Jackdaw - Corvus monedula

[OldGreenVulture]

Jackdaw.



The smallest of the crow family in the UK, the Jackdaw is easy identify with its shiny-black and silver-grey plumage. The pale grey eye is also diagnostic. It is a sociable bird, and not just with its own species but will also flock with Rooks and Starlings to form large feeding groups.

Jackdaw nesting and breeding habits
Unusually for a corvid, the Jackdaw's nest is in a hole in a tree, suitable opening in a building's wall, or large crevice in a cliff. Large nest boxes put up for other species, such as owls, will also be readily taken, plus, and notoriously, chimney pots on houses will also be used. Within the hole or other opening, the nest is constructed of twigs and then lined with wool and other soft material. The size of the nest varies considerably and can end up as an enormous structure, or just be a relatively small pile of twigs, and then lined. Incubation is by the female alone, though both parents feed the young. There is one brood per year, with the clutch size usually being between four and six eggs.

Jackdaw diet and food
The diet is highly varied, with this being a factor in the bird’s success and relatively high population numbers. Food includes invertebrates and their larvae, seeds, nuts, fruit and carrion. Some young nestlings and fledgling of songbirds are also taken, but this is not a major food source. Although not generally a particularly welcome visitor to feeding stations, Jackdaws will eat almost any wild bird food available, and, despite their size, are able to cling onto peanut and suet ball feeders.

Jackdaw history and population trends
The population trend is very much on the up and has been since the 1970s. Although there is no firm evidence as to why this is, it is probably due to increased breeding success as a result of greater food availability – notably in gardens.

Behaviour traits of Jackdaws
The Jackdaw is a sociable bird and will not only form flocks of its own species outside of the breeding season, but also with Rooks, Starlings and the odd Carrion Crow. Like all corvids, Jackdaws are highly intelligent and will problem solve to get to food. They are also very loyal to their partner and will often pair for life, with an interesting and related behaviour being that the pair will often stay together – even when flying – in large winter feeding flocks.

Distribution Map and Info
Throughout the UK, though largely absent from the central, west and NW Highlands of Scotland, and the Western Isles.

www.vinehousefarm.co.uk/birds/jackdaw/

[Eaglehawk]

Birds Give Evil Eye to Ward Off Intruders

By Tanya Lewis, Staff Writer | February 05, 2014 09:43am ET


Jackdaws may be the first animal besides primates found to use their eyes to communicate.

Primates aren't the only animals that communicate with their eyes — some birds do it too, a new study finds.

Much is known about how humans use their eyes to convey sentiments, but very little is known about how birds use this mode of communication. New research suggests jackdaws — a bird in the crow family found in Europe, western Asia and North Africa — use their peepers to deter competitors from approaching their nests.

This is the first time scientists have shown that animals besides primates use their eyes to communicate.

Jackdaws are perching birds, or passerines. About 10 percent of passerines have colored irises, the circular structures in the eyes that control how much light gets in.

Unlike their dark-eyed relatives, rooks and crows, "jackdaw eyes are almost white, and their striking pale irises are very conspicuous against their dark feathers," Gabrielle Davidson, lead author of the study, detailed Tuesday (Feb. 4) in the journal Biology Letters, said in a statement.

But do jackdaws use their bright eyes for communication? asked Davidson, an animal behavior researcher at the University of Cambridge in the United Kingdom.

In the study, Davidson installed one of four different pictures in natural jackdaw nest boxes near Cambridge, England, before the spring breeding season. One was solid black, one had just a pair of jackdaw eyes, one had a jackdaw's face with jackdaw eyes and one had a jackdaw's face with black rook eyes. Then, she filmed the birds to see how they behaved in response to each image.

The videos revealed the nest box containing the jackdaw with bright eyes was the most likely of all the images to deter other birds from approaching the nest. The findings suggest that jackdaws use their eyes to send a warning message to other birds.

Jackdaws nest in hollow tree cavities, which are in limited supply. The birds also nest close together and fight over the best real estate. The trouble often starts when jackdaws approach nests belonging to other birds.

