Thursday, February 25, 2016

Thick-billed Murre

Rare Murres Storm-Blown to New Brunswick

Thick-billed Murre [Mark Morse Photo]
Recently one of our severe winter storms caused a rare phenomenon.  Heavy winds blew sea birds landward, birds who normally spend their time at sea.  

Murres are members of the alcid family, birds that typically spend their lives at sea and come to land only to breed.  Members of this family who inhabit our part of the world include puffins, auks and murres.  We have two species of murres, the Common Murre and the Thick-billed Murre.  The Common Murre is just that, common (relatively speaking).  The Thick-billed Murre is rare.  "Birds of New Brunswick: An Annotated List" lists it as an uncommon winter resident and migrant.  

The Thick-billed Murre normally spends its winters far  out to sea.  In summer it comes to land to breed, usually on rocky cliffs above the  ocean.  It breeds and spends its summers off Newfoundland and northward to Baffin Island and beyond.  It is usually seen solitary or in small groups.  It feeds on fish which it catches under water.  

Thick-billed Murre
The wind storm that brought the murres to shore in NB brought them into the Northumberland Strait and the Bay of Fundy.  This would be well off course for them.  Some were seen along our east coast and some are still present off Grand Manan.  Some were even blown onto land or found injured and taken to the Atlantic Wildlife Rehabilitation Centre.  When an event like that happens, it is important to get the birds back to the ocean as soon as possible.  They are nearly incapable of walking on land and would die soon if not returned to the ocean.  They are unable to take flight from land so need human intervention to survive.

The Thick-billed Murre is a torpedo-shaped bird.  That is very evident when you see them flying.  They are 42 cm (18 in) long and weigh about 1 kg.  In winter plumage they are distinguished from the Common Murre, which is similar in size, by the thicker bill, the presence of more black on the head and neck and the clean white sides.  They do not have the pointed tail of the Razorbill.

Thick-billed Murre
The murres seen in the above photos were seen off Grand Manan.  We visited there on Feb. 20 and found one off Swallowtail Light and 4 at Seal Cove.  The birds at Seal Cove were resting and feeding around the salmon cages and seen by looking over the break wall at the wharf.  

I was privileged to experience a Thick-billed Murre storm-blown event while living in Norway in September 1997.  Hundreds of birds were blown inland.  We saw them in fields, on highways, and many in local bays.  I tried to help but unfortunately most were dead and there were too many to deal with.  I was able to examine one of them and found it a lot larger and heavier than expected.  I was struck by the beauty of the birds.  The sight of so many dead and stressed birds was difficult for me.  It seems that when they are blown inland, the survivors tend to hang around in bays for a considerable time before returning out to sea.  It must be because they are hungry, confused, physically injured, or perhaps just taking advantage of shelter while they can.

Below is a photo of the Thick-billed Murre in breeding plumage.  The white line on its bill differentiates it from the Common Murre which lacks the white line.  The Thick-billed Murre also retains its clean flanks and the Common Murre keeps its flank streaking in breeding plumage.

Thick-billed Murre [Internet Photo]

The Thick-billed Murre is a holarctic species.  As well as North America, it occurs off Greenland, Iceland, Scandinavia, Russia and Japan.  In Europe it is known as Brunnich's Guillemot (named after a Danish ornithologist) and in Norway it is known as 'Polarlomvi'.  These are all the same species, Uria lomvia.

Many thanks to Mark Morse for making us aware of the presence of these birds and for his excellent photo seen above.

Friday, February 19, 2016

Great Backyard Bird Count

GBBC 2016

The Great Backyard Bird Count for this year took place February 12-15.  It is sponsored by Cornell Laboratory of Ornithology and is a major project in citizen science designed to gather ornithological data from all over the world.  See the map below showing areas of the world from which Cornell has received data so far for this year.

World Map Showing Areas From Which Data Has Been Received (Dark Areas) [Cornell Website]
As you can see, the program is extensive and the data will be very useful for research and management.  To this point (and the results are not final yet) they have had the following submissions: 150,161 checklists submitted,  5,296 species reported, 16,958,689 individual birds counted.

To participate, go to http://gbbc.birdcount.org.  There you can read about the parameters and your data can be entered there.  Participating is easy.  All you need to do is stay in one place and count the species and individual numbers for a minimum of 15 minutes.  You can count longer than that and you can count on any or all of the days in the period.  You can make more than one count in each day, preferably from different areas.  It is easy to do especially if you count your feeder birds.  It is also fun to go to a good birding spot in your area and count from there.

