Bird vocalization includes both bird calls and bird songs . In non-technical use, bird songs are the bird sounds that are melodious to the human ear. In ornithology and birding , songs (relatively complex vocalizations) are distinguished by function from calls (relatively simple vocalizations).
125-460: The distinction between songs and calls is based upon complexity, length, and context. Songs are longer and more complex and are associated with territory and courtship and mating , while calls tend to serve such functions as alarms or keeping members of a flock in contact. Other authorities such as Howell and Webb (1995) make the distinction based on function, so that short vocalizations, such as those of pigeons, and even non-vocal sounds, such as
250-399: A combination of both visual and olfactory advertising of the territory. The male ring-tailed lemur has a specialised adaptation to assist in leaving visual/olfactory territorial marks. On their inner forearm (antebrachial) is a scent gland which is covered by a spur . In a behaviour called "spur marking", they grasp the substrate, usually a small sapling, and drag the spur over it, cutting into
375-476: A cue to conspecific eavesdroppers. In black-throated blue warblers , males that have bred and reproduced successfully sing to their offspring to influence their vocal development, while males that have failed to reproduce usually abandon the nests and stay silent. The post-breeding song therefore inadvertently informs the unsuccessful males of particular habitats that have a higher likelihood of reproductive success. The social communication by vocalization provides
500-621: A facultative purpose for this species, in which the more fragrance-rich sites there are, the greater the number of habitable territories. Since these territories are aggregated, females have a large selection of males with whom to potentially mate within the aggregation, giving females the power of mate choice . Similar behaviour is also observed in the Eulaema meriana orchid bee. Males in this species of bee show alternative behaviours of territoriality and transiency. Transient male bees did not defend territories, but instead flew from one territory to
625-471: A female bird may select males based on the quality of their songs and the size of their song repertoire. The second principal function of bird song is territory defense. Territorial birds will interact with each other using song to negotiate territory boundaries. Since song may be a reliable indicator of quality, individuals may be able to discern the quality of rivals and prevent an energetically costly fight. In birds with song repertoires, individuals may share
750-408: A group of animals occupies an area that it habitually uses but does not necessarily defend; this is called its home range . The home ranges of different groups of animals often overlap, and in these overlap areas the groups tend to avoid each other rather than seeking to confront and expel each other. Within the home range there may be a core area that no other individual group uses, but, again, this
875-405: A larger predator, but when a large group is involved, the risk to each group member is reduced or diluted. This so-called dilution effect proposed by W. D. Hamilton is another way of explaining the benefits of cooperation by selfish individuals. Lanchester's laws also provide an insight into the advantages of attacking in a large group rather than individually. Another interpretation involves
1000-781: A less aggressive act than song-type matching. Song complexity is also linked to male territorial defense, with more complex songs being perceived as a greater territorial threat. Birds communicate alarm through vocalizations and movements that are specific to the threat, and bird alarms can be understood by other animal species, including other birds, in order to identify and protect against the specific threat. Mobbing calls are used to recruit individuals in an area where an owl or other predator may be present. These calls are characterized by wide frequency spectra, sharp onset and termination, and repetitiveness that are common across species and are believed to be helpful to other potential "mobbers" by being easy to locate. The alarm calls of most species, on
1125-537: A memorized song template, and what he produces. In search of these auditory-motor neurons, Jonathan Prather and other researchers at Duke University recorded the activity of single neurons in the HVCs of swamp sparrows . They discovered that the neurons that project from the HVC to Area X (HVC X neurons) are highly responsive when the bird is hearing a playback of his own song. These neurons also fire in similar patterns when
1250-403: A minimal level. With aseasonal irregular breeding, both sexes must be brought into breeding condition and vocalisation, especially duetting, serves this purpose. The high frequency of female vocalisations in the tropics, Australia and Southern Africa may also relate to very low mortality rates producing much stronger pair-bonding and territoriality. The avian vocal organ is called the syrinx ; it
1375-412: A nasty neighbour strategy. Group-living male breeders are nearly five times more aggressive towards their neighbours than towards strangers, leading to the prediction that neighbours are the most important competitors for paternity. Using a molecular parentage analysis it has been shown that 28% of offspring are sired by neighbouring males and only 7% by strangers. In certain species of butterflies, such as
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#17327866959021500-428: A perspective. Several other type of resource may be defended including partners, potential mates, offspring, nests or lairs, display areas or leks . Territoriality emerges where there is a focused resource that provides enough for the individual or group, within a boundary that is small enough to be defended without the expenditure of excessive effort. Territoriality is often most strong towards conspecifics , as shown in
1625-442: A powerful animal away from food. Costs of mobbing behavior include the risk of engaging with predators, as well as energy expended in the process. The black-headed gull is a species which aggressively engages intruding predators, such as carrion crows . Classic experiments on this species by Hans Kruuk involved placing hen eggs at intervals from a nesting colony, and recording the percentage of successful predation events as well as
1750-474: A primary role in error correction, as it detects differences between the song produced by the bird and its memorized song template and then sends an instructive error signal to structures in the vocal production pathway in order to correct or modify the motor program for song production. In their study, Brainard & Doupe (2000) showed that while deafening adult birds led to the loss of song stereotypy due to altered auditory feedback and non-adaptive modification of
1875-470: A role in intraspecies aggressive competition towards joint resource defense. Duets are well known in cranes, but the Sarus Crane seems unique in infrequently also having three bonded adults defending one territory who perform "triets". Triets had a lower frequency relative to duets, but the functional value of this difference is not yet known. Sometimes, songs vocalized in the post-breeding season act as
