Instruct: Given a question, retrieve relevant documents that can help answer the question.
Query: Do birds use magnetoreception?
Magnetoreception (also magnetoception) is a sense which allows an organism to detect a magnetic field to perceive direction, altitude or location. This sensory modality is used by a range of animals for orientation and navigation,[1] and as a method for animals to develop regional maps. For the purpose of navigation, magnetoreception deals with the detection of the Earth's magnetic field.
The avian magnetic compass of the robin has been extensively researched and uses vision-based magnetoreception, in which the robin's ability to sense the magnetic field of the earth for navigation is affected by the light entering the bird's eye. The physical mechanism of the robin's magnetic sense is not fully understood, but may involve quantum entanglement of electron spins.
An example of a magnetobiological effect is the magnetic navigation by migrant animals by means of magnetoreception. 
Many animal orders, such as certain birds, marine turtles, reptiles, amphibians and salmonoid fishes are able to detect small variations of the geomagnetic field and its magnetic inclination to find their seasonal habitats. They are said to use an "inclination compass". Certain crustaceans, spiny lobsters, bony fish, insects and mammals have been found to use a "polarity compass", whereas in snails and cartilageous fish the type of compass is as yet unknown. Little is known about other vertebrates and arthropods. Their perception can be on the order of tens of nanoteslas.
Then there is the distinction of magnetic usage. Some species may only be able to sense a magnetic compass to find north and south, while others may only be able to discern between the equator and the pole. Although the ability to sense direction is important in migratory navigation, many animals also have the ability to sense small fluctuations in earth’s magnetic field to compute coordinate maps with a resolution of a few kilometers or better.[73] For a magnetic map, the receptor system would have to be able to discern tiny differences in the surrounding magnetic field to develop a sufficiently detailed magnetic map. This is not out of the question, as many animals have the ability to sense small fluctuations in the earth's magnetic field. This is not out of the question biologically, but physically has yet to be explained. For example, birds such as the homing pigeon are believed to use the magnetite in their beaks to detect magnetic signposts and thus, the magnetic sense they gain from this pathway is a possible map.[72] Yet, it has also been suggested that homing pigeons and other birds use the visually mediated cryptochrome receptor as a compass.[72]
The quantum Zeno effect is used in commercial atomic magnetometers and naturally by birds' magnetic compass sensory mechanism (magnetoreception).
Magnetoception (or magnetoreception) is the ability to detect the direction one is facing based on the Earth's magnetic field. Directional awareness is most commonly observed in birds, which rely on their magnetic sense to navigate during migration. It has also been observed in insects such as bees. Cattle make use of magnetoception to align themselves in a north-south direction. Magnetotactic bacteria build miniature magnets inside themselves and use them to determine their orientation relative to the Earth's magnetic field.
Magnetobiology Quantum biology §Magnetoreception Salmon run
In 2008, Reppert discovered the necessity of "Cry" for light-dependent magnetoreception responses in "Drosophila". He also showed that magnetoreception requires UVA/blue light, the spectrum corresponding with the action spectrum of "Drosophila" CRY.
These data were the first to genetically implicate CRY as a component of the input pathway or the chemical-based pathway of magnetoreception. Applying these findings to his work with the monarch, Reppert has shown that both monarch CRY1 and CRY2 proteins, when transgenically expressed in CRY-deficient flies, successfully restore magnetoreception function. These results propose the presence of a CRY-mediated magnetosensitivity system in monarchs that may act in concordance with the sun compass to aid navigation. In 2011, Reppert also discovered that human CRY2 can substitute as a functional magnetoreceptor in CRY-deficient flies, a discovery that warrants additional research into magnetosensitivity in humans.
