Wednesday, February 27, 2008

Birds-in-Flight: Herring Gull

Reminder: Click on the photo to see an enlarged copy.
Back in the fall of 2003, we took an extended weekend trip to Cape Cod and included a ferry ride from Falmouth to Martha's Vineyard.
There is nothing like a daily ferry with tourist to attrack sea gulls. Of course, a crew member throwing popcorn from the top deck helps also.

The gulls came within 10 feet of the top deck - the gulls got popcorn while I got lots of photos.
All of these are Herring Gulls, a common gull found throughout North America.

Without a reference in these photos it is hard to appreciate that these gulls are the size of a red-shouldered hawk with a 4 1/2 foot wingspan.
The Herring Gull is part of a complex of large, white-headed gulls that breed across the northern hemisphere. Some people consider all of the forms as one species, while others would recognize 10 or more species. [Cornell]

Tuesday, February 26, 2008

Birds-in-Flight: Red-Shouldered Hawk Perched on Habitat Feeder

The red-shouldered hawk can be observed in Colvin Run Habitat about once every 6 to 8 weeks. When observed, the red-shouldered hawks are in flight overhead or perched in one of the trees on the perimter of the one acre backyard habitat.
But two days ago, a mature male red-tailed shouldered hawk perched right on top of the sunflower seed feeder. He stayed less than a minute, then flew at about 5 feet off the ground and then perched in one of the perimter maple trees.
As soon as his mate called out, he was off to the top of white pine trees, calling out to her as he went.
Fifty weeks ago, a mating pair of red-souldered hawks was observed in the Habitat. At that time, an immature female was the one on the ground in the Habitat. Could today's hawk be the male from that pair? As red-shouldered hawks ofter return year after year to the same spot, I am betting that this is the same pair.

Monday, February 25, 2008

Birds-in-Flight: Cedar Waxwing

As a quick follow-up to the last post, here are two more photos of the cedar waxwing in flight - well, sort of.
In both of these photos, the cedar waxwing is landing on the water pump tub. Given the rarity of the cedar waxwing in the Colvin Run Habitat, I just could not resist a second, and highly likely last, post about the cedar waxwing.

Sunday, February 24, 2008

Migration Underway: Cedar Waxwing

In our last post, a migrating flock of robin visited the Colvin Run Habitat and brought with them the bird perched on the water pump tub (middle of the photo, back to the camera). Who is this? This perviously never observed in the Habitat bird is a cedar waxwing.
This regal looking bird is the size of robin, but is usually one of the last birds migrating north as they eat berries and fruit, which certainly are not available in Viriginia in late February or even early March. My guess is that this particular waxwing was wintering with other birds including these robins. When the robins came north, this waxwing just came along.
As you can see from this third photo, the coloring and the crown of the waxwing, especially when perched in the trees, is very similar to the female cardinal. Once you notice the yellow-tiped tail and the orange (nearly red)-tiped wings, you'll never confuse the waxwing with the femal cardinal.

Cedar waxwings with orange instead of yellow tail tips began appearing in the northeastern United States and southeastern Canada beginning in the 1960s. The orange color is the result of a red pigment picked up from the berries of an introduced species of honeysuckle. If a waxwing eats the berries while it is growing a tail feather, the tip of the feather will be orange.
The cedar waxwing is one of the few temperate dwelling birds that specializes in eating fruit. It can survive on fruit alone for several months. Unlike many birds that regurgitate seeds from fruit they eat, the cedar waxwing defecates fruit seeds. The cedar waxwing is vulnerable to alcohol intoxication and death after eating fermented fruit. Cornell

Saturday, February 23, 2008

Migration Underway: American Robin

Last Sunday at about 3 in the afternoon as I was completing my work for the Great Backyard Bird Count, I noticed a single robin perched in the oak tree among a number of male and female cardinals.
Then, another robin appeared in the dogwood and still another appeared in the Bradford pear tree. Within a minute, there were two dozen robins in the Habitat. Clearly, a migrating flock of robins had picked the Habitat as a stop over on their way north.
They quickly found and enjoyed the water available in the tub and the flower pots. The robins mingled with the other birds and were still in the Habitat when the sun went down. I did not see them the next morning. I have not seen them since. In this 2 hour period, I saw more robins in the Habitat than will be observed throughout the spring and summer months.
Take a close look at this last photo. Notice a bird other than a robin? Who is this previously unobserved-in-the-Habitat visitor? Stay tuned. We'll talk about this fellow in our next posting.