The observation that jackdaws use their eyes to communicate raises the question of "whether this is unique to jackdaws, or if other cavity nesting birds also use their eyes in a similar way," Davidson said.

www.livescience.com/43104-rds-give-evil-eye-to-intruders.html

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Salient eyes deter conspecific nest intruders in wild jackdaws (Corvus monedula)

Gabrielle L. Davidson, Nicola S. Clayton1 and Alex Thornton
Published 5 February 2014 doi: 10.1098/rsbl.2013.1077
Biol. Lett. February 2014 vol. 10 no. 2 20131077

Abstract
Animals often respond fearfully when encountering eyes or eye-like shapes. Although gaze aversion has been documented in mammals when avoiding group-member conflict, the importance of eye coloration during interactions between conspecifics has yet to be examined in non-primate species. Jackdaws (Corvus monedula) have near-white irides, which are conspicuous against their dark feathers and visible when seen from outside the cavities where they nest. Because jackdaws compete for nest sites, their conspicuous eyes may act as a warning signal to indicate that a nest is occupied and deter intrusions by conspecifics. We tested whether jackdaws’ pale irides serve as a deterrent to prospecting conspecifics by comparing prospectors’ behaviour towards nest-boxes displaying images with bright eyes (BEs) only, a jackdaw face with natural BEs, or a jackdaw face with dark eyes. The jackdaw face with BEs was most effective in deterring birds from making contact with nest-boxes, whereas both BE conditions reduced the amount of time jackdaws spent in proximity to the image. We suggest BEs in jackdaws may function to prevent conspecific competitors from approaching occupied nest sites.

rsbl.royalsocietypublishing.org/content/10/2/20131077 

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Jackdaws learn from each other about 'dangerous' humans

by University of Exeter


Jackdaw. Credit: Guill McIvor

Jackdaws can learn from each other to identify "dangerous" humans, new research shows.

The birds are known to recognise individual people, and respond differently to those they see as a threat.

In the new study, by the University of Exeter, a person unknown to the jackdaws approached their nest, and scientists played a recording of either a warning call or "contact calls" (suggesting no threat).

The next time the jackdaws saw this person, the birds that had heard the warning call reacted defensively by retuning more quickly to their nests.

"One of the big challenges for a lot of animals is how to live alongside humans," said lead author Victoria Lee, a Ph.D. researcher at the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall.

"People can provide some benefits, such as the food at bird feeders, but in some cases humans are also a threat.

"Being able to discriminate between dangerous and harmless people is likely to be beneficial, and in this case we see jackdaws can learn to identify dangerous people without having had a bad experience themselves."

The study was carried out at three sites in Cornwall, focussing on 34 jackdaw nest boxes.

The jackdaws that were played a warning call on seeing a new human returned to their nest boxes more than twice as quickly (53%) on average when seeing that human again, whereas birds that heard contact calls took longer to return to their nest (63% on average).

Though jackdaws returned to their nests more quickly after seeing a human associated with a warning call, the calls did not appear to influence how long birds took to enter their nest box or how long they spent inside.

phys.org/news/2019-09-jackdaws-dangerous-humans.html

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Journal Reference:
Victoria E. Lee, Noémie Régli, Guillam E. McIvor and Alex Thornton Social learning about dangerous people by wild jackdaws, Royal Society Open Science, rsos.royalsocietypublishing.or … /10.1098/rsos.191031

Abstract
For animals that live alongside humans, people can present both an opportunity and a threat. Previous studies have shown that several species can learn to discriminate between individual people and assess risk based on prior experience. To avoid potentially costly encounters, it may also pay individuals to learn about dangerous people based on information from others. Social learning about anthropogenic threats is likely to be beneficial in habitats dominated by human activity, but experimental evidence is limited. Here, we tested whether wild jackdaws (Corvus monedula) use social learning to recognize dangerous people. Using a within-subjects design, we presented breeding jackdaws with an unfamiliar person near their nest, combined with conspecific alarm calls. Subjects that heard alarm calls showed a heightened fear response in subsequent encounters with the person compared to a control group, reducing their latency to return to the nest. This study provides important evidence that animals use social learning to assess the level of risk posed by individual humans.

royalsocietypublishing.org/doi/10.1098/rsos.191031

[brobear]

Members of the corvus family are among the world's most intelligent animals. The top 5 ( in no particular order ) are the corvus birds, bears, elephants, cetaceans ( whales and dolphins ), and the great apes. Another very smart bird, the African Gray Parrot may be as smart as the corvus birds.

