The Connecticut Warbler’s Amazing Migration

Connecticut warbler in western PA, September 2013 (photo by Steve Gosser)
Connecticut warbler in western PA, September 2013 (photo by Steve Gosser)

Connecticut warblers are rarely seen on migration and it's not just because they skulk in dense underbrush.  A study published last May in Ecology shows they have a very unusual migration route.

McKinnon, Arturo and Love attached geolocators to 29 male Connecticut warblers in Manitoba in 2015, then recaptured four of them the following spring when they returned to breed.  The data from the geolocators shows the four birds followed similar routes to their wintering grounds in South America.

After flying east to the Atlantic coast with stopovers along the way each bird launched out over the open ocean and flew two days non-stop to the Greater Antilles, probably Haiti. After refueling in the Caribbean they flew again over the ocean to South America and the Amazon basin.

To give you an idea of this feat I drew a very rough map based on my reading of the study.  This map is not the real thing!  Click on the image to see one of the actual maps or here for all four.

Very rough drawing of the warblers' route by Kate St. John. CLICK ON THIS IMAGE to see the real maps.
My own rough drawing of the warblers' route. CLICK on this IMAGE to see the real maps.

With two long flights over open water, no wonder we don't see many Connecticut warblers in migration.

If you're really lucky you might see one this month in Pennsylvania.  Otherwise you'll have to wait until next year.

 

(photo by Steve Gosser .  map adapted from satellite image of the world at Wikimedia Commons)

p.s. Additional information about the study is here at Bird Watchers' Daily.

Webs in the Trees

In the spring we saw tents in the trees.  Now we see webs. Though similar in concept, the structures aren't made by the same species.

The springtime tent, located in the crotch of a tree, is made by eastern tent caterpillars (Malacosoma americanum) who emerge from their tent to eat young leaves as they unfurl.  The webs, located on the branches, are made by fall webworms (Hyphantria cunea) who hide in the web and eat leaves that will fall off in a month or two.

Since late summer female moths have been laying egg masses on deciduous trees.

Fall webworm moth (photo from Wikimedia Commons)
Fall webworm moth (photo from Wikimedia Commons)

After a week the eggs hatch into tiny caterpillars who build a web to completely enclose themselves and their food.  As they eat, they build the web larger to enclose more leaves.

Fall webworms avoid coming out of the web until they're ready to pupate. Then they hide their cocoons under flaps of bark to overwinter and emerge next year.

Though the webs look ugly they don't harm the trees because the leaves will drop soon anyway.

See webworms in action in the video above from The Capitol Naturalist in D.C.  Read more in this vintage article from 2011:  Coming Soon To A Tree Near You

 

(photo of fall webworm moth from Wikimedia Commons; click on the image to see the original)

Traveling Together?

Blackpoll warbler, Sept 2012 (photo by Marcy Cunkelman)
Blackpoll warbler, Sept 2012 (photo by Marcy Cunkelman)

As warblers migrate through Pennsylvania we find them feeding together in mixed flocks during the day.  Does that mean they were traveling together overnight?  Maybe not.  Warblers often have very different breeding and wintering destinations, making it hard to coordinate their trips.

Here are two extreme examples. Blackpoll and pine warblers look similar but you can't find two more different migration strategies. Their breeding and wintering grounds are as far apart as it gets.

The blackpoll warbler, above, is a long distance champion who travels 7,000 miles from his breeding grounds in North America's boreal spruce and fir forests to wintering grounds in South America.  To shorten the trip some of them fly non-stop over the Atlantic Ocean for 88 hours to reach South America's shore.

The pine warbler, below, never travels that far. His breeding and winter ranges are completely contained within North America from southern Canada to Florida and he's found year-round in the southern U.S.  Pine warblers breed in parts of Pennsylvania.

Pine warbler in April (photo by Anthony Bruno)
Pine warbler (photo by Anthony Bruno)

 

The maps below -- blackpoll (left), pine warbler (right) -- tell the story in three colors: Yellow is breeding range, Blue is wintering range, Green is year-round.

Range maps for Blackpoll and Pine warblers (maps from Wikimedia Commons) Colors: yellow=breeding, blue=wintering, green=year-round
Range maps for blackpoll and pine warblers (maps from Wikimedia Commons). Colors are: yellow=breeding, blue=wintering, green=year-round

 

As you can see, blackpolls leapfrog over the pine warbler's range.

Though I saw blackpoll and pine warblers in a mixed flock in Perry County last weekend, they probably weren't traveling together.

