Oct 19 2017

When Birds Lost Their Teeth

Published by under Bird Anatomy

 Model of Archaeopteryx on display at Geneva natural history museum (image via Wikimedia Commons)

Model of Archaeopteryx on display at Geneva natural history museum (image via Wikimedia Commons**)

Birds have no teeth but that wasn't always the case. We know that they're descended from toothy theropod dinosaurs -- in fact birds are dinosaurs -- so when did they lose their teeth?

In 2014, genome sequencing studies led by Robert W. Meredith worked to determine whether several branches of birds' ancestry lost their teeth independently (convergent evolution) or whether all birds have a common ancestor that evolved a toothless beak.

The project did full genome sequencing on 48 birds species representing nearly all modern bird orders.  They then focused their study on six genes related to tooth enamel.  All six genes became non-functional in a common bird ancestor around 116 million years ago.  That's when birds lost their teeth.

Birds eat plenty of things that require chewing so how do they do it?  Read this 2010 blog post Anatomy: Where Are Their Teeth? to find out.

 

More information on the bird genome project is here in Science magazine.

(cropped image of Archaeopteryx model on display at Geneva natural history museum via Wikimedia Commons; click on the image to see the original.  **Note that this Archaeopteryx model has accurate teeth but has other inaccurate/disputed features as described on Wikimedia Commons: "Archaeopteryx had a more round shape of its wings, the primary feathers were attached to the second finger unlike here, and these colours are now known to be wrong.")

One response so far

Oct 18 2017

Sea Level Fingerprints

As ice sheets melt around the world, fresh water that used to be held on land is pouring into the ocean and sea level is rising.  But it's not rising uniformly.  The transfer of mass (water) from land to sea causes changes in Earth's gravity field.  Mirroring the ripples in gravity, the water is high in some places and low in others like the ridges on a fingerprint.

The mysteries of gravity *

Gravity is a force of attraction.  It works on everything and in both directions. The Earth's mass pulls you toward it while your mass pulls Earth toward you.  The bigger the mass, the stronger the object's gravitational pull.  Greenland with an ice sheet on top has more mass than Greenland without one, so as the ice melts Greenland's gravitational pull goes down.

As Greenland's gravity wanes it doesn't hug the ocean to its shore like it used to.  The water has to go somewhere so it rises in the tropics.  The effect is tiny, measured in millimeters per year.   The pattern is called a sea level fingerprint.

The pattern revealed

Many things contribute to sea level at any given point including the Moon's gravitational pull (causing tides) and the wind (causing waves) so it took lots of data and some serious number crunching to reveal Earth's gravitational fingerprint.  The data came from the GRACE satellite project.

GRACE satellites have been circling the Earth since 2002, measuring the pull of gravity on the globe below.  (Here's how GRACE works.)  Each orbit provides a snapshot.  Years of data show the change in gravity over time.  Most gravitational changes are due to the movement of water, especially groundwater.

Using GRACE data, scientists from NASA and the University of California Irvine mapped gravitational changes affecting sea level from 2002 to 2014, shown on the map below.  Blue means low water, red is high. The calculations were verified using readings of ocean-bottom pressure from stations in the tropics.

Sea level fingerprints (patterns of variation in sea level rise) calculated from GRACE satellite observations, 2002-2014. The blue contour (1.8 millimeters per year) shows the average sea level rise if all the water added to the ocean were spread uniformly around Earth. Image credit: NASA/UCI

Sea level fingerprints (patterns of variation in sea level rise) calculated from GRACE satellite observations, 2002-2014. The blue contour (1.8 millimeters per year) shows the average sea level rise if all the water added to the ocean were spread uniformly around Earth.
Image credit: NASA/UCI

Notice that the ocean has receded the most near Greenland at the rate of -2.5 mm/year.  That's 32.5 mm or 1.28 inches in the 13 years that GRACE measured it.  As NASA explains:

The loss of mass from land ice and from changes in land water storage increased global average sea level by about 0.07 inch (1.8 millimeters) per year, with 43 percent of the increased water mass coming from Greenland, 16 percent from Antarctica and 30 percent from mountain glaciers.

Click here to read more about the study and see an animated map of sea level changes 2002-2014.

Unfortunately some of the hardest hit places will be tiny Pacific islands and Florida.

Who knew that the sea has a "fingerprint."

 

(fingerprint image from Wikimedia Commons; click on the caption link to see the original. Sea level fingerprint map from NASA/UCI joint project using GRACE satellite data)

* p.s. Note that gravity is so mysterious that I initially described it incorrectly.  Thanks to Dr. Allen Janis, I've corrected the description. See his comment below.

