| orientation of migratory birds under ultraviolet light. | in view of the finding that cryptochrome 1a, the putative receptor molecule for the avian magnetic compass, is restricted to the ultraviolet single cones in european robins, we studied the orientation behaviour of robins and australian silvereyes under monochromatic ultraviolet (uv) light. at low intensity uv light of 0.3 mw/m(2), birds showed normal migratory orientation by their inclination compass, with the directional information originating in radical pair processes in the eye. at 2.8 mw/m( ... | 2014 | 24718656 |
| magnetoreception: activated cryptochrome 1a concurs with magnetic orientation in birds. | the radical pair model proposes that the avian magnetic compass is based on radical pair processes in the eye, with cryptochrome, a flavoprotein, suggested as receptor molecule. cryptochrome 1a (cry1a) is localized at the discs of the outer segments of the uv/violet cones of european robins and chickens. here, we show the activation characteristics of a bird cryptochrome in vivo under natural conditions. we exposed chickens for 30 min to different light regimes and analysed the amount of cry1a l ... | 2013 | 23966619 |
| a strong magnetic pulse affects the precision of departure direction of naturally migrating adult but not juvenile birds. | the mechanisms by which migratory birds achieve their often spectacular navigational performance are still largely unclear, but perception of cues from the earth's magnetic field is thought to play a role. birds that possess migratory experience can use map-based navigation, which may involve a receptor that uses ferrimagnetic material for detecting gradients in the magnetic field. such a mechanism can be experimentally disrupted by applying a strong magnetic pulse that re-magnetizes ferrimagnet ... | 2013 | 23389901 |
| quantum coherence and sensitivity of avian magnetoreception. | migratory birds and other species have the ability to navigate by sensing the geomagnetic field. recent experiments indicate that the essential process in the navigation takes place in the bird's eye and uses chemical reaction involving molecular ions with unpaired electron spins (radical pair). sensing is achieved via geomagnetic-dependent dynamics of the spins of the unpaired electrons. here we utilize the results of two behavioral experiments conducted on european robins to argue that the ave ... | 2012 | 23005606 |
| the magnetic retina: light-dependent and trigeminal magnetoreception in migratory birds. | recent advances have brought much new insight into the physiological mechanisms and required characteristics of the sensory molecules that enable birds to use magnetic fields for orientation. european robins almost certainly have two magnetodetection senses, one associated with the ophthalmic branch of the trigeminal nerve, and one based on light-dependent radical-pair processes in both eyes. the first brain areas processing magnetic information from each of these two senses have been identified ... | 2012 | 22465538 |
| magnetoreception of directional information in birds requires nondegraded vision. | the magnetic compass orientation of birds is light dependent. the respective directional information, originating in radical pair processes, is mediated by the right eye. these findings suggest possible interactions between magnetoreception and vision, in particular with the perception of contours, because the right eye has been found to be dominant in discrimination tasks requiring object vision. here we report tests in the local geomagnetic field with european robins wearing goggles equipped w ... | 2010 | 20619654 |
| visual but not trigeminal mediation of magnetic compass information in a migratory bird. | magnetic compass information has a key role in bird orientation, but the physiological mechanisms enabling birds to sense the earth's magnetic field remain one of the unresolved mysteries in biology. two biophysical mechanisms have become established as the most promising magnetodetection candidates. the iron-mineral-based hypothesis suggests that magnetic information is detected by magnetoreceptors in the upper beak and transmitted through the ophthalmic branch of the trigeminal nerve to the br ... | 2009 | 19865170 |
| light-dependent magnetoreception: orientation behaviour of migratory birds under dim red light. | magnetic compass orientation in migratory birds has been shown to be based on radical pair processes and to require light from the short wavelength part of the spectrum up to 565 nm green. under dim red light of 645 nm wavelength and 1 mw m(-2) intensity, australian silvereyes and european robins showed a westerly tendency that did not change between spring and autumn, identifying it as a 'fixed direction' response. a thorough analysis revealed that this orientation did not involve the inclinati ... | 2008 | 18840669 |
