Archive for July, 2008

Jul 31 2008

What to my wondering eyes should appear…

Published by under Doves & Chickens

…but two pigeons in the Pitt peregrines’ nest box!

Based on the time stamp on this photo, the pigeons showed up in Dorothy and E2′s nest only 20 minutes after I posted my blog about pigeon overpopulation yesterday.

Do they have ESP?  Did they read my blog and decide to make a point?  Did they get the feeling they ought to put in a defiant appearance?

Obviously the peregrines weren’t paying attention.  They’ve been napping a lot because they’re molting.

Yesterday at lunch my friend Karen and I saw Dorothy and E2 perched in nooks on the edge of the 32nd floor, facing the wall, their backs to the world.  I guess if you’re at the top of the food chain you can turn your back to the world with confidence.

No need to worry the peregrines will go hungry.  They can have breakfast in bed if they want!

(photo from the National Aviary falconcam at University of Pittsburgh)

4 responses so far

Jul 30 2008

Too much of a good thing

Rock pigeon flock (photo by Chuck Tague)

Being a peregrine fanatic I’m kind of fond of pigeons – at least from the prey point of view – so when I was in downtown Pittsburgh on Sunday I stopped by Mellon Square to check out the scene.

Even for a peregrine falcon the number of pigeons at Mellon Square is way too much of a good thing.  I counted more than 150 and I couldn’t see all of them.  The pigeons outnumbered people more than 30 to 1.

This explains why peregrines hang out on the Oliver Building window sills.  It’s like visiting an all-you-can-eat restaurant.  The food may not be that great but there’s so much of it!

This kind of pigeon over-population repulses most people and they want a quick fix, the quickest being poison.  But if you poison a pigeon, you’ll poison a peregrine.  After a culling episode pigeons reproduce fast to fill the void – in fact lethal control actually increases the flock - but the peregrines take years to recover.  And peregrines are endangered in Pennsylvania.  It’s bad, bad, bad to poison an endangered species.

So what to do?

Pigeons need two things to reach the numbers found at Mellon Square:  lots of food and places to nest.  They reproduce in direct proportion to their food supply.  If food is scarce some won’t nest at all.  If food is plentiful they lay the next clutch of eggs before the first set has hatched, producing more than 12 chicks per year.

The food problem is obvious.  Sidewalks at Mellon Square are coated with bird seed.  Control the food source (the people who feed them) and you’ve got most of the problem licked.   To make a really dramatic difference, control the nest sites as well.

City pigeons nest on buildings and bridges.  They also nest in buildings.   Find the buildings involved and spend the time and money to block the access holes.  Last summer the University of Pittsburgh cleaned the Cathedral of Learning and blocked off the pigeon nest holes as part of the cleaning job.  One year later there are far fewer pigeons at Schenley Plaza.

And finally, there’s a foolproof solution that makes both the pigeon-feeders and the pigeon-haters happy.  Many European cities have solved their pigeon problem permanently by building dovecotes and pigeon lofts.  Yes, they built nest sites.  They control the population at the dovecotes by substituting dummy eggs and they control the food level by giving pigeon lovers an approved place to feed and interact with the birds.

This keeps the pigeons and the birdseed off the street.  An elegant solution.

(photo by Chuck Tague)

5 responses so far

Jul 28 2008

Trying to hunt

Published by under Birds of Prey

Drinking coffee on my front porch has its advantages.  Saturday morning I saw an immature coopers hawk trying to find breakfast at Magee Field.  

When he first showed up he looked pretty good chasing a flock of pigeons.  But they were too fast for him and the flock was too dense.  They could tell he was harmless and just wheeled in circles.

Meanwhile all the birds fell silent until they figured out the hawk was inept.  He jumped from branch to branch pausing to see if anything was easy to catch.  No, not as easy as he expected.  He was so unskilled that he made a lot of noise and motion with every jump.

