Welcome back and Stamp Sunday

crow3 It's been awhile since we posted. Sorry! We haven't given up our love for crows, life just gets busy. We are back now and look forward to posting more regularly. We saw this beautiful crow by the waterfront. I wonder what he was thinking about...such intelligent birds. As it is a Sunday, we will throw in a corvid stamp -- and start a new tradition -- Stamp Sunday! Hope you enjoy!
Raven Stamp from Russia
Raven Stamp from Russia

Steller’s Jay at Crater Lake in Oregon

Copyright © 2012 Corvid Corner. All rights reserved.
  What a beautiful little bird! According to the Crater Lake Institute, four of the six birds mostly like to be seen at Crater Lake in Oregon are corvids: Ravens, Gray Jays, Stellers' Jays, and Clark's Nutcrackers (see yesterday's post about this clever little corvid!) Maybe we can nickname it Corvid Lake =). ((http://www.craterlakeinstitute.com/planning-visit/faqs/birds-crater-lake.htm))

The Revered, Reviled Crow Clan by Howard Youth

I read an excellent article about corvids from their habitat to myths and legends about them in the May/June 2001 issue of Zoogoer. I think it is worth the read. Here is an excerpt: For centuries, a dark specter haunted the bloody battlefields of Europe. Waiting to feast on the dead, common ravens lined up at bloody clashes between invaders and invaded, tribes and kingdoms. War-weary observers could not ignore the jet-black scavengers, with their four-foot-wide wingspreads and cross-shaped flight profiles. Ravens, not surprisingly, were branded harbingers of bad luck, or death. Away from the carnage, common ravens (Corvus corax) also coasted into folklore, legend, and language, strongly hinting that these creatures and their 100-plus brethren in the family Corvidae are not your average birds. Two ravens, Hugin (Thought) and Munin (Memory), rode the broad shoulders of the Norse god Odin. In Inuit legend, the raven became creator and trickster. In the Bible, Noah sent not only a dove but also a raven to seek land, as did many ancient mariners. Tame ravens still stroll within the Tower of London's walls, where for centuries they've been sequestered as guardians against invasion. One reason why ravens, crows, jackdaws, rooks, magpies, treepies, choughs, nutcrackers, and jays stand out is that they have above-average brains—proportionately, they possess the largest cerebral hemispheres of the feathered set. Plucky, crafty, curious, social, vocal, and adaptable, corvids, as family members are known, are among our most familiar yet enigmatic neighbors. On all continents save Antarctica, they flourish in backyards and wilderness, although more than 20 species barely hang on within shrinking habitats. Ethiopia's thick-billed raven (Corvus crassirostris), bigger than a red-tailed hawk, is the world's largest songbird, while the dun-colored Hume's ground-jay (Pseudopodoces humilis) of the Tibetan plains is the smallest family member. In between lies a broad spectrum of glossy, splashy, and plume-tailed characters. You can read the rest of the article here.

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.

Biggest and Smallest Corvids

Most people do not know that there are over 120 species of corvid family of birds---including many jays, choughs and treepies---not just crows, ravens and magpies. Well, I was not certain where to begin with this fascinating family of birds so I decided to start with telling you the biggest and the smallest amongst them. The largest corvids are the Common Raven (Corvus corax) and the Thick-billed Raven (Corvus crassirostris), both of which regularly exceed 1400 grams (3 lbs) and 65 cm (26 inches).1 I will do thorough posts about these specific birds in the next couple of days. For now I will share a picture of each.
Dwarf Jay
Dwarf Jay

Common Raven
Common Raven

Thick-billed Raven
Thick-billed Raven
  1. http://en.wikipedia.org/wiki/Corvidae []

Are crows monogamous?

two crows Originally uploaded by mikE~510
I regularly peruse crow photographs on flickr. Today I found this one. What an excellent photograph, don't you think? Under the photograph the question was asked, "Are crows monogamous?" Are crows monogamous? Are ravens monogamous? I thought this would be a good post for today. Yes, crows and ravens are monogamous. They generally mate for life. They are social birds. John M. Marzluff and Tony Angell stated the following about crows in their book In the Company of Crows and Ravens, "Crows and ravens care for each other, spend years living at home, engage in foreplay, and mate for life but now and then mate with others. Large groups cooperate to sleep in safety, drive away mutual enemies, and maybe even dole out justice." Interesting, eh? We could learn a thing or two from crows and ravens. Maybe being close with family and friends is not just for the birds... Thanks to mikE~510 for the photograph, the question and the inspiration to write this post!

