American Crow - An Amazing Bird

American Crow - Gift Giver and Problem Solver

American Crow  [Internet Photo]

The American Crow (Corvus brachyrhynchos) is a member of the Corvidae family which also includes ravens, jays, magpies and one nutcracker.   Crows are very common and widespread in North America and known by almost everybody.  There are 7 species in North America and they are well represented worldwide.

Crows are intelligent and adaptable and this post will discuss crow behaviour rather than their life history.  We have been feeding the American Crows in our area for many years.  We use an elevated platform with a surrounding lip so that the food does not blow off.  We don't feed on the ground so that dogs and cats and varmints cannot eat the food.  Some of it would not be good for dogs, for example. We often give them fat and that can make dogs very sick.  

American Crow on Feeding Platform

Feeding crows is an enjoyable endeavour.  They wait everyday for their ration.  They even sit in a tree close to the house from which they can see inside our bedroom.  They appear to be watching for when we get up.  When they see motion they appear to get excited in anticipation of getting their 'breakfast'.  When we go outside with the obvious food dishes in hand, one crow will give a 'whoop' sound which alerts the whole family which is in the area.  To me it sounds like, 'Whoop, here she come!'  What is not to love about crows!

When we first started feeding crows I (tongue in cheek) told them that if I fed them I wanted them to stop tearing our garbage apart as it sat on the side of the road on garbage pickup days.  Well, they seem to have obliged!  I don't know if they understood, or if they are no longer hungry or if in these years we have started composting organic kitchen waste.  Whatever the reason, we have a good arrangement with our local crows.  

There are many reasons why crows are special birds.  One area that has been studied widely is their problem-solving ability.  They can figure out 2 or 3 step solutions to problems.  Food is usually the prize and the crow can, for example, figure out how to pull a string and step on it in various stages of pulling in order to stop the food from dropping down out of reach.  Crows can also make tools in order to solve problems.  This has been proven many times by behavioural studies.  Through these studies it has been shown that crows are as intelligent as some primates.  

Crows are mimics.  They can reproduce human and environmental sounds.  Many of us have heard wild crows say 'hello' from high up in a tree.  Some crows can reproduce other bird songs and industrial sounds.  They have tricked many people this way.  Captive individuals can develop a substantial vocabulary.  Studies have shown that they are better mimics than parrots because they can reproduce sounds in both the high and the low registers giving them more diversity than parrots.  

Crows have a fascination with humans.  This must be because we have interacted for thousands of years.  They think about what we are doing and exploit us to suit their needs.  Note the example of watching for me to get out of bed and then telling all crowdom that food will be coming shortly.  An important fact is that crows recognize us as individuals.  They recognize faces.  Many studies have been done to prove this.  In one case they recognized a certain person on a university campus and warned others that this person was 'bad'.  They remembered this person and changed their behaviour around him for many years.  They even passed this behaviour towards this individual on to the next generation of crows.  

Crows can count.  This has been proven in different ways but one way was to put a certain number of persons in a blind and then take a certain number away.  The crows could figure out without fail that some people were left in the blind and thus they could not go about their normal activity near the blind.   Experiments have shown they can count objects and keep tack of where they are.  Our observations also show that they probably have good memories involving numbers.  The crows we feed haul the feed away and hide it in the field nearby.  I don't believe they randomly find it later.  What I observe is that when the feeders are empty the crows fly directly to various places in the field and retrieve the stashed food.  They don't appear to walk around searching for stashed food.  Scientific research indicates that the crow remembers every place it has stashed food.

Crows have 'funerals'.  I think most of us 'birders' have witnessed this behaviour.  There will be a huge gathering of crows, perhaps 100.  They seem to appear out of nowhere and are all over the ground, trees, bushes, etc.  On looking closely there will be a dead crow on the ground.  They seem to each fly down and look at the deceased.  Shortly afterwards they will move away and more will come and take a look.  It is thought that this behaviour is done to teach each crow the danger of the place and whatever or whoever was responsible for the death of the individual.  

