Eurasian jays are preyed on by many animals, including cats, birds of prey, and small terrestrial predators. Eggs and young are taken by martens (Martes) and cats (Felis). Adults and fledglings are largely taken by birds of prey.
Eurasian jays exhibit a variety of responses to predators, depending on the species and the circumstances. When they see a hawk flying above, they freeze, watch it flying, and emit a low moan in alarm. Mobbing is a common defense mechanism, and they use it against nearly all species of predators. Sometimes a threatened bird will emit the calls of more powerful birds, like tawny owls (Strix aluco), perhaps in an effort to frighten the attacker. Another use of mimicry in predation defense is when Eurasian jays fly out of sight of a threatening bird and then call it using its own species’ call notes. For instance, they have been observed to fly away from their nest in the presence of a carrion crow (Corvus corone, a nest predator) and mimic the crow’s own calls. Eurasian jays sitting on a nest can also sit quietly or sneak away rather than draw attention to their nest. A valuable defense measure is to simply avoid open spaces, where they are more vulnerable to avian predators.
Known Predators:
Anti-predator Adaptations: mimic
Eurasian jay plumage is mainly light reddish brown. Their feathers reflect UV light. Their crests, which are frequently raised during communication, are white with black speckles. Their beaks are black, and black moustache stripes extend downward from the ends of their beaks. Their tails are black dorsally with a white patch around the base. Their wings have bright blue spots with black speckles. These blue areas appear like triangles or a band, though their orientation and size changes when the wings are spread (they enlarge when spread). There are white bands on the wings, visible during flight. The rest of the wings are black, except for a red triangle where the wing attaches to the body. They often carry their wings so the tips are both on one side of the tail.
When compared to other corvids, like Corvus and Pica species, Eurasian jays hold their tail rather high. For this reason the tail feathers incur less damage than in the other genera. Unlike other corvids, Eurasian jays have two plumage phases: juvenile and adult. Other corvids can be aged by a sequence of plumages, but ageing is more difficult in Eurasian jays. They lose their juvenile plumage by autumn of the first year, so birds seen in autumn all appear to be adults.
Eurasian jay average basal metabolic rate is 4.99 kJ per hour.
Average mass: 170 g.
Average length: 34 cm.
Average wingspan: 55 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
The oldest bird recorded in Britain was 16 years, 9 months of age.
Average lifespan
Status: wild: 16.75 years.
Eurasian jays prefer dense foliage, with plenty of trees, bushes, and undergrowth. Trees are essential due to their arboreal lifestyles, though they also forage on the ground. High levels of biodiversity are important so they can enjoy varied diets. Eurasian jays store and eat acorns, so oak trees are important features of their habitat. Deciduous oak forests are preferred for foraging, but coniferous forests provide the best nesting places. Eurasian jays do not like open areas and will avoid entering them if possible. They are most vulnerable to predators in open areas.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: forest ; scrub forest
Other Habitat Features: suburban ; agricultural ; riparian
Garrulus glandarius is widely distributed throughout Europe and Asia. It is a mostly temperate species that lives in forested areas and near human settlements.
Biogeographic Regions: palearctic (Native )
Eurasian jays are omnivores and opportunistic, eating pretty much whatever they can find. Acorns represent the largest part of their diet. They crack the shell by biting it and using their beaks to lever the shell pieces open until they can get the meat out. They collect the acorns of Quercus oaks in the autumn and bury them to eat throughout the year. They rely on stored food the most from May to July, when they are feeding offspring. One bird can hide between 4500 and 11,000 acorns and will use its memory to locate caches up to ten months later. When hiding acorns, they usually hide only one in a spot, but may hide two or three acorns there. The impulse to store acorns for later use is so strong that captive jays without access to a surplus of acorns will store things that look like acorns, including properly shaped stones.
Eurasian jays prefer the acorns of Quercus ilex, Quercus suber, and Quercus faginea, but avoid acorns from Quercus coccifera. Preference is probably linked to relative nutritional value. Quercus ilex acorns have the highest fat content and Quercus coccifera acorns have the highest amount of tannins, at least of the four species studied by Pons and Pausas (2007). Eurasian jays prefer bigger acorns over smaller ones. They usually transport one acorn at a time, but they have been observed carrying up to five at once. Single acorns are carried in the bill. If more than one is carried, the first one or ones are swallowed and carried in the crop while the last, and usually largest, is held in the bill.