All the birds joined in jeering at him.  The adults made warning noises while the young cowered.  Seven crows showed up and made rattling sounds in his direction.

Time and hunting practice are crucial for this immature hawk.  He must master the art of hunting very soon or he won’t survive his first year of life.  

Such a baby.  Even though he eats the birds I love, I hope he makes it.

(photo by Chuck Tague of an immature coopers hawk at a rehab facility)

4 responses so far

Jul 26 2008

Seasonal Indicators

Published by under Insects, Fish, Frogs

I know summer is half over because I can hear it – a buzzing in the trees that rises and falls in waves.  The cicadas are singing.

Every year by July 15th the annual cicadas come out in Pittsburgh, a convenient marker of summer’s midpoint.   Some people call them dog-day cicadas because they appear in July. 

Cicadas are harmless insects who live most of their lives underground, emerging as winged adults for a brief time to mate and die.  As soon as they emerge they climb a tree and molt their exoskeleton.  When I was a kid my brother and I used to collect the shells: me to examine them, he to place them in unlikely places – like on my back – as a surprise. 

Most cicadas live 2-5 years underground but part of the population matures every year so they look “annual” to us.  This is in stark contrast to the periodic cicadas whose entire brood emerges every 17 years, swamping the area with millions of bugs.  The last time I saw this phenomenon was in Beaver County in 2002.   I’m happy to see a few cicadas but that many bugs was like an insect horror flick. 

The cicada’s buzz is the male’s way of attracting a mate.  He’s specially equipped with timbals on the sides of his abdomen that make clicking sounds when they expand and contract and his abdomen is partly hollow to amplify the sound.  He vibrates the timbals incredibly fast – and it’s loud.  The noise gives away his location.  That’s good for finding a mate but bad for avoiding predators. 

And that’s the bird connection here.  Many birds eat cicadas.  The 17th year brood is probably a feast for birds but at other times they have to work hard to catch them.  I’ve seen house sparrows chase them down and beat them up until they stop moving.  The bugs are as big as a house sparrow’s head – a rather evenly matched battle. 

For some reason I’ve never paid attention to the point when cicadas disappear.  I wonder if they’re gone when the Dog Days end in September.

(photo by Chuck Tague of an annual cicada on a Swamp Thistle)

4 responses so far

Jul 24 2008

The babies’ crib

Two weeks ago Chuck Tague sent me photos of a red-eyed vireo’s nest and a baby bird quietly resting in it.  The vireo’s nesting season is nearly over so you may not see these wonders now, but I couldn’t resist writing about them as they’re such a great illustration of the energy a small bird puts into nesting. 

The red-eyed vireo suspends her nest from the fork of a thin horizontal branch.  Though she hides it in a leafy place, she often builds it only 5-10 feet off the ground so it’s possible to encounter it at eye level.  The nest is 2.75 to 3 inches in diameter - so small you could hold it in the palm of your hand. 

The female builds the nest alone in only five days using spider webs to attach it to the branches and hold it all together.  She uses bark, grasses and thin paperlike substances and lines the inside with finer material such as pine needles and animal hair.  Sometimes she decorates the outside with lichens. 

All of this work is done for only one purpose – to provide a safe, hidden bed for her babies. 

Three to five days after she finishes construction she lays 2-4 eggs, one egg per day, and incubates them alone.  In 12-14 days they hatch.  She and her mate both feed the nestlings; ten to twelve days later they fledge. 

As soon as the babies leave the nest it is never used again.  It is truly a babies’ crib, not a permanent home.

Sadly, brown-headed cowbirds sometimes find the vireo’s nest and force her to raise their young instead of her own.  I’m happy to see Chuck found a baby red-eyed vireo in this nest and not a cowbird.  This mother’s work was not in vain.

(photos by Chuck Tague)

6 responses so far

Jul 22 2008

V is for Vulture

Published by under Birds of Prey

Turkey vulture in flight (photo by Chuck Tague)

Lately several people have asked for help identifying huge dark birds.  Based on the descriptions I think they’re seeing turkey vultures.  Here are some pointers so you can solve the mystery on your own.