Common Ravens and Egg

Common Ravens and Egg Originally uploaded by poecile05
This is the second raven baby/egg photograph and post. Thanks to the photographer, poecile05, for sharing this on flickr and allowing us to blog it. If you read yesterday's post, you know how much a baby raven can and must consume. I shared with you a small part of a book I read, "Mind of the Raven" by Bernd Heinrich. The high maintenance baby ravens don't stop with just a need for attention and an enormous amount of food. They also require some special attention to see to their "bathroom" needs, if you will. You may recall from yesterday's post that nestlings eat A LOT of food. For every action there is an equal and opposite reaction. Yep! That is right. Almost every amount that goes into the baby ravens must come out. Since they can't lift themselves up to hang over the side of the nest for at least a couple of weeks, their parents must take care of this expediently. Remember, if they eat six woodfrogs and two mice IN ONE FEEDING, then you can imagine how much waste that much food produces after EACH and EVERY FEEDING! They would quite literally be drowning in a bowl (their nest) full of their own liquid dung (also known as 'mutes'). In order to prevent this from happening, the parents scoop up the "mute" with their beaks as it is coming out and dumps it over the side of the nest. They are the equivalent of live pooper-scoopers. Not so fun, not so simple. Imagine how much time this takes and then recall how much food they need. You can see clearly how much time parenting takes in a raven's life. We are lucky as humans that we only need to go to the local grocery store to obtain food for our young. Imagine the raven's life...

Common Raven Nestling and Egg

I found this photograph on flickr as well (my new favorite place to find great corvid pictures!) and I had to share it. Look at them! They are soooooooo cute. They look like baby dinosaurs. While I have your attention, let me share a little story about baby ravens with you. I discovered this stuff while reading "Mind of the Raven" by Bernd Heinrich. In case you are debating on whether you should check it out, you definitely should. Back to my point... When ravens are babies, also known as nestlings, they require an enormous amount of food and parental care. Ravens need a lot of protein to grow healthy and strong. In his book, "Mind of the Raven", Heinrich tells us what he fed six nestlings at about five weeks of age: Day One: One woodchuck and one snowshoe hare Day Two: Three red squirrels, one chipmunk, six frogs, eight chicken eggs (crunched up shells and all) Day Three: Two gray squirrels, five frogs, six eggs, six mice Day Four: One hindquarter of a Holstein calf That is ALOT of food! OMG! He goes on to describe how a few days later EACH of the nestlings could eat six woodfrogs and two mice IN ONE FEEDING! And then they'd be ready in an hour or two to eat the same amount! This is outrageous. Now, I feel infinitely guilty for only feeding them two pieces of bread. Goodness! Young Ravens needs A LOT of care, food, and attention. Our hats go off to the raven parents. And we highly suggest you DO NOT take baby ravens as domestic pets unless you have an enormous amount of time, energy and determination and the resources needed to provide the adequate diet needed for them. I will write more about nestlings and fledglings in future posts, keep your eye out for them!

I Never Met a Raven I Didn’t Like

Ok, so who couldn't love this little guy? And how could I NOT share it? What a great photograph. Thanks again to the Robinsegg (on flickr) for this most excellent photograph capturing clearly the interesting personality and charm Ravens possess. What do you think he is thinking? Cheese? Perhaps. Or maybe he is thinking, "When you finish taking my photograph, would you mind terribly going and fetching me some McDonald's?"