3 responses so far

Oct 17 2017

In November: Bald Eagles at Conowingo

Screenshot of video, bald eagles at Conowingo Dam, fall 2016 (from video by Gerry Devinney)

Screenshot of video, bald eagles at Conowingo Dam, fall 2016 (from video by Gerry Devinney)

Want to see a lot of bald eagles?

Make a trip to Conowingo Dam in Darlington, Maryland, just south of the PA border on the Susquehanna River.  There the dam's tail-waters attract hundreds of bald eagles in November.

Last year Annette and Gerry Devinney captured great footage of adult and juvenile bald eagles fishing and chasing below the dam.  Click on the screenshot above to see Gerry's video.

If you don't mind crowds, join the fun at Conowingo Bald Eagle Day on Saturday November 4, 2017.  Conowingo Bald Eagles and Support Conowingo Dam on Facebook posted this:

SAVE THE DATE: Eagles Day 2017 is here! Join us Saturday, November 4th 10:00am to 3pm at the Conowingo Dam Pavilion. This is a great opportunity to learn about breeding, nesting, and foraging of bald eagles around Conowingo Dam as well as the overall environmental impact of the dam. Exciting vendors and presentations throughout the day! If you plan on attending, please call 410-457-2427 or email takeaction@supportconowingodam.com. We hope to see you all there!

If you miss November 4, don't worry.  The eagles stay at Conowingo for many weeks.

Make a trip any time next month to see them here on the Susquehanna.  Click here for a larger version of the map below.

 

(screenshot from video by Gerry Devinney,"Gerry Raptor" on Facebook)

One response so far

Oct 16 2017

Peregrine At Arrivals

Published by under Peregrines

Peregrine at Landside Arrivals area, Pittsburgh International Airport, 9 Oct 2017 (photo by Becky Shott)

Peregrine at Landside Arrivals area, Pittsburgh International Airport, 9 Oct 2017 (photo by Becky Shott)

Sometimes a peregrine falcon shows up in the most unlikely place.  This one was hanging out at the Landside Arrivals area at Pittsburgh International Airport.

On October 10 Ed Shott left a comment on my How Old Is That Peregrine? post.

My wife [Becky Shott] is an Allegheny County Police officer at the Pittsburgh International Airport. Yesterday [Oct 9, 2017], she saw an adult Peregrine Falcon on the public arrivals area sitting on a wall between the Landside Terminal and the parking garage. Using her cell phone, she got a video and several still pictures of the bird. She was not able to get close enough to see if there were any leg bands. She also said she has seen possibly the same bird for the past six months. It has made repeated passes around the area possibly trying to grab one of the numerous pigeons that roost in the steel beams. However, she has not seen any evidence of a nest.   -- Ed Shott

When Becky sent her photos and video she wrote:

I was pretty close to this bird & could not see any bands. I have been seeing a peregrine (maybe more than one) around here for at least 6 months. Sometimes I see it chasing pigeons around the Landside terminal. Always a beautiful sight.

Indeed this is a gorgeous bird.  Here are more views of it on October 9, 2017.  And no, I don't see any bands either, even when I zoomed in.

Peregrine walking the wall at Pittsburgh airport Arrivals, 9 Oct 2017 (photo by Becky Shott)

Peregrine walking the wall at Pittsburgh airport Arrivals, 9 Oct 2017 (photo by Becky Shott)

Peregrine walking the wall at Pittsburgh airport Arrivals, 9 Oct 2017 (photo by Becky Shott)

Peregrine at Arrivals, 9 Oct 2017 (photo by Becky Shott)

Peregrine at Landside Arrivals area, Pittsburgh International Airport, 9 Oct 2017 (photo by Becky Shott)

Peregrine at Pittsburgh airport Arrivals area, 9 Oct 2017 (photo by Becky Shott)

 

Wow!  This bird doesn't seem to care that people are nearby as long as they don't disturb it.

Many times at the airport I've thought about the number of birds at the parking lots and garage, especially the huge flocks of starlings in winter.  But it never occurred to me that a peregrine would show up to eat them.

Thanks to the Shotts for alerting me to this peregrine.

If you're waiting to be picked up at the airport, watch across the driveway for a peregrine falcon.  You never know what you'll see.

 

(photos and video by Becky Shott)

4 responses so far

Oct 15 2017

Upcoming Events

Published by under Books & Events

Staghorn sumac in early November 2016 (photo by Kate St.John)

Staghorn sumac in early November 2016 (photo by Kate St.John)

Even though we're heading for winter the calendar is filling up with lots of bird events, so many that I'll list just four: three of mine and one at the National Aviary.

