭区域,获得"导航图"信息。最后,简要总结近年来哺乳动物地磁导航的研究进展,并指出动物地磁导航研究当前亟待解决的几个重要科学问题。     

鸟类迁徙的研究方法和研究进展

鸟类的迁徙长期以来一直是人类最感兴趣的自然现象之一。随着科技的不断发展,各种先进的仪器设备和研究方法被应用到鸟类迁徙的研究中,为深入了解鸟类的迁徙活动起到了重要作用。介绍了野外观察、雷达监测、环志、卫星跟踪、稳定同位素和室内控制实验等鸟类迁徙的主要研究方法、并介绍了近年来在鸟类的迁徙停歇地和迁徙路线以及鸟类迁徙的能量代谢方面的研究成果,供广大读者参考和借鉴。     

稳定同位素分析在鸟类生态学中的应用

稳定同位素作为一种自然标记物是研究鸟类生态学的重要工具之一,与传统研究方法相比其呈现的信息更为真实全面,是一种日趋成熟的鸟类生态学研究方法。近几年该方法在鸟类迁徙生态学、取食生态学等方面取得较大成就,展现出传统研究方法无可比拟的优越性。但目前该方法在我国鸟类生态学上的应用较少,基于此,从迁徙、取食等方面分别阐述稳定同位素在鸟类生态学上的应用,以促进我国鸟类生态学的快速发展和推动稳定同位素生态学与其它学科的交叉融合。     

迁徙鸟类对中途停歇地的利用及迁徙对策

中途停歇地是迁徙鸟类在繁殖地和非繁殖地之间的联系枢纽,对于迁徙鸟类完成其完整的生活史过程具有重要作用。从鸟类的迁徙对策、中途停歇地的选择、鸟类在中途停歇地的停留时间、体重变化和种群特征以及中途停歇地的环境状况等方面,回顾了中途停歇生态学在近年来的研究进展,并提出了在迁徙对策理论的实验研究,小型鸟类在中途停歇地的停歇时间及体重变化的准确确定等目前有待解决的问题。     

怎样开展鸟类环志

环志是了解鸟类迁徙规律最有效的方法,通过环志活动可掌握鸟类迁徙时间、路线、范围及迁徙鸟的性比、种群数量、年龄等方面的情况,环志工作对保护珍稀鸟类,科学地利用鸟类资源,监测环境,降低鸟害等方面都有重要的科研意义。鸟类环志于本世纪２０年代初始于丹麦,目前...     

迁徙鸟类中途停歇期的生理生态学研究

大多数候鸟的迁徙活动由迁徙飞行和中途停歇两个部分组成。在迁徙过程中,鸟类要多次交替经历消耗能量的飞行阶段和积累能量的中途停歇阶段。从鸟类在中途停歇时期的能量积累速度、体重变化模式以及迁徙飞行中的禁食或食物限制、食物种类的改变、中途停歇的能量快速积累过程对消化器官的影响等方面,对目前迁徙鸟类的生理生态学研究成果进行回顾,并提出有待解决的问题及今后的研究方向。     

鸟类迁徙:在全球变暖趋势下的演化、调控与发展(英文)

最近几十年的研究证实 ,鸟类迁徙在很大程度上受到遗传因素的直接控制。有证据表明 ,存在某种先天的迁徙动因并涉及以下几方面的遗传调控 :(1)迁徙过程的起始、持续以及结束 ;(2 )迁徙活动量 ,即决定鸟类飞行距离的遗传参数 ;(3)迁徙方向 ;(4)生理参数 ,特别是迁徙期间的脂肪贮存 ,以及对于那些部分个体迁徙的鸟种而言 ,决定个体迁徙与否的生理参数。双因素选择实验表明 ,部分迁徙群经由几个世代的选择即可转变成完全的迁徙群或非迁徙群。新迁徙方向以及由此导致的新越冬区的改变 ,也能在野生鸟类中迅速实现。至少在以往研究得最为透彻的鸟种 (黑顶林莺Sylviaatricapilla)中 ,“迁徙”或“非迁徙”是先天性的 ,与特异性迁徙活动量相关 (尤如一时间程序 ) ,前者 (迁徙的 )已证实是由一种阈机制所控制的。一项新的鸟类迁徙理论假设 ,即使好些完全迁徙的类群 ,较低水平的迁徙活动量选择也会导致阈的异位 ,低于这一阈值就会出现非迁徙个体。因此 ,通过选择作用 ,一个迁徙型种群可以通过部分迁徙型转变为非迁徙型。这种中间阶段在现存鸟类中十分普遍。它始见于生物演化早期 ,就鸟类而言 ,可能在原始鸟类就已具备。模型运算表明 ,在施以强定向选择情况下 ,迁徙鸟类经过约 4 0年可转变为留鸟 ,反之亦然。这就解     

