Banner clouds are stationary, orographic clouds that only form in high wind on the leeward side of an isolated, steep mountain. The Matterhorn, pictured above, is famous for them.
Banner clouds are so picky that we’ll never see them in western Pennsylvania simply because we have no isolated steep mountains.
… except …
Under the right moisture conditions a banner cloud can form above or just behind an airplane’s wings. Click here for an example.
Airplanes form banner clouds because there’s lower air pressure on top of their wings (to generate lift). The lower pressure results in lower temperature which results in condensation. Hence a cloud.
And for a really weird effect, check out this cloud around a fighter jet on the verge of breaking the sound barrier. The shape is so perfect it’s hard to call it a banner.
(photo by Zacharie Grossen on Wikimedia Commons. Click on the photo to see the original)
On Thursday the weather was warmer with much less wind. By mid afternoon I’d tallied three Best Birds: a merlin, an American golden-plover and a pectoral sandpiper.
When I was ready to leave I dawdled in the parking lot with the car doors open while I stashed my gear and ate a snack. Then I hit the road for South Portland more than an hour away.
I shouldn’t have dawdled.
Halfway between Bath and Brunswick I felt a sharp burning pinprick on the skin near my ankle. A pause… and then another pain right next to it. A pause… and then a third pain on my shin.
This was happening to my driving leg, the leg that was maintaining a steady 50-55 mph on Route 1, the leg responsible for applying the brake, the leg sheathed in a hiking sock and long pants. The leg I could not even look at until I found a place to pull off the expressway.
I remember wondering: Is something wrong with my leg? Had my nervous system developed a strange pain syndrome? Three more pinpricks!! What is causing this!??
And then a large mosquito flew up from the area near the gas pedal and headed slowly for the back of the car.
This was not a mosquito I was prepared for. This was no ordinary Pennsylvania woodland mosquito, the kind you can escape if you just keep moving, the kind that can’t cope with wind, that bites you almost painlessly, that can’t bite through clothing and would just as soon bite your neck as your ankle.
No, this was a salt marsh mosquito, a persistent and repetitive biter, the kind that flies with you as you walk, that bites right through your clothing, that prefers to eat your ankles and legs, that ruins many a day at the beach.
I was outraged! How dare she!
When I reached Brunswick the expressway ended. I pulled over and parked in a fast food parking lot. I looked in the back of the car and saw her resting on the wall near the back window.
Carefully, I opened the back passenger door. And then in one swat I killed her.
Last evening as I left work I heard a scrabbling on the edge of this huge satellite dish behind WQED. It sounded like claws scratching metal — almost as unpleasant as fingernails on a chalkboard. The noise attracted the attention of everyone nearby.
The sound was made by a red-tailed hawk who had landed on the dish to hunt rabbits in the weeds below. Not a good move! He slid down to the seam and stood lopsided, one foot higher than the other, gripping the edge.
Since he didn’t care that I was watching I took his picture with my cellphone. (He’s in the exact center of the photo.)
Fortunately it doesn’t matter if he hurts this dish as we haven’t used it for years. Trees have grown up around it and mossy dirt stains the inside. Like many defunct structures it’s too expensive to take down, so it’s slowly surrounded by urban wildlife.
I arrived in the afternoon, two hours before high tide and just after the remnants of Hurricane Isaac had passed. The wind was strong, the waves were enormous, and the shorebirds were crowded on the last bit of sand above the high water mark.
There was so little space for the birds that I could sit near two resting flocks of sandpipers and plovers — all semi-palmated — and watch them closely as they preened and slept.
At one point they all looked behind me. Over the far sand spit a pale, juvenile arctic peregrine zoomed low and raised the shorebirds into tightly synchronized flocks that wheeled and turned as one. The birds near me hunkered down and watched him try to split a bird from the flocks so he could close in and capture it.
But he was unsuccessful. I watched too, torn between wanting to see him to catch a meal and feeling protective toward “my” shorebirds.
