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Pinyon Jay - Gymnorhinus cyanocephalus
Topic Started: Apr 16 2018, 04:16 PM (28 Views)
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Pinyon Jay - Gymnorhinus cyanocephalus

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Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Corvidae
Genus: Gymnorhinus Wied-Neuwied, 1841
Species: Gymnorhinus cyanocephalus Wied-Neuwied, 1841

The pinyon jay (Gymnorhinus cyanocephalus), historically known as the blue crow or Maximilian's jay, is a jay between the North American Blue Bay and the Eurasian Jay in size. It is the only member of the genus Gymnorhinus, (monotypic). Its overall proportions are very nutcracker-like and indeed this can be seen as convergent evolution as both birds fill similar ecological niches. The pinyon jay is a bluish-grey coloured bird with deeper head colouring and whitish throat with black bill, legs and feet.

This species occurs in western North America from central Oregon to northern Baja California and east as far as western Oklahoma though it wanders further afield out of the breeding season. It lives in foothills where the pinyon pines Pinus edulis and Pinus monophylla occur.

This species is highly social, often forming very large flocks of 250 or more birds, and several birds always seem to act as sentries for the flock, watching out for predators while their companions are feeding. The seed of the pinyon pine is the staple food but they supplement their diet with fruits and berries. Insects of many types are also eaten and sometimes caught with its feet.

The nest is always part of a colony but there is never more than one nest in a tree. Sometimes the colony can cover quite extensive areas with a single nest in each tree (usually juniper, live oak or pine). There are usually 3–4 eggs laid, quite early in the season. Incubation is usually 16 days. The male bird normally brings food near to the nest, and the female flies to him to receive it and take back to the nest to feed the chicks that fledge around 3 weeks later. Young are normally fed only by their parents, but once they reach near-fledging size they can sometimes receive a meal from any passing member of the colony, which can continue for some time after leaving the nest.

The pinyon jay was first collected, recorded and described as a species from a specimen shot along the Maria River in Northern Montana during the Prince Maximilian of Wied-Neuwied, Expedition to the Interior of North America in 1833.

The voice is described as a rhythmic krawk-kraw-krawk repeated two or three times.

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A member of the crow family, the pinyon jay is a highly social bird with a truly remarkable memory. Although the body and head are uniform in colour, the pinyon jay can appear to be a variety of blue shades due to the way light is reflected from its feathers. The eyes are dark brown, the legs and feet are black, and the tail is relatively short. The adult male and female are generally similar in appearance, although the male has a darker crown and longer bill, while the juveniles are a dull, grey colour. The genus name of the pinyon jay, Gymnorhinus, means “naked nostrils”, a reference to the fact that, unlike most other corvids, the nostrils of its bill are not covered by feathers. Bill shape is long and pointed, but varies according to geographical region, with birds found in the northern part of its range having shorter and thinner bills than those in the south-western regions. The pinyon jay makes a variety of noises, but its typical call is a high, nasal ‘caw’ .

Length: 26 – 29 cm Wingspan: 46 cm Weight 90 – 120 g

The pinyon jay’s common name derives from its close association with the pinyon pine, a collective name for a number of pine species bearing cones that produce edible seeds. In late August, when the pinyon seeds begin to ripen, the jays start foraging, skilfully extracting the seeds using their long, pointed beaks. Having bare nostrils allows the jays to probe deep into the pine cone using the entire length of their bill, avoiding the problem of feathers becoming fouled by the sticky pine-resin exuded by the cone. Once the cones fully mature and the seeds become exposed, the pinyon jays commence their amazing, food-caching behaviour. After evaluating whether the seeds are good, they break the seed coat open by pounding it with their bill and then swallow the kernel. Storing about four to five of these seeds in their expandable oesophagus, the jays then fly to a communal cache site, usually between one and five kilometres away from the main colony, where they bury the seeds in loose soil. Studies of pinyon jays in New Mexico found that a group of 250 birds managed to cache an incredible four and a half million seeds in one season. Using their phenomenal spatial memories, the birds are able to find many of these subterranean seed stores again, even under a covering of snow, which supply them with the nutrition and energy to be able to start their breeding season in the winter.

The pinyon jay is normally found in large, loose communal flocks of around 250 birds, with a distinct social hierarchy, and form extensive nesting colonies during the breeding season. Breeding pairs are established following courtship around November and generally remain together for life. Both sexes in the pair work to create a fairly bulky, well-insulated nest from twigs, shredded grass and other available materials. Three to four eggs are laid and incubated by the female, while the male joins a feeding flock, returning regularly to supply the female with food. After about 16 days the eggs hatch, and for the first ten days the nestlings are brooded by the female, until capable of maintaining their body temperature. After this time, the young gather into communal crèches of hundreds of individuals, where they continue to be fed by both parent birds. Such behaviour may serve as an anti-predator mechanism, since it allows for continual guarding of the nest by adults, while the others forage. The pinyon jay is relatively long-lived with adults reaching up to 16 years in the wild.

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The pinyon jay is widely distributed throughout the foothills and mountainous regions of the western and south-western regions of the USA. At its northern end, the pinyon jay’s range runs from central Oregon, east to western South Dakota, extending southwards, on the western side, all the way to southern California and Arizona and, on the eastern side, through Wyoming and Colorado down to New Mexico. In years when food is scarce, large flocks will travel long distances, and have been found as far as western Texas, Mexico and even British Columbia.

