Monthly Archives: October 2013

Radar Shows Decline

Migration, Tenth Page

Southern Mississippi Sector weather radar, 9 Oct 2013, 6:38am (image from NOAA)

In one way this is very old news.  In another way it’s sadly up-to-date.

In the early days of radar surveillance, scientists learned that those mysterious blobs on the screen in spring and fall were flocks of night-migrating birds.  In 1965, as part of his graduate study at Louisiana State University, Dr. Sidney A. Gauthreaux, Jr. studied spring migration using radar images at Lake Charles and New Orleans along with his own on-the-ground counts as birds flew past his light beam or the moon.

Twenty years later, the news said that songbirds had declined.  Gauthreaux wondered if this was evident on radar so he collected data from the same two sites and compared the images from good-weather migration nights in 1965-1967 to those in 1987-1989.  In only 20 years he could see that the number of migrating songbirds had declined by 50%.   Half the number of warblers, tanagers, hummingbirds, shorebirds, flycatchers and thrushes made the trip.

That was 24 years ago.  It has only gotten worse.  I don’t know of a recent radar comparison (was there one comparing the 1980’s to 2000’s?) but our ground-based counts show that birds such as the king rail, cerulean warbler and olive-sided flycatcher are in dangerous decline now.  Just last month the eastern red knot was proposed for Endangered Species protection by US Fish and Wildlife.

Meanwhile, it seems ironic that so many people are becoming interested in birds while birds are becoming scarce, but it’s a good thing too.  The more of us that care about birds, the more likely we’ll learn what they need and work to insure their future.

 

(screenshot of NOAA weather radar, 9 Oct 2013, 6:38am EDT. Click on the image to see the current radar page.  Today’s Tenth Page is inspired by page 278 of Ornithology by Frank B. Gill.)

 

p.s.  This NOAA image shows the radar stations that were part of Dr. Gauthreaux’s study.   On Wednesday morning the weather concentrated migrants east of the Mississippi as they approached the Gulf Coast.

Peregrines As A Fitness Program

Bird Behavior, Peregrines, Water and Shore
Peregrine falcon at Lake Erie, Presque Isle, PA (photo by Steve Gosser)
Peregrine falcon at Lake Erie, Presque Isle, PA (photo by Steve Gosser)

10 October 2013

Here’s my favorite bird patrolling Lake Erie’s shore at Presque Isle State Park, looking for a meal.

And here’s a potential food source — a flock of dunlin.

Dunlin at Lake Erie, Presque Isle, PA (photo by Steve Gosser)
Dunlin at Lake Erie, Presque Isle, PA (photo by Steve Gosser)

The peregrine is looking for a bird that’s easy to catch, one that’s flying alone. The dunlin are sitting ducks (er… dunlin) if they stay on the ground so they fly and flock tightly as soon as they see a peregrine.  This interaction has made dunlin more fit in the years since the peregrine population has recovered from the DDT crash.

A 2009 study at the Fraser River delta on the Pacific coast backs this up.  Peregrines never went extinct on the West Coast but they were very scarce in the 1970’s.  During this period wintering flocks of dunlin safely roosted on the sand at high tide and became fat — and a bit slower — in early winter.

The peregrine population began to recover in the 1990’s and soon found tasty dunlin meals as they migrated past the Fraser River delta in fall and spring. The dunlin quickly learned it was unsafe to roost at high tide during the day because peregrines were on patrol.  Instead they began to spend high tide flocking over the open ocean, flying continuously for three to five hours.  With this exertion they became much more fit and are now are measurably thinner in early winter, the time when peregrines are passing by.

Peregrine falcons have provided dunlin with a fitness program.  Be fit or be eaten.

Click here to read more about the Fraser River dunlin study.

(photos by Steve Gosser)

Cute, Curious, Combative

Mammals

Red squirrel (photo by Shawn Collins)

So cute!  But watch out, he’s fierce.

His small size, soft red fur, fluffy tail and big eyes are certainly cute but the red squirrel is also curious and combative.  I think his food habits made him that way.