The most promising leads — cryptochromes, iron-based systems, electromagnetic induction — each have their own pros and cons. Cryptochromes have been observed in various organisms including birds and humans, but does not answer the question of night-time navigation. Iron-based systems have also been observed in birds, and if proven, could form a magnetoreceptive basis for many species including turtles. Electromagnetic induction has not been observed nor tested in non-aquatic animals. Additionally, it remains likely that two or more complementary mechanisms play a role in magnetic field detection in animals. Of course, this potential dual mechanism theory raises the question, to what degree is each method responsible for the stimulus, and how do they produce a signal in response to the low magnetic field of the Earth?[72]
Magnetoreception has also been reported in the European eel by at least one study.[35]
Magnetoreception is well documented in honey bees, ants and termites.[32] In ants and bees, this is used to orient and navigate in areas around their nests and within their migratory paths.[33] For example, through the use of magnetoreception, the Brazilian stingless bee Schwarziana quadripunctata is able to distinguish differences in altitude, location, and directionality using the thousands of hair-like particles on its antennae.[34]
The majority of study on magnetoreception in reptiles involves turtles. Some of the earliest support for magnetoreception in turtles was found in Terrapene carolina, a species of box turtle. After successfully teaching a group of these box turtles to swim to either the east or west end of an experimental tank, the introduction of a strong magnet into the tank was enough to disrupt the learned routes.[42] As such, the learning of oriented paths seems to rely on some internal magnetic compass possessed by box turtles. Subsequent discovery of magnetite in the dura mater of Sea Turtle hatchlings supported this conclusion, as magnetite provides a means by which magnetic fields may be perceived.[43]
Magnetoreception has also been reported in the European eel by at least one study, and may be used for navigation.
Scientists are still studying whether or not animals are affected by this, some suggesting this is why whales beach themselves. Some have stated the possibility that other migrating animals including birds and honey bees, might be affected since they also use magnetoreception to navigate, and geomagnetic storms alter the Earth's magnetic fields temporarily.Links related to power grids:
Magnetoreception is present in bacteria, arthropods, molluscs and members of all major taxonomic groups of vertebrates.[1] Humans are not thought to have a magnetic sense, but there is a protein (a cryptochrome) in the eye which could serve this function.[2]
For animals the mechanism for magnetoreception is unknown, but there exist two main hypotheses to explain the phenomenon.[5] According to one model, magnetoreception is possible via the radical pair mechanism.[6] The radical-pair mechanism is well-established in spin chemistry,[7][8][9] and was speculated to apply to magnetoreception in 1978 by Schulten et al.. In 2000, cryptochrome was proposed as the "magnetic molecule", so to speak, that could harbor magnetically sensitive radical-pairs. Cryptochrome, a flavoprotein found in the eyes of European robins and other animal species, is the only protein known to form photoinduced radical-pairs in animals.[6] The function of cryptochrome is diverse across species, however, the photoinduction of radical-pairs occurs by exposure to blue light, which excites an electron in a chromophore.[10] The Earth's magnetic field is only 0.5 gauss and so it is difficult to conceive of a mechanism, other than phase shift, by which such a field could lead to any chemical changes other than those affecting the weak magnetic fields between radical pairs.[11] Cryptochromes are therefore thought to be essential for the light-dependent ability of the fruit fly Drosophila melanogaster to sense magnetic fields.[12]
Homing pigeons can use magnetic fields as part of their complex navigation system.[45] William Keeton showed that time-shifted homing pigeons are unable to orient themselves correctly on a clear, sunny day which is attributed to time-shifted pigeons being unable to compensate accurately for the movement of the sun during the day. Conversely, time-shifted pigeons released on overcast days navigate correctly. This led to the hypothesis that under particular conditions, homing pigeons rely on magnetic fields to orient themselves. Further experiments with magnets attached to the backs of homing pigeons demonstrated that disruption of the bird's ability to sense the Earth's magnetic field leads to a loss of proper orientation behavior under overcast conditions.[46] There have been two mechanisms implicated in homing pigeon magnetoreception: the visually mediated free-radical pair mechanism and a magnetite based directional compass or inclination compass.[47] More recent behavioral tests have shown that pigeons are able to detect magnetic anomalies of 186 microtesla (1.86 Gauss).[48]
The second proposed model for magnetoreception relies on clusters composed of iron, a natural mineral with strong magnetism. The idea is favorable as it builds up on the magnetoreceptive abilities of magnetotactic bacteria. These iron clusters have been observed mainly in homing pigeons in the upper beak,[13] but also in other taxa[14].