Friday, February 22, 2008

Migration Underway: Yellow-Bellied Sapsucker

This week in 2007, I observed for the first time a yellow-bellied sapsucker. Yes, the yellow-bellied sapsucker is real and not a fictional bird. Since that time in 2007, the yellow-bellied sapsucker has not been seen. Until this morning.
This morning, two yellow-bellied sapsuckers - a male and female (chin and throat red in male, white in female). They were both on the same maple tree. In fact, it was only when I looked closely at the photos that I realized these were two different birds.
Given the timing of these two observations and limited observations, it is clear that these are migrating woodpeckers. The yellow-bellied sapsucker is the only woodpecker in eastern North America that is completely migratory. [Cornell] That is, their summer and winter regions do not over lap; or, they do not stay in one region year around.
After some additional study, two other observations. First, it is clear that the yellow-bellied sapsucker has been in the Colvin Run Habitat for the last week or so based on the song provided at [Cornell]. Second, shown in the last photo are deep round holes that the sapsucker inserts its bill into to probe for sap and rectangular holes which are shallower. New holes usually are made in a line with old holes, or in a new line above the old.

Saturday, February 16, 2008

Birds-in-Flight: Red-Tailed Hawk

On a quick excursion out of the Colvin Run Habitat today, we found this red-tailed hawk perched at the top of a tall oak tree.
We stopped the car, grabbed the camera, and began shooting.
I wanted to get a shot of him still perched, but he saw me coming and got airborne.
Identifying Birds-Cornell Ornithology reports a maximum perched height of 26" and a maximum wingspan of 52". This red-tailed was certainly reached that size - if not larger.
He was visable at least 100 yards before his perch as we approached in the car.
These are great examples of the red-tails features: the red tail, the light unederside, and the dark head.
When perched and viewed from the back, this red-tail showed only dark brown.

Monday, February 11, 2008

Birds-in-Flight: Cooper's Hawk

Four species of hawks have been observed in the Colvin Run Habitat: Red-Tailed Hawk, Red-Shouldered Hawk, Sharp-Shinned Hawk, and Cooper's Hawk. In our birds-in-flight series, we showed the first two in the last two postings. The Sharp-Shinned Hawk has been photographed, but never in flight. The Cooper's Hawk is perhaps the most frequently observed hawk in the Habitat, but the least frequently photographed in flight.
In the last post, I discussed the poor technical quality of some of the in-flight photos - low light, hawk subject in motion, photographer in motion, difficulty of auto-focus when hawks are in the trees. In these photos of the Cooper's Hawk, we eliminate the low-light and photographer in motion challenges. In the first photo, the Cooper's Hawk is stationery. In fact, he allowed me to get directly under his perch 15 deep up a tree; he then stayed still for several minutes while I photographed him. The result was a clear, crisp photograph.
On a different day, but with similar lighting, I took the last three photos. The Coop was stationery, perched about 30 feet up in a different tree. I approach a step at a time (that is, approach, stop, photograph, take one step, then repeat). When the Coop gets uncomfortable with my approach he takes to flight.
When the Coop did take to flight, he simply leaned foward and began to glide (second overall photo) - wings are tucked. As seen in the last two photo, the Coop finally extended his complete wingspan and began his down stroke.
These are great examples of the Cooper's Hawk navigating in flight through thick tree branches.