2000-756: A role in the seasonal changes of singing behavior in songbirds that live in areas where the amount of daylight varies significantly throughout the year. Several other studies have looked at seasonal changes in the morphology of brain structures within the song system and have found that these changes (adult neurogenesis, gene expression) are dictated by photoperiod, hormonal changes and behavior. The gene FOXP2 , defects of which affect both speech production and comprehension of language in humans, becomes highly expressed in Area X during periods of vocal plasticity in both juvenile zebra finches and adult canaries. The songs of different species of birds vary and are generally typical of
2125-399: A shortcut to locating high quality habitats and saves the trouble of directly assessing various vegetation structures. Some birds are excellent vocal mimics . In some tropical species, mimics such as the drongos may have a role in the formation of mixed-species foraging flocks . Vocal mimicry can include conspecifics, other species or even man-made sounds. Many hypotheses have been made on
2250-588: A strategy termed the dear enemy effect in which two neighbouring territorial animals become less aggressive toward one another once territorial borders are well-established and they are familiar to each other, but aggression toward unfamiliar animals remains unaffected. The converse of this is the nasty neighbour effect in which a territory-holder shows heightened aggression toward neighbouring territory-holders but unaffected aggression to unfamiliar animals or distant territory-holders. These contrasting strategies depend on which intruder (familiar or unfamiliar) poses
2375-506: A study by Billings (2018) examining, specifically the low-frequency acoustic structure of mobbing calls across habitat types (closed, open, and urban) in three passerine families (Corvidae, Icteridae, Turdidae), it was discovered that the size of the bird was a factor in the variation of mobbing calls. Additionally, species in closed and urban habitats had lower energy and lower low frequencies in their mobbing calls, respectively. Mobbing calls may also be part of an animal's arsenal in harassing
2500-420: A study conducted by Dagan & Izhaki (2019), wherein mobbing behavior was examined particularly observing the effects of Pine Forest structure. Their findings showed that mobbing behavior varied by season, i.e., high responses in the winter, and moderate response in the fall. Additionally, the presence of a forest understory had a significant impact on mobbing behavior, i.e., the denser the understory vegetation,
2625-450: Is a lekking reptile. Males start to establish small display territories two months ahead of the mating season. Rather than retaining a territory simply by fighting, for some animals this can be a 3-stage process. Many animals create "sign-posts" to advertise their territory. Sometimes these sign-posts are on the boundary thereby demarcating the territory, or, may be scattered throughout the territory. These communicate to other animals that
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#17327866959022750-421: Is a behaviour used by animals to identify their territory. Most commonly, this is accomplished by depositing strong-smelling substances contained in the urine , faeces , or, from specialised scent glands located on various areas of the body. Often, the scent contains pheromones or carrier proteins such as the major urinary proteins to stabilize the odours and maintain them for longer. The animal sniffing
2875-414: Is a bony structure at the bottom of the trachea (unlike the larynx at the top of the mammalian trachea). The syrinx and sometimes a surrounding air sac resonate to sound waves that are made by membranes past which the bird forces air. The bird controls the pitch by changing the tension on the membranes and controls both pitch and volume by changing the force of exhalation. It can control the two sides of
3000-527: Is a large (up to 8 cm in length) limpet. It lives in association with an approximately 1,000 cm^2 area of algal film in which its grazing marks can be seen, whereas the remainder of the rock surface is usually free of any visible film. These areas of algal film represent the territories of the Lottia; within them the animals do all their grazing. They keep their territories free of other organisms by shoving off any intruders: other Lottia, grazing limpets of
3125-484: Is a series of stylised postures, vocalisations, displays, etc. which function to solve the territory dispute without actual fighting as this could injure either or both animals. Ritualized aggression often ends by one of the animals fleeing (generally the intruder). If this does not happen, the territory may be defended by actual fighting, although this is generally a last resort. Scent marking, also known as territorial marking or spraying when this involves urination ,
3250-518: Is akin to babbling in human infants. Soon after, the juvenile song shows certain recognizable characteristics of the imitated adult song, but still lacks the stereotypy of the crystallized song – this is called "plastic song". After two or three months of song learning and rehearsal (depending on species), the juvenile produces a crystallized song, characterized by spectral and temporal stereotypy (very low variability in syllable production and syllable order). Some birds, such as zebra finches , which are
3375-589: Is ambient low-frequency noise. Traffic noise was found to decrease reproductive success in the great tit ( Parus major ) due to the overlap in acoustic frequency. During the COVID-19 pandemic , reduced traffic noise led to birds in San Francisco singing 30% more softly. An increase in song volume restored fitness to birds in urban areas, as did higher frequency songs. It has been proposed that birds show latitudinal variation in song complexity; however, there
3500-590: Is an anti-predator adaptation in which individuals of prey species cooperatively attack or harass a predator , usually to protect their offspring . A simple definition of mobbing is an assemblage of individuals around a potentially dangerous predator. This is most frequently seen in birds , though it is also known to occur in many other animals such as the meerkat and some bovines . While mobbing has evolved independently in many species, it only tends to be present in those whose young are frequently preyed upon. This behavior may complement cryptic adaptations in
3625-411: Is as a result of avoidance. The ultimate function of animals inhabiting and defending a territory is to increase the individual fitness or inclusive fitness of the animals expressing the behaviour. Fitness in this biological sense relates to the ability of an animal to survive and raise young. The proximate functions of territory defense vary. For some animals, the reason for such protective behaviour
3750-636: Is different from normal urination, which is done while squatting. This posture is exclusive to alpha wolves of either sex, although the alpha male does this most often. The alpha female usually urinates on a scent post that her breeding partner has just urinated on, although during the mating season, the female may first urinate on the ground. All other females in the pack, and also young wolves and low-ranking male wolves, urinate while squatting. Similar urination postures are used by coyotes and golden jackals . Males and female ring-tailed lemurs ( Lemur catta ) scent-mark both vertical and horizontal surfaces at