The mollusk Tochuina tetraquetra (formerly Tritonia diomedea or Tritonia gigantea) has been studied for clues as to the neural mechanism behind magnetoreception in a species. Some of the earliest work with Tochuina showed that prior to a full moon Tochuina would orient their bodies between magnetic north and east.[25] A Y-maze was established with a right turn equal to geomagnetic south and a left turn equal to geomagnetic east. Within this geomagnetic field 80% of Tochuina made a turn to the left or magnetic east. However, when a reversed magnetic field was applied that rotated magnetic north 180° there was no significant preference for either turn, which now corresponded with magnetic north and magnetic west. These results, though interesting, do not conclusively establish that Tochuina uses magnetic fields in magnetoreception. These experiments do not include a control for the activation of the Rubens’ coil in the reversed magnetic field experiments. Therefore, it is possible that heat or noise generated by the coil was responsible for the loss of choice preference. Further work with Tochuina was unable to identify any neurons that showed rapid changes in firing as a result of magnetic fields.[26][27] However, pedal 5 neurons, two bisymmetric neurons located within the Tochuina pedal ganglion, exhibited gradual changes in firing over time following 30 minutes of magnetic stimulation provided by a Rubens’ coil. Further studies showed that pedal 7 neurons in the pedal ganglion were inhibited when exposed to magnetic fields over the course of 30 minutes. The function of both pedal 5 neurons and pedal 7 neurons is currently unknown.
Schulten also began to explore the possibility that fast triplets could explain compass sensors in biological species such as migrating birds. That the European robin used some form of magnetoreception was demonstrated by Wolfgang Wiltschko and Fritz Merkel in 1965, and further studied by Wolfgang and Roswitha Wiltschko. Schulten proposed that quantum entanglement of a radical-pair system could underlie a biochemical compass. Schulten and others have since extended this early work, developing a model of the possible excitation of cryptochrome proteins in photoreceptors within the retina of the eye.
Several species of birds are known to incorporate magnetite crystals in the upper beak for magnetoreception, which (in conjunction with cryptochromes in the retina) gives them the ability to sense the direction, polarity, and magnitude of the ambient magnetic field.
Red foxes (Vulpes vulpes) may use magnetoreception when predating small rodents. When foxes perform their high-jumps onto small prey like mice and voles, they tend to jump in a north-eastern compass direction. In addition, successful attacks are "tightly clustered" to the north.[65] One study has found that when domestic dogs are off the leash and the Earth's magnetic field is calm, they prefer to urinate and defecate with their bodies aligned on a north-south axis.[66]
Magnetoreception refers to the ability of animals to navigate using the inclination of the magnetic field of the earth. A possible explanation for magnetoreception is the entangled radical pair mechanism. The radical-pair mechanism is well-established in spin chemistry, and was speculated to apply to magnetoreception in 1978 by Schulten et al.. The ratio between singlet and triplet pairs is changed by the interaction of entangled electron pairs with the magnetic field of the earth. In 2000, cryptochrome was proposed as the "magnetic molecule" that could harbor magnetically sensitive radical-pairs. Cryptochrome, a flavoprotein found in the eyes of European robins and other animal species, is the only protein known to form photoinduced radical-pairs in animals. When it interacts with light particles, cryptochrome goes through a redox reaction, which yields radical pairs both during the photo-reduction and the oxidation. The function of cryptochrome is diverse across species, however, the photoinduction of radical-pairs occurs by exposure to blue light, which excites an electron in a chromophore. Magnetoreception is also possible in the dark, so the mechanism must rely more on the radical pairs generated during light-independent oxidation.
Despite more than 50 years of research, a sensory receptor in animals has yet to be identified for magnetoreception.[70] While research is ongoing, it is possible that the entire receptor system could fit in a one-milimeter cube and have a magnetic content of less than one ppm. As such, even discerning the parts of the brain where the information is processed presents a challenge.[71]
The homing pigeon is a variety of domestic pigeon ("Columba livia domestica") derived from the rock pigeon, selectively bred for its ability to find its way home over extremely long distances. The wild rock pigeon has an innate homing ability, meaning that it will generally return to its nest, (it is believed) using magnetoreception. This made it relatively easy to breed from the birds that repeatedly found their way home over long distances. Flights as long as have been recorded by birds in competitive pigeon racing. Their average flying speed over moderate distances is around and speeds of up to have been observed in top racers for short distances.