Garrulus glandarius

Geographic Range

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 palearctic
  • native native

Habitat

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 temperate
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• scrub forest scrub forest

• Other Habitat Features
• suburban suburban
• agricultural agricultural
• riparian riparian

Physical Description

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

Reproduction

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 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.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous 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 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

Lifespan/Longevity

The oldest bird recorded in Britain was 16 years, 9 months of age.

Behavior

Eurasian jays are primarily arboreal but also forage on the ground. They are sedentary unless acorn crops fail, when they must migrate to other areas for food. Like other corvids , Eurasian jays have complex social behavior. They exhibit play behaviors, mostly chases that resemble their fleeing response to hawks ( Accipitridae ).

Dominance between jays is not always determined by strength, and hierarchies are not stable. Males are usually dominant over females, but in certain circumstances, like when a male is moulting or his mate is persistent, the female may be dominant. Dominance struggles may be settled with actual tussles, with birds grappling and pulling out each other’s feathers, but they may also be settled without fighting. In dominance contests that don't involve fighting, the outcome of the contest seems to rely on psychological factors which are not fully understood. Overall, jays are not particularly pugnacious toward conspecifics.

Eurasian jays perform "anting" when ants of the appropriate species, like wood ants ( Formica rufa ), are available. A jay will jump down onto the mass of ants and rub its body, tail, and wings against the ground so that the ants are soon crawling all over the bird’s body. The jay will shudder and sit upright, often with its tail under its body and between its legs. They probably do not eat the ants which crawl on them. They prefer to ant no more frequently than every other day, possibly two days in a row on occasion. They will bathe in water several times a day.

• Key Behaviors
• arboreal arboreal
• flies
• diurnal diurnal
• motile motile
• sedentary sedentary
• social social
• dominance hierarchies dominance hierarchies

Home Range

Home range sizes in Eurasian jays vary with season and habitat type. Home ranges in winter and spring were smaller than home ranges in summer and fall. Larger home ranges are found in areas with higher habitat heterogeneity. Home ranges overlap substantially among individuals.

Communication and Perception

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 visual
• tactile tactile
• acoustic acoustic

• Other Communication Modes
• mimicry mimicry

• Perception Channels
• visual visual
• ultraviolet
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

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.

• Primary Diet
• herbivore herbivore
  • granivore granivore
• omnivore omnivore

• Animal Foods
• birds
• mammals
• eggs
• carrion carrion
• insects
• terrestrial non-insect arthropods
• terrestrial worms

• Plant Foods
• seeds, grains, and nuts
• fruit

• Foraging Behavior
• stores or caches food stores or caches food

Predation

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.

• Anti-predator Adaptations
• mimic

Ecosystem Roles

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 biodegradation

Economic Importance for Humans: Positive

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.

Economic Importance for Humans: Negative

There are no known adverse effects of Eurasian jays on humans.

Conservation Status

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."

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Aqua Nara Dakota (author), Special Projects.

References

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Clayton, N., D. Griffiths, A. Bennett. 1994. Storage of stones by Jays ( Garrulus glandarius ). IBIS , 136: 331-334.

Clayton, N., R. Mellor, A. Jackson. 1996. Seasonal patterns of food storing in the Jay Garrulus glandarius . IBIS , 138: 250-255.

Davies, N., S. Butchart, T. Burke, N. Chaline, I. Stewart. 2003. Reed warblers guard against cuckoos and cuckoldry. Animal Behavior , 65: 285-295.

Goodwin, D. 1956. Further observations on the behavior of the jay Garrulus glandarius . IBIS , 98: 186-219.

Goodwin, D. 1951. Some aspects of the behavior of the jay Garrulus glandarius . IBIS , 93: 414-442, 602-625.

Hougner, C., J. Golding, T. Soderqvist. 2006. Economic valuation of a seed dispersal service in the Stockholm National Urban Park, Sweden. Ecological Economics , 59: 364-374.

McNab, B. 2009. Ecological factors affect the level and scaling of avian BMR. Comparative Biochemistry and Physiology, Part A , 152: 22-45.

Mosandl, R., A. Kleinert. 1998. Development of oaks ( Quercus petraea (Matt.) Liebl.) emerged from bird-dispersed seeds under old-growth pine ( Pinus silvetris L.) stands. Forest Ecology and Management , 106: 35-44.

Palma, L., P. Beja, M. Pais, L. Cancela da Fonseca. 2006. Why do raptors take domestic prey? The case of Bonelli's eagles and pigeons. Journal of Applied Ecology , 43: 1075-1086.

Pons, J., J. Pausas. 2008. Modelling jay ( Garrulus glandarius ) abundance and distribution for oak regeneration assessment in Mediterranean landscapes. Forest Ecology and Management , 256: 578-584.

Pons, J., J. Pausas. 2007. Not only size matters: Acorn selection by the European jay ( Garrulus glandarius ). Acta Oecologica , 31: 353-360.

Randler, C. 2006. Red Squirrels ( Sciurus vulgaris ) Respond to Alarm Calls of Eurasian Jays ( Garrulus glandarius ). Ethology , 112: 411-416.

Robinson, R. 2005. "BirdFacts: profiles of birds occurring in Britain & Ireland" (On-line). Jay Garrulus glandarius [Linnaeus, 1758]. Accessed January 09, 2009 at http://blx1.bto.org/birdfacts/results/bob15390.htm .

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