3875-1130: Is exceptional in producing sounds at about 11.8 kHz. It is not known if they can hear these sounds. The range of frequencies at which birds call in an environment varies with the quality of habitat and the ambient sounds. The acoustic adaptation hypothesis predicts that narrow bandwidths, low frequencies, and long elements and inter-element intervals should be found in habitats with complex vegetation structures (which would absorb and muffle sounds), while high frequencies, broad bandwidth, high-frequency modulations (trills), and short elements and inter-elements may be expected in open habitats, without obstructive vegetation. Low frequency songs are optimal for obstructed, densely vegetated habitats because low frequency, slowly modulated song elements are less susceptible to signal degradation by means of reverberations off of sound-reflecting vegetation. High frequency calls with rapid modulations are optimal for open habitats because they degrade less across open space. The acoustic adaptation hypothesis also states that song characteristics may take advantage of beneficial acoustic properties of
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4000-509: Is eye-opening, it still does not answer the question of why male birds sing more when females are absent. The acquisition and learning of bird song involves a group of distinct brain areas that are aligned in two connecting pathways: The posterior descending pathway (PDP) is required throughout a bird's life for normal song production, while the anterior forebrain pathway (AFP) is necessary for song learning, plasticity, and maintenance, but not for adult song production. Both neural pathways in
4125-415: Is known as the “attract the mightier hypothesis.” Within this hypothesis, prey species produce a mobbing call in order to attract stronger secondary predator to address the threat of the present primary predator. A study conducted by Fang et al., showed significant findings for this unproved functional thesis, utilizing three different call types for the prey species light-vented bulbuls, Pycnonotus sinensis :
4250-457: Is laid in well defined piles. There may be 20 to 30 of these piles to alert passing rhinoceroses that it is occupied territory. Other males may deposit dung over the piles of another and subsequently the sign-post grows larger and larger. Such a dung heap can become up to five metres wide and one metre high. After defecating, greater one-horned rhinos scratch their hind feet in the dung. By continuing to walk, they "transport" their own smell around
4375-554: Is least likely with insectivorous birds, where the food supply is plentiful but unpredictably distributed. Swifts rarely defend an area larger than the nest. Conversely, other insectivorous birds that occupy more constrained territories, such as the ground-nesting blacksmith lapwing may be very territorial, especially in the breeding season during which they not only threaten or attack many kinds of intruders, but have stereotyped display behaviour to deter conspecifics sharing neighbouring nesting spots. The owl limpet ( Lottia gigantea )
4500-415: Is no strong evidence that song complexity increases with latitude or migratory behaviour. According to a study published in 2019, the white bellbird makes the loudest call ever recorded for birds, reaching 125 dB . The record was previously held by the screaming piha with 116 dB. A 2023 study found a correlation between the dawn chorus of male birds and the absence of females. The research
4625-492: Is not always a fixed behavioural characteristic of a species. For example, red foxes ( Vulpes vulpes ) either establish stable home ranges within particular areas or are itinerant with no fixed abode . Territories may vary with time (season). For example, European robins defend territories as pairs during the breeding season but as individuals during the winter. Resource availability may cause changes in territoriality. For example, some nectarivores defend territories only during
4750-752: Is partially responsible for these differences in the brain. Female zebra finches treated with estradiol after hatching followed by testosterone or dihydrotestosterone (DHT) treatment in adulthood will develop an RA and HVC similar in size to males and will also display male-like singing behavior. Hormone treatment alone does not seem to produce female finches with brain structures or behavior exactly like males. Furthermore, other research has shown results that contradict what would be expected based on our current knowledge of mammalian sexual differentiation. For example, male zebra finches castrated or given sex steroid inhibitors as hatchlings still develop normal masculine singing behavior. This suggests that other factors, such as
4875-399: Is reversed. Animals may use several strategies to defend their territories. The first game theory model of fighting is known as the hawk-dove game . This model pits a hawk strategy (always try to injure your opponent and only withdraw from the contest if an injury is received) against a dove strategy (always use a non-injurious display if the rival is another dove and always withdraw if
5000-444: Is the sociographical area that an animal consistently defends against conspecific competition (or, occasionally, against animals of other species ) using agonistic behaviors or (less commonly) real physical aggression . Animals that actively defend territories in this way are referred to as being territorial or displaying territorialism . Territoriality is only shown by a minority of species. More commonly, an individual or
5125-422: Is to acquire and protect food sources, nesting sites, mating areas, or to attract a mate. Among birds, territories have been classified as six types. Reports of territory size can be confused by a lack of distinction between home range and the defended territory. The size and shape of a territory can vary according to its purpose, season, the amount and quality of resources it contains, or the geography. The size
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5250-797: Is usually a compromise of resource needs, defense costs, predation pressure and reproductive needs. Some species of squirrels may claim as much as 10 hectares (25 acres) of territory. For European badgers , a home range may be as small as 30 hectares (74 acres) in a good rural habitat, but as large as 300 hectares (740 acres) in a poor habitat. On average, a territory may be approximately 50 hectares (120 acres), with main setts normally at least 500 metres (1,600 ft) apart. In urban areas, territories can be as small as 5 hectares (12 acres), if they can obtain enough food from bird tables, food waste or artificial feeding in suburban gardens. Spotted hyenas ( Crocuta crocuta ) have highly variable territory sizes, ranging from less than 4,000 hectares (9,900 acres) in
5375-483: The Australian painted lady butterfly and the speckled wood butterfly , the male defends territories that receptive females are likely to fly through such as sunny hilltops and sunspots on a forest's floor. Territory defence in male variegated pupfish ( Cyprinodon variegatus ) is dependent on the presence of females. Reduced aggression consistent with the dear enemy effect occurs between conspecific neighbours in
5500-821: The Ngorongoro Crater to over 100,000 hectares (250,000 acres) in the Kalahari . In birds, golden eagles ( Aquila chrysaetos ) have territories of 9,000 hectares (22,000 acres), least flycatchers ' ( Empidonax minimus ) territories are about 600 square metres (6,500 sq ft) and gulls have territories of only a few square centimetres in the immediate vicinity of the nest. Territories can be linear. Sanderlings ( Calidris alba ) forage on beaches and sandflats. When on beaches, they feed either in flocks or individual territories of 10 to 120 metres of shoreline. The time to develop territories varies between animals. The marine iguana ( Amblyrhynchus cristatus )
