Monthly Archives: September 2013

Invasion Of A Thousand Leaves

Plants & Fungi

Eurasian watermilfoil (photo by Charlie Hickey)

What are these spiky flowers Charlie Hickey found peeking out of a lake near his home?

Charlie identified them as Eurasian Water-milfoil (Myriophyllum spicatum) an invasive aquatic weed with soft, feathery, submerged leaves that form thick mats in North American lakes. Click on the photo and scroll down to read his description of it.

When I looked further I was amazed to learn that…

  • Eurasian Water-milfoil can propagate from a small piece of stem so a little bit caught in the boat propeller in one lake can be carried to another lake and spawn a new invasion.  I saw signs in Maine warning people to clean their boats after they take them out of the water.
  • North America has its own native water-milfoil called Northern Water-milfoil (Myriophyllum sibiricum).  The two species can be identified by their leaves but they hybridize and the hybrid inherits characteristics of both.  Very hard to identify.
  • The invader is hard to get rid of.  Many techniques have been tried including imported biological controls using a moth, a weevil and a fish.  The fish didn’t work out so well.  It prefers to eat native plants so it denuded the lakes and left the Eurasian water-milfoil for last.
  • In the Adirondacks and New England divers remove it by hand every year.  This technique is so successful that according to Wikipedia:  “After only three years of hand harvesting in Saranac Lake the program was able to reduce the amount harvested from over 18 tons to just 800 pounds per year.”

How did water-milfoil get its name?  My guess is that “milfoil” is a contraction of the French “mille feuille” which means “thousands of leaves.”

When it overruns a lake it looks like an invasion of a thousand — no, a million — leaves.

(photo by Charlie Hickey. Click on the image to see the original)

Duck Watching Downtown

Books & Events

Two ducks on the Allegheny River, mallard and giant rubber ducky (photo by Kate St. John)

Last night I went duck watching in Downtown Pittsburgh.

It’s easy to identify the large duck. Look closely and you’ll see he has company, a mallard in the foreground.

Rubber ducky is huge!  Here he’s about to go under the Ft. Duquesne Bridge.

Giant rubber ducky about to go under the Ft. Duquesne Bridge, Pittsburgh, 27 Sep 2013 (photo by Kate St. John)

Read more about the rubber duck and see photos and videos of his debut at the Pittsburgh Post-Gazette, KDKA and Pittsburgh Magazine.

See him for yourself on the Allegheny River near the Point.  He’ll be watching Downtown until (approximately) October 20.

 

(photos by Kate St. John)

Birds On The Wires

Bird Behavior, Tenth Page

European starlings on wires in Germany (photo from Wikimedia Commons)

Early this month Beth Lawry asked about the noisy flocks of songbirds now congregating in the Pittsburgh area.  She wrote, “I am seeing strings of them along the signs on the Parkway –- sometimes 50+.”    And on the wires.

These are flocks of European starlings (Sturnus vulgaris), some of the 200 million descendants of 100 starlings introduced in Central Park, New York in 1890-91.

Flocking has helped them survive and thrive in North America.  In flocks they have:

  • Better foraging success:  Individual starlings get more to eat when they can see their flock mates eating (Fernandez-Juricic, 2005).  They watch each other as they methodically walk across my yard eating grubs.
  • Reduced predation:  In flocks they have statistical safety in numbers, more look-out birds to warn of danger, and the ability to hide within the flock when they’re under attack as shown in this video of starlings evading a peregrine falcon in Torino, Italy.
  • Thermoregulation at the roost: Starlings hang out with each other all day and then gather into huge roosts at night where they huddle to stay warm.  At very large roosts they swarm at dusk, as seen in this amazing video from Ireland.

And they are noisy.  They mimic other birds (poorly) and make wiry sounds and wolf whistles.  Click here to hear.

The starling flocks we see this month are only a hint at what we’ll see by the end of the year.  More starlings are on their way.  Those who live in the northern part of their range fly south for the winter.  Those who live south of 40oN latitude do not.

