Clark’s Nutcracker (Nucifraga columbiana)

Copyright © 2012 Corvid Corner. All rights reserved.
  A member of the corvidae family, Clark's Nutcracker is a lovely bird slightly smaller than the Spotted Nutcracker. It eats mostly seeds from the pine tree. And it has a pouch in the floor of it's mouth in front of its tongue (a sublingual pouch -- See below) which can hold up to 95 pinyon pine seeds (depending on the seed this number can vary from 50 to 150).
Sublingual pouch
  To put this in perspective, 95 Pinyon pine seeds weigh up to 13% of the total weight of the bird!! How neat is that? They have a pouch in their mouth where they can store and carry almost 15% of their own weight! The Clark's Nutcracker also has a "long, heavy, sharp bill... used for hacking open green, closed cones, many of which are covered with pitch. Nutcrackers can open the green cones of most of the pines. The bill is also used to thrust seeds into the substrate with strong japes of the head and neck. As their name implies, nutcrackers can open thick-hulled pine seeds by crushing them in their bills."1 Most jays must wait for the cones to open naturally, but the Clark's nutcracker (and the pinyon jay) are able to open the tightly closed green cones. Lucky for them, they don't have to wait for a good seed.
In a year with a heavy cone crop a single nutcracker can cache between 22,000 and 33,000 seeds in over 7,000 individual cache sites (Vander Wall & Balda, 1977). Birds may place between one and 14 seeds per cache. Birds continue caching until the crop is depleted or snow covers the caching areas (Vander Wall & Balda, 1977). Possibly, birds curtail caching after snow remains on the ground because to cache in these conditions would reveal cache location by their foot prints left in the snow.2
Copyright © 2012 Corvid Corner. All rights reserved.
  The Clark's Nutcracker possesses a number of abilities and physical attributes that help them thrive. They have excellent spatial memory abilities which allow these clever corvids to "learn and generalize geometric rules about the placement of landmarks." They use the landscape and even the sun (as a compass) to help them cache seeds. Their strong beaks help them crack open seeds, hence their name. Their long, pointed wings help them for strong flight to great distances. They can cache up to 22 km (a little over 13 and a half miles!). The Clark's Nutcracker "can carry seeds 1,900 m up the side of the Peaks."3 They use 'bill-clicking' which is the rapid opening and closing of the mandibles, to help determine if the seed is full as well as determine the thickness of the seed coat which saves time when seeds are abundant in the spring and summer.
Copyright © 2012 Corvid Corner. All rights reserved.
  So intelligent are they, the Clark's Nutcracker can discern between pinyon pine seeds that have nut meet and those that are empty just by observing the color of the shell. WOW! Corvids are so intelligent!   Sources:
  1. http://www.pigeon.psy.tufts.edu/asc/Balda/ []
  2. Balda, Russell P. and Kamil, Alan C. Linking Life Zones, Life History Traits, Ecology, and Spatial Cognition in Four Allopatric Southwestern Seed Caching Corvids []
  3. Balda and Kamil []