Crows will also murder some of their kin.  They kill the individual by picking it to death.  More than one individual may be the perpetrator.  The victim is usually a weak, injured or sick flock member.  It is thought this behaviour has evolved in order to protect the flock from attracting predators which might kill some of the healthy crows.    

The most fascinating crow trait for me is their supposed gift giving.  There are many examples of this but I will tell you mine.  After feeding the crows for sometime, one day I noticed a small object on the otherwise empty crow feeding tray.  It was a small red plastic object.  I wondered how it got there and what it was.  There was no way it could have blown there.  It did not come included in the feed.  It was not anything I had seen before.  I concluded it was a gift from the crows. Following are other examples of crow gift giving.  

In 2006, after feeding crows for two years, a man said to a group of crows waiting in a nearby tree for their daily feed, 'Hey, how come you never bring me anything?  I always give you food, and you never bring me anything.'  He then went in the house and the crows cleaned up the food.  Late that afternoon, long after the food had been all eaten, he noticed a small object sitting in the middle of the tray.  Taking a look he was stunned to find a small purple candy heart that on one side was written the word, 'LOVE'.

A woman from Indiana was sitting outside reading when out of nowhere a crow dropped from the sky, landed on her lap and left her an inch-long necklace bead.  Another woman from Seattle was a regular crow feeder.  She regularly went out for a walk and threw dog kibble on the sidewalks for the crows.    The crows would unceremoniously drop onto the sidewalk to feed near her.  One day as she went about her usual feeding stroll she heard a sound as a metallic object dropped at her feet.  A crow had dropped a key for her.  The crow ate his food and then flew away leaving her the key.  

Corvids have been giving gifts for hundreds of years.  The Old Testament tells us the ravens brought food to Elijah while he was in the desert.  There are examples throughout literature of crows giving gifts.  For example, a play written by Ben Jonson in the 1600s is based on a crow giving gifts to a fox.  

Crows are clearly successful problem solvers and have used their many talents to survive in our changing world.  They are ignored or scorned by most of us.  But to those who pay attention, they are fascinating creatures who do not get enough credit for the 'work' they do in society.  Think of how they clean up our highways.  They have learned to fit well into our many different habitats and environments.  For this tool-maker species,  it may be that the most important intelligent feature they have is to adapt to live closely with and from us.  

References: 

Lesley the Bird Nerd, YouTube.com

Marzluff, John, Angell, Tony; Gifts of the Crow, Atria, 2013.

What do Birds See?

A 'Look' at Bird Sight and Seeing

Bald Eagle Showing Forward Vision [Internet Photo]

Recent research has revealed a lot of interesting features about bird eyesight.  This post will present some of them.  The Bald Eagle shown above has excellent eyesight.  It can clearly see prey from hundreds of feet in the air prior to making its catch.  A relative of the Bald Eagle, the Australian Wedge-tailed Eagle has the greatest visual acuity of any known animal.  We have good reason to feel envious of avian visual abilities because they can see so much better than we can.  That gives us good reason to study their eyesight.

I will first present what birds see followed by some of the anatomical and physiological reasons.  We see objects with what we think is good visual acuity.  Objects to us are clear, bright, crisp and in vivid colour.  Well, take it as a fact now that we are desperately disadvantaged compared to birds.  Birds can see with greater clarity, more shades and contrasts and they can even see ultraviolet (UV) light.

Black-crowned Night-Heron [Internet Photo]

Humans see light with the red/green/blue spectrum.  We are trichromats.  Birds are tetrachromats!  They see with four colours; red/green/blue/UV.  By being able to see UV, birds have a whole realm of colour and form available to them that we do not.  UV has no colour but birds can see many different 'colours' (for want of a term) in the UV range.  Note the photo below.  On the left is how we see the bird with no UV.  On the right is how birds see the bird with UV.  When you translate these differences over the plumage of all birds, vegetation and other parts of the bird universe, you can see that birds live in a vastly difference system than we do.  