Guess where Pittsburgh is.  40oN.  We’re probably a starling hotspot because our local birds stay put and the northern crowd joins them.

By the end of December we usually have 6,000 starlings(*).

Thousands of birds on the wires.

 

(photo from Wikimedia Commons. Click on the image to see the original. Today’s Tenth Page is inspired by page 320 of Ornithology by Frank B. Gill.)

 

(*) average of Pittsburgh and Pittsburgh-South CBC counts, 2001 through 2011.

Thousands Of Blue Jays

Migration

Blue jay (photo by Charlie Hickey)

There are times when I ask myself, “Where have the blue jays gone?” but this is not one of them.  They’re everywhere right now.

I think of blue jays as year-round residents — and they are through most of their range — but a good number of them migrate.  Their travels, however, are poorly understood because they’re unpredictable.

Some blue jays stay, others go.  Those who leave may be young or old (not just juveniles) and an individual who stayed last winter might leave this year and not the next.  Some don’t bother to come “home” in the spring and are found nesting further south. Others come home to nest but go further south each winter.  The only hint is that blue jays store and eat acorns in the winter so the mast crop may influence their decision to travel.

Blue jays migrate during the day in loose flocks of 10 to 30 birds that often pass by hawk watches. At Cape May, New Jersey, 1,000 to 5,000 blue jays pass by each day from late September through early October.  For the really huge numbers visit Holiday Beach Migration Observatory in Amherstburg, Ontario, 23 miles south of Detroit.

Because jays are reluctant to fly over Lake Erie, they hug the northern shore and funnel past Holiday Beach as they travel southward out of Canada. Typical days in late September and early October see 30,000 to 40,000 blue jays fly by.  The highest count was 264,410 on September 28, 2001.  Observers must have wondered if any blue jays were left in Canada after a day like that!

We never see numbers like this in Pennsylvania though we get a bump up in spring and fall.  Here’s a quick visual from eBird of blue jay population fluctuation in Pennsylvania, years 2009-2013.  Click on the image to see the real graph.

Frequency of Blue Jays in PA, 2009-2013 as of 9/24/2013 (screenshot from eBird)

 

The low point for blue jays in Pennsylvania is late December to early March.

Remind me of this when I ask you where the blue jays are this winter.

(photo by Charlie Hickey. Click on the image to see the original.)

 

p.s. Here are the blue jay record-setting dates from Holiday Beach, Migration Observatory.  Click here for all non-hawk species counts.
Blue Jay Record High Counts:
Sep 26: 1986 = 49,280,  1991 = 59,650
Sep 28: 2001 = 264,410*
Sep 30: 1990 = 51,470, 1993 = 87,000
Oct 1: 2009 = 158,300
Oct 5: 2009 = 152,750

The Sun Compass

Insects, Migration
Male monarch butterfly (photo by Marcy Cunkelman)
Monarch butterfly, 2008 (photo by Marcy Cunkelman)

25 September 2013

A week ago I saw my first and only monarch butterfly of 2013.  Their sudden disappearance is both troubling and saddening.  It’s now possible to imagine a world without monarch butterflies.  We are nearly there.

Last winter’s monarch survey in Mexico showed their population was down 59%, a record low.  There have always been population fluctuations but the trend has been running low and lower since 2004.  Scientists believe that agricultural pesticides and herbicides have reduced available poison-free habitat for butterflies (similar to the bees’ problem), so this spring monarch enthusiasts encouraged people to grow safe-haven milkweed for the butterflies.  It wasn’t enough.

Each species has an intrinsic value.  If, or when, the eastern monarch butterfly goes extinct we will lose its pollination contribution, milkweed symbiosis, beauty, and the amazing adaptations that allow multiple generations to migrate from Mexico to Canada and back.

One of the adaptations that will disappear is this:  Monarch butterflies have a sun compass in their antennae.