5625-561: The Uganda kob (a grazing antelope ) and the marine iguana, males defend the lek site which is used only for mating. Many species demonstrate polyterritoriality, referring to the act of claiming or defending more than one territory. In the European pied flycatcher ( Ficedula hypoleuca ), researchers assert that males exhibit polyterritoriality to deceive females of the species into entering into polygynous relationships. This hypothesis, named
5750-453: The brain stem , while the AFP has been considered homologous to the mammalian cortical pathway through the basal ganglia and thalamus. Models of bird-song motor learning can be useful in developing models for how humans learn speech . In some species such as zebra finches, learning of song is limited to the first year; they are termed "age-limited" or "close-ended" learners. Other species such as
5875-418: The comparative method can also be employed to investigate hypotheses such as those given by Curio above. For example, not all gull species show mobbing behavior. The kittiwake nests on sheer cliffs that are almost completely inaccessible to predators, meaning its young are not at risk of predation like other gull species. This is an example of divergent evolution . Another hypothesis for mobbing behavior
6000-491: The deception hypothesis, claims that males have territories at distances sufficiently great that females are unable to discern already-mated males. The observation that males travelled long distances, ranging from 200m to 3.5 km, to find a second mate supports this argument. The debate about polyterritoriality in this species may initiate research about the evolution and reasons for polyterritoriality in other unrelated species. Mobbing behaviour Mobbing in animals
6125-468: The oilbird and swiftlets ( Collocalia and Aerodramus species), use audible sound (with the majority of sonic location occurring between 2 and 5 kHz) to echolocate in the darkness of caves. The only bird known to make use of infrasound (at about 20 Hz) is the western capercaillie . The hearing range of birds is from below 50 Hz ( infrasound ) to around 12 kHz, with maximum sensitivity between 1 and 5 kHz. The black jacobin
6250-460: The swallows also mob predators, however more distantly related groups including mammals have been known to engage in this behavior. One example is the California ground squirrel , which distracts predators such as the rattlesnake and gopher snake from locating their nest burrows by kicking sand into the snake's face, thus disrupting its sensory organs; for crotaline snakes, this includes
6375-404: The 1990s have looked at the neural mechanisms underlying birdsong learning by performing lesions to relevant brain structures involved in the production or maintenance of song or by deafening birds before and/or after song crystallization. Another experimental approach was recording the bird's song and then playing it back while the bird is singing, causing perturbed auditory feedback (the bird hears
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#17327866959026500-580: The Americas almost all song is produced by male birds; however, in the tropics and to a greater extent the desert belts of Australia and Africa it is more typical for females to sing as much as males. These differences have been known for a long time and are generally attributed to the much less regular and seasonal climate of Australian and African arid zones requiring that birds breed at any time when conditions are favourable, although they cannot breed in many years because food supply never increases above
6625-517: The BOS-tuned error correction model, as the firing rates of LMAN neurons were unaffected by changes in auditory feedback and therefore, the error signal generated by LMAN appeared unrelated to auditory feedback. Moreover, the results from this study supported the predictions of the efference copy model, in which LMAN neurons are activated during singing by the efference copy of the motor signal (and its predictions of expected auditory feedback), allowing
6750-440: The HVC and RA regions. Melatonin is another hormone that is also believed to influence song behavior in adults, as many songbirds show melatonin receptors in neurons of the song nuclei. Both the European starling ( Sturnus vulgaris ) and house sparrow ( Passer domesticus ) have demonstrated changes in song nuclei correlated with differing exposures to darkness and secretions of melatonin. This suggests that melatonin might play
6875-506: The absence of females, but the presence of a female in a male's territory instigates comparably greater aggression between the neighbours. In the Skylark ( Alauda arvensis ), playbacks of neighbour and stranger songs at three periods of the breeding season show that neighbours are dear enemies in the middle of the season, when territories are stable, but not at the beginning of the breeding season, during settlement and pair formation, nor at
7000-495: The activation of genes on the z chromosome, might also play a role in normal male song development. Hormones also have activational effects on singing and the song nuclei in adult birds. In canaries ( Serinus canaria ), females normally sing less often and with less complexity than males. However, when adult females are given androgen injections, their singing will increase to an almost male-like frequency. Furthermore, adult females injected with androgens also show an increased size in
7125-432: The animal is present, but can travel long distances and over varied habitats. Examples of animals which use auditory signals include birds, frogs and canids. Wolves advertise their territories to other packs through a combination of scent marking and howling. Under certain conditions, wolf howls can be heard over areas of up to 130 km (50 sq mi). When howling together, wolves harmonize rather than chorus on
7250-582: The bird (i.e. badge) is highly visible when it sings (vocal marking) at the boundary of its territory. The ring-tailed lemur ( Lemur catta ) advertises its territory with urine scent marks. When it is urinating for marking purposes, it holds its extremely distinctive tail high in the air adding a visual component to the advertisement; when it is urinating for eliminative purposes, its tail is only slightly raised. Rhinoceros have poor vision but may use visual marking. Dominant white rhino bulls mark their territory with faeces and urine (olfactory marking). The dung
7375-564: The bird does not pass for another species). As early as 1773, it was established that birds learned calls, and cross-fostering experiments succeeded in making linnet Acanthis cannabina learn the song of a skylark, Alauda arvensis . In many species, it appears that although the basic song is the same for all members of the species, young birds learn some details of their songs from their fathers, and these variations build up over generations to form dialects . Song learning in juvenile birds occurs in two stages: sensory learning, which involves
7500-418: The bird is singing that same song. Swamp sparrows employ 3–5 different song types, and the neural activity differs depending on which song is heard or sung. The HVC X neurons only fire in response to the presentation (or singing) of one of the songs, the primary song type. They are also temporally selective, firing at a precise phase in the song syllable. Territory (animal) In ethology , territory