沈阳桃仙国际机场鸟类夜间迁徙规律

在鸟类迁徙季节,夜间鸟击事故频发是机场鸟击发生的一个显著特点.了解鸟类的夜间迁徙规律对于改进夜间鸟击防范措施具有重要的指导意义.本研究综合采用网捕法和声音记录法对沈阳桃仙机场夜间鸟类迁徙物种组成和迁徙规律进行研究.结果表明: 56种鸟类(占比88.9%)具有夜间迁徙习性,且以后半夜迁徙为主;鸟类夜间迁徙具有明显的时间动态和迁徙次序,春季鸟类迁徙较为集中,迁徙高峰在5月中旬,主要鸟类由鹌鹑、红尾伯劳、栗耳鹀、黑喉石鵖、普通夜鹰、黄眉柳莺等组成,秋季迁徙较为分散,迁徙高峰出现在9月下旬至10月上旬,主要由鹌鹑、灰背鸫、红喉鹨、丘鹬、矛斑蝗莺和灰头鵐等组成.对夜间迁徙鸟类的危险等级评估发现,春季严重危险物种是鹌鹑和红尾伯劳,秋季严重危险物种是鹌鹑、纵纹腹小鸮、灰背鸫和丘鹬.分别从夜间迁徙鸟类组成、迁徙动态、时间节律和物种危险等级等角度提出了相应的鸟击防范对策,为桃仙机场鸟击防范提供参考.     

Evidence for calibration of magnetic migratory orientation in Savannah sparrows reared in the field

The orientation system of migratory birds consists of a magnetic compass and compasses based upon celestial cues. In many places, magnetic compass directions and true or geographic compass directions differ (referred to as magnetic declination). It has been demonstrated experimentally in several species that the innate preferred direction of magnetic orientation can be calibrated by celestial rotation, an indicator of geographic directions. This calibration process brings the two types of compass into conformity and provides the birds with a mechanism that compensates for the spatial variation in magnetic declination. Calibration of magnetic orientation has heretofore been demonstrated only with hand-raised birds exposed to very large declination (90° or more). Here we show that the magnetic orientation of wild birds from near Albany, New York, USA (declination = 14° W) was N–S, a clockwise shift of 26° from the NNW–SSE direction of birds raised entirely indoors. Hand-raised birds having visual experience with either the daytime sky or both day and night sky orientated N–S, similar to wild-caught birds. These data provide the first confirmation that calibration of magnetic orientation occurs under natural conditions and in response to modest declination values.     

Compass orientation and possible migration routes of passerine birds at high arctic latitudes

The use of celestial or geomagnetic orientation cues can lead migratory birds along different migration routes during the migratory journeys, e.g. great circle routes (approximate), geographic or magnetic loxodromes. Orientation cage experiments have indicated that migrating birds are capable of detecting magnetic compass information at high northern latitudes even at very steep angles of inclination. However, starting a migratory journey at high latitudes and following a constant magnetic course often leads towards the North Magnetic Pole, which means that the usefulness of magnetic compass orientation at high latitudes may be questioned. Here, we compare possible long‐distance migration routes of three species of passerine migrants breeding at high northern latitudes. The initial directions were based on orientation cage experiments performed under clear skies and simulated overcast and from release experiments under natural overcast skies. For each species we simulated possible migration routes (geographic loxodrome, magnetic loxodrome and sun compass route) by extrapolating from the initial directions and assessing a fixed orientation according to different compass mechanisms in order to investigate what orientation cues the birds most likely use when migrating southward in autumn. Our calculations show that none of the compass mechanisms (assuming fixed orientation) can explain the migration routes followed by night‐migrating birds from their high Nearctic breeding areas to the wintering sites further south. This demonstrates that orientation along the migratory routes of arctic birds (and possibly other birds as well) must be a complex process, involving different orientation mechanisms as well as changing compass courses. We propose that birds use a combination of several compass mechanisms during a migratory journey with each of them being of a greater or smaller importance in different parts of the journey, depending on environmental conditions. We discuss reasons why birds developed the capability to use magnetic compass information at high northern latitudes even though following these magnetic courses for any longer distance will lead them along totally wrong routes. Frequent changes and recalibrations of the magnetic compass direction during the migratory journey are suggested as a possible solution.     