| the decoy matters! hormonal and behavioural differences in the reaction of territorial european robins towards stuffed and live decoys. | simulated territorial intrusions (stis) represent a commonly used experimental manipulation to test behavioural and hormonal responses of birds towards conspecific intruders. they are typically either conducted with live birds in a cage or with stuffed decoys. to our knowledge, nobody has tested whether these two different kinds of stimuli elicit the same kind of behavioural and hormonal response. we compared the reactions of european robins to stis with stuffed and live decoys to see whether th ... | 2008 | 17904139 |
| 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 fl ... | 2005 | 16111946 |
| light-dependent magnetoreception in birds: interaction of at least two different receptors. | passerine migrants require light from the blue-green part of the spectrum for magnetic compass orientation; under yellow light, they are disoriented. european robins tested under a combination of yellow light and blue or green light showed a change in behavior, no longer preferring their seasonally appropriate migratory direction: in spring as well as in autumn, they preferred southerly headings under blue-and-yellow and northerly headings under green-and-yellow light. this clearly shows that ye ... | 2004 | 15034663 |
| magnetic compass orientation in european robins is dependent on both wavelength and intensity of light. | magnetic compass orientation in birds has been shown to be light dependent. results from behavioural studies indicate that magnetoreception capabilities are disrupted under light of peak wavelengths longer than 565 nm, and shifts in orientation have been observed at higher light intensities (43-44x10(15) quanta s(-1) m(-2)). to investigate further the function of the avian magnetic compass with respect to wavelength and intensity of light, we carried out orientation cage experiments with juvenil ... | 2002 | 12432008 |
| magnetic compass orientation of european robins under 565 nm green light. | european robins tested under monochromatic green light with a peak wavelength of 565 nm at an intensity of 2.1 mw m-2 in the local geomagnetic field preferred their migratory direction, heading southward in autumn and northward in spring. inverting of the vertical component of the magnetic field caused the robins to reverse their headings, indicating that the birds used a magnetic inclination compass to locate their migratory direction. the behavior recorded under green light at an intensity of ... | 2001 | 11688414 |
| asymmetric territorial contests in the european robin: the role of settlement costs | a widespread feature of territorial systems is that residents almost invariably defeat challengers. this phenomenon has been explained by the existence of value asymmetries, variations in resource-holding potential or an 'owners always win' convention. removal-replacement experiments were performed on 75 robins, erithacus rubeculato test these hypotheses. the settling behaviour of newcomers was also examined in order to identify energetic costs incurred during territory establishment. in winter, ... | 1997 | 9268431 |
| deuterium and oxygen-18 abundance in birds: implications for dlw energetics studies. | the doubly labeled water (dlw) technique for measuring energy expenditure may employ one (18o) or two (18o and deuterium) stable isotopes as tracers. these occur naturally in the environment, so when they are used as tracers it is necessary to subtract the background levels. few studies report data on background concentrations. this work provides such data for a range of avian species. overall, there was a strong positive correlation (r = 0.63) between the 18o and deuterium concentrations in bir ... | 1990 | 2316726 |
| orientation of european robins to kramer cages. eliminating possible sources of error and bias in kramer cage studies. | | 2009 | 4785204 |
| magnetic compass of european robins. | the magnetic compass of european robins does not use the polarity of the magnetic field for detecting the north direction. the birds derive their north direction from interpreting the inclination of the axial direction of the magnetic field lines in space, and they take the direction on the magnetic north-south axis for "north" where field lines and gravity vector form the smaller angle. | 1972 | 17784420 |