Turkey vultures are large dark birds of prey with a 5.5 foot wingspan.  Because of their size they are confused with many hawks and even eagles. The best way to know the difference is to watch how they fly.

Hawks tend to soar with their wings held flat.  Bald eagles have such a flat profile that they look as if they have “wings like planks.”

Turkey vultures soar with their wings in a dihedral — a shallow V.  They rarely flap and even seem to avoid flapping by teetering from side to side.  No other big bird consistently teeters with its wings in a V.  “V is for Vulture.”

From a distance, turkey vultures look different than other large birds because they have relatively small heads and beaks (compared to hawks and eagles) and their legs don’t extend beyond their bodies (compared to herons and cranes).  As you can see in Chuck Tague’s pictures, these birds are dark below with a pale trailing edge on their wings and small red faces.

Until a few years ago I only saw vultures in the country but now they’ve come to town.  They nest along our rivers’ wooded hillsides and rise aloft on the heat from Downtown and the stadium parking lots.

In the afternoon they soar in search of carrion which they locate by their keen sense of smell.  They’re so good at finding rotten odors that natural gas companies out West located leaks in their pipelines by watching where the turkey vultures congregated.

When you see large soaring birds teetering with their wings in a V, think “V is for Vulture.”

(photos by Chuck Tague)

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Jul 20 2008

City raccoons

Published by under Mammals

Birds are pre-empted by mammals today because…

Early this morning as I drank coffee on the front porch I heard an unusual scrabbling noise at the base of my neighbor’s blue spruce.  A raccoon was running up the tree!

Raccoons living near people is no surprise, but you rarely see them during the day.  I hated to see a coon at that tree because it’s loaded with bird nests so I made my best cat-hissing sound.  Stupid me.  The raccoon got scared and climbed even higher. 

I went inside to get my binoculars and returned quietly.  After a while four raccoons came out of the tree and ran across the street to Magee Field.  At the edge of the park they nosed around for fruit and considered crossing the street again.  I could follow them with my ears as carolina wrens, blue jays and robins announced their every move.  

I got a laugh when the tom cat who rules our neighborhood noticed the raccoons and charged across the street at them.  The coons’ hair stood up on the backs of their necks and they all reached for a tree to climb.  The cat stared them down and left.

There were certainly determined to cross the street.  At one point I was surprised to see three sets of eyes peering out from under my car.  I cat-hissed again.

Four!  All of them were adult sized so they must be this year’s grown-up kits and mother on the prowl for food.  Yow.  If these coons reproduce next winter the neighborhood will be overrun!

(photo by Chuck Tague of a raccoon family in Florida.  They’re everywhere!)

 

 

 

p.s.  Aha!  Now I know why they wanted to come over here.  It hasn’t rained for days and I have a bird bath in the backyard that sits on the ground.  After I finished this blog I noticed the bird bath was empty but damp.  Thirsty raccoons.

One response so far

Jul 18 2008

Scarlet baby

Published by under Songbirds

Scarlet Tanager nestling (photo by Chuck Tague)There are so many baby birds to write about that I’m having a hard time keeping up.   Chuck Tague sent me this photo a month ago.  That’s how far behind I am.

You’re probably wondering why I called this little brown bird a scarlet baby.  It’s because he’s a prematurely fledged scarlet tanager.   You can see what he’ll look like as an adult if you click on his picture.  Quite a difference.

Male scarlet tanagers change color many times as they mature.  If this baby is male, it will take him two years to become solid red and black like his father.  You can see all the scarlet tanager plumage variations – both male and female – by clicking here.  It’s bewildering how many colors the same bird can be.

Scarlet tanagers molt twice a year.   The male is red and black in breeding season, green and black in the non-breeding season which tanagers spend in northwestern South America (Columbia, Ecuador, Peru).  The female is always yellowish green.