Sunday October 29, 8:30-10:30a
Duck Hollow and Lower Frick Park Bird Walk

Meet me at the Duck Hollow parking lot at the end of Old Browns Hill Road. We'll see migrating waterfowl on the river and walk the beginning of the nearby Lower Nine Mile Run Trail. Bring binoculars and scopes (for river watching) if you have them.  Check my Events page for updates or cancellations.

 

Thursday November 2, 6:00pm
Biophilia at Phipps: "Finding Pittsburgh's Winter Birds"

We often think there are no birds here in winter but that's far from the case in the city. On November 2 I'll give a short presentation at Phipps' Biophilia about Pittsburgh's winter birds and where to find them. Click here for more information.

Two male Northern Cardinals in winter (photo by Steve Gosser)

Two male Northern Cardinals in winter (photo by Steve Gosser)

 

Saturday-Sunday November 4-5, 10a - 5p, National Aviary Event
Opening Soirée, Friday November 3
Wings and Wildlife Art Show at the National Aviary.

The Wings & Wildlife Art Show is the National Aviary's annual juried show highlighting wildlife artists from across the region. Artists will be exhibiting and selling their art throughout the National Aviary during the first weekend of November. It's a great time to visit the Aviary's birds and buy a treat for yourself or gifts for the holidays. Click here for more information.

Wings and Wildlife Art Show 2017, National Aviary

 

Friday November 17, 10a
Audubon Day at Hillman Library: The Story of Peregrine Falcons at Pitt: The Dynasty Continues.

Why do peregrine falcons nest at the University of Pittsburgh's Cathedral of Learning? Where did they come from and where do they go? Come to the University of Pittsburgh's annual Audubon Day at Hillman Library where I'll tell the story of Pitt's peregrine falcons. Watch my Events page for more details including a link to Pitt's Audubon Day activities.

Peregrine falcon, Dorothy, defends her territory, May 25, 2004 (photo by Jack Rowley)

Peregrine falcon, Dorothy, defends her territory, May 25, 2004 (photo by Jack Rowley)

 

 

(photo credits: staghorn sumac by Kate St. John, northern cardinals in winter by Steve Gosser, peregrine falcon at Pitt by Jack Rowley)

No responses yet

Oct 14 2017

Autumn Raptors

Peregrine falcon, Hillary, in autumn in Ohio (photo by Chad+Chris Saladin)

Peregrine falcon, Hillary, in autumn in Ohio, before 2011 (photo by Chad+Chris Saladin)

Today, three scenes of raptors in autumn.

Above, a peregrine falcon flies over the Rocky River.  This photo of Hillary, who nested at the Hilliard Road Bridge in Rocky River, Ohio, was taken by Chad+Chris Saladin prior to 2011.

 

A bald eagle ascends at Glade Dam Lake, Butler County, October 2017.  Photo by Steve Gosser.

Bald eagle at Glade Dam Lake, October 2017 (photo by Steve Gosser)

Bald eagle at Glade Dam Lake, October 2017 (photo by Steve Gosser)

 

A red-tailed hawk migrates south past the Allegheny Front Hawk Watch, October 2012. Photo by Steve Gosser.

Red-tailed hawk flies by the Allegheny FrontHawk Watch, October 2012 (photo by Steve Gosser)

Red-tailed hawk flies by the Allegheny Front Hawk Watch, October 2012 (photo by Steve Gosser)

 

(photos by Chad+Chris Saladin and Steve Gosser)

One response so far

Oct 13 2017

Autumn’s Flying Ants

Published by under Insects, Fish, Frogs

Citronella ant, Lasius interjectus, with wings (photo by Alex Wild via SmugMug)

Citronella ant, Lasius interjectus (photo by Alex Wild via SmugMug)

On warm fall days look up and you might see swarms of flying ants.  Flying high, they're annoying at hawk watches.  What are these ants and what are they doing?  The answer is more interesting than you might think.

Flying ant swarms are the mating dance, the nuptial flight, of winged male ants and virgin queens.  Each species has its own time of year for mating.

If you've never seen a swarm here's what it looks like, filmed at a tall grass prairie in Nebraska (20 seconds).

 

The ants are so preoccupied with mating that they don't pay attention to what's nearby and are easy prey for migrating dragonflies, cedar waxwings, and even ring-billed gulls.

 

Don't worry. The swarms are not termites. Termites make their nuptial flights in the spring and, if you look closely, they're different from ants.  Ants have pinched waists and "nodes" at their waistlines. Termites do not.  Here's a visual comparison -- not to scale -- of fire ants on the left and eastern subterranean termites on the right.