 

(photo of blackpoll warbler by Marcy Cunkelman; pine warbler by Anthony Bruno; maps from Wikimedia Commons: blackpoll and pine)

Schenley Park Outing: September 24, 8:30am

Monarch butterfly on goldenrod (photo by Marcy Cunkelman)
Monarch butterfly on goldenrod (photo by Marcy Cunkelman)

Let's get outdoors!

Join me on a bird and nature walk in Schenley Park on Sunday September 24, 2017 -- 8:30am - 10:30am.

Meet me at Schenley Park Cafe and Visitor Center where Panther Hollow Road meets Schenley Drive.

We'll visit Phipps Run and Panther Hollow Lake, looking for fall flowers and migrating birds.  I'm sure we'll see goldenrod though I won't know what species it is. (Goldenrods are hard to identify!)  Perhaps we'll see migrating monarch butterflies because the weather has been so warm.

Dress for the weather and wear comfortable walking shoes. Bring binoculars and field guides if you have them.

Before you come, visit the Events page in case there are changes or cancellations.  The outing will be canceled if there’s lightning (unlikely this Sunday but you never know).

NOTE!  The Great Race will run on Forbes and Fifth Avenue this Sunday. Approach Schenley Park from the Boulevard of the Allies and you'll avoid the detours.  Here's the road closure list and timing.

 

Rainbow Wonders

Double rainbow in my neighborhood at dusk, 14 Sept 2017 (photo by Kate St. John)
Double rainbow in my neighborhood at dusk, 14 Sept 2017 (photo by Kate St. John)

Last Thursday evening my husband and I were treated to a gorgeous double rainbow with parallel color bands under the main arc.  What are these wonders and what causes them?

First, some fascinating basics: Rainbows are caused by light hitting water droplets and being reflected, refracted and dispersed by them:

We saw the rainbow at dusk while the sun peeked below rain clouds and were surprised we could see the entire arc. Only those located at the geometric center of the rainbow, the antisolar point, can see it end to end.

Rainbow panomara (photo by Rick St. John)
Rainbow panomara (photo by Rick St. John)

Have you ever noticed that the sky under the rainbow is brighter than the sky outside it?  True!  Click here for an explanation (fourth paragraph).

And then there's the fancy stuff: the double rainbow and the extra bands under the arc.  To illustrate them I'll use this photo from Alaska that shows all of the features at the same time. Click on the image to open a high definition version in a new window and see them up close.

Double rainbow and supernumerary rainbows on the inside of the primary arc, Alaska (photo by Eric Rolph via Wikimedia Commons)
Double rainbow and supernumerary rainbows on the inside of the primary arc, Wrangell-St. Elias National Park, Alaska (photo by Eric Rolph via Wikimedia Commons)

Double rainbows happen when light bounces twice inside the raindrops before it exits.  The light goes inside, reflects off the back wall, reflects off the front wall, and then exits.  Double rainbows are parallel to the main rainbow, are not as bright, and their colors are reversed -- red-to-violet instead of violet-to-red.  I never noticed that. I'll have to watch for it next time.

The faint color bands just under the main rainbow arc are called supernumerary rainbows.  Wikipedia says they cannot be explained using classical geometric optics but they occur when the water droplets are less than 1 mm in diameter.  Fancy rainbows are complicated!

And finally, the end of the rainbow. From our vantage point it was in front of that tree on the horizon.

End of the rainbow in my neighborhood, 14 Sept 2017 (photo by Kate St. John)
End of the rainbow in my neighborhood, 14 Sept 2017 (photo by Kate St. John)

Irish legend has it that leprechauns hid their pots of gold at the end of the rainbow. I wonder whose house was there.

Rainbows move away as you approach.  There's no way to know.

 

(photos of neighborhood rainbow by Rick & Kate St. John. Alaskan rainbow by Eric Rolph via Wikimedia Commons)

The Marbled Godwit’s Bill

Marbled godwit (screenshot of video by Steve Gosser)
Marbled godwit (from video by Steve Gosser)

Yesterday's blog described an online class from Cornell Lab for identifying shorebirds.  Here's a shorebird you'll really enjoy seeing, especially when you know who he is.

The marbled godwit (Limosa fedoa) breeds in northern prairies and at Hudson Bay, then migrates to the Atlantic, Pacific and Gulf coasts to spend the winter.

The bird is 16.5 to 19 inches long but that includes a 3-5 inch dark-tipped pink bill.  The females are larger than males, big for a shorebird but small compared to a roseate spoonbill (click here to see).

The godwit's bill is a great tool for finding food.  Its length allows him to probe deeply for small mollusks, bristle worms, insects, leeches (yes!) and sago pondweed tubers, and it's so sensitive that he can feel his prey without having to see it.