In addition to acorns, Eurasian jays eat fruit, grains, and nuts. They also take invertebrates, including worms, snails, slugs, and insects. Eggs are not instinctively recognized as food, but once a bird learns to crack it open and eat the insides, it will continue to do so with other eggs it encounters. They will eat small birds, their young, and their eggs. Reed warblers (Acrocephalus scirpaceus) are an example of a common prey species. Eurasian jays eat plenty of carrion. Researchers studying carrion consumers have found jays will visit about half of available carcasses, especially those in the forest. They use their feet to hold food, but not if the food is sticky. They look everywhere they can for food, including in crevices, loose bark, small holes, under leaves, or any other spot a prey item might be hiding. However, they avoid food that is on open ground instead of covered with foliage. To open something, they insert their beaks and then try to open them. To turn something over, they pull on it with their beaks or put their beaks under the edges and push sideways.
Animal Foods: birds; mammals; eggs; carrion ; insects; terrestrial non-insect arthropods; terrestrial worms
Plant Foods: seeds, grains, and nuts; fruit
Foraging Behavior: stores or caches food
Primary Diet: herbivore (Granivore ); omnivore
Eurasian jays use a variety of visual displays to communicate. Displays involve changing body positions, raising feathers on certain parts of their bodies, and movements when necessary. Each display can be given in intense versions or simpler versions. For example, a very submissive bird will extend her wings completely during display, while a less submissive bird will only extend them partway. The displays are undoubtedly more colorful to the bird than to a human observer because their feathers reflect UV light, which we cannot see. Displays are accompanied by vocalizations in some cases, like when the bird is expressing friendliness or alarm.
Males and females have different sexual displays, both of which involve spreading their wings, lifting their feathers, and making a call. The female’s sexual display is similar to the submissive display. The submissive display can be used in a variety of settings, from admitting defeat in a fight to reacting to a human owner, if the bird is tame. They use an aggressive posture to threaten enemies. Jerky alarm movements are performed in silence when the bird does not feel too threatened, serious threats are signaled with the same movements accompanied by alarm screeches. Anxiety is expressed by exaggerated bill wiping and anger is expressed by overzealous feeding movements which only involve actual swallowing if the anger is vented on something edible.
Eurasian jays possess a range of jay-specific calls. One of these, the “appeal note,” is used by birds of all ages when they want something. In young birds, the call is directed to the parents as a request for food, but adults have been heard to utter the same notes while foraging on their own, as if talking to themselves. They use alarm calls to signal the presence of predators. The alarm call is a loud screech emitted once or twice. They also vocalize to express anger, playfulness, affection, warnings about predators, and a myriad of other emotions, intentions, or observations.
Eurasian jays are accomplished mimics and will sing songs composed of all sorts of sounds they have heard. They may mimic crying babies, passerine songs, water dropping from a tap, lawn mowers, and even the alarm calls of their predators. Goodwin (1951) supposes they repeat sounds according to the emotional state they experienced when they originally heard the sound. Thus, when threatened or mobbing they copy alarm notes from blackbirds, magpies, and tawny owls, but at more relaxed times may emulate woodpeckers, sparrows, and human whistling. Young birds spend a great deal of time practicing their mimicry until they can perfectly replicate the original sound.
Communication Channels: visual ; tactile ; acoustic
Other Communication Modes: mimicry
Perception Channels: visual ; ultraviolet; tactile ; acoustic ; chemical
Eurasian jays have an extensive range, populations are estimated in the millions of individuals, and there are no detected declining population trends. As a result, the IUCN Red List has determined they are "Least Concern."
US Migratory Bird Act: no special status
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
There are no known adverse effects of Eurasian jays on humans.
Eurasian jays are important in the regeneration of oak forests through acorn dispersal. Oaks are important to people because of their wood, beauty, and ability to enhance biodiversity. One study from a park in Sweden estimated how much money it would cost for humans to do the same job as Eurasian jays. The researchers determined it would cost between 1 and 6 million kroners (about 125,000 to 751,000 U.S. dollars) to replace Eurasian jays with people planting acorns in the 2700 hectare park.
A study in Germany found oaks regenerated in pine forests at a rate of 2,000 to 4,000 trees per hectare. Since mother oak trees were largely unavailable, they attributed this regeneration to Eurasian jays. The area was clearcut about 30 years before the study was performed and mostly pines regenerated. Oak trees were not recruited into the regenerating forest until Eurasian jays moved into the pine forest and began caching acorns.
Eurasian jays perform many functions which benefit the ecosystems they inhabit. Their alarm calls alert other species, including red squirrels (Sciurus vulgaris), to the presence of predators. They consume carrion, removing potential disease sources and helping in making nutrients available in the ecosystem.
One of their most important ecosystem roles is the dispersal of acorns from Quercus trees. Eurasian jays eat most of the acorns they take, but they also bury acorns and forget about them, leading to oak regeneration. Eurasian jay prefer collecting and burying viable acorns over infertile, dead, or damaged acorns, making them excellent dispersal agents. They preferentially store acorns on the edges of clear spaces, which is the best place for seedlings to get the right amount of light for germination. Oak trees, including Quercus robur and Quercus petrea, are keystone species in their habitats, providing homes and food for many species of animals, plants, fungi, and lichen. About 80% of all insects on the IUCN Red List need oak trees as part of their life cycle.