Legendary Ravens

Ravens are majestic birds and thus inspire great and terrible legends, myths, folklore and superstitions. It is no wonder with their capacity for intelligence. Ravens have exactly the same brain-to-body ratio as dolphins and almost the same as humans. "If crows were human, their average IQ would be 135 (the average for humans is 100!)"1 With such a proclivity for intelligence it is no surprise many cultures have created elaborate myths, stories, legends, and superstitions about the raven. The Raven in many mythological traditions was often reported to be the creator of the world. The raven is tied to the flood many thought once overtook the earth as well.
The Koyukon people, hunters living on the Koyukuk River in Alaska, believed that the great raven Dot-son-paa made the world, and that when the great flood came he placed two of every animal, bird, and insect upon a raft so that they would survive. To this day, the Koyukon people treat all wildlife with the courtesy that they accord to human beings, but make a special point of showing particular respect to the raven.
For the neighbors of the Koyukon people, the Tlingit Tribe, the raven is also important as is depicted in their beliefs.2
The [Tlingit Tribe] believed that the raven was the mythical ancestor of their race and performaned many deeds at the beginning of the world. Among these was deciding what particular task each bird should perform, where they should live and what colour their plumage was to be. One story relates that the raven decreed that the (American) Robin should give pleasure to man through its beauty, and the hummingbird through its song; another tells how he commanded all birds to dress differently so that they would be able to recognize each other---the blue jay, for example, was told to pile its hair high and tie it with a string. As for himself, the magical raven could transform himself into whatever shape he chose and could remove his feathers like a coat. As a spirit of creation he had no beginning and no end.
Ravens were worshipped and revered by the Vikings. The raven was the symbol of one of their Gods, Odin and it was said that the shields and banners of his men donned raven images. Such was the case with the Landeyda or Land ravager war banner which bore the emblem of the raven and was reputed to have been woven in one day by the granddaughter of Sigurd, a hero of Norse mythology who had the power to understand the language of the birds.((Tate, Peter (2008). Flights of Fancy: Birds in Myth, Legend and Superstition. New York, NY: Delacorte Press.)) Odin owned two ravens named Hugin and Munin. Hugin represent thought and Munin, memory.  You can read more about them in this post. This myth is also belived in Ireland where the phrase 'raven's knowledge' is still used to refer to anyone who appears to see and know all.3 The Vikings so admired the ravens powers of observation they even sang about them in this song:
How is it with you ravens, whence are you come With gory beak at the dawning of the day? You lodged last night I ween [suppose] Where you knew the corpses were lying.
Many references in literature can be found that indicate the negative superstitions believed to be true about ravens such as found in Christopher Marlowe's The Jew of Malta,
...the sad presaging raven, that tolls The sick man's passport in her hollow beak, And in the shadow of the silent night Doth shake contagion from her sable wings.
Or in Shakespeare's Macbeth when Lady Macbeth welcomes the man she wishes dead, Duncan with these words:
The raven himself is hoarse That croaks the fatal entrance of Duncan Under my battlements
This is definitely not all the legends, myths, folklores, superstitions or beliefs about the raven. We will write more in the future.
  1. Tate, Peter (2008). Flights of Fancy: Birds in Myth, Legend and Superstition. New York, NY: Delacorte Press. []
  2. Tate, Peter (2008). Flights of Fancy: Birds in Myth, Legend and Superstition. New York, NY: Delacorte Press. []
  3. Tate, Peter (2008). Flights of Fancy: Birds in Myth, Legend and Superstition. New York, NY: Delacorte Press. []

Ravens in Norse Mythology

Ravens have often been featured in myths and legends, stories, poems, and religious beliefs. For example, the Norse God Odin was said to have a pair of ravens, Huginn (thought) and Muninn (memory). They were said to travel the world from early morning to late into the evening each and every day in search of information and news from every corner of this planet to bring back to Odin. Upon their return every evening they would whisper what they learned into his ear as they perched upon his shoulder. It is the story of Huginn and Muninn from which Odin's nickname, the raven-god was born. In Grímnismál the ravens are mentioned:
The whole world wide, every day,
fly Huginn and Muninn;
I worry lest Huginn should fall in flight,
yet more I fear for Muninn.
Another translation reads, Every morning the two ravens Huginn and Muninn, are loosed and fly over Midgard; I always fear that Thought may not wing his way home, but my fear for Memory is greater.1
  1. http://en.wikipedia.org/wiki/Hugin_and_Munin []

Corvid cognition

Copyright © 2005 Elsevier Ltd All rights reserved. Nicola Clayton and Nathan Emery
aDepartment of Experimental Psychology and Sub-department of Animal Behaviour, University of Cambridge, Cambridge, UK
Available online 7 February 2005.