| ascorbic acid may not be involved in cryptochrome-based magnetoreception. | seventeen years after it was originally suggested, the photoreceptor protein cryptochrome remains the most probable host for the radical pair intermediates that are thought to be the sensors in the avian magnetic compass. although evidence in favour of this hypothesis is accumulating, the intracellular interaction partners of the sensory protein are still unknown. it has been suggested that ascorbate ions could interact with surface-exposed tryptophan radicals in photoactivated cryptochromes, an ... | 2017 | 29263128 |
| double-cone localization and seasonal expression pattern suggest a role in magnetoreception for european robin cryptochrome 4. | birds seem to use a light-dependent, radical-pair-based magnetic compass. in vertebrates, cryptochromes are the only class of proteins that form radical pairs upon photo-excitation. therefore, they are currently the only candidate proteins for light-dependent magnetoreception. cryptochrome 4 (cry4) is particularly interesting because it has only been found in vertebrates that use a magnetic compass. however, its structure and localization within the retina has remained unknown. here, we sequence ... | 2018 | 29307554 |
| parasites in space and time: a case study of haemosporidian spatiotemporal prevalence in urban birds. | prevalence responses to anthropic factors differ across hosts and parasite species. we here analyzed the spatiotemporal variation of avian haemosporidian prevalence in bird assemblages of the mooswald forest (i.e., urban greenspace; freiburg, germany), in response to local environmental features (e.g., water sources, human presence (visited)/absence (unvisited)) and bird-level traits (e.g., body condition, age, sex) in 2 years. we used a nested pcr protocol (mitochondrial (mt)dna cytochrome b (c ... | 2019 | 30673588 |
| dogs can be trained to find a bar magnet. | magnetoreception, the ability to sense the earth's magnetic field (mf), is a widespread phenomenon in the animal kingdom. in 1966, the first report on a magnetosensitive vertebrate, the european robin (erithacus rubecula), was published. after that, numerous further species of different taxa have been identified to be magnetosensitive as well. recently, it has been demonstrated that domestic dogs (canis lupus familiaris) prefer to align their body axis along the north-south axis during territori ... | 2018 | 30588405 |
| free-ranging avifauna as a source of generalist parasites for captive birds in zoological settings: an overview of parasite records and potential for cross-transmission. | captive birds in zoological settings often harbor parasites, but little information is available about the potential for free-ranging avifauna to act as a source of infection. this review summarizes the gastrointestinal parasites found in zoo birds globally and in seven common free-ranging avian species [mallard (anas platyrhynchos), eurasian blackbird (turdus merula), common starling (sturnus vulgaris), eurasian jackdaw (corvus monedula), house sparrow (passer domesticus), european robin (erith ... | 2020 | 33005675 |
| isospora oliveirai n. sp. (chromista: miozoa: eimeriidae) from the greenish schiffornis schiffornis virescens (lafresnaye, 1838) (passeriformes: tyranni: tityridae) in south america. | coccidia are obligatory intracellular parasites with at least one intestinal phase in their life cycles, being isospora schneider, 1881 the main coccidian genus related to the order passeriformes. however, there is no record of isosporans from the passerine family tityridae, which is the family of the greenish schiffornis schiffornis virescens (lafresnaye, 1838). | 2020 | 32494953 |
| effects of forest structure on the interaction between avian hosts, dipteran vectors and haemosporidian parasites. | forest habitats are important biodiversity refuges for a wide variety of bird species. parasitism may modulate host species presence and abundance, and parasite effects can change according to forest management practices. such processes are not well studied in vector-borne avian haemosporidians. we analyzed the effects of forest management on bird-dipteran-haemosporidian interactions, using seven common bird species in managed and unmanaged beech forest habitats in northeastern germany. we assum ... | 2020 | 32814584 |
| high brdu sensitivity of passeriformes chromosomes: conservation of brdu-sensitive fragile sites on their z chromosomes during evolution. | amongst 15 bird species, representative of 7 orders, recurrent breakages evocating the presence of fragile sites were detected in the chromosomes of the 5 species belonging to passeriformes. these breaks appeared when 5-bromodeoxyuridine (brdu) was added to the cell culture medium at a dose inefficient for inducing chromosome structure alterations in other birds and mammals. they involved, similarly in male and female, 3 loci on the z chromosome of 3 turdus species (turdidae). labeling by brdu a ... | 2019 | 30974432 |