How Humans See (left); How Birds See (right) [unknown source]

In a study done in 2007 scientists analyzed the colours of 166 North American songbird species that (to us) did not appear to have any physical differences between the two genders.  What they found reveals in one way how different the bird environment is compared to us.  They found that even though the two genders looked alike to us, their colours differed greatly when viewed in the UV spectrum.  So, we are the ones lacking here!

So, birds see with high density resolution; they see well from great distances; and they see with great colour variation and acuity.  Just imagine a colour you have never seen and multiply it by 11!  Wow!  Plus, they can see different colours in the infrared spectrum which we can see only as red.  I am feeling severely disadvantaged now!

Brown Pelican [Internet Photo]

Birds are the most colourful animals on the planet.  That in itself shows that they have good perception of colour.  It is also why we find them so appealing.  Let's consider one of the most highly coloured birds on Earth, the Andean Cock-of-the-Rock.  The male of this species is intensely scarlet red with a black tail and outer wing feathers.  The inner wing feathers are silver.  It gets its name because it nests on rocky cliff edges.  The males perform in groups in leks.  These leks are in small sunny spots in the heavy South American forest.  The strange thing is that when the males step out of the sunshine, they appear black and become difficult to see.  So how do these birds change from such brilliant plumage to a well-camouflaged plumage?  It appears that as the light is filtered through the heavy green foliage of the forest it neutralizes the brilliant red to a dark colour.  There are many other species with a similar plumage trait.  They need sunshine in order to display for their mates (and us if we are lucky enough to be watching).  They have to choose their display sites with care.  Some birds-of-paradise in New Guinea and manakins in South America actually create their own sunny spots for their leks by clearing away the foliage.  

Peregrine Falcon [Internet Photo]

So how have birds developed anatomically and physiologically to have such good eyesight?  A lot of it is out of necessity.  Birds with better eyesight would naturally have survival and reproductive advantages.  Raptors, for example, need exceedingly good visual acuity to spot prey for afar and to focus at extreme speeds.  The Peregrine Falcon seen above is the fastest bird on Earth on its prey dives.  Seabirds can see their mates flying in with food for the nestlings from great distances.  

Great Horned Owl [Internet Photo]

Anatomically birds have large eyes.  The globes are very big compared to mammals.  Large eyes give them large retinas and larger fields of view both of which improve sight.  In fact, their eyes are bigger than they appear because a large part of the globe is concealed in bone and soft tissue.  Excellent vision is necessary for avoiding collisions and capturing fast-moving prey.  Nocturnal species such as owls have larger eyes than birds that are active during the day.  Larger eyes gather more light making it so they can see better in the dark.

Birds cannot (for the most part) move their eyes.  We are all familiar with the owl swivelling its head nearly 360º in order to see around it.  They can actually see 270º from a single perch.  Some birds have their eyes facing forward, some on the sides of the head and some on the side of the head but placed so that the bird can see forward as well.  See the photo of the Bald Eagle at the beginning of this post.  All these different positions are suited to the visual needs of each species.  

Birds, being tetrachromats, have four single-cone types in their eyes.  Not only do they have more cone types than we do, but they have more of them as well.  Most other mammals other than humans and primates have two cone types.

Another interesting anatomical feature of avian sight is that many bird species use their right and left eyes differently.  Each eye is controlled from a separate hemisphere of the brain; left controls right and right controls the left eye.  Many studies have shown that birds use the right or the left eye for different activities.  Peregrine Falcons, for example, zero in on their prey in an arc using their right eye.  Male Black-winged Stilts use their left eye to direct courtship displays to the female.  It has been shown the strong sidedness produces better performance and efficiency.  

