Tag Archives: corvidae

What’s the difference between a raven and a crow?

Although these two terms are used interchangeably, these two species are not the same. Although the differences between them are subtle, we can learn to tell the two apart. So let’s get to it!

Image via Pixabay.

Ravens and crows are closely related. They both belong to the Corvus genus of the Corvidae family of birds. Outwardly, they’re very similar — both are jet black and share several morphological features. Their natural ranges also have a lot of overlap, so they’re often seen (and mistaken for one another) in the same areas of the world.

Here is where the terms get a bit muddy, however. “Crow” is often used as a catch-all term for any bird in the genus Corvus. At the same time, people tend to refer to any larger bird from this genus as a “raven”. Taken together, it’s easy to see why very few people seem to be able to describe with any real detail what truly differentiates these species.

But — lucky you! — we’re about to go through them today.

Crow or raven?

One of the first indications that you’re seeing a crow rather than a raven is that the former generally travels in large groups, while the latter prefers to hang out in pairs. If we happen upon a solitary bird, however, such context clues won’t do us much good; so we’ll have to look at the characteristics of the individual.

Common ravens (Corvus corax) are, indeed, larger than your average crow. This is especially useful to know in rural areas, where size can be a pretty reliable indicator of which of these birds you’re dealing with. Ravens aren’t particularly fond of urban areas and their bustling crowds, however, so if you’re in a city, you’re probably more likely to be seeing a ‘really big crow’ than a raven. As a rule of thumb, crows are about the size of a pigeon and weigh on average 20 oz / o.55 kgs, while ravens are roughly as large as hawks, typically weighing 40 oz / 1.1 kgs.

A stuffed common raven and carrion crow, side by side, at the Natural History Museum of Genoa. Image via Wikimedia.

Meanwhile “crows” — typically the Carrion Crow (Corvus corone) in Europe and American Crow (Corvus brachyrhynchos) in the U.S. — are quite fond of cityscapes and generally not people-shy.

The two species also produce different sounds. Crows vocalize through ‘caw’s or ‘purr’s (sound sample for carrion crows, American crows) while ravens use much lower, rougher croaks. Personally, I find the latter to sound much more ominous, and use this as a rough but reliable guideline when trying to identify ravens.

If vocalizations are not forthcoming, either, we can start looking at the physical features of the birds in question. As far as the plumage is concerned, both species sport jet-black feathers. Raven feathers are very glossy with green, blue, and purple iridescence; they can also have a wet or oily sheen. Crow feathers are iridescent blue and purple but are far less shiny than those of ravens (although they still do have a little bit of sheen to them).

Ravens have larger and curvier beaks than crows. Both sport bristles at the base of the beak, but for ravens, these are much more pronounced. Ravens tend to have ruffled feathers on the throat, whereas crows’ are swept neat and tidy.

On the ground, both birds behave similarly. One reliable way to tell a raven apart here, however, is by how they walk: ravens tend to mix little hops in their gait when moving more rapidly. At a slow pace, a raven’s walking pattern is the same as those employed by crows.

If you happen to spot the birds mid-flight, a few more tell-tale differences become apparent. A raven’s wingspan is much greater than that of a crow (3.5-4 ft / 1-1.2 m and 2.5 ft / 76 cm, respectively) and raven’s wing beats make a distinctive swishing sound while a crow’s are silent. In flight, the raven’s neck is also longer than a crow’s. Crows tend to actively flap their wings more often than ravens, which tend to prefer soaring on rising masses of air (they are heavier, and this helps them save energy). If you see such a bird soaring — gliding along with outstretched wings — for more than a few seconds at a time, chances are it’s a raven.

Ravens like to do all sorts of fancy acrobatics during flight, including somersaults (loops) or even flying upside-down, possibly just for fun. Such behavior is a dead giveaway that you’re looking at a raven, but it’s not very reliable; they tend to only engage in such playful behavior on windy days, or those with powerful thermals (rising masses of hot air) to keep them aloft.

As far as the shape of their wings is concerned, ravens have pointed wings with long primary feathers near their tip. Crows, meanwhile, have blunter wingtips; although their primaries are splayed as well, they are shorter and less pronounced than a raven’s.

Perhaps the single most distinctive difference between the two is the shape of their tails. All the feathers in a crow’s tail are the same length; in flight, their extended tails look like fans, with a rounded outline. Ravens meanwhile have longer feathers in the middle of their tails, giving them a wedge-like outline while the birds are in flight.

The differences between these two species are subtle — as well they should be, they are closely related, after all! The Corvidae family is also very numerous, and each species that belongs to it has its own particularities, some of which may not fit with what we’ve discussed here today. In general, however, they’re distinctive enough to tell apart.