Compare body shape of two wingless insects: fireants and eastern subterranean termites (photos from Wikimedia Commons)

Compare body shape of two wingless insects: fire ants and eastern subterranean termites (photos from Wikimedia Commons)

 

In autumn in Pennsylvania the swarms are sometimes citronella ants, Lasius interjectus (shown at top) or Lasius claviger, described here by Penn State Cooperative Extension.  The name comes from their lemon smell when threatened or crushed.

Citronella ants spend their whole lives underground except when they emerge to mate.  They're actually "farmers" who tend their livestock -- aphids -- and harvest the aphids' honeydew.  This video describes a citronella ant colony.

 

After the nuptial flight the male ants die and the fertilized queens shed their wings.  They don't just shed them, they yank them off!  Watch this citronella ant use two of her six legs to pull off each wing (7 seconds).

And then the queen walks off to find an underground place to nest.

There are so many ant species that it takes an expert to identify them.  If you know which ones fly at the Allegheny Front Hawk Watch in September, please let me know.

 

(photo credits: citronella ant photo Lasius interjectus by Alex Wild via SmugMug, composite photo of fire ants and eastern subterranean termites from Wikimedia Commons.  video credits: Ant swarm in Nebraska by Evan Barrientos on YouTube. Citronella ants by Chris Egnoto - The Naturalist's Path on YouTube.  Ant yanking off its wings by David Shane on YouTube)

3 responses so far

Oct 12 2017

When Will The First Junco Arrive?

Published by under Migration

Dark-eyed Junco (photo by Bobby Greene)

Dark-eyed Junco (photo by Bobby Greene)

Since mid-September summer has lingered in Pittsburgh with temperatures spiking 15-20 degrees above normal.  Does this mean fall arrivals will be delayed?

Here's what normally happens outdoors in late October and early November.  Let's watch to see if it's on schedule.

  • Fall colors peak in mid-October, especially red and sugar maples.  The oaks turn red at the end of the month.
  • First frost in Pittsburgh around October 20.  First hard frost around Halloween. (Really?!?  Keep your eye on this one.)
  • Most trees will lose their leaves by November 8.
  • Most flowers have gone to seed though witch hazel, bottle gentian, hardy goldenrods and asters are blooming.
  • The warblers are gone but white-throated sparrows, dark-eyed juncos and American tree sparrows will arrive to stay through winter.
  • Broad-winged hawks are gone but red-tailed hawks, kestrels and sharp-shins are now on the move. Don't miss seeing golden eagles at the Allegheny Front Hawk Watch from late October through November.
  • Fill your hummingbird feeder in October in case a rufous hummingbird shows up.
  • Big flocks of robins, grackles and starlings form at dusk and dawn. The Pittsburgh crow flock becomes noticeable in early November.
  • The first wave of migrant ducks and geese arrive with October cold fronts.
  • Chipmunks, squirrels, and groundhogs are storing food and putting on weight.
  • It's hunting season. Wear blaze orange and be aware of Pennsylvania’s hunting seasons.  Remember: Though Sunday is generally safer, some game can be hunted on Sundays.
  • Be prepared to "fall back" on the first Sunday in November when we set our clocks to Standard Time.  After that, evening rush hour will be in the dark.

When will the first frost come? When will the first junco arrive?

Stay tuned.

For more information, see Chuck Tague's Western Pennsylvania Phenological Perspective for October, first published in 2010.

 

(photo by Bobby Greene)

5 responses so far

Oct 11 2017

Warming Up to the Next Ice Age

Published by under Weather & Sky

screenshot from This Is Not Cool with Peter Sinclair, Yale Climate Connections

screenshot from This Is Not Cool with Peter Sinclair, Yale Climate Connections

The ocean is warming, the ice sheets are melting, and the sea is rising. Does global warming mean we'll be warmer here in the northern hemisphere?  Maybe not.

In this video by Yale Climate Connections, Jørgen Peder Steffensen, an expert in ice core analysis from the Niels Bohr Institute, explains how the Earth can become hotter yet simultaneously plunge Europe into an ice age and North America into ice or drought.  It's a matter of distribution.