Their antennae have light sensors that track the amount of light each day.  According to a study in 2009 by Merlin, Gegear and Reppert, this circadian clock “provides the internal timing device that allows the butterflies to correct their flight orientation, relative to skylight parameters, and maintain a southerly flight bearing, as the sun moves across the sky during the day.”  Migratory monarchs without antennae fly in aimless directions.  Monarchs with antennae always orient southwest.

The monarch’s sun compass was discovered only a few years ago.  Now there are almost no monarch butterflies to study.  The world will be a poorer place without them.

Click here for more information on the monarch’s amazing sun compass.

(photo credits: monarch by Marcy Cunkelman, 2008)

Longest Migration

Migration, Water and Shore

While songbirds, hawks, and dragonflies are migrating this month there’s a bird whose journey beats them all.

The arctic tern sets long distance records in its pole-to-pole round-trip migration of 44,000 miles (71,000 km).  Since arctic terns can live 30 years, an individual can rack up a lifetime achievement of 1.5 million miles (2.4 million km).

The data behind this amazing feat was published in 2010 by the Arctic Tern Migration Project which studied arctic terns that nest in Greenland and winter in Antarctica.

To track the terns the scientists used tiny geolocator tags from the British Antarctic Survey, the same tags used to track wood thrushes.  In both studies scientists captured each bird, affixed a tag, then had to find the same bird on its breeding grounds a year later and recapture it to gather the data.  Wood thrushes don’t put up a fight but arctic terns relentlessly dive bomb their enemies to drive them away.  This study had bird hazards.

Attacking terns were not the only hazards.  Camping on an island off the coast of Greenland is no picnic.  “Our tents blew out to sea in the storm.”  Yow!

Watch this video from the Encyclopedia of Life to see the terns’ amazing migration and why it’s worthwhile for these birds to travel so far.

 

For more information, visit the Arctic Tern Migration Project at www.arctictern.info.

(video by the Encyclopedia of Life)

Green Darner Picnic

Insects
Common green darner dragonfly (photo by Tim Vechter)
Green darner dragonfly (photo by Tim Vechter)

23 September 2013

The weather was sunny and cold a week ago when I visited Flagstaff Hill so I was surprised to see over a hundred Green Darner dragonflies patrolling in the chilly breeze.  They were having a picnic.

Each dragonfly faced the wind and hovered, then wheeled away to a new spot and hovered again.  With binoculars I could see thousands of small insects being blown uphill in the wind.  The dragonflies reached out and grabbed them. Their wings glinted orange in the sun.

Green darners migrate south in the fall so I was witnessing a “flock” that happened to stop there for an easy meal.

I don’t have a video of their amazing maneuvers but this one shows how they do it.

(photo by Tim Vechter)

Sleepy Oranges

Insects

Male Sleepy Orange butterflies in New Mexico (photo by Steve Valasek)

I was captivated by this photo Steve Valasek took in New Mexico.  What butterflies are these?

Chuck Tague filled me in:

These are Sleepy Orange butterflies, Eurema nicippe (or Abaeis nicippe), a common sulphur butterfly in the southern U.S.  They range as far north as western Pennsylvania and occur regularly in a field near Mark and Loree’s place in Rostraver.   Some years they irrupt northward in good numbers.

The two in this photo are males.  They need minerals to reproduce which they’re extracting from wet mud or sand (called puddling).

Sleepy Oranges are common now in Florida.  I’ve raised several this year and collected an egg about a month ago that should emerge from its chrysalis this week.  Here’s a photo of one that just eclosed:

Sleepy Orange butterfly eclosing (photo by Chuck Tague)

 

Google “Eurema nicippe” and you’ll see that the ventral side of the butterfly (underwing, wings closed) is not as interesting as the dorsal side (top, wings open).  Click here to see a Sleepy Orange with its wings open.

 

And why “sleepy”?  There are two theories:  It flies slowly for a sulphur (this notion is disputed) –or– The two spots on its dorsal wings look like sleepy eyes.

 

(photo of two butterflies on mud by Steve Valasek, photo of eclosing Sleepy Orange by Chuck Tague)