Crows and ravens are some of the most similar — and most often-confused — species in this family. Hopefully the tips here will help you better tell them apart, and impress your friends with your knowledge of Corvidae!

Credit: Wikimedia Commons

Crows are the first non-human animals we know of that employ tools to carry objects

Credit: Wikimedia Commons

Credit: Wikimedia Commons

Corvidae birds have exceptionally large brains and are adept tool users, despite having no hands, let alone opposable thumbs. New Caledonian crows are no exception. Scientists have witnessed captive crows add another remarkable tool use to their already rich repertoire. Not one, but two crows were seen inserting sticks into objects to carry both at once. Some of these objects were too cumbersome to carry by beak alone, which is telling of the birds’ ingenuity.

Four such instances were observed by researchers at Lund University in Sweden, including the slipping of a wooden stick inside a metal nut or into the hole of a large wooden ball. In all instances, both stick (carrying tool) and the hooked objects were flown away by the crows, the researchers reported in the journal Animal Cognition.

Scientists are not sure at this point if this kind of behaviour is employed by other crows or Corvidae members such as ravens in the wild. It’s possible that one of the crows was the innovator, and the other captive individual observed, learned and mimicked this. It’s really difficult to tell at this point, judging from the actions of only two individuals. But if you were to ask me, I see no reason why wild crows aren’t doing this already — to carry food too big for their beaks, for instance, and stash it for later use. Indeed, a 2002 paper published in Science recounts how a New Caledonian crow named Betty took a piece of wire, bent it into a hook, then retrieved some food otherwise out of reach. Betty was also captive, though.

Tools and objects used for insert-and-transport tool use. a Experimental square wooden stick. Credit: Animal Cognition, Springer

Tools and objects used for insert-and-transport tool use. A is an experimental square wooden stick. Credit: Animal Cognition, Springer

Wild crows doing the same wouldn’t be surprising considering their track record. Time and time again, animal behaviorists have observed crows doing amazing things with their environments to solve new problems. Besides crafting hooks to reach food from sticks, crows can recognize people’s faces and understand water displacement on the same level as a child. That’s among other amazing things. Most people don’t hold crows in high esteem due to their allegedly repulsive appearance (I think they look very cool, actually), which is a shame. By judging crows by their cover, they might be missing out on a spectacle of nature. Me, you and crows aren’t all that different in many ways.

 

" Whatcha' lookin' at, bub?" Crows know when humans are watching them.

Crows remember and respond to people’s faces akin to humans themselves

Crows, like most other species from the corvid family (ravens, rooks, etc.), are some of the most intelligent animals on the planet, actually rivaling apes and dolphins. Tool use is common among these birds, but where they shine is in their social and emotional intelligence. For instance, a few years ago I reported how ravens point at things with their beaks to relay and communicate insights and intentions with their peers. Eurasian Jays, another corvid, can infer the desire of another bird – say, its partner – and bring it food that it considers at treats (corvids have strong personalities).

There’s never a shortage of new, amazing things we learn about this most gifted family of birds though. Crows, the most familiar bird of the family, possess some of the most amazing social skills in the animal kingdom. A new study published in the journal Ethology, led by Barbara Clucas of Humboldt State University, revealed new dimensions in the crow’s social reasoning. Namely, boggling as it is (remember, we’re talking about a bird), crows can recognize, respond and adapt to specific human faces.

For instance, it was proven that crows take off much sooner when people are heading their way with gaze fixed on the crows, as opposed to people marginally looking the crows’ way. Basically, crows have learned to differentiate between people who are just strolling by them and people who are actually heading their way. Most birds or animals scatter when a human is approaching no matter what. Crows know when to play it cool, and when it’s time to scram. Scientists believe this is a direct response to living in an urban environment, and that’s not that big of  a surprise considering it’s been shown urban birds have a significantly larger brain than their rural counterparts.

" Whatcha' lookin' at, bub?" Crows know when humans are watching them.

” Whatcha’ lookin’ at, bub?” Crows know when humans are watching them.

Proving further on that crows indeed read and respond to human eye contact, John Marzluff of the University of Washington, a co-author of the paper, made a most interesting experiment, for which his patience was duly rewarded. Five years ago, he invited some of his researcher friends for a walk in the park; not your typically promenade, mind you. The researchers were divided into two groups: each would wear a particular type of mask on their faces, however one of the groups would trap crows, while the other would just pass crows by. Fast forward to present day and the findings are nothing short of amazing. The researchers returned to the park with their masks on. The birds present at the original trapping remembered which masks corresponded to capturing—and they passed this information to their young and other crows. All the crows responded to the sight of a researcher wearing a trapping mask by immediately mobbing the individual and shrieking.