As if better eyesight and seeing much better through UV sightedness isn't enough, it has been shown that birds can sleep with one eye open (and thus alert through that open eye).  So far it has been shown that songbirds, ducks, falcons and gulls can sleep with one eye open.  This makes them alert to predation.  It enable them to sleep more efficiently.  And, they can even fly while sleeping!  That is correct.  They are asleep but the one open eye keeps them on track while migrating!  That idea seems ridiculous but it has been shown to be true.  No wonder they can fly from Mary's Point non-stop to Surinam!  

The last physiological trait I mention here is their ability to use their senses in combination.  This really helps in migration.  We have known for a long time that birds can navigate by the stars and sun.  It has been found recently that they also can read the Earth's magnetic fields.  They have magnetite receptors in the beak which help with navigation.  It is also possible that they have a chemical structure in the eye which also aids with navigation.  The eye structure provides the direction of the magnetic field and the beak receptors detect the strength of the magnetic field.  The birds can then integrate stimuli from both receptors to find their way home without land or celestial features.  More research is being done in this area.  

This post has provided a lot of information about bird eyesight and behaviour.  We are just beginning to understand the abilities of birds by studying their amazing vision.  We have a lot to learn yet!

Reference:  Audubon.org; 'Bird's-Eye View'; nwf.org; Google

Common Goldeneye

Common Goldeneye - A 'Common' Duck 

Common Goldeneye Male  [Internet Photo]

The Common Goldeneye (Bucephala clangula) is a common diving duck in New Brunswick.  It can readily be seen in open water in winter as well as in summer.  In summer they prefer ponds and lakes but winter mostly on coastal bays and estuaries.  The male shows a lot of white on its breast, flanks and neck with black on its back, tail and head.  Of importance for identification is the large round white spot on its face and the bright golden eye.  The female is gray with a brown head and a mostly black beak.  In adult breeding females the beak shows yellowish orange on the tip.  It is important to note that the yellowish colour is only on the tip of the beak compared to the beak of the female Barrow's Goldeneye which is all orangish colour, not just the tip.  

The male Common Goldeneye has a roundish head shape without the steep slope to the forehead as in the male Barrow's Goldeneye.  The male Common Goldeneye also has a ladder on its back which is mainly white with black lines which do not extend down into the breast with a spur.  This ladder is very modest compared to the bold ladder on the Barrow's Goldeneye.  

Common Goldeneye Male (Back); Barrow's Goldeneyes Male (Front) [Internet Photo]

In the photo above note the comparative differences in the facial spot and the ladder in both species.  These two species are very closely related but not difficult to tell apart with experience.

The Common Goldeneye has a wide range throughout Canada.  Their summer/breeding range covers most of Canada.  They permanently inhabit southern Quebec, the Maritimes and the very southern part of most of Canada.  They winter in most of the United States except some parts of the southeast.  

Common Goldeneyes breed on wooded lakes and ponds.  They nest in tree cavities and will use the same cavity in succeeding years.  Five to nineteen pale green eggs are laid in the down-filled nest and are incubated for 28 to 32 days by the female.  Common Goldeneyes feed on insects, crustaceans, mollusks, small fish and aquatic plants.  These are diving ducks so they feed in deep water.  What you often see is most of the flock on the water and they often all dive about the same time.  If you watch for a couple of minutes you then see them pop up one by one to the surface.  They seem very buoyant and appear to come up perfectly dry.  

Common Goldeneyes are vocal and the male often make a 'jeeeep' sound.  The males in breeding season perform enthusiastically for the females by putting their heads back onto their backs.  The male in the photo at the top of this post is performing.  

Common Goldeneye Female [Internet Photo]

When the Common Goldeneye is in flight its rapid wingbeats make a loud whistling sound which is a good identifier for this species.  That is the reason many hunters call them, 'Whistlers'.  This species has adapted to the acidification of lakes and is the only North American duck to have done so.  It feeds on the acid-tolerant insects in lakes that have been acidified.  Most fish cannot live in these environments so there is a preponderance of acid-tolerant insects.  