[OldGreenVulture]

Welcome to my forum, Brobear. Glad to see you are reading the profiles. Feel free to add any information as you please.

[Eaglehawk]

Jackdaw mobs flip from chaos to order as they grow

by University of Exeter


Chaotic mobs of jackdaws suddenly get organised once enough birds join in, new research shows. Credit: Alex Thornton

Chaotic mobs of jackdaws suddenly get organised once enough birds join in, new research shows.
The birds form mobs to drive away predators near their nests, and are initially disordered.
But the new study, by biologists at the University of Exeter, physicists at Stanford University and computer scientists from Simon Fraser University in Canada, shows a dramatic switch to "ordered motion" once the group reaches a certain density.
The study also reveals that jackdaws follow different rules when mobbing predators than when flying to winter roosts.
"Traditionally, it is thought that flocking—and other collective behaviour like swarms, fish schools and human crowds—occurs when each individual follows an identical set of rules to every other in the group," said Dr. Alex Thornton, of the Centre for Ecology and Conservation on Exeter's Penryn Campus in Cornwall.
"This study shows that these rules are actually flexible.
"When flying to their winter roosts, jackdaws follow what we call 'topological rules' - meaning that they respond to the movements of a fixed number of neighbours, and groups remain ordered regardless of how many birds are flying together.
"When mobbing a predator, however, the jackdaws instead use 'metric rules' where they respond to all the neighbours that are within a given distance. Here, we see order emerging from chaos.
"Jackdaws issue an alarm call to draw other birds to the mob, and at first these groups are completely disordered.
"Then, when the density of birds reaches a certain threshold, it suddenly flips into an ordered, cohesive state where the birds are aligned with their neighbours and move together in an organised way.
"This sudden transition from disorder to order is similar to the phase transitions we see in physics, like when water turns to ice."
This finding that rules of collective behaviour can change in different contexts could have implications for the design of autonomous vehicles, Dr. Thornton said.
"Swarms of unmanned aerial vehicles or drones have potential uses in many applications including ecological surveys, fire-fighting and search-and-rescue in remote regions," he said.


Chaotic mobs of jackdaws suddenly get organised once enough birds join in, new research shows. Credit: Alex Thornton

"By learning from the behaviour of jackdaws, we can begin to design drones that modify their swarming behaviour to maximise their efficiency in different contexts."
The study used high-speed cameras to film flocks of wild jackdaws at sites in Cornwall, UK, to create 3-D reconstructions of the movements of each bird in the flock.
The paper, published in Nature Communications, is entitled: "Behavioural plasticity and the transition to order in jackdaw flocks."

phys.org/news/2019-11-jackdaw-mobs-flip-chaos.html

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Journal Reference:
Ling, H., Mclvor, G.E., Westley, J. et al. Behavioural plasticity and the transition to order in jackdaw flocks. Nat Commun 10, 5174 (2019) doi:10.1038/s41467-019-13281-4
More information: Nature Communications (2019). DOI: 10.1038/s41467-019-13281-4

Abstract
Collective behaviour is typically thought to arise from individuals following fixed interaction rules. The possibility that interaction rules may change under different circumstances has thus only rarely been investigated. Here we show that local interactions in flocks of wild jackdaws (Corvus monedula) vary drastically in different contexts, leading to distinct group-level properties. Jackdaws interact with a fixed number of neighbours (topological interactions) when traveling to roosts, but coordinate with neighbours based on spatial distance (metric interactions) during collective anti-predator mobbing events. Consequently, mobbing flocks exhibit a dramatic transition from disordered aggregations to ordered motion as group density increases, unlike transit flocks where order is independent of density. The relationship between group density and group order during this transition agrees well with a generic self-propelled particle model. Our results demonstrate plasticity in local interaction rules and have implications for both natural and artificial collective systems.

www.nature.com/articles/s41467-019-13281-4#Abs1