Article Outline

What is a corvid? There are just over 120 species of corvids, a family of songbirds that includes the crows, ravens, rooks and jackdaws, as well as the more colourful jays, magpies and nutcrackers. Although belonging to the same order as nightingales and other birds with melodious songs (Oscines), corvids tend to be identified by their raucous calls. Little is known about corvid songs, perhaps because they are surprisingly quiet. Corvids can be found throughout the globe, except for the southern most tip of South America and the polar ice caps. In Britain, many of the common species, such as magpies and crows, steal other birds' eggs and raid agricultural crops. They are therefore treated with disdain by many birdwatchers and farmers. Why study intelligence in crows? Corvids have not always had such a bad press. Native Americans believed that a raven had created the earth; the Norse god, Odin, consulted two ravens Hugin (Thought) and Munin (Memory) for their wisdom; and Aesop cast corvids as the smart protagonists in many of his fables. Along with their reputation in folklore as the wisest of animals, corvids have the largest brains for their body size of any bird. Perhaps most surprisingly, the crow brain is the same relative size as the chimpanzee brain. Other aspects of corvid biology also give us clues to their intelligence. In the wild, young corvids have an extensive developmental period before they become independent from their parents. This allows them more opportunities to learn the essential skills for later life. Many corvids also live in complex social groups. For example, in the cooperatively breeding Florida scrub-jay, several closely related family members share the responsibility of raising the young with the parents. Furthermore, rooks congregate in large colonies, where juveniles associate with many non-relatives as well as kin. In both cases, this long developmental period provides increased opportunities for learning from many different group members. Perhaps it is not surprising then that many corvids are also renowned for their innovative feeding skills. For example, Japanese crows in Sendai City have learned to crack nuts safely by dropping them onto pedestrian crossings and waiting until the traffic lights turn red before retrieving the nut's contents. Rooks at a motorway service station in England have discovered a novel method for gaining access to food thrown in rubbish bins. Two birds cooperate in pulling up the bin liner and then either feeding from the raised food or tossing the contents onto the ground where the waiting crowd of colony mates reap the rewards. As the crow flies… Most of the corvids that have been studied in detail hide food for the future in times of food abundance and then rely on memory to recover the food caches at a later date when food is scarce. For example, the Clark's nutcracker is estimated to hide over 30,000 pinyon seeds in many different places during the autumn in preparation for the harsh months ahead. Laboratory experiments have shown that they have highly accurate spatial memories, which enable them to recover these caches up to 9 months later. This is no mean feat when there are so many caches to keep track of, scattered throughout the territory, and when many aspects of the landscape change so dramatically across seasons. It has been suggested that Clark's nutcrackers rely on remembering the location of large vertical landmarks such as trees and rocks in the environment, because these landmarks are unlikely to be blown away or buried under the snow. What do scrub-jays recall about past caching events? Although western scrub-jays do not hide as many seed caches as the nutcrackers, they are known to cache a variety of perishable foods, such as insects and fruit, as well as non-perishable nuts and seeds. In the laboratory, these birds demonstrate remarkable memories for what they have cached on a given day, and how long ago, as well as where they hid the various food items during that particular caching episode. This ability to remember the ‘what, where and when’ of specific past events is thought to be akin to human episodic memory, because it involves recalling a particular episode that has happened in the past. Until recently, this ability was thought to be unique to humans. Avian espionage… Food-caching is a risky strategy, however, because the caches can be stolen by other birds. In addition to hiding their own food caches, corvids also play the role of thief: they watch and remember where other birds have hidden their caches and use this information to steal those caches when the owner has left the scene. When playing the role of thief, speed is of the essence and may make the difference between a successful raid and vicious attack by the owner of the food-cache. Not surprisingly, corvids also employ a number of counter strategies to reduce the risk that their own caches will be stolen by another bird. For example, they attempt to cache out of sight from potential thieves, or wait until the raider is distracted before hiding their caches, and if that is not possible, they hide caches in places that are difficult for the thief to see. When there is little option but to cache when others are around, then the birds will return to the caches once the others have left, and quickly re-hide any remaining caches in new places unbeknown to the potential raider. Laboratory experiments have established that western scrub-jays use all these techniques to protect their caches from potential thieves, and only do so if another bird is present at the time of caching. Furthermore, they only move their caches to new hiding places if they have been thieves themselves in the past. Naı̈ve jays, even ones who have watched other birds caching but have never had the opportunity to raid those caches, do not do so. This suggests that experienced birds relate information about their previous experience of being a thief to the possibility of future theft by another bird, and adjust their caching behaviour accordingly. Using your own experience to predict another individual's future behaviour in relation to your own – ‘putting yourself in someone else's shoes' – is thought to be one of the hallmarks of Theory of Mind, another ability that was thought to be uniquely human. Cultural tool use in crows? New Caledonian crows are extraordinarily skilled at making and using tools. In the wild, they make two types of tool. The hooked tools consist of twigs that are trimmed and sculpted into a functional hook, which the crows use to poke insect larvae out of tree holes. The crows also manufacture stepped-cut Pandanus leaves, which they use in different ways for different jobs: they make rapid back and forth movements for prey under soil, yet slow deliberate movements if the prey is in a hole. These tools are consistently made to a standardized pattern and carried around on foraging expeditions. The only other animals that display this diversity and flexibility in tool use and manufacture are the great apes. Thus, chimpanzees have been observed to manufacture a range of different tools that are used for specific purposes, and different geographical populations of chimpanzees use different tools for different uses, suggesting that there may be cultural variations in tool use. Observations of the crows' tool use in the wild also suggest similar levels of cultural complexity. For example, there is potential cumulative evolution in the complexity of stepped tools (increasing the number of steps required to make a more complex tool), analogous to minor technological innovations in humans. Crows from different geographical areas have different designs of tool, suggesting that crows may also show cultural variations in tool use.
Laboratory experiments confirm the sophisticated intellectual capabilities of these crows. One tool-using crow, called Betty, can manipulate novel man-made objects to solve a problem, such as reaching food in a bucket only accessible by using a hook to pull the bucket up. When the bent wire was stolen by another bird, Betty found a piece of straight wire that was lying on the floor, bent this wire into a hook and used it to lift up the bucket and reach the food! Betty proceeded to do this consistently. Furthermore, when given a tool box containing a variety of different tools to reach normally inaccessible food, she was able to select one of the correct length and width. So evidence of tool use and manufacture suggests that these crows can sometimes combine past experiences to produce novel solutions to problems.Feathered apes? Corvids are large-brained, social birds. They have an extensive developmental period in which they are dependent on their parents, and so have a long time-window in which to learn many different things from their parents and peers. They show a great propensity to find innovative solutions to novel problems, from the manufacture of tools to the protection of food from competitors. Furthermore, they appear to be particularly adept at predicting the future behaviour of conspecifics. These features are things they share in common with the apes. The common ancestor of mammals and birds lived over 280 million years ago, so it is hardly surprising that they have very different brains. It follows that intelligence in corvids and apes must have arisen independently in two groups with very different brains. Interestingly, the thinking part of the brain is correlated with propensity to innovate in both birds and primates, with the corvids and apes as the ‘star inventors’. So when it comes to intelligence, corvids are feathered apes.