Sunday, February 10, 2008

Birds-in-Flight: Red-Shouldered Hawk from Ground to Tree Perch

This red-shouldered hawk, along with its mate, appeared in the Colvin Run Habitat early last March. They were observed perched, calling, and flying together for over an hour.
They had been seen for a few minutes at a time for the preceding month. Given the time and the amount of calling this day, I believe that they proceeded to the top of one of the white pine for mating.
I include them here for two reasons. First, I used the third photo (using markings on a branch cropped out of the photo) to measure the wingspan of this hawk after the fact. The wingspan measure 64" (yes 5 foot 4 inches). Given the size, I believe that this is the female of the pair. Given the markings, I believe that this is a realatively young (on the immature side) hawk.
Second, this is an excellent example of power - consider what it took for this large, heavy hawk to simultaneously jump, spread its over 5 feet of wings, and get a down stroke in before falling back to the ground.
These next photos show the progression from in-flight barely off the ground to being perched on a tree branch about 7 feet off the ground.
As it approaches its targeted perch, the hawk seeks more lift and less speed. Similar to an airplane, the hawk puts its flaps down.
It does this by, rotating its wings from a horizontal to a near vertical position - increasing lift and decreasing speed. All birds do this as they approach a perch. The result is that they, counter to our intuition, approach a perch from below, not from above - they flight up to, not glide down to the perch.
And, with that power and lift, the hawk perches on the tree branch.

You might ask why the technical quality of these photos are, well shall we say, not the best. First, the hawk was in near constant motion. Second, I was in near constant motion - these photos were taken by me walking to within 30 feet of this hawk. Third, the photos were taken on a cloudy day - not lots of light. The telephoto lense that I was using requires lots of light, else the shutter speed and aperture are not optimal for crisp photos. Fourth, the hawk is flying among tree branches. These tree branches confuse the camera's autofocus mechanism. In short, subject and photographer moving, low light, and focus in progress as photo is shot. Oh, to be sitting still to take slow walking marine birds on a beach in sunny Florida.

Friday, February 08, 2008

Birds-in-Flight: Red-Shouldered and Red-Tailed Hawks

Let's take our birds-in-flight series to the raptors - a type of bird that we find soaring high about the Colvin Run Habitat, as well as down perched on tree branches and sometimes on the ground.
We start with the Red-Shouldered Hawk shown in all but the very last photo. In the first photo through a bit of digital darkroom magic, we have a red-shouldered hawk circling a few hundred feet above the Habitat. Same hawk, each photo taken about a second apart.
In the second and third photos, we get a from-the-underside and from a head-on perspective. The hawk in the third photo was only 20 to 30 feet above the camera location.
A friend, who recently moved to Austin, Texas, sent an email this week saying that her new residence had lots of hawks. In the exchange of emails, we shared our mutual frustration in attempting to identify specific species. The identification is made difficult as the hawks typically do not allow get close enough to make possible an identification (long lens are required). Further there are multiple subspecies (the red-shouldered has 5 subspecies) - and then there are the variations of immatures versus matures (immatures are sometimes larger than mature males), female versus male (female hawks are typically the larger of the two), then eastern versus western variety within each species, and the complexity grows from there.
There are three photos here of red-shouldered hawks with trees in the photo.
I include these trees-in-the-photo shots to give some reference of size. I have measured red-shouldered hawks in the Habitat with wingspans of nearly 5 feet.
In the next photo, we have a red-shouldered hawk (bottom right hand corner) and a red-tailed hawk. So how do I typically tell the two apart? First, the red-shouldered hawks have alternating white and dark bars on the tail; the red-tailed hawks have as the name says a red tail. Second, the red-shouldered hawk as its name says has a red shoulder and redish-orange breast, where the red-tailed hawk has pale wing undersides and pale breast. Thank goodness these photos were taken in January, when the broad-winged hawks are in central and south America, where they winter. The broad-winged and the red-shouldered are primarily differentiated by the size and number of bars on their tails.
The closest observed red-tailed hawk was one about 50 feet above the Habitat.