We counted our feeder activity on each of 2 days.  Here is a list of what we saw.

Feb 13 - Mourning Dove 30, Downy Woodpecker 1, Hairy Woodpecker 1, Blue Jay 2, American Crow 4, Common Raven 1, Black-capped Chickadee 10, White-breasted Nuthatch 1, American Goldfinch 30.

Feb 14 - Sharp-shinned Hawk 1, Cooper's Hawk 1, Bald Eagle 1, Mourning Dove 20, Downy Woodpecker 1, Blue Jay 2, American Crow 3, Black-capped Chickadee 4, White-breasted Nuthatch 1.

It is interesting to see how variable the results can be just over 2 days.  Of course the feeder area was not watched the whole day so there could have been more or the hawks could have been there the day before and not counted.
Bald Eagle

Blue Jay
Participating in the GBBC is fun and rewarding.  Why not try it next year?

Friday, February 12, 2016

Sharp-shinned or Cooper's?

Differentiating Sharp-shinned Hawks from Cooper's Hawks

Sharp-shinned and Cooper's Hawks [Internet Photo]
Differentiating Sharp-shinned from Cooper's Hawks is a problem for the experienced birder.  These species look a lot alike and need careful scrutiny and experience to separate.  They are both members of the Accipiter family, the true hawks.  They are both fast killing machines of mainly birds.  So, their behaviour is similar.  The size of prey can help telling which species it is.  The Cooper's Hawk is larger than the Sharp-shinned Hawk; 36-51 cm compared to 25-36 cm.  The smaller Sharp-shinned preys on small birds.  A robin is often too large for it.  The Cooper's usually preys on larger birds, often doves.  In both species the females are larger than the males.  Looking at the sizes above, you can see that a female Sharp-shinned can be the same size as a male Cooper's.  Since both genders look very much alike, we have to observe fine details closely to tell them apart.

Both species take two years to mature.  The young are generally brownish above and streaked below on a pale background.  The adults are bluish gray above and orange barred below.  Both juveniles and adults have banded wings and tails.  In both species the juveniles are streaked on the breast (streaks run vertically) and the adults have bars on the breast (fine lines running horizontally).  

The Sharp-shinned is more common here.  It nests in mixed forests and is present year round especially in the southern part of the province.  The Cooper's nests further south, preferring broad-leafed forests.  The Cooper's seems to be more common here in winter.  Both species seem to know where the bird feeders are in your area and they check them out regularly for prey.  

Sharp-shinned Hawk Juvenile
The juveniles can be told apart by their streaking.  The Sharp-shinned has 'messy' streaking on its breast; the Cooper's has fine streaking often tear-dropped shaped.  In the Cooper's the streaking is often just on the chest (upper breast) and it covers the whole breast on the Sharp-shinned.  See the breast streaking on the Sharp-shinned pictures above.  The streaks are broad and ill-defined (messy) and the streaks go down to the legs.

Cooper's Hawk Juvenile [Internet Photo]
In the Cooper's Juvenile shown above note the streaking is tear-dropped shaped and is mainly on the upper breast.  Also notice that in both juveniles the colour is brownish on the head and wings.

Sharp-shinned Hawk Adult [Carmella Melanson Photo]
Above is a Sharp-shinned Hawk young adult.  Note that the vertical streaking is changing to the orange horizontal bars of an adult.  Note that the back is still brown and has not changed to the blue gray.

Another help on a perched bird is the finer details of the head.  The head of a Sharp-shinned is rounder than the flatter head of the Cooper's.  The Sharp-shinned has an orange cheek compared to the gray cheek of the male Cooper's (female has orange cheek).  Both have a dark cap but in the Cooper's it contrasts with a paler nape (back of neck) and in the Sharp-shinned the dark cap blends in with the dark nape.  Note these features in the photo below taken from The Sibley Guide to Birds, 2nd edition. 


Note in the photo at the beginning of this post the demarcation of the cap from the nape is not clear enough to differentiate the species.  That is probably because of the lighting in the photo and the head position.