Click on the screenshot above to see Steve Gosser's video of a marbled godwit at Conneaut Harbor, Ohio early this month. Watch as she probes rapidly, then pulls up her beak to swallow a morsel.  She plunges her bill so deeply that her face goes underwater.

She was one hungry bird!

 

(screenshot from video by Steve Gosser)

Shorebird ID Class: Online from Cornell

Be A Better Birder - online Shorebird ID class with Kevin McGowan

Do you find shorebirds hard to identify?  Cornell's Bird Academy has the online class for you.

logo_cornell_bird_academy

"As summer ends, shorebirds head from their Arctic breeding grounds to their southern wintering areas, passing through most of North America on their way.

What better time to build your shore-birding skills?

To celebrate the season, we have re-issued the recordings of Kevin McGowan's 5-part webinar series on Shorebird Identification, last presented live in 2014.

Over five hours of video instruction help you get to know the markings and behaviors of all the common shorebirds found in North America, 47 species in all.

The entire series is only $29.99 with unlimited access to all the archived video material plus downloadable handouts for each session to help you take notes."

Learn at your own pace with this archived five-part class.  Click here or on the logo above to sign up for the series.

 

(screenshots from Cornell Bird Academy)

The Chimney Air Show

This month chimney swifts (Chaetura pelagica) are migrating to South America, leaving before the weather's too cold for the flying insects they eat on the wing.

At dusk the flocks swirl around large chimneys then dive in to roost.  This video from New Glasgow, Nova Scotia shows them streaming into an old schoolhouse chimney.  Wow!

Don't worry when you see smoke coming out of the chimney at the end of the video. An observer explains:  "There are actually two flues in the chimney. The chimney swifts use the larger flue, while the smoke is vented from the smaller flue, so the birds are safe. In fact, they probably benefit from the bit of heat that comes from the smaller flue."

Stake out a chimney in town to enjoy the air show or monitor a wooden chimney swift tower near you.

Chimney swifts are declining and listed as "Near Threatened" so Audubon of Western Pennsylvania has placed chimney swift towers in our area.  ASWP needs your help tracking whether swifts are using the towers during migration.  Click here for information on how you can help.

 

(video from JimHowDigsDirt on YouTube)

p.s. Thanks to Joe Fedor for sending me ASWP's chimney swift news.

Where Peregrines Nest in the Wild

Precipice Trail, Acadia National Park (photo from Wikimedia Commons)
Precipice Trail, Acadia National Park (photo from Wikimedia Commons)

This year, for the first time since 1984, my husband and I aren't at Acadia National Park this month but I think of it every day.  If I was there I'd be stopping by the base of this mountain to scan for peregrines.  It's one of the few wild places where I know they nest.

On Throw Back Thursday here's a description of the peregrines' wild nest sites at Acadia with news from 2010:

Where The Peregrines Nest

 

(photo of the Precipice Trail at Acadia National Park from Wikimedia Commons; click on the image to see the original)

In Hot Water

Two men holding an Atlantic sailfish caught off the coast of Port St. Lucie, Florida (photo from Wikimedia Commons)
Two men holding an Atlantic sailfish caught off the coast of Port St. Lucie, Florida, 2010 (photo from Wikimedia Commons)

The warming ocean has been in the news lately as the most powerful Atlantic hurricanes ever recorded -- Harvey's rain and Irma's wind -- slammed into Texas, the Caribbean, and Florida.  The ocean is hotter now than any time since record keeping began in the 1880's and, though hotter water doesn't cause hurricanes we've learned it makes them worse.  Uh oh!

There's another sign the ocean is warming.  Fish are on the move.  A wide variety of species including sole, haddock, herring, and black sea bass have left places too warm for them and migrated to cooler water.

For example an enormous Atlantic sailfish (Istiophorus albicans), normally off the coast of Florida above, was caught in the Cape Cod Canal in August 2013.  It was the first Massachusetts record.

It's not just temperature that makes fish move.  Warm water has less oxygen, so it's harder to breathe, and more carbon dioxide so it's more acidic.  Acidic water holds less calcium carbonate, the building block of sea shells including those of tiny copepods.  With fewer tiny organisms there's less food all the way up the food chain.

Fish swim away from these "deserts" but some animals can't move very far. Think of lobsters, now gone from Long Island Sound.

The changes in species affect both fishermen and nesting seabirds.  The old catch limits refer to fish that can't be found because they've moved north, and baby puffins starve because the new species are too big for them to swallow.

From more powerful hurricanes to fish leaving home, we're in hot water!

 

Read more in this article from Yale e360: Feeling the Heat: How Fish Are Migrating from Warming Waters

(photo from Wikimedia Commons; click on the image to see the original)