A visual pathway links brain structures active during magnetic compass orientation in migratory birds

The magnetic compass of migratory birds has been suggested to be light-dependent. Retinal cryptochrome-expressing neurons and a forebrain region, "Cluster N", show high neuronal activity when night-migratory songbirds perform magnetic compass orientation. By combining neuronal tracing with behavioral experiments leading to sensory-driven gene expression of the neuronal activity marker ZENK during magnetic compass orientation, we demonstrate a functional neuronal connection between the retinal neurons and Cluster N via the visual thalamus. Thus, the two areas of the central nervous system being most active during magnetic compass orientation are part of an ascending visual processing stream, the thalamofugal pathway. Furthermore, Cluster N seems to be a specialized part of the visual wulst. These findings strongly support the hypothesis that migratory birds use their visual system to perceive the reference compass direction of the geomagnetic field and that migratory birds "see" the reference compass direction provided by the geomagnetic field.     

Magnetic compass orientation research with migratory songbirds at Stensoffa Ecological Field Station in southern Sweden: why is it so difficult to obtain seasonally appropriate orientation?

More than three decades ago, Thomas Alerstam initiated the study of orientation and navigation of migratory songbirds in southern Sweden. Stensoffa Ecological Field Station, located approx. 20 km east of Lund, has since been a primary location for orientation experiments. However, it has often been difficult to record well‐oriented behaviour in the seasonal appropriate migratory directions, in particular in magnetic orientation experiments under simulated overcast or indoors. Here, we summarise all available experiments testing magnetic compass orientation in migratory songbirds in southern Sweden, and review possible explanations for the poor magnetic compass orientation found in many studies. Most of the factors proposed can be essentially excluded, such as difficulties to extract magnetic compass information at high latitudes, methodological or experimenter biases, holding duration and repeated testing of individual birds, effects of magnetic anomalies and temporal variations of the ambient magnetic field, as well as anthropogenic electromagnetic disturbances. Possibly, the geographic location of southern Sweden where many birds captured and/or tested at coastal sites are confronted with the sea, might explain some of the variation that we see in the orientation behaviour of birds. Still, further investigations are needed to conclusively identify the factors responsible for why birds are not better oriented in the seasonal appropriate migratory direction at Stensoffa.     

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.     

Bats use magnetite to detect the earth's magnetic field

While the role of magnetic cues for compass orientation has been confirmed in numerous animals, the mechanism of detection is still debated. Two hypotheses have been proposed, one based on a light dependent mechanism, apparently used by birds and another based on a "compass organelle" containing the iron oxide particles magnetite (Fe(3)O(4)). Bats have recently been shown to use magnetic cues for compass orientation but the method by which they detect the Earth's magnetic field remains unknown. Here we use the classic "Kalmijn-Blakemore" pulse re-magnetization experiment, whereby the polarity of cellular magnetite is reversed. The results demonstrate that the big brown bat Eptesicus fuscus uses single domain magnetite to detect the Earths magnetic field and the response indicates a polarity based receptor. Polarity detection is a prerequisite for the use of magnetite as a compass and suggests that big brown bats use magnetite to detect the magnetic field as a compass. Our results indicate the possibility that sensory cells in bats contain freely rotating magnetite particles, which appears not to be the case in birds. It is crucial that the ultrastructure of the magnetite containing magnetoreceptors is described for our understanding of magnetoreception in animals.     