7625-452: The bird's own song to the memorized song template), which adaptively alters the motor program for song output. The generation of this instructive signal could be facilitated by auditory neurons in Area X and LMAN that show selectivity for the temporal qualities of the bird's own song (BOS) and its tutor song, providing a platform for comparing the BOS and the memorized tutor song. Models regarding
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#17327866959027750-546: The birds that most frequently engage in mobbing include mockingbirds, crows and jays, chickadees, terns, and blackbirds. Behavior includes flying about the intruder, dive bombing, loud squawking and defecating on the predator. Mobbing can also be used to obtain food, by driving larger birds and mammals away from a food source, or by harassing a bird with food. One bird might distract while others quickly steal food. Scavenging birds such as gulls frequently use this technique to steal food from humans nearby. A flock of birds might drive
7875-434: The body with urine), to communicate. Many ungulates , for example the blue wildebeest , use scent marking from two glands, the preorbital gland and a scent gland in the hoof . Territorial scent marking may involve behaviours specific to this activity. When a wolf marks its territory , it lifts a hind leg and urinates on a scent post (usually an elevated position like a tree, rock, or bush). This raised leg urination
8000-405: The canaries can develop new songs even as sexually mature adults; these are termed "open-ended" learners. Researchers have hypothesized that learned songs allow the development of more complex songs through cultural interaction, thus allowing intraspecies dialects that help birds to identify kin and to adapt their songs to different acoustic environments. Early experiments by Thorpe in 1954 showed
8125-488: The case of redlip blenny . This is because the conspecifics share exactly the same set of resources. Several types of resource in a territory may be defended. Food: Large solitary (or paired) carnivores, such as bears and the bigger raptors require an extensive protected area to guarantee their food supply. This territoriality only breaks down when there is a glut of food, for example when grizzly bears are attracted to migrating salmon . Food related territoriality
8250-419: The cricket Gryllus texensis showcases this by activating high predation risk repeatedly to examine how animals in general perceive such risks. Based on perceived threat, crickets took action to save themselves or attempted to preserve their offspring. Mobbing calls are signals made by the mobbing species while harassing a predator. These differ from alarm calls , which allow con-specifics to escape from
8375-415: The degree to which adult birds could recover crystallized song over time after being removed from perturbed feedback exposure. This study offered further support for role of auditory feedback in maintaining adult song stability and demonstrated how adult maintenance of crystallized birdsong is dynamic rather than static. Brainard & Doupe (2000) posit a model in which LMAN (of the anterior forebrain) plays
8500-411: The direction from which the call came). In the case of the alarm call, it could be disadvantageous to the sender if the predator picks up on the signal, hence selection has favored those birds able to hear and employ calls in this higher frequency range. Furthermore, bird vocalizations vary acoustically as a byproduct of adapting to the environment, according to the acoustic adaptation hypothesis. In
8625-409: The drumming of woodpeckers and the " winnowing " of snipes ' wings in display flight, are considered songs. Still others require song to have syllabic diversity and temporal regularity akin to the repetitive and transformative patterns that define music . It is generally agreed upon in birding and ornithology which sounds are songs and which are calls, and a good field guide will differentiate between
8750-423: The duets are so perfectly timed as to appear almost as one call. This kind of calling is termed antiphonal duetting. Such duetting is noted in a wide range of families including quails, bushshrikes , babblers such as the scimitar babblers , and some owls and parrots. In territorial songbirds, birds are more likely to countersing when they have been aroused by simulated intrusion into their territory. This implies
8875-576: The end, when bird density increases due to the presence of young birds becoming independent. Thus, this dear enemy territoriality relationship is not a fixed pattern but a flexible one likely to evolve with social and ecological circumstances. Some species of bees also exhibit territoriality to defend mating sites. For example, in Euglossa imperialis , a non-social bee species, males have been observed to occasionally form aggregations of fragrance-rich territories, considered to be leks. These leks serve only
9000-418: The environment. Narrow-frequency bandwidth notes are increased in volume and length by reverberations in densely vegetated habitats. It has been hypothesized that the available frequency range is partitioned, and birds call so that overlap between different species in frequency and time is reduced. This idea has been termed the "acoustic niche". Birds sing louder and at a higher pitch in urban areas, where there
9125-421: The following characteristics: Because mirror neurons exhibit both sensory and motor activity, some researchers have suggested that mirror neurons may serve to map sensory experience onto motor structures. This has implications for birdsong learning– many birds rely on auditory feedback to acquire and maintain their songs. Mirror neurons may be mediating this comparison of what the bird hears, how it compares to
9250-421: The functions of vocal mimicry including suggestions that they may be involved in sexual selection by acting as an indicator of fitness, help brood parasites, or protect against predation, but strong support is lacking for any function. Many birds, especially those that nest in cavities, are known to produce a snakelike hissing sound that may help deter predators at close range. Some cave-dwelling species, including
9375-430: The genus Acmaea, predatory snails, and sessile organisms such as anemones and barnacles. Nests and offspring: Many birds, particularly seabirds, nest in dense communities but are nonetheless territorial in defending their nesting site to within the distance they can reach while brooding. This is necessary to prevent attacks on their own chicks or nesting material from neighbours. Commonly the resulting superimposition of
9500-489: The greatest threat to the resident territory-holder. In territory defence by groups of animals, reciprocal altruism can operate whereby the cost to the benefactor in helping defend the territory is less than the gains to the beneficiary. An animal chooses its territory by deciding what part of its home range it will defend. In selecting a territory, the size and quality play crucial roles in determining an animal's habitat. Territory size generally tends to be no larger than
9625-588: The ground nearby, thereby leaving a visual advertisement of the territory. This includes domestic dogs . Several species scratch or chew trees leaving a visual mark of their territory. This is sometimes combined with rubbing on the tree which may leave tufts of fur. These include the Canada lynx ( Lynx canadensis ) and the American black bear ( Ursus americanus ). Many animals have scent glands in their paws or deposit fur during tree-marking, so tree-marking may be