“It’s one thing to learn from one’s own experience and another to observe that happening to other individuals and infer it could happen to you,” Marzluff explains.

Indeed this is a fundamental difference, in most instances one that has helped the human race evolve and prosper. This is how teaching is passed on, this is how human culture has been raised. Seeing crows communicate an abstract information or symbol (the particular type of mask associated with trapping) to other crows that did not have first hand, affective information is , to me, mind boggling!

How do crows have such a fine and efficient human face recognition behavior, and moreover such a powerful adaptive capacity? PET scans reveal that when crows viewed human faces that they associated with threat or care, the birds had increased activity in the amygdala, thalamus and brain stem—areas related to emotional processing and fear learning. In response to threatening faces, areas that regulate perception, attention and fleeing also lit up. Similarities to the human brain in this case are most striking.

Again, crows prove they’re some of the most intelligent species on the planet. They use tools, they recognize people’s faces and voices, they can tell when one of their peers has died, and so much more. Truly, they’re amazing animals, unworthy of the ‘harbinger of death’ stigma cast on by people based solely on their appearance. Owls? You’d better refine your wisdom animal totem.

For more on crows and their amazing abilities, check out this informative, but best of all entertaining article from cracked.

via Sci American

cacaktoo experiment

Cackatoos exhibit remarkable self-control akin to humans

You might be used to seeing birds peck grains as soon as you throw the food in front of them, so it’s no wonder why might find this surprising. University of Vienna established a cognitive experiment centered around a most intelligent type of bird – Cackatoos – and found that they’re capable of self-control, restraining themselves from immediately eating food put at their disposal, despite being highly tempted to do so. The findings suggest that yet another personality trait typically believed to be encountered in humans or primates only is present in other animals as well.

The experiment itself was inspired by a famous psychological experiment from the 1970s that studied self-control ability in babies, in order to see how early on this highly valuable cognitive trait is developed. In the ‘Stanford Marshmallow Experiment’ babies were asked to restrain from eating the marshmallow right in front of them for the time being and were promised another one if they behaved. This is a perfect example of economics decision making, and for many years the ability to foresee a delayed reward has been thought to be encountered in humans only

Now, simply waiting might not seem like much to you, but truth of the matter is it proves the presence of an important cognitive ability which is believed to be encountered in large brained animals only. It’s not only about the ability to control one’s instincts and impulses, but more about foreseeing – the capability of assessing present conditions and establishing whether taking action or staying passive will rend more rewards in the future.

cacaktoo experiment

For their experiment, the Austrian researchers chose to study an Indonesian cockatoo species – the Goffin’s cockatoo. The birds were instructed to pick pecan nuts and return them back to the researchers after a time delay. If they were successful and returned the food back without nibbling on it, the birds would then receive cashew nuts – an even greater treat.

“If the initial food item had not been nibbled, the bird received another reward of an even more preferred food type or of a larger quantity than the initial food,” explained researcher Isabelle Laumer (pictured, top of page). “We picked pecan nuts as an initial reward as they are highly liked by the birds and would under normal circumstances be consumed straight away, [but] we found that all 14 of the birds waited for food of higher quality – such as a cashew nut – for up to 80 seconds.”

Lead researcher Alice Auersperg was particularly impressed by the cackatoos surprising ability to assess economic advantages, liking them to human economic agents,  flexibly trading-off between immediate and future benefits.

“They did so, relative not only to the length of delay, but also to the difference in trade value between the ‘currency’ and the ‘merchandise,’ tending to trade their initial items more often for their most preferred food, than for one of intermediate preference value,” she noted.

What’s maybe more impressive is the extent of their self-control. In the marshmallow experiment, babies were faced with the choice of eating the marshmallow placed in front of them. How many of them would have been able to resist the temptation if the food was placed right in their mouths, like in the case of the cackatoos who have no other means of transportation other than their beaks?

Cackatoos, belong to an order of highly intelligent birds called Corvidae, which also includes ravens, crows and rooks.;

“Until recently, birds were considered to lack any self-control. When we found that corvids could wait for delayed food, we speculated which socio-ecological conditions could favor the evolution of such skills. To test our ideas we needed clever birds that are distantly related to corvids. Parrots were the obvious choice and the results on Goffins show that we are on the right track,” said Thomas Bugnyar, one of the study authors.

The study’s findings were reported in a paper published in the journal Biology Letters.