Ecosystem Impact: disperses seeds; creates habitat; biodegradation
Mutualist Species:
Eurasian jays are monogamous and breed once a year in the spring. At the beginning of spring, usually in March and April, unpaired birds spontaneously form gatherings where they choose their mates. In these gatherings, birds pair up and display to each other. They use a wide range of vocalizations, one of which is named the “flight appeal” and is an invitation to fly. Males display more than females and they also chase them. Mating gatherings appear random and may be started by already paired birds chasing and displaying to each other, which excites nearby unpaired birds and encourages them to join in. The gatherings may be as small as three or four birds, but are often as large as thirty or more. These gatherings also sometimes happen later in the season, like in June, though those gatherings are most likely the result of a paired bird losing its mate or nest rather than new birds finding their first mates.
Males offer their mates food as part of courtship. He crushes or tears portions off a food source and offers it to her. If she acts too nervous to accept, he may try approaching her from below, as this is a less threatening way to approach a jay. The birds may call affectionately to each other and engage in a tug-of-war during the ritual. If the female brings the food to her mate, they may pass the food back and forth until one or the other eats it. The ritual appears to strengthen their bond. Later, when the female is busy with the nest, the male will continue to supply her with food.
Mating System: monogamous
Both parents build and line the nest. Their nests are cup shaped and built in bushes or trees. They are constructed of sticks, freshly broken off of branches, and lined with fine roots, hairs, and the birds’ own feathers. Egg-laying commences around the end of March, and usually only one brood is raised per season, 4 to 5 eggs are laid, each weighing about 8.5 grams, 6% of which is the shell’s weight. Both parents incubate. The young hatch in 18 days and are naked and blind. They fledge and first leave the nest when they are 20 to 23 days old, but they remain dependent on their parents. The parents begin to wean them when they are around 40 days old, and they are independent around two months of age, though they continue to rob food from their parents for a few days. Eurasian jays reach breeding age at 2 years.
Breeding interval: Eurasian jays breed once a year.
Breeding season: Eurasian jays breed from March through June.
Range eggs per season: 4 to 5.
Average time to hatching: 18 days.
Range fledging age: 20 to 23 days.
Average time to independence: 2 months.
Average age at sexual or reproductive maturity (female): 2 years.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Sometimes only the females incubates, though in many pairs it is both parents. Incubating females clean the nest of parasites by eating them. This behavior seems to be caused by a need to eat anything she finds in the nest that isn’t an egg, lining, or young. Sometimes her need to clean the nest can be exaggerated if she is stressed by the presence of a predator or other stimulus, and she may eat her eggs or young.
When a predator approaches, the incubating bird will react according to the situation. If the intruder is far away and may not have noticed the bird, the parent will simply sneak away from the nest or fly off altogether, sometimes making alarm cries as he or she leaves. If the predator approaches, the parent will crouch lower in the nest, facing the threat, with her bill open. An even closer predator will warrant a defensive threat posture, which involves spreading the wings and crouching down. If the parent decides the only course of action is to attack, she will fly at the predator, attacking it with her claws and beak and crying out using any number of alarm calls, either her own jay calls, the predator’s own calls, or the alarm calls of an entirely different animal.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Male, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)
The Eurasian jay (Garrulus glandarius) is a species of passerine bird in the crow family Corvidae. It has pinkish brown plumage with a black stripe on each side of a whitish throat, a bright blue panel on the upper wing and a black tail. The Eurasian jay is a woodland bird that occurs over a vast region from western Europe and north-west Africa to the Indian subcontinent and further to the eastern seaboard of Asia and down into south-east Asia. Across this vast range, several distinct racial forms have evolved which look different from each other, especially when comparing forms at the extremes of its range.
The bird is called jay, without any epithets, by English speakers in Great Britain and Ireland.