9750-491: The heat-detecting organs in the loreal pits . This social species also uses alarm calls. Some fish engage in mobbing; for example, bluegills sometimes attack snapping turtles . Bluegills, which form large nesting colonies, were seen to attack both released and naturally occurring turtles, which may advertise their presence, drive the predator from the area, or aid in the transmission of predator recognition. Similarly, humpback whales are known to mob killer whales when
9875-421: The importance of a bird being able to hear a tutor's song. When birds are raised in isolation, away from the influence of conspecific males, they still sing. While the song they produce, called "isolate song", resembles the song of a wild bird, it shows distinctly different characteristics from the wild song and lacks its complexity. The importance of the bird being able to hear itself sing in the sensorimotor period
10000-400: The individual and benefits (payoffs) to the individual and others. The individuals themselves are often genetically related, and mobbing is increasingly studied with the gene-centered view of evolution by considering inclusive fitness (the carrying on of one's genes through one's family members), rather than merely benefit to the individual. Mobbing behavior varies in intensity depending on
10125-444: The juvenile listening to the father or other conspecific bird and memorizing the spectral and temporal qualities of the song (song template), and sensorimotor learning, which involves the juvenile bird producing its own vocalizations and practicing its song until it accurately matches the memorized song template. During the sensorimotor learning phase, song production begins with highly variable sub-vocalizations called "sub-song", which
10250-505: The known types of dimorphisms in the brain include the size of nuclei, the number of neurons present, and the number of neurons connecting one nucleus to another. In the extremely dimorphic zebra finches ( Taeniopygia guttata ), a species in which only males typically sing, the size of the HVC and RA are approximately three to six times larger in males than in females, and Area X does not appear to be recognizable in females. Research suggests that exposure to sex steroids during early development
10375-406: The latter are attacking other species, including other cetacean species, seals, sea lions, and fish. There is a distinction though, between mobbing in animals, and fight-or-flight response . The former relies heavily on group dynamics, whereas the latter’s central focus conceptually is on that of the individual and its offspring in some cases. A study conducted by Adamo & McKee (2017) examining
10500-491: The more birds responded to mobbing calls. That is to say, the presence of cover in the forest highly contributes to willingness to respond to the aforementioned call. Another way the comparative method can be used here is by comparing gulls with distantly related organisms. This approach relies on the existence of convergent evolution , where distantly related organisms evolve the same trait due to similar selection pressures . As mentioned, many bird species such as
10625-426: The mornings when plants are richest in nectar. In species that do not form pair bonds, male and female territories are often independent, i.e. males defend territories only against other males and females only against other females. In this case, if the species is polygynous , one male territory probably contains several female territories, while in some polyandrous species such as the northern jacana , this situation
10750-566: The most combative spiders have the largest territories. Some species of penguin defend their nests from intruders trying to steal the pebbles from which the nest is constructed. Mating opportunities: The striped mouse ( Rhabdomys pumilio ) is group living with one single breeding male and up to 4 communally breeding females per group. Groups typically contain several philopatric adult sons (and daughters) that are believed not to breed in their natal group and all group members participate in territorial defence. Males defend their territory using
10875-454: The most popular species for birdsong research, have overlapping sensory and sensorimotor learning stages. Research has indicated that birds' acquisition of song is a form of motor learning that involves regions of the basal ganglia . Further, the PDP (see Neuroanatomy below) has been considered homologous to a mammalian motor pathway originating in the cerebral cortex and descending through
11000-732: The motor program, lesioning LMAN in the anterior forebrain pathway of adult birds that had been deafened led to the stabilization of song (LMAN lesions in deafened birds prevented any further deterioration in syllable production and song structure). Currently, there are two competing models that elucidate the role of LMAN in generating an instructive error signal and projecting it to the motor production pathway: Bird's own song (BOS)-tuned error correction model Efference copy model of error correction Leonardo tested these models directly by recording spike rates in single LMAN neurons of adult zebra finches during singing in conditions with normal and perturbed auditory feedback. His results did not support
11125-418: The nest site entrance to establish their territory. Wombats use feces to mark their territory. They have evolved specialized intestinal anatomy to produce cubical feces to ensure the feces do not roll away. Visual sign-posts may be a short-term or long-term mode of advertising a territory. Short-term communication includes the colouration or behaviour of the animal, which can only be communicated when
11250-427: The neurons to be more precisely time-locked to changes in auditory feedback. A mirror neuron is a neuron that discharges both when an individual performs an action and when he/she perceives that same action being performed by another. These neurons were first discovered in macaque monkeys, but recent research suggests that mirror neuron systems may be present in other animals including humans. Mirror neurons have
11375-625: The offspring themselves, such as camouflage and hiding. Mobbing calls may be used to summon nearby individuals to cooperate in the attack. Konrad Lorenz , in his book On Aggression (1966), attributed mobbing among birds and animals to instincts rooted in the Darwinian struggle to survive. In his view, humans are subject to similar innate impulses but capable of bringing them under rational control (see mobbing ). Birds that breed in colonies such as gulls are widely seen to attack intruders, including encroaching humans. In North America,
11500-407: The organism requires to survive, because defending a larger territory incurs greater energy, time and risk of injury costs. For some animals, the territory size is not the most important aspect of territoriality, but rather the quality of the defended territory. Behavioural ecologists have argued that food distribution determines whether a species is territorial or not, however, this may be too narrow
11625-827: The other hand, are characteristically high-pitched, making the caller difficult to locate. Communication through bird calls can be between individuals of the same species or even across species. For example, the Japanese tit will respond to the recruitment call of the willow tit as long as it follows the Japanese tit alert call in the correct alert+recruitment order. Individual birds may be sensitive enough to identify each other through their calls. Many birds that nest in colonies can locate their chicks using their calls. Calls are sometimes distinctive enough for individual identification even by human researchers in ecological studies. Over 400 bird species engage in duet calls. In some cases,