| mitochondrial dna in ixodus ricinus (acari: ixodidae) on birds reflects ticks' transportation routes to lista, norway. | ticks are important pathogen vectors, and large mammals and birds have the greatest potential for dispersing them. to study tick dispersal by migrating birds, we have analysed genetic variations in mitochondrial dna control region from ixodes ricinus from northward migrating blackbird, turdus merula, and (european) robin, erithacus rubecula, at the lista bird observatory in southwestern norway. we compared their genetic structure with that of resident tick populations from areas covering their e ... | 2020 | 33130437 |
| stopover departure decisions in songbirds: do long-distance migrants depart earlier and more independently of weather conditions than medium-distance migrants? | songbirds following distinct migration strategies (e.g. long- vs. short- to medium-distance migrants) often differ in their speed of migration during autumn and, thus, are assumed to face different time constraints. during migration, most songbird species alternate migratory flights with stopover periods. many of them restrict these migratory flights to the night, i.e., they are nocturnal migrants. at stopover, nocturnal migrants need to select a specific night (night-to-night decision) and time ... | 2020 | 32047634 |
| screening for multiple tick-borne pathogens in ixodes ricinus ticks from birds in denmark during spring and autumn migration seasons. | presently, it is uncertain to what extent seasonal migrating birds contribute to the introduction of ticks and tick-associated pathogens in denmark. to quantify this phenomenon, we captured birds during the spring and autumn migration at three field sites in denmark and screened them for ticks. bird-derived ticks were identified to tick species and screened for 37 tick-borne pathogens using real-time pcr. overall, 807 birds, representing 44 bird species, were captured and examined for ticks duri ... | 2019 | 30709658 |
| meteorological factors affecting refueling of european robin (erithacus rubecula) during migrations. | weather ultimately affects avian migration. the significance of meteorological variables is relatively well known for flights of migrants and for departure/landing decisions at stopover sites. success of migration greatly depends on storage of fat and body mass gain at stopovers; however, the influence of weather on refueling at stopovers is surprisingly poorly studied. we tested the hypothesis that body mass change of european robins during their migratory stopovers is affected by meteorologica ... | 2020 | 33068144 |
| temperature change is an important departure cue in nocturnal migrants: controlled experiments with wild-caught birds in a proof-of-concept study. | the decision-making process of migrating birds at stopover sites is a complex interplay of the innate migration program and both intrinsic and extrinsic factors. while it is well studied how variation in precipitation, wind and air pressure influence this process, there is less evidence of the effects of temperature changes on the departure decision. thus, we lack knowledge on how the predicted changes due to global climate change in temperature alone may affect the decision-making process durin ... | 2020 | 33023413 |
| a novel isoform of cryptochrome 4 (cry4b) is expressed in the retina of a night-migratory songbird. | the primary sensory molecule underlying light-dependent magnetic compass orientation in migratory birds has still not been identified. the cryptochromes are the only known class of vertebrate proteins which could mediate this mechanism in the avian retina. cryptochrome 4 of the night-migratory songbird the european robin (erithacus rubecula; ercry4) has several of the properties needed to be the primary magnetoreceptor in the avian eye. here, we report on the identification of a novel isoform of ... | 2020 | 32978454 |
| a quasi-experimental approach using telemetry to assess migration-strategy-specific differences in the decision-making processes at stopover. | migrant birds travel between their breeding areas and wintering grounds by alternating energetically and physiologically demanding flights with periods of rest and fuelling, so-called stopovers. an important intrinsic factor influencing the decision to resume migration is the amount of energy stores available for the next flight. correlative studies with free-flying birds and experimental studies with caged birds have shown that the amount of energy stores affects the day-to-day, within-day and ... | 2020 | 32641125 |