Here are some points that stunned me in the video:

  • In the last 1 million years there have been 10 ice ages.  Each ice age lasted about 90,000 years.
  • Ice ages aren't uniformly cold. Far from it!  Steffensen says, "Inside an ice age the climate is extremely unstable, and you have this sequence of abrupt climate changes [semi-cold to very cold] that happen basically from one year to the next."
  • In-between ice ages are interglacial periods of milder, more stable climate that last about 10,000 years. We're in an interglacial period right now.  It's already 11,000 years old.
  • Earth can have an ice age in one place and be hot elsewhere.  Ice cores indicate that when Greenland has an ice age, Antarctica is warm -- and vice versa.
  • Earth's current mild climate is due to a global distribution pattern of ocean currents and pressure systems that keep temperatures mild and rainfall moderate.
  • The global distribution pattern can change abruptly.  We don't know where the trigger is, though we do know our emissions add fuel to the fire.

As Steffensen says, "The climate does not play nice all the time,"

Learn more at Yale Climate Connections:  Humans experimenting with climate's 'playing nice'

 

(screenshot and video from This Is Not Cool with Peter Sinclair, Yale Climate Connections)

 

One response so far

Oct 10 2017

How Old Is That Peregrine?

Adult peregrine falcon in flight, Univ.of Pittsburgh, 2016 (photo by Peter Bell)

Adult peregrine falcon in flight, Univ.of Pittsburgh, 2016 (photo by Peter Bell)

Now's a good time to brush up on identifying peregrine falcons since they pass by hawk watches in October, especially on the coast.  When you identify a peregrine you can also tell how old it is because the plumage is different in each age group:  adult, juvenile, and sub-adult.

Plumage provides an exact age for two groups in October:  Juveniles are first year birds, 6 months old, that hatched last spring. Sub-adults are second year birds, 18 months old, with nearly complete adult plumage.

Adults -- two or more years old -- all have the same plumage.  Unfortunately you can't know an adult's exact age unless the bird is banded and you find out its provenance.

Here's what they look like:

Adult peregrines (2+ years old in October) have fresh plumage in charcoal gray and white.  The photo at top shows an adult male in flight.  The photo below is an adult female.  Adults have:

  • Solid dark charcoal helmet (head)
  • Dark charcoal malar stripes (on face)
  • Clean white or slightly rosy chest and throat
  • Horizontal charcoal+white stripes on belly and flanks
  • Gray back: Male's is pale blue-gray.  Female's is "muddy" gray.

Adult peregrine, Univ of Pittsburgh, 2017 (photo by Peter Bell)

Adult peregrine, Univ of Pittsburgh, 2017 (photo by Peter Bell)

 

Juvenile peregrines (6 months old in October) are the same size as adults but their colors are brown+cream.  Juveniles have:

  • Variable brown helmet with some cream-colored traces (head)
  • Brown malar stripes (on face)
  • Cream colored chest that's striped all the way up to the throat
  • Vertical brown+cream stripes on belly and flanks
  • Brown back.
  • (Bonus!) Juveniles have cream-colored tips on their tails, visible as the sun shines through them in flight.

Juvenile peregrine in flight, Univ of Pittsburgh, 2012 (photo by Peter Bell)

Juvenile peregrine in flight, Univ of Pittsburgh, 2012 (photo by Peter Bell)

Above, a juvenile in flight.  Below a juvenile shows off the vertical stripes on his chest and belly.  His variable brown helmet with "eyes on the back of his head" and horizontal cream-colored line at his crown.

Juvenile peregrine falcon, Univ. of Pittsburgh, 2016 (photo by Peter Bell)

Juvenile peregrine falcon, Univ. of Pittsburgh, 2016 (photo by Peter Bell)

 

Sub-adults are 18 months old with nearly complete adult plumage except for a few juvenile feathers.  They began to molt into adult plumage last spring at 10-12 months old.  By October their few juvenile feathers are hard to see without a photograph.  They are ready to breed next spring.

Below, an 18-month-old peregrine named Spirit is in rehab at Medina Raptor Center in the autumn of 2014.  You can see her back is mostly gray with just a few brown feathers.  Her head shows faint traces of the juvenile cream colors.

18-month-old peregrine falcon, Spirit, in rehab at Medina Raptor Center, Nov. 2015 (photo by Kate St.John)

18-month-old peregrine falcon, Spirit, in rehab at Medina Raptor Center, Nov. 2015 (photo by Kate St.John)

For a view of sub-adult plumage in the spring, see these photos taken in March 2016 of a 10-month-old Juvenile Peregrine Falcon Transitioning Into Adult Plumage.

For additional tips, see Ageing Peregrine Falcons in the Field by Alex Lamoreaux at Nemesis Bird.

 

(all photos taken at University of Pittsburgh by Peter Bell ... except for the peregrine on the glove, "Spirit" at Medina Raptor Center, photo by Kate St. John)

2 responses so far

Next »