Those who see green-colored scarlet tanagers from November to March must wonder why we call them scarlet.   I’m sure they have a different name for them. 

Maybe one of you can tell me what it is.

p.s.  See the comments below for the answer!

(photo by Chuck Tague)

5 responses so far

Jul 16 2008

Rough wings

Published by under Songbirds

Last Saturday I walked along the Monongahela River on the South Side trail.  Near the Liberty Bridge I heard the familiar spitting sound of northern rough-winged swallows.   “Brrrt   brrrt  brrrt”.  

I looked up in the deep blue sky and finally found them, zipping by so fast that they were hard to see.  Fortunately, Chuck Tague photographed one so I can show you what they look like:  uniformly brown on top and on their throat, with a white belly and a square tail.  

Why are they called “rough-winged?”  Because their outer primary feather (the long flight feather) feels rough when you stroke it.  The males have recurved barbs on this leading feather that are rougher than those found on the females.  No one knows why they have this feature.

Swallows hunt insects in the air and swallow them as they fly.  Just like the goldfinch, their diet governs when they nest.  In the swallows’ case they lay eggs in May and the young fledge by mid-July so they can start life when insects are most plentiful. 

Northern rough-winged swallows nest in burrows excavated by other species.  This includes burrows humans have made such as drain holes in the sides of retaining walls and small pipes under bridges.   Perhaps the swallows I saw had nested at the Liberty Bridge or in the holes in the walls along the river.

I’m glad to see swallows.  I am not fond of bugs!

(photo by Chuck Tague)

One response so far

Jul 14 2008

Male Peregrine at Pitt identified

Published by under Peregrines

Early this spring I noticed a new male peregrine falcon had claimed the nest site at the University of Pittsburgh replacing the original male, Erie, who had nested there since 2002.  The new bird’s identity was a mystery because no one had read his bands.  Knowing we would refer to him frequently, my friend Karen and I gave him a temporary name for the sake of convenience.  The name E2, meaning “the second Erie,” turned out to be prescient.

For many months he eluded us.  He wouldn’t perch in sight of people and the webcam images were not robust enough to read his bands.  So, after the young had left the nest Dr. Todd Katzner agreed to zoom the Aviary’s webcam in hopes we could capture a close-up of the bands.

Last week I obtained several good snapshots of E2’s bands and sent them out for second opinions with no hint as to what I saw.  Six of us read the bands.  Everyone saw Black/Green, 5*/4*.   This means E2 was born at Pittsburgh’s Gulf Tower in 2005, offspring of Louie and Tasha2. 

This year he successfully fledged three young peregrines at the Cathedral of Learning with his mate Dorothy.   Because he was not recorded nesting elsewhere, we presume this was his first successful nesting year.

The most interesting part of E2’s identity is his ancestry – and it’s why I asked so many people to read his bands.  His father Louie was born at Pitt in 2002, offspring of Dorothy and Erie, so E2 is a second-generation descendant of his mate. 

This is no big deal because: 

  • Peregrines are wild birds who do not socialize in flocks. They have no extended family. They know only their parents and nest mates.
  • Peregrine genealogies have been well tracked for more than 30 years. Closer relationships between mates have occurred, including brother-sister and parent-child, without ill effects.
  • Peregrine falcons choose mates from a relatively small gene pool.  They were extinct east of the Mississippi only 35 years ago and have rebounded thanks to a captive breeding program begun in 1974 from the few remaining available adults. I don’t know how many pairs were bred at that time but I’ve heard it was about 20.
  • There are very few excellent peregrine nesting sites, thus concentrating the competition.

I had thought that E2 was a temporary name and we would find out his real name when we learned his identity, but Pennsylvania peregrines are not named when banded.   Interestingly, his identity as Erie’s descendant means that we stumbled on his real name from the start.  He really is “E2.”

Amazing how that worked out.

(photo from the National Aviary falconcam at University of Pittsburgh)

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Bird Stories from OnQ