Further reading

Where can I find out more?

R.P. Balda, A.C. Kamil and P.A. Bednekoff, Predicting cognitive capacities from natural histories: examples from four corvid species, Curr. Ornithol. 13 (1996), pp. 33–66.

N.S. Clayton, T.J. Bussey and A. Dickinson, Can animals recall the past and plan for the future?, Nat. Rev. Neurosci. 4 (2003), pp. 685–691.

N.J. Emery and N.S. Clayton, The mentality of crows: Convergent evolution of intelligence in corvids and apes, Science 306 (2004), pp. 1903–1907.

Heinrich, B. (1999). The Mind of the Raven (Harper Collins).

G.R. Hunt and R.D. Gray, Diversification and cumulative evolution in New Caledonian crow tool manufacture, Proc. Roy. Soc. Lond. B. 270 (2003), pp. 867–874.

L. Lefebvre, S.M. Reader and D. Sol, Brains, innovations and evolution in birds and primates, Brain Behav. Evol. 63 (2004), pp. 233–246.

A.A.S. Weir, J. Chappell and A. Kacelnik, Shaping of hooks in New Caledonian crows, Science 297 (2002), p. 981


“Reprinted from Current Biology, Vol 15 / Issue No 3, Author(s) Nicola Clayton and Nathan Emery, Corvid cognition, Page No. 1, Copyright 8 February 2005, with permission from Elsevier.”
Direct Link to Article click here.

Crows Can Recognize The Calls Of Relatives

ScienceDaily (2007-03-20) -- Most of us would know our mother's voice on the phone from the first syllable uttered. A recent Cornell study suggests that crows also can recognize the voices of their relatives. Read the rest of the article here. This woman did a lot of in-depth research for this study. I am not surprised in the least to find out that crows recognize each others voices. We do. We are so egocentric sometimes!