These are very fast birds and we often don't get to see these finer details on birds in flight.  They both fly with the flap-flap-flap-glide characteristic of Accipiters.  The Sharp-shinned, however, has a faster wing-beat than the Cooper's.  They have a similar body shape in flight; long tube-shaped body with long tail and rounded wings.  So, it often comes down to shape and size.

The Cooper's in flight shows the shape of a cross.  The Sharp-shinned in flight has the shape to a 'T'.  The reason for this shape difference is that the Cooper's has proportionately longer wings and the anterior line of the wings is straighter than that of the Sharp-shinned.  That makes the head project further ahead.  The slightly rounded forewing line of the Sharpie and smaller head makes the head appear to be farther back, making the shape of the 'T'.  I have found this is quite helpful in identification.

Tail shape is also helpful in identification.  The Cooper's tail is rounded and has a wider white band on the tip than that of the Sharp-shinned.   The Sharpie tail tip is straight across and has less white on the outermost band.  The straight tail tip of the Sharpie gives it a right-angle on the edge which can be seen sometimes.

Now, what about the shins?  This is a strange identifying feature which goes back to the days when birds were identified by shooting them and mounting the specimens.  When museum specimens are prepared the birds are laid on their backs and thus the shins are very visible.  As you would expect, the shins, or actually the metatarsi, of the Sharp-shinned are 'sharp'.  They are narrow in cross-section with a sharp edge.  The Cooper's has a thicker, sturdier leg.  This feature is not very useful in the field.

This posting may be too detailed for the beginner naturalist.  It is, however, the 'stuff' experienced birders have to consider in order to identify some of our difficult species.  It all depends on the quality of the view we have, whether the bird is perched or in flight and how long we are privileged to have the bird in our sight.

Good birding, all!

References: Sibley, David Allen. The Sibley Guide to Birds. 2nd edition. Knopf, Borzoi Books. 2000.

Cooper's and Sharp-shinned Hawks. Alvaro Jaramillo. In Bird Watchers Digest. Vol 38 No 1. Sept/Oct 2015.

Thursday, February 4, 2016

Hairy and Downy Woodpeckers

Distinguishing Hairy from Downy

Hairy Woodpecker (Male)
It is sometimes difficult to tell a Hairy Woodpecker from a Downy Woodpecker.  After all, they really do look a lot alike.  These are our most common woodpecker species, the Downy being more numerous than the Hairy.  They are generally non-migratory so they are with us year round.  They are loyal feeder birds where they enjoy suet, peanut butter and seeds.

Downy Woodpecker (Female)
The Downy and Hairy Woodpeckers are birds of both coniferous and deciduous forests.  They feed on insects, caterpillars and pupae, spiders, nuts and fruit.  They play a significant role in keeping our forests healthy.  They nest in holes in trees.

The male of both species can be distinguished from the female by the red nuchal patch.  That is the small red patch at the top back part of the head.  This is lacking in the female.

Hairy Woodpecker (Female)
The Downy and Hairy Woodpeckers can be told from other woodpecker species by the white patch on the back and the white flanks.  After that it gets more difficult.  The Hairy is larger; 24 cm compared to 17 cm for the Downy.  The bill length is useful to distinguish the two species.  In the Downy, the bill length is much less than half the width of the head.  In the Hairy, the bill length is more than half the width of the head.  The Downy also has dark bars on the white outer tail feathers which the Hairy does not have.  These are not always easily seen but are evident in the female Downy above.

Downy Woodpecker (Male)
That more-or-less makes it reasonably easy to tell them apart.  The only other problem is that bills are longer in males than in females.  So, that makes the male Downy approach the female Hairy in bill length.  The bill of the male Downy is still shorter than half the width of the head, however.  Note in the photo above of the male Downy the bill is longer than in the female Downy but is still shorter than half the width of the head.  The barring on the white outer tail feathers is not visible in this photo.

Isn't birding fun?  It certainly has its challenges.  Now, we have one more difficult question.  I have wondered this for a long time.  Why do we have two species which are so similar?  If you think about it, we have similar situations in other animal species; for example, red fox and gray fox, brook trout and lake trout.  But these woodpeckers are so similar!  And they are distinct species.  They do not hybridize (interbreed).  The only answer I can find to this question is that that have evolved in the same niche.  They probably came from the same ancestor and split off a long time ago and then evolved in the same habitat and geographical location.  It is strange and amazing how nature works.

Perhaps you would like to comment!