11750-715: The other. They also did not engage in physical contact with the territorial males. On the other hand, territorial males patrolled an area around a tree and used the same territory for up to 49 days. It also appeared that they gave up territories to new males without violence. Males defend territories solely for mating, and no other resources such as fragrances, nests, nest construction materials, nectar, or pollen are found at these territories. Although most territories contain multiple (potential) resources, some territories are defended for only one purpose. European blackbirds may defend feeding territories that are distant from their nest sites, and in some species that form leks, for example in
11875-481: The overlaps in their home ranges using their anogenital scent glands . To do this, they perform a handstand to mark vertical surfaces, grasping the highest point with their feet while applying the scent. In the Eastern carpenter bee, Xylocopa virginica , both sexes have glands that evolved for marking the nest. Males, although they have the gland, are unable to produce the marking substance. Females secrete it near
12000-414: The owls' diet. Furthermore, the intensity of mobbing was greater in autumn than spring. Mobbing is thought to carry risks to roosting predators, including potential harm from the mobbing birds, or attracting larger, more dangerous predators. Birds at risk of mobbing such as owls have cryptic plumage and hidden roosts which reduces this danger. Environment has an effect on mobbing behavior as seen in
12125-407: The paths, thus establishing a scent-marked trail. Another method of visually marking their territory is wiping their horns on bushes or the ground and scraping with the feet, although this is likely combined with the smell of the marking animal. The territorial male scrape-marks every 30 m (98 ft) or so around its territory boundary. After leaving a urination mark, some animals scrape or dig
12250-457: The perceived threat of a predator according to a study done by Dutour et al. (2016). However, particularly in terms of its surfacing in avian species, it is accepted to be the byproduct of mutualism , rather than reciprocal altruism according to Russell & Wright (2009). By cooperating to successfully drive away predators, all individuals involved increase their chances of survival and reproduction. An individual stands little chance against
12375-559: The predator species, directly injuring the predator or attracting a predator of the predator itself. The much lower frequency of attacks between nesting seasons suggests such behavior may have evolved due to its benefit for the mobber's young. Niko Tinbergen argued that the mobbing was a source of confusion to gull chick predators, distracting them from searching for prey. Indeed, an intruding carrion crow can only avoid incoming attacks by facing its attackers, which prevents it from locating its target. Besides experimental research,
12500-441: The predator, making stealth attacks impossible. Mobbing plays a critical role in the identification of predators and inter-generational learning about predator identification. Reintroduction of species is often unsuccessful, because the established population lacks this cultural knowledge of how to identify local predators. Scientists are exploring ways to train populations to identify and respond to predators before releasing them into
12625-607: The predator. Studies of Phainopepla mobbing calls indicate it may serve to enhance the swooping attack on the predators, including scrub jays . In this species, the mobbing call is smoothly upsweeping, and is made when swooping down in an arc beside the predator. This call was also heard during agonistic behavior interactions with conspecifics , and may serve additionally or alternatively as an alarm call to their mate. The evolution of mobbing behavior can be explained using evolutionarily stable strategies , which are in turn based on game theory . Mobbing involves risks (costs) to
12750-448: The predator. The great tit , a European songbird , uses such a signal to call on nearby birds to harass a perched bird of prey , such as an owl. This call occurs in the 4.5 kHz range, and carries over long distances. However, when prey species are in flight, they employ an alarm signal in the 7–8 kHz range. This call is less effective at traveling great distances, but is much more difficult for both owls and hawks to hear (and detect
12875-436: The probability of the crow being subjected to mobbing. The results showed decreasing mobbing with increased distance from the nest, which was correlated with increased predation success. Mobbing may function by reducing the predator's ability to locate nests (as a distraction) since predators cannot focus on locating eggs while they are under attack. Besides the ability to drive the predator away, mobbing also draws attention to
13000-412: The quality of bird song may be a good indicator of fitness. Experiments also suggest that parasites and diseases may directly affect song characteristics such as song rate, which thereby act as reliable indicators of health. The song repertoire also appears to indicate fitness in some species. The ability of male birds to hold and advertise territories using song also demonstrates their fitness. Therefore,
13125-425: The real-time error-correction interactions between the AFP and PDP will be considered in the future. Other current research has begun to explore the cellular mechanisms underlying HVC control of temporal patterns of song structure and RA control of syllable production. Brain structures involved in both pathways show sexual dimorphism in many bird species, usually causing males and females to sing differently. Some of
13250-724: The resident is present. Other animals may use more long-term visual signals such as faecal deposits, or marks on the vegetation or ground. Visual marking of territory is often combined with other modes of animal communication. Some animals have prominent "badges" or visual displays to advertise their territory, often in combination with scent marking or auditory signals. Male European robins are noted for their highly aggressive territorial behaviour. They attack other males that stray into their territories, and have been observed attacking other small birds without apparent provocation. Such attacks sometimes lead to fatalities, accounting for up to 10% of adult robin deaths in some areas. The red breast of
13375-418: The risk of injury. This is ritualized aggression . Such defense frequently involves a graded series of behaviours or displays that include threatening gestures (such as vocalizations, spreading of wings or gill covers, lifting and presentation of claws, head bobbing, tail and body beating) and finally, direct attack. Territories may be held by an individual, a mated or unmated pair, or a group. Territoriality
13500-408: The rival is a hawk). Another strategy used in territory defence is the war of attrition . In this model of aggression, two contestants compete for a resource by persisting while constantly accumulating costs over the time that the contest lasts. Strategically, the game is an auction in which the prize goes to the player with the highest bid, and each player pays the loser's low bid. Some animals use