Two different types of light-dependent responses to magnetic fields in birds

A model of magnetoreception proposes that the avian magnetic compass is based on a radical pair mechanism, with photon absorption leading to the formation of radical pairs. Analyzing the predicted light dependency by testing migratory birds under monochromatic lights, we found that the responses of birds change with increasing intensity. The analysis of the orientation of European robins under 502 nm turquoise light revealed two types of responses depending on light intensity: under a quantal flux of 8.10(15) quanta m(-2) s(-1), the birds showed normal migratory orientation in spring as well as in autumn, relying on their inclination compass. Under brighter light of 54.10(15) quanta m(-2) s(-1), however, they showed a "fixed" tendency toward north that did not undergo the seasonal change and proved to be based on magnetic polarity, not involving the inclination compass. When birds were exposed to a weak oscillating field, which specifically interferes with radical pair processes, the inclination compass response was disrupted, whereas the response to magnetic polarity remained unaffected. These findings indicate that the normal inclination compass used for migratory orientation is based on a radical-pair mechanism, whereas the fixed direction represents a novel type of light-dependent orientation based on a mechanism of a different nature.     

Wintergoldh?hnchen (Regulus regulus) besitzen einen Inklinationskompa?

During autumn migration, orientation tests were performed with Goldcrests in the morning immediately after the birds had been caught. In the local geomagnetic field (vertical component pointing downward), they showed a significant tendency towards 144° SE; in a magnetic field with the vertical component pointing upward, their mean was at 321° NW. This response to an inversion of the vertical component reveals that the Goldcrests used the magnetic field for orientation and that their magnetic compass is an inclination compass as it has been described for several other species of migrants.     

Das Orientierungssystem der V?gel I. Kompa?mechanismen

Zusammenfassung V?gel stellen den Bezug zum Ziel indirekt über ein externes Referenzsystem her. Der Navigationsproze? besteht deshalb aus zwei Schritten: zun?chst wird die Richtung zum Ziel als Kompa?kurs festgelegt, dann wird dieser Kurs mit Hilfe eines Kompa?mechanismus aufgesucht. Das Magnetfeld der Erde und Himmelsfaktoren werden von den V?gel als Kompa? benutzt. In der vorliegenden Arbeit werden der Magnetkompa?, der Sonnenkompa? und der Sternkompa? der V?gel in ihrer Funktionsweise, ihrer Entstehung und ihrer biologischen Bedeutung vorgestellt. Der Magnetkompa? erwies sich als Inklinationskompa?, der nicht auf der Polarit?t, sondern auf der Neigung der Feldlinien im Raum beruht; er unterscheidet „polw?rts“ und „?quatorw?rts“ statt Nord und Süd. Er ist ein angeborener Mechanismus und wird beim Vogelzug und beim Heimfinden benutzt. Seine eigentliche Bedeutung liegt jedoch darin, da? er ein Referenzsystem bereitstellt, mit dessen Hilfe andere Orientierungsfaktoren zueinander in Beziehung gesetzt werden k?nnen. Der Sonnenkompa? beruht auf Erfahrung; Sonnenazimut, Tageszeit und Richtung werden durch Lernprozesse miteinander verknüpft, wobei der Magnetkompa? als Richtungsreferenzsystem dient. Sobald er verfügbar ist, wird der Sonnenkompa? bei der Orientierung im Heimbereich und beim Heimfinden bevorzugt benutzt; beim Vogelzug spielt er, wahrscheinlich wegen seiner Abh?ngigkeit von der geographischen Breite, kaum eine Rolle. Der Sternkompa? arbeitet ohne Beteiligung der Inneren Uhr; die V?gel leiten Richtungen aus den Konfigurationen der Sterne zueinander ab. Lernprozesse erstellen den Sternkompa? in der Phase vor dem ersten Zug; dabei fungiert die Himmelsrotation als Referenzsystem. Sp?ter, w?hrend des Zuges, übernimmt der Magnetkompa? diese Rolle. Die relative Bedeutung der verschiedenen Kompa?systeme wurde in Versuchen untersucht, bei denen Magnetfeld und Himmelsfaktoren einander widersprechende Richtungs-information gaben. Die erste Reaktion der V?gel war von Art zu Art verschieden; langfristig scheinen sich die V?gel jedoch nach dem Magnetkompa? zu richten. Dabei werden die Himmelsfaktoren umgeeicht, so da? magnetische Information und Himmelsinformation wieder im Einklang stehen. Der Magnetkompa? und die Himmelsfaktoren erg?nzen einander: der Magnetkompa? ersetzt Sonnen- und Sternkompa? bei bedecktem Himmel; die Himmelsfaktoren erleichtern den V?geln das Richtungseinhalten, zu dem der Magnetkompa? offenbar wenig geeignet ist. Magnetfeld und Himmelsfaktoren sollten deshalb als integrierte Komponenten eines multifaktoriellen Systems zur Richtungsorientierung betrachtet werden.