| protein-protein interaction of the putative magnetoreceptor cryptochrome 4 expressed in the avian retina. | migratory birds can sense the earth's magnetic field and use it for orientation over thousands of kilometres. a light-dependent radical-pair mechanism associated with the visual system is currently discussed as the underlying mechanism of the magnetic compass sense. the blue light receptor cryptochrome 4 (cry4) is considered as the most likely primary sensory protein that detects the geomagnetic field. since the protein interaction partners of cry4 are completely unknown at present, here, we aim ... | 2020 | 32355203 |
| no evidence for the use of magnetic declination for migratory navigation in two songbird species. | determining the east-west position was a classical problem in human sea navigation until accurate clocks were manufactured and sailors were able to measure the difference between local time and a fixed reference to determine longitude. experienced night-migratory songbirds can correct for east-west physical and virtual magnetic displacements to unknown locations. migratory birds do not appear to possess a time-different clock sense; therefore, they must solve the longitude problem in a different ... | 2020 | 32330188 |
| mechanical and structural adaptations to migration in the flight feathers of a palaearctic passerine. | current avian migration patterns in temperate regions have been developed during the glacial retreat and subsequent colonization of the ice-free areas during the holocene. this process resulted in a geographic gradient of greater seasonality as latitude increased that favoured migration-related morphological and physiological (co)adaptations. most evidence of avian morphological adaptations to migration comes from the analysis of variation in the length and shape of the wings, but the existence ... | 2020 | 32282960 |
| host dispersal shapes the population structure of a tick-borne bacterial pathogen. | birds are hosts for several zoonotic pathogens. because of their high mobility, especially of longdistance migrants, birds can disperse these pathogens, affecting their distribution and phylogeography. we focused on borrelia burgdorferi sensu lato, which includes the causative agents of lyme borreliosis, as an example for tick-borne pathogens, to address the role of birds as propagation hosts of zoonotic agents at a large geographical scale. we collected ticks from passerine birds in 11 european ... | 2020 | 31846173 |
| temporary caging results in reduced levels of circulating melatonin in migratory robins. | the hormone melatonin, a main component of the avian circadian system, plays an important role in the physiological transitions that accompany activation of the migratory phenotype in passerine birds. most small passerines migrate at night when circulating concentrations of melatonin are elevated. previous work measured nocturnal melatonin levels of migratory birds only in captive animals, because free-living individuals are usually caught in the daytime. in this study, we compared nocturnal mel ... | 2019 | 31767734 |
| signal complexity communicates aggressive intent during contests, but the process is disrupted by noise. | contestants use displays to signal their aggressive intent and settle disputes before they escalate. for birds, this is often in the form of song, which can vary in structural complexity. the role of song complexity in signalling aggressive intent has not been fully established, and its efficacy could be influenced by background noise levels. using playback experiments, we found that in european robins, erithacus rubecula, song complexity signalled sender aggression and affected receiver respons ... | 2019 | 30991914 |
| magnetic storms disrupt nocturnal migratory activity in songbirds. | birds possess a magnetic sense and rely on the earth's magnetic field for orientation during migration. however, the geomagnetic field can be altered by solar activity at relative unpredictable intervals. how birds cope with the temporal geomagnetic variations caused by solar storms during migration is still unclear. we addressed this question by reproducing the effect of a solar storm on the geomagnetic field and monitoring the activity of three songbird species during autumn migration. we foun ... | 2019 | 30862307 |
| ticks (acari: ixodida) on birds (aves) migrating through the polish baltic coast. | seasonal bird (aves) migration between breeding and wintering areas, often located on different continents, can facilitate the spreading of tick species (acari: ixodida) and of tick-borne pathogens. the aim of the study was to analyse the occurrence of ticks dispersed by birds migrating along the polish baltic coast during spring and autumn migration. field research was conducted at the bird ringing station in wicie, located on the middle of the polish baltic coast, in 2011 and 2012 during sprin ... | 2019 | 30771037 |