13625-514: The same note, thus creating the illusion of there being more wolves than there actually are. Wolves from different geographic locations may howl in different fashions: the howls of European wolves are much more protracted and melodious than those of North American wolves, whose howls are louder and have a stronger emphasis on the first syllable. Animals use a range of behaviours to intimidate intruders and defend their territories, but without engaging in fights which are expensive in terms of energy and
13750-425: The same song type and use these song types for more complex communication. Some birds will respond to a shared song type with a song-type match (i.e. with the same song type). This may be an aggressive signal; however, results are mixed. Birds may also interact using repertoire-matches, wherein a bird responds with a song type that is in its rival's repertoire but is not the song that it is currently singing. This may be
13875-460: The scent frequently displays a flehmen response to assist in detecting the mark. Scent marking is often performed by scent rubbing in many mammals. In many mammal species, scent marking is more frequent during the breeding season . Bears and felids such as leopards and jaguars scent-mark by urinating on or rubbing against vegetation. Prosimians and New World monkeys also use scent marking, including urine washing ( self-anointing
14000-511: The short-range repulsion onto the long-range attraction characteristically leads to the well-known roughly hexagonal spacing of nests. One gets a similar hexagonal spacing resulting from the territorial behaviour of gardening limpets such as species of Scutellastra . They vigorously defend their gardens of particular species of algae, that extend for perhaps 1–2 cm around the periphery of their shells. The desert grass spider, Agelenopsis aperta , often engages in fights over its territory and
14125-457: The song system begin at the level of HVC , which projects information both to the RA (premotor nucleus) and to Area X of the anterior forebrain. Information in the posterior descending pathway (also referred to as the vocal production or motor pathway) descends from HVC to RA, and then from RA to the tracheosyringeal part of the hypoglossal nerve (nXIIts), which then controls muscular contractions of
14250-422: The species. Species vary greatly in the complexity of their songs and in the number of distinct kinds of song they sing (up to 3000 in the brown thrasher ); individuals within some species vary in the same way. In a few species, such as lyrebirds and mockingbirds , songs imbed arbitrary elements learned in the individual's lifetime, a form of mimicry (though maybe better called "appropriation" (Ehrlich et al.), as
14375-548: The superposition of its own song and a fragmented portion of a previous song syllable). After Nordeen & Nordeen made a landmark discovery as they demonstrated that auditory feedback was necessary for the maintenance of song in adult birds with crystallized song, Leonardo & Konishi (1999) designed an auditory feedback perturbation protocol in order to explore the role of auditory feedback in adult song maintenance further, to investigate how adult songs deteriorate after extended exposure to perturbed auditory feedback, and to examine
14500-491: The syrinx. Information in the anterior forebrain pathway is projected from HVC to Area X (basal ganglia), then from Area X to the DLM (thalamus), and from DLM to LMAN, which then links the vocal learning and vocal production pathways through connections back to the RA. Some investigators have posited a model in which the connection between LMAN and RA carries an instructive signal based on evaluation of auditory feedback (comparing
14625-449: The territory is occupied and may also communicate additional information such as the sex, reproductive status or dominance status of the territory-holder. Sign-posts may communicate information by olfactory , auditory, or visual means, or a combination of these. If an intruder progresses further into the territory beyond the sign-posts and encounters the territory-holder, both animals may begin ritualized aggression toward each other. This
14750-476: The trachea independently, which is how some species can produce two notes at once. In February 2023, scientists reported that the possible sounds that ankylosaur dinosaurs may have made were bird-like vocalizations based on a finding of a fossilized larynx from the ankylosaur Pinacosaurus grangeri . One of the two main functions of bird song is mate attraction. Scientists hypothesize that bird song evolved through sexual selection , and experiments suggest that
14875-449: The two. Bird song is best developed in the order Passeriformes . Some groups are nearly voiceless, producing only percussive and rhythmic sounds, such as the storks , which clatter their bills. In some manakins ( Pipridae ), the males have evolved several mechanisms for mechanical sound production, including mechanisms for stridulation not unlike those found in some insects. The production of sounds by mechanical means as opposed to
15000-586: The typical call (TC, the control treatment), a mobbing call to a collared scops owl (the MtO treatment) and a mobbing call to a crested goshawk, Accipiter trivirgatus (the superior predator; the MtH treatment). Looking at variation in the behavioural responses of 22 different passerine species to a potential predator, the Eurasian Pygmy Owl, extent of mobbing was positively related with a species prevalence in
15125-500: The use of the syrinx has been termed variously instrumental music by Charles Darwin , mechanical sounds and more recently sonation . The term sonate has been defined as the act of producing non-vocal sounds that are intentionally modulated communicative signals, produced using non-syringeal structures such as the bill, wings, tail, feet and body feathers. Song is usually delivered from prominent perches, although some species may sing when flying. In extratropical Eurasia and
15250-409: The wild. Adaptationist hypotheses regarding why an organism should engage in such risky behavior have been suggested by Eberhard Curio , including advertising their physical fitness and hence uncatchability (much like stotting behavior in gazelles), distracting predators from finding their offspring, warning their offspring, luring the predator away, allowing offspring to learn to recognize
15375-474: The wood and spreading the gland's secretions. When on the ground, ring-tailed lemurs preferentially mark small saplings and when high in the trees, they usually mark small vertical branches. European wildcats ( Felis silvestris ) deposit their faecal marks on plants with high visual conspicuousness that enhances the visual effectiveness of the signal. Many animals use vocalisations to advertise their territory. These are short-term signals transmitted only when
15500-428: Was conducted in southern Germany, with male blue tits being the birds of interest. Researchers "found that the males sang at high rates while their female partners were still roosting in the nest box at dawn, and stopped singing as soon as the females left the nest box to join them". The males were also more likely to sing when the females entered the nests in the evening or even during the daytime. While this information
15625-427: Was later discovered by Konishi. Birds deafened before the song-crystallization period went on to produce songs that were distinctly different from the wild type and isolate song. Since the emergence of these findings, investigators have been searching for the neural pathways that facilitate sensory/sensorimotor learning and mediating the matching of the bird's own song with the memorized song template. Several studies in
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