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The pinyon jay occupies forest composed predominantly of pinyon pines and junipers, located in the region between lowland desert scrub and pine forests of the upper mountain slopes. This species can also be found occupying other habitats such as sagebrush, scrub oak woodland and higher-altitude ponderosa pine forests.

Classified as Vulnerable (VU) on the IUCN Red List.

IUCN Red List species status – Vulnerable

The key threat to the pinyon jay is the loss of pinyon-juniper forest, with which its life-history is so intrinsically linked. In the past, the main source of this habitat loss was through the clearance of the forest for firewood, lumber and, in particular, to convert the land into pasture for grazing livestock. Today, clearance for pasture persists in many regions, and is compounded by widespread urban expansion.

Along with deliberate forest clearance, forest fires are also a threat to the pinyon jay’s habitat. A long-standing policy to put out all forest fires as quickly as possible has led to large amounts of vegetation accumulating because the smaller, natural wildfires that would have kept this growth under control were prevented. In the late 1990s, this accumulated vegetation resulted in massive, uncontrolled wildfires consuming vast areas of forest. To stop this reoccurring, current fire prevention policies involve widespread thinning of pinyon-juniper forest, which reduces wild fires, but removes sources of food and nesting sites for the pinyon jay. In addition to these factors, large areas of pinyon pine have, as a result of drought, suffered from infestation by the pinyon engraver beetle, which in some localities has caused up to 90 percent of the trees to die.

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Although there are no current land management practices in place to protect the pinyon jay’s habitat, it is on the watch lists of the conservation organisations The National Audubon Society and Partners in Flight. The Colorado branch of Partners in Flight has recommended that the pinyon-juniper habitat be managed so that during forest thinning, the older, cone-bearing pinyon pines are left and the younger trees selectively removed so that food sources for the pinyon jay remain available. There is also a need to protect this species’ nesting areas from urban development, discouraging the building of roads nearby, which results in nest abandonment due to disturbance. While estimates of the pinyon jay’s population totalled a substantial 4,100,000 birds in 2003, this population is believed to be rapidly declining by an average of almost four percent per year. It is, therefore, critical that land management practices are introduced that will help to protect this remarkable bird.

Mesotocin found to be the driver behind prosocial behavior in pinyon jays

April 11, 2018 by Bob Yirka, Phys.org report

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Pinyon jay in flight. Credit: Pinyon Jay/CC BY 2.0

A team of researchers with the University of Nebraska has found that the hormone mesotocin plays a major role in pinyon jay prosociality. In their paper published in the journal Biology Letters, the group describes experiments they conducted with the birds and what they found.

Most people have heard of the hormone oxytocin, which has been described as the "love hormone," because past research associates it with the symptoms people report when they fall in love. It has also been found to be involved in sexual responses, including orgasms. Less well known is the part it plays in causing uterine contractions during childbirth and serving as a signal for new mothers to release breast milk. The researchers wondered if the role it plays in human social bonding might hold for other animals. In this case, they studied pinyon jays—a species known to be very social. The slightly bluish birds are related to crows and have been observed to share food, a very clear sign of prosocial behavior. Prior research had shown that many birds (including pinyon jays) produce mesotocin, a hormone that is essentially the same as oxytocin. The researchers wondered if it was responsible for the social behavior exhibited by the birds. To find out, they set up experiments with the birds in cages.

Some of the birds received doses of mesotocin and some did not. All were given food while their neighbors were not. The researchers then observed sharing behavior. They report that those birds given doses of the hormone (via intranasal droplets) were more generous than those that did not receive the hormone. This, the team suggests, indicates that the hormone does, indeed, play a role in the prosocial behavior exhibited by the birds.

The researchers next plan to investigate the reason behind the natural mesotocin boost in the birds and their prosocial behavior to find out what benefit the birds get from it—they suspect it serves to bond the birds, increasing social connections.


Journal Reference:
J. F. Duque et al. Mesotocin influences pinyon jay prosociality, Biology Letters (2018). DOI: 10.1098/rsbl.2018.0105

Many species exhibit prosocial behaviour, in which one individual's actions benefit another individual, often without an immediate benefit to itself. The neuropeptide oxytocin is an important hormonal mechanism influencing prosociality in mammals, but it is unclear whether the avian homologue mesotocin plays a similar functional role in birds. Here, we experimentally tested prosociality in pinyon jays (Gymnorhinus cyanocephalus), a highly social corvid species that spontaneously shares food with others. First, we measured prosocial preferences in a prosocial choice task with two different pay-off distributions: Prosocial trials delivered food to both the subject and either an empty cage or a partner bird, whereas Altruism trials delivered food only to an empty cage or a partner bird (none to subject). In a second experiment, we examined whether administering mesotocin influenced prosocial preferences. Compared to choices in a control condition, we show that subjects voluntarily delivered food rewards to partners, but only when also receiving food for themselves (Prosocial trials), and administration of high levels of mesotocin increased these behaviours. Thus, in birds, mesotocin seems to play a similar functional role in facilitating prosocial behaviours as oxytocin does in mammals, suggesting an evolutionarily conserved hormonal mechanism for prosociality.

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