| malaria infection status of european robins seems to associate with timing of autumn migration but not with actual condition. | avian malaria parasites can negatively affect many aspects of the life of the passerines. though these parasites may strongly affect the health and thus migration patterns of the birds also during autumn, previous studies on avian malaria focused mainly on the spring migration and the breeding periods of the birds. we investigated whether the prevalence of blood parasites varies in relation to biometrical traits, body condition and arrival time in the european robin (erithacus rubecula) during a ... | 2019 | 30638174 |
| coxiella burnetii in ticks and wild birds. | the study objective was to get more information on c. burnetii prevalence in wild birds and ticks feeding on them, and the potentialities of the pathogen dissemination over europe by both. | 2019 | 30509727 |
| first evidence for the joint dispersal of mycorrhizal fungi and plant diaspores by birds. | seed dispersal allows plants to colonise new sites and escape from pathogens and intraspecific competition, maintaining plant genetic diversity and regulating plant distribution. conversely, most plant species form mutualistic associations with arbuscular mycorrhizal (am) fungi in a symbiosis established immediately after seed germination. because am fungi are obligate symbionts, using the same dispersal vector as their host should be highly advantageous for their survival, but the co-dispersal ... | 2019 | 30372538 |
| lidocaine is a nocebo treatment for trigeminally mediated magnetic orientation in birds. | even though previously described iron-containing structures in the upper beak of pigeons were almost certainly macrophages, not magnetosensitive neurons, behavioural and neurobiological evidence still supports the involvement of the ophthalmic branch of the trigeminal nerve (v1) in magnetoreception. in previous behavioural studies, inactivation of putative v1-associated magnetoreceptors involved either application of the surface anaesthetic lidocaine to the upper beak or sectioning of v1. here, ... | 2018 | 30089685 |
| atomistic insights into cryptochrome interprotein interactions. | it is striking that the mechanism by which birds sense geomagnetic fields during the biannual migration seasons is not entirely understood. a protein believed to be responsible for avian magnetoreception is the flavoprotein cryptochrome (cry), which fulfills many of the criteria for a magnetic field sensor. some experiments, however, indicate that magnetoreception in birds may be disturbed by extremely weak radio frequency fields, an effect that likely cannot be described by an isolated cry prot ... | 2018 | 30078611 |
| baseline and stress-induced corticosterone levels are higher during spring than autumn migration in european robins. | during spring and autumn migrations, birds undergo a suite of physiological and behavioral adaptations known as migratory disposition. the position of migratory seasons within the annual cycle and specifics of environmental conditions in each season could lead to formation of specific regulatory mechanisms of spring and autumn migratory disposition. however, this topic remains largely unstudied. here we compared corticosterone (cort) concentration (baseline and stress-induced) in european robins ... | 2018 | 29288637 |
| migratory birds as disseminators of ticks and the tick-borne pathogens borrelia bacteria and tick-borne encephalitis (tbe) virus: a seasonal study at ottenby bird observatory in south-eastern sweden. | birds can act as reservoirs of tick-borne pathogens and can also disperse pathogen-containing ticks to both nearby and remote localities. the aims of this study were to estimate tick infestation patterns on migratory birds and the prevalence of different borrelia species and tick-borne encephalitis virus (tbev) in ticks removed from birds in south-eastern sweden. | 2020 | 33272317 |
| three babesia species in ixodes ricinus ticks from migratory birds in sweden. | migratory birds can cross geographical and environmental barriers and are thereby able to facilitate transmission of tick-borne pathogens both as carriers of infected ticks and as reservoirs of pathogenic microorganisms. ixodes ricinus is one of the most abundant tick species in the northern hemisphere and a main vector of several babesia species, some which pose a potential threat to human and animal health. at present only two cases of overt babesiosis in humans have so far been reported in sw ... | 2021 | 33794970 |