“My” flocks must have felt some borrowed safety in my presence. Surely the peregrine wouldn’t hunt near a human — so they remained motionless with a wary eye to the sky, hoping that camouflage and my presence would be enough.
But the juvenile peregrine had other ideas. Suddenly he made a pass close to us. Some of the shorebirds flew to escape. I stood up for a better look at the peregrine and he made a second and third pass right next to me! At chest height!
By then I was cheering for the peregrine (I can’t help it), but my voice and enthusiasm were too much for him. He left for the far sand spit and then flew away southwest along the coast.
Of course, I don’t have a picture of the peregrine at Popham … but you can get an idea from this photo.
p.s. Yesterday Dorothy and E2 spent time bowing at their nest at the Cathedral of Learning. Soon the amount of daylight will be the same as in March when Dorothy lays eggs. Perhaps the light level reminds them of nesting season.
p.p.s. There were hundreds of monarch butterflies migrating last Wednesday at Popham — more than I’ve ever seen before.
At this time of year migrating thrushes and warblers spend their days eating and resting. Then at sunset they don’t sleep, they fly!
Most birds that flap to migrate choose to travel at night because the calmer air makes flying easier and they can see the stars by which they navigate.
From sunset until 2:00am — sometimes until sunrise — they are in the air above us flying in loose flocks kept together by contact calls. The number of travelers peaks between 11:00pm and 1:00am on nights with a north wind. We know this because they’re seen on radar.
Back when radar was first widely used during World War II operators noticed that many things showed up as blips on the screen including rain, snow, birds and insects. After the war, radar came into its own as a weather forecasting tool. Nowadays it’s easy for birders to monitor nighttime migration because weather radar is available on the Internet.
To demonstrate how birds show up on radar, Cornell University created a time-lapse video showing migration over the U.S. on the night of October 1, 2008. Read the explanation below, then watch the video above:
“This animation created by Cornell University researchers illustrates the use of a network of surveillance weather radar to record nocturnal migrating birds, bats, and insects in the continental U.S. from sunset to sunrise Oct. 1, 2008. The blocky green, yellow, and red patterns, especially visible on the east coast, represent precipitation; but within an hour after sunset, radar picks up biological activity, as seen in the widening blue and green circles spreading from the east across the country. The birds, bats, and insects take off, fly past, and get sampled by the radar beam. Note, the black areas on the map do not represent places without birds, necessarily, but rather places where radar does not sample.” — from futurity.org
You can watch migration, too. Tonight Pittsburgh’s wind will be from the north so you’ll see birds on the move if you tune in to the National Weather Service radar loops after sunset. Pittsburgh appears on two maps: Central Great Lakes and Northeast. Click on the links and watch bird activity appear after sunset and subside at sunrise. Remember that the best time is 11:00pm to 1:00am.
For more in-depth observations and hard core science, this 10 minute tutorial by David La Puma explains how to use Nexrad images to monitor migration. La Puma used to post daily radar migration updates for New Jersey on his blog at woodcreeper.com but has taken a break from it this fall.
(video from October 1, 2008 by Cornell University via YouTube)
p.s. Click here for Drew Weber’s analysis of last night’s activity posted on Nemesis Bird.
Though I’m back in Pittsburgh for International Rock Flipping Day (IRFD) I decided to flip a rock while in Maine, hoping for better results than I’ve found at home.
At first I met with no success.
I rolled the smooth egg-shaped rock pictured in my IRFD announcement blog but found only spider webs.
I tried a few rocks in a tidal pool but was unable to get a clear photograph of the underwater inhabitants.
Then I tried this one, a granite rock in Northeast Harbor. It was obviously cut for a purpose with an odd notch at the top left, a half moon circle at bottom, and a chiseled mark on its face, but it was discarded and became a garden border.
And so I flipped it…
… and found the best stash I’ve seen in the four years I’ve participated in IRFD.
Pictured above are a proliferation of grubs (top center), two translucent copper-colored insects with hind legs like crickets (I have since learned these are camel crickets) and one gray snail with leopard spots and no shell (right side).