The Eurasian jay was formally described by the Swedish naturalist Carl Linnaeus in 1758 in the tenth edition of his Systema Naturae under the binomial name Corvus glandarius.[2] Linnaeus specified the locality as "Europa" but this was restricted to Sweden by Ernst Hartert in 1903.[3][4] The Eurasian jay is now one of three species placed in the genus Garrulus that was established in 1760 by the French zoologist Mathurin Jacques Brisson.[5][6] The genus name Garrulus is a Latin word meaning "chattering", "babbling" or "noisy". The specific epithet glandarius is Latin meaning "of acorns".[7]
Eight racial groups (33 subspecies in total) were recognised by Steve Madge & Hilary Burn in 1994:[8]
The International Union for Conservation of Nature (IUCN) and Birdlife International split the Eurasian jay into three species. The subspecies G. g. leucotis becomes the white-face jay (Garrulus leucotis)[9] and the bispecularis group containing six subspecies becomes the plain-crowned jay (Garrulus bispecularis).[10]
G. g. bispecularis
Uttarakhand, India
G. g. atricapillus
Jerusalem, Israel
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G. g. glaszneri
Troodos Mountains, Cyprus
The Eurasian jay is a relatively small corvid, similar in size to a western jackdaw (Coloeus monedula) with a length of 34–35 cm (13–14 in) and a wingspan of 52–58 cm (20–23 in).[11] The nominate race has light rufous brown to a pinkish brown body plumage. The whitish throat is bordered on each side by a prominent black moustache stripe. The forehead and crown are whitish with black stripes. The rump is white. The complex colouring on the upper surface of the wing includes black and white bars and a prominent bright blue patch with fine black bars. The tail is mainly black.[8]
The most characteristic call is a harsh, rasping screech that is used upon sighting various predators and as a advertising call. The jay is well known for its mimicry, often sounding so like a different species that it is difficult to distinguish its true identity unless the bird is seen. It will imitate the calls of birds of prey such as the mew of the common buzzard and the cackle of the northern goshawk.[12][13]
A member of the widespread jay group, it inhabits mixed woodland, particularly with oaks, and is a habitual acorn hoarder. In recent years, the bird has begun to migrate into urban areas, possibly as a result of continued erosion of its woodland habitat. Before humans began planting the trees commercially on a wide scale, Eurasian jays were the main source of movement and propagation for the European oak (Q. robur), each bird having the ability to spread more than a thousand acorns each year. Eurasian jays will also bury the acorns of other oak species, and have been cited by the National Trust as a major propagator of the largest population of holm oak (Q. ilex) in Northern Europe, situated in Ventnor on the Isle of Wight.[14] Jays have been recorded carrying single acorns as far as 20 km, and are credited with the rapid northward spread of oaks following the last ice age.[15]
Eurasian jays normally first breed when two years of age, although they occasionally breed when only one year. Both sexes build the nest which is usually placed in a fork or on a branch of a tree close to the main trunk at a height of 2–5 m (6 ft 7 in – 16 ft 5 in) above the ground. Very occasionally the nest is located on a building. The nest has a base of twigs 3–15 mm (0.12–0.59 in) in diameter and a lining of thinner twigs, roots, grass, moss and leaves. The eggs are laid daily, normally early in the morning. The clutch is 3–6 eggs which are pale green to pale olive brown and are covered with fine darker speckles. They sometimes have brown or black streaks concentrated at the broader end. The eggs are 31.3 mm × 23.0 mm (1.23 in × 0.91 in) and weigh around 8.5 g (0.30 oz). They are incubated by the female and hatch after 16–19 days. While the female is on the nest the male brings her food. Both parents feed and care for the young which fledge after 19–23 days. The parents continue to feed the fledgelings until they are 6–8 weeks of age. Only a single brood is raised each year.[16]
The maximum recorded age is 16 years and 9 months for a bird in Skelton, York, United Kingdom, that was ringed in 1966 and found dead in 1983.[17][18]
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Nest with eggs
Juvenile Eurasian jay in South Korea
Garrulus glandarius atricapillus - MHNT
Feeding in both trees and on the ground, it takes a wide range of invertebrates including many pest insects, acorns (oak seeds, which it buries for use during winter),[19] beech and other seeds, fruits such as blackberries and rowan berries, young birds and eggs, bats, and small rodents. Like most species, the jay's diet changes with the seasons but is noteworthy for its prolific caching of food—especially oak acorns and beechnuts—for winter and spring. While caching occurs throughout the year, it is most intense in the autumn.[20]
In order to keep its plumage free from parasites, it lies on top of anthills with spread wings and lets its feathers be sprayed with formic acid.
Similar to other corvids, Eurasian jays have been reported to plan for future needs.[21] Male Eurasian jays also take into account the desires of their partner when sharing food with her as a courtship ritual[22] and when protecting food items from thieving conspecifics.[23]
The Eurasian jay (Garrulus glandarius) is a species of passerine bird in the crow family Corvidae. It has pinkish brown plumage with a black stripe on each side of a whitish throat, a bright blue panel on the upper wing and a black tail. The Eurasian jay is a woodland bird that occurs over a vast region from western Europe and north-west Africa to the Indian subcontinent and further to the eastern seaboard of Asia and down into south-east Asia. Across this vast range, several distinct racial forms have evolved which look different from each other, especially when comparing forms at the extremes of its range.
The bird is called jay, without any epithets, by English speakers in Great Britain and Ireland.