Unlike gray and fox squirrels, red squirrels (Tamiasciurus hudsonicus) don’t bury one nut at a time.  Instead they gather food in a big cache called a midden in a hollow tree or underground.  This takes a lot of time and effort:  climb the trees, walk the branches, bite off the green cones, watch them fall, scurry down later and collect the cones, repeat the process. Along the way they pause to eat at the same prominent locations leaving debris piles, also called middens, that seem to say “I am here!”

The red squirrel defends a 1 – 8 acre territory against everyone, especially other red squirrels.  He’s curious about new arrivals but then, watch out!

First line of defense?  Shout at the competition!  Burst into a sudden loud chatter that slows to a wheezy hiccup.  Really mad?  Jerk your tail and stamp your feet.  Really, really mad?  Chase!

In coniferous forests that’s usually another red squirrel but in mixed forests gray squirrels also get a verbal beating and relentless pursuit.  Though the red squirrels are only 1/2 to 1/3 the size of the grays, the red ones always win.

I, too, have been ejected from a red squirrel’s territory.  He used his voice.  Click here to read about it.

Now that winter is coming the red squirrels are changing into their drabber winter coats and rushing to increase their middens.  They have no patience for anyone.

Cute… ?

Don’t push me!

(photo by Shawn Collins)

Broad-Wings Pass Veracruz

Birds of Prey, Migration

At Hawk Mountain Sanctuary, this fall’s high count of 1,338 broad-winged hawks flew by the watch on September 20.  That number sounds large but those hawks join all their cohorts from North America to pass a small strip of land between the mountains and the Gulf of Mexico near Veracruz.

The Veracruz Hawk Watch is called the River of Raptors because more than 100,000 hawks per day may pass through between the September 20 and October 25.  During the first two weeks of the watch almost all of them are broad-winged hawks.  On September 23 the broad-wing count at River of Raptors in Cardel was 354,091.

Above, a slideshow video from a 2011 birding trip to Veracruz celebrates the hawk migration and shows the birds and scenery in the area. (Sorry about the ads.)

Below, a very short video shows the “river of raptors.”  A huge kettle of hawks circles up, then tails off in a broad river to the left, heading south.  The Spanish title of this video “Vortex Cambiando a Una Linea Ancha” means “Vortex Switching to a Wide Line.”

Wish I’d been there…

 

(videos from YouTube)

 

On Caffeine

Insects, Musings & News
Spider webs with and without the spide on caffeine (photo from Wikipedia)

7 October 2013

This blog is made possible by caffeine…  administered every morning in a 16 oz mug of coffee at 5:00am.  Boing!  I’m awake!   It works.  And it makes me happy.

Apparently it is not good for everyone.

According to Wikipedia, Swiss pharmacologist Peter Witt began testing different drugs on European garden spiders in 1948 because a zoologist friend of his, H. M. Peters, was annoyed that the spiders always wove their webs between 2:00am and 5:00am.  Dr. Peters wanted to study web building when he was awake, not when the spiders were.

Naturally it made sense to try caffeine.  Perhaps it would keep the spiders awake longer so that they’d “sleep in” and start weaving after dawn.

Not so!  Instead of time-shifting their web construction, caffeine made the spiders build whacky dysfunctional webs.

In 1995 NASA conducted a similar study and took photographs of the spider webs both before and after caffeine (above).

So much for Dr. Peters’ brilliant idea.  He was forced to study his subjects in the dark.  I’m sure he had to be on caffeine to do it.

(photo from Wikipedia. Click on the image to see the original)

This Is Exciting

Migration, Schenley Park, Songbirds

Yellow-rumped warbler, October 2013 (photo by Shawn Collins)

They’re here!  The yellow-rumped warblers are back from Canada, on their way to the lower Ohio Valley, the southern U.S., and Central America for the winter.

Yesterday Karyn Delaney and her husband stopped counting at 100 when they found so many yellow-rumps on the Pine Tree Trail at Presque Isle State Park.  Shawn Collins snapped this one in Crawford County.

Like the first snowfall I’m excited to see my first big flock of yellow-rumped warblers in southwestern Pennsylvania.  I haven’t found a flock yet but I think I’ve heard one bird — just one — at Schenley Park.

Unfortunately, just like snow I soon tire of them.  I remember at Magee Marsh last May when my first reaction to seeing yellow-rumped warblers was “Wow!” and within an hour it was “Darn!  Another yellow-rump.”  Their abundance becomes boring.