I couldn’t identify the grubs and cricket-insects but I googled “gray snail with leopard spots in Maine” and found the Limax maximus otherwise known as the great grey slug or leopard slug.
The leopard slug is truly an exotic creature. Consider this:
According to Wikipedia it’s one of the largest keeled air-breathing land slugs in the world. Adults can be 4-8 inches long.
Originally from Europe they were first documented in basements in Philadelphia in 1867. By now they live in both Maine and Pittsburgh so I could have found this slug at home.
Though it looks like a snail without a shell it actually has a small shell on its back under its skin shield. When frightened it draws its head under the shield. That’s why this one looks headless.
Leopard slugs are active at night and even then they aren’t very active.
They will eat anything, even other slugs. So I wonder: Why are there other critters under the rock? Won’t the slug eat them?
They live about 3 years, taking 2 years to reach sexual maturity.
They are hermaphrodites, each one equipped with eggs, sperm, and a large, elaborate, translucent, white penis that emerges from a hole on the right side of their necks.
Most amazing of all is their elaborate courtship and mating ritual in which they entwine and drop down on a strand of slime (read about it here).
Just like their leopard namesake, their spot patterns are unique from one individual to the next. So, yes, I found a leopard under a rock.
(photos by Kate St. John)
p.s. Be sure to see the comments below for links and videos of more under-rock finds.
Northern gannets were the most numerous sea bird on my whale watch trip this year. Some were adults, some were juveniles, but few had the peachy colored head feathers of these breeding adults.
This pair was a lucky shot. When the photographer took their picture they were mirror images of each other.
Posed perfectly. Frozen in time.
(photo by Des Colhoun via Wikimedia Commons. Click on the photo to see the original, including a link to its geographic location.)
As I’ve said before I live in a deciduous place so the ways of conifers are sometimes mysterious.
Take pine sap for instance. My annual visits to Maine have taught me to check before sitting down under a white pine. Mainers know that their state flower drips sap (yes, white pine cones are the State Flower of Maine) so they don’t put lawn furniture in the drip zone. I had some unfortunate experiences with pine sap before I learned this.
Only the female cones cause this problem. Male cones are small pollen-laden structures that appear in the spring at the base of new growth. They release huge amounts of pollen, then fall off the tree.
The female cones form on the branch tips and capture the wind borne pollen. It takes two years for them to mature into the familiar woody cone that opens when dry to release the seeds. Along the way they’re green and drippy.
Why do immature cones drip sap?
That question spawned this post but I haven’t been able to find the answer.
However I have some theories.
Theory 1: The cone has to dry out as it matures. Maybe dripping is part of that process.
Theory 2: Pine sap has insecticidal properties. Maybe the oozing sap keeps insects away from the developing seeds.
Theory 3: Maybe the sap also keeps squirrels away from the immature cones.
I don’t know why they drip, but the sap certainly keeps me away from them.
p.s. If you know why pine cones drip sap, please leave a comment and let me know. It’s driving me nuts!
True confessions. When I’m in Maine I usually go on a whale watching trip but my real goal isn’t whales, it’s pelagic birds.
I’m not the only birder on the whale watch boat. There’s usually a dozen of us keeping our eyes peeled for gannets, shearwaters, jaegers and storm petrels.
Storm petrels are my favorites because they’re so dainty. Only the size of starlings, they appear to walk on water as they search for food.
The most common type in the Gulf of Maine in early September is Wilson’s storm petrel, pictured above. When I learned where they came from I was amazed.
Wilson’s breed in colonies on the coast of Antarctica. Like most storm petrels they nest out of sight in crevices and burrows and only visit their nests under cover of darkness. That’s how they hide their eggs and young from raiding gulls and skuas.
When not breeding they live on the open ocean and never come to the land, but they’re easy to see on a pelagic trip because they’re willing to approach boats.
So while it’s winter on the southern ocean I get to see this Antarctic visitor off the coast of Maine. Soon they’ll journey back.
(photo by Patrick Coin via Wikimedia Commons. Click on the photo to see the original)