An interesting fact about Common Goldeneyes is that the females typically return to breed to the areas in which they were hatched.  They then return to this area year after year.  So, the ducks you seen around your locale in breeding season have likely been hatched there and have come there every summer.  They are truly 'our ducks'.  Let's do our best to protect them.

Barrow's Goldeneye

Barrow's Goldeneye - a Barnacle-eating Duck

Barrow's Goldeneye - Male and Female [Internet Photo]

The Barrow's Goldeneye (Bucephala islandica) is a waterfowl species of the northern hemisphere.  It inhabits mainly North America but also Iceland, Greenland and occasionally the United Kingdom. It is a permanent resident of both our west and east coasts.  It breeds in the west in Alaska, Yukon and British Columbia.  In the east it breeds in northern Labrador and north of the St. Lawrence River.  It is a winter resident of New Brunswick, being found mainly along the east coast but also in small numbers in open water along the St. John River.  

So, do they really eat barnacles?  Yes, the  Barrow's Goldeneyes seen hanging around wharves and other structures along our coasts are often stripping barnacles from these structures.  Barrow's Goldeneyes normally feed on aquatic insects, crustaceans, molluscs, small fish and aquatic plants.  They feed by diving from the surface.  It is common to see a mixed flock of goldeneyes on the surface and then, all of a sudden they are all dive to feed together, only to pop up individually soon afterwards.  Barrow's Goldeneyes usually flock with their close cousins, the Common Goldeneyes.

Barrow's Goldeneye - Male

Barrow's Goldeneyes are dressed in a sharply-contrasting black and white.  The males show a white crescent on the head and a white 'ladder' marking which makes a spur which separates the white breast from the white flank.  The female is more subdued in colour with a dark brown head, gray body, and an orange bill that becomes black in summer.  

Barrow's Goldeneye - Male and Females [Nelson Poirier Photo]

How do I tell a Barrow's Goldeneye from a Common Goldeneye?  For the beginning birder this can be a problem.  The male's important distinguishing features are the large white crescent on his face and the ladder jutting down into the white between the breast and flank.  He also has a distinct steep slope to his forehead as seen in the photo above.  The females are more difficult to tell apart.  The bill is important - it is almost completely orange in the Barrow's but only the tip is a yellowish orange in the Common Goldeneye.  As noted earlier the bill in the female cannot be used as a distinguishing feature in summer because it turns dark in the Barrow's.  This is not a problem for us since Barrow's Goldeneyes depart for breeding grounds in the north so we don't see them in summer.

Barrow's Goldeneyes (front), Common Goldeneye (back) [Brian Stone Photo]

In the photo above note the crescent on the face of the Barrow's Goldeneyes compared to the roundish spot on the face of the Common.  Also note how the ladder spur juts down in the Barrow's and not in the Common.

This species is not very vocal.  Apparently they do make a 'ka kra' sound.  What we often see are the males performing for the females as they approach breeding season before they leave here.  It is fun to see them throw their heads back and raise partly out of the water, hoping for female attention.  They are attempting to pair up before leaving for the north. 

In the north Barrow's Goldeneyes nest on coastal ponds and wetlands in tree or rock cavities.  Abandoned Pileated Woodpecker holes are very desirable.  The female builds the nest, lines it with her breast down, and lays 5 to 15 pale olive or blue green eggs.  She incubates these for 28 to 34 days.  

The population of Barrow's Goldeneyes is not large in New Brunswick.  A study is being conducted now to determine how many are wintering here.  I have seen 3 this winter at Mactaquac Dam and it would be fairly easy to see several off the east coast along the Shediac area.  

The Barrow's Goldeneye is a long-lived duck with an individual recorded to have lived 18 years.  They are slow maturing as well, females not breeding until the age of 3.  The Barrow's Goldeneye is a beautiful, stately breed and named after a British statesman, Sir John Barrow.  Undoubtedly it was after a group of these ducks that were wintering in the United Kingdom.

Now is the time to get out and try to find this challenging species.  It is beautiful and worth the try.  See you out there!