But I haven’t seen them yet, so for the moment this bird is exciting.

 

(photo by Shawn Collins)

Baby Grays

Birds of Prey

Great Gray Owl nest Aitkin Co 640×360 from Sparky Stensaas on Vimeo.

 

Have you ever seen a great gray owlet?

Most of us haven’t because the bird nests in bogs in the remote north woods.

Last summer photonaturalist Sparky Stensaas jumped at the chance to film a family of great gray owls at their nest in Aitkin County, Minnesota.

His video captured the owlets when they were just ready to leave the nest.  They’re fluffy and almost cute — except they have to grow up to match their beaks.

I’m impressed at how wise and old Mother Owl looks as she watches nearby.  I am also very impressed by the constant noise and vision of bugs flying close to the camera.  Were there mosquitoes in the bog?  Need I ask?

Play the imbedded video above or click here to watch the full screen video on Vimeo.

These babies are growing up great.

 

(video by Sparky Stensaas, thephotonaturalist.com)

p.s. A quiz for those who can bird by ear!  Can you identify the bird songs in the background?

Acorns Are Connected

Deer, Schenley Park, Trees, Winter Weeds & Trees
Acorns of northern red oak (photo from Wikimedia Commons)
Red oak acorns (photo from Wikimedia Commons)

3 October 2013

Stop and listen in Schenley Park right now and you’ll hear acorns falling, blue jays calling and squirrels scurrying.   It looks like a bumper crop for acorns in Pittsburgh. (*see p.s.)

Right now the red oaks are putting on a show.  Acorns in the white oak group mature in the same year they flower.  Acorns in the red oak group take two years to mature so those falling now were formed in the hot spring and summer of 2012, influenced by spring precipitation, summer temperatures and the date of the last killing frost.

Though we (usually*) don’t eat them, acorns are a key link in the woodland food web.  They’re so popular that oaks have evolved an abundance-scarcity strategy to throw off their consumers.  In some years acorns are so abundant that the crop overwhelms the acorn-eaters.  In other years they’re so scarce the consumers go hungry.  To further confuse things the oak groups cycle on different schedules: white oaks have a bumper crop in 4-10 years, red oaks on a 3-4 year basis.

Who eats these acorns?  Squirrels and chipmunks are the obvious consumers but plenty of other species depend on them including white-footed and deer mice, blue jays, red-headed woodpeckers and wild turkeys.  Deer, ruffed grouse, bears, mallards and wood ducks eat acorns, too.

The bumper crops have a ripple effect.  A 24-year study, headed by Clotfelter and Pedersen in the southern Appalachian Mountains of Virginia, followed the effects of acorn crops on rodent abundance, raptor abundance and the nesting success of ground-nesting birds.  They focused on white-footed mice, deer mice and dark-eyed juncoes and found these amazing acorn effects:

  • The population of white-footed and deer mice increases in the year after a bumper crop of acorns.
  • Rodents attract predators so the raptor population increases.
  • Too many rodents and raptors causes junco nest failure due to predation on eggs, nestlings and birds.
  • Mice eat gypsy moths so the gypsy moth population drops.
  • The number of ticks increases as white-footed mice and deer increase.

And then, this information from PLOS links acorns to Lyme disease:  Lyme disease increases predictably two years after an acorn bumper crop because white-footed mice are a main reservoir for the Borrelia burgdorferi bacteria.

Don’t blame the acorns.

Everything is connected to everything else.

(photo from Wikimedia Commons. Click on the image to see the original)

*p.s. Is this a bumper crop year?  I wrote about acorns because I’ve been dodging them in Schenley Park as they fall, but not all the trees are prolific.  Hmm….

*”We don’t usually eat acorns”:   Well, we can if we put a lot of work into it.  See kc’s comment!

RADical Day — Free Admission to the National Aviary – Oct 6

Books & Events

Regional Asset District Logo

RADical Days, an annual event now in its 12th year, is sponsored by the Allegheny Regional Asset District (RAD) and its funded assets to thank the public for the sales tax funds that support the region’s parks, libraries, sports and civic facilities and programs, and arts and culture organizations.

Visit the National Aviary on October 6th from 10 a.m. – 5 p.m. for no cost to all!