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The orientation system of birds — I. Compass mechanisms

Summary Because of the large distances involved, birds establish contact with their goal indirectly via an external reference. Hence any navigation is a two-step process: in the first step, the direction to the goal is determined as a compass course; in the second step, this course is located with a compass. The geomagnetic field and celestial cues provide birds with compass information. The magnetic compass of birds, the sun compass the star compass and the interactions between the compass mechanisms are described in the present paper. Magnetic compass orientation was first demonstrated by testing night-migrating birds in experimentally altered magnetic fields: the birds changed their directional tendencies according to the deflected North direction. The avian magnetic compass proved to be an inclination compass: it does not use polarity; instead it is based on the axial course of the field lines and their inclination in space, distinguishing “poleward” and “equatorward” rather than North and South. Its functional range is limited to intensities around the local field strength, but this biological window is flexible and can be adjusted to other intensities. The magnetic compass is an innate mechanism that is widely used in bird migration and in homing. Its most important role, however, is that of a basic reference system for calibrating other kinds of orientation cues. Sun compass orientation is demonstrated by clock-shift experiments: Shifting the birds' internal clock causes them to misjudge the position of the sun, thus leading to typical deflections which indicate sun compass use. The analysis of the avian sun compass revealed that it is based only on sun azimuth and the internal clock; the sun's altitude is not involved. The role of the pattern of polarized light associated with the sun is unclear; only at sunset has it been shown to be an important cue for nocturnal migrants, being part of the sun compass. The sun compass is based on experience; sun azimuth, time of day and direction are combined by learning processes during a sensitive period, with the magnetic compass serving as directional reference. When established, the sun compass becomes the preferred compass mechanism for orientation tasks within the home region and homing: in migration, however, its role is minimal, probably because of the changes of the sun's arc with geographic latitude. The star compass was demonstrated in night-migrating birds by projecting the northern stars in different directions in a planetarium. The analysis of the mechanism revealed that the internal clock is not involved; birds derive directions from the spatial relationship of the star configurations. The star compass is also established by experience; the directional reference is first provided by celestial rotation, later, during migration, by the magnetic compass. The relative importance of the various compass mechanisms has been tested in experiments in which celestial and magnetic cues gave conflicting information. The first response of birds to conflicting cues differs considerably between species; after repeated exposures, however, the birds oriented according to magnetic North, indicating a long-term dominance of the magnetic compass. Later tests in the absence of magnetic information showed that celestial cues were not simply ignored, but recalibrated so that they were again in agreement with magnetic cues. The magnetic compass and celestial cues complement each other: the magnetic field ensures orientation under overcast sky; celestial cues facilitate maintaining directions, for which the magnetic compass appears to be ill suited. In view of this, the magnetic field and celestial cues should be regarded as integrated components of a multifactorial system for directional orientation.

     

Magnetic Orientation in the Savannah Sparrow

Although magnetic compass orientation has been reported in a number of invertebrate and vertebrate taxa, including about a dozen migratory bird species, magnetic orientation capabilities in animals remain somewhat controversial. We have hand-raised a large number of Savannah sparrows (Passerculus sandwichensis) to study the ontogeny of orientation behavior. Young birds with a variety of early experience with visual and magnetic orientation cues have been tested for magnetic orientation during their first autumn migration. Here we present data from 80 hand-raised sparrows, each tested several times in both normal and shifted magnetic fields. Birds reared indoors with no experience with visual orientation cues showed axial north-south orientation that shifted by almost exactly the magnitude of 90° clockwise and counterclockwise shifts in the direction of magnetic north. Other groups of birds with varying early experience with visual orientation cues showed different preferred orientation directions, but all groups shifted orientation direction in response to shifts in the magnetic field. The data thus demonstrate a robust magnetic orientation ability in this species.