Outside My Window

Now that the leaves are off the trees you can see birds’ nests that were used last summer.  The nests are abandoned now because most birds don’t use them outside the breeding season. 

The cactus wren is an exception.  The male and female build a selection of domed stick nests in the cactuses in their territory, usually in prickly pear or cholla.  You can see a nest hole in the middle of this photo of an old-man cactus.

The nests provide good protection from weather and predators so after the breeding season is over the wrens continue to roost in them.  Most of the time the cactus spines keep the birds safe, though some very careful climbing snakes can successfully raid the nests.

Here’s what the owner of such a nest looks like.  This cactus wren appears to be taking a dim view of the photographer.

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Roosting in one’s nest may be a wren trait.  On Sunday Marcy Cunkelman told me that a Carolina wren is again roosting in the woven nest on her front porch. 

Have you noticed this among wrens in your area?

(photo of nest in the public domain on Wikimedia Commons;  photo of cactus wren by Mark Wagner from Wikimedia Commons.  Click on each photo to see its original.)

Last week when I wrote about the Avian Architecture book, Sharon Leadbitter commented on two amazing nests she’d seen on the web.  Here’s one of them.

Sociable weavers (Philetairus socius) are sparrow-sized birds who live in the Kalahari desert in Namibia, Botswana and South Africa.

Unlike most birds who build a nest for their own babies and then abandon it when the young have flown, sociable weavers build a permanent structure that functions as a communal nest and roost.  It’s the size of a small car, the largest nest found anywhere, and can house up to 100 pairs of birds, their children and grandchildren.

The top of the nest is basically flat while the underside, shown above, is dotted with entries to the chambers.  The weavers build it entirely of straws which they shove into the structure.  This BBC video by David Attenborough shows how the weavers do it.

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Sociable weavers are such good builders that other species, such as the pygmy falcon, nest in the empty chambers while the weavers live there.

It’s an amazing feat for a small bird. They’ve built a city in a tree.

(photo BBC Worldwide video posted on YouTube.com)

The peregrines have flown and the eagles have fledged.  Most of the raptors are gone from the webcams but you don’t have to go through withdrawal.  You can still watch wild birds online.

Cornell Lab of Ornithology’s Nestcams website has many live webcams to choose from.  There are barn owls, bluebirds, wood ducks and even seabirds.  They also have archives from prior years.

Right now the chimney swifts in Glenham, New York are particularly busy.  They just hatched three fluffy white chicks on June 30. 

Click on the screenshot above to watch them.  Be patient.  It takes a while for the black square to become a video.  (I had better luck with Internet Explorer than with Firefox.)

When it’s hot outdoors, stay inside and feed your nestcam addiction.

(screenshot of chimney swifts from Cornell Lab of Ornithology NestCams)

This spring I’ve been amazed at the diversity of birds nesting in the city.  Why are they here?  Isn’t it more dangerous to nest in an urban area?

It turns out that city living offers some protection.

From 2004 through 2009, Ohio State University’s School of Environment and Natural Resources conducted a study on nesting success in the cities, suburbs and forests of central Ohio.  The results were surprising.

In rural areas, as expected, the study showed that where the number of predators is high, nest survival is low. 

But in the city this correlation breaks down.  Even though there are more predators, nest survival has no relationship to their number.

Why is this?

“We think that the reason for the lack of connection between predator and prey within urban landscapes is due to the amount of food provided by humans in urban areas,” said Amanda Rodewald, first author of the study and professor at OSU.

In other words, if the predators find something else to eat they don’t raid nests.

So now I don’t feel bad when the crows eat garbage.  It’s far better than eating baby robins!

Read more about the OSU study in Science Daily.

(photo of a black redstart’s nest by Michael Apel in Wikimedia Commons)

Purple martins (Progne subis) are our largest swallow and very social birds.  They flock together year-round and nest in colonies that may contain hundreds of pairs.

Originally, purple martins nested in natural cavities — and they still do in the West – but in eastern and midwestern North American they rely almost exclusively on man-made structures.  This habit began even before Europeans arrived on this continent.  Native Americans provided gourds, similar to the “condos” shown above. Our European ancestors started the tradition of multi-story “apartment houses” shown below:

Though highly social, purple martins are very territorial and will be aggressive to their own.  When the males first arrive in the spring they claim many nest holes and sometimes fight over them to the point of grappling in mid-air, locking claws and falling to the ground, still fighting. 

The females arrive later and fight over the holes too, but when egg-laying begins the territorial lines are well drawn and the colony settles into a period of peace.  Their condo living is so well settled that a bird may even defend his neighbor’s nest hole from an intruder while the neighbor is away.

Fighting among themselves is not really a threat to purple martin well-being.  The greatest threats are prolonged cold, wet weather and the invasive species who covet their nest holes.   The cold wet summers of Hurricanes Abby (1968) and Agnes (1972) so suppressed the flying insects that purple martins eat that Pennsylvania’s purple martin population crashed for a decade. 

Starlings and house sparrows are ongoing threats because they want the nest sites.  Their threat is best managed by the landlords who own (and must maintain!) the martin houses.  If you’re interested in attracting purple martins to your area, contact the Purple Martin Conservation Association based in Erie, PA (www.purplemartin.org) or the Purple Martin Preservation Alliance based in the Alle-Kiski area (www.purple-martin.org).  They’ll be happy to teach you how to attract and protect purple martins.  Get help from an expert before you begin. 

The purple martin houses pictured here are in a colony in Everett, Pennsylvania, a town on the Juniata River.  The colony was first established by a gentleman who set up three “apartment” houses many, many years ago.  His backyard has plenty of open space and is near the river so there’s a good supply of insect food. 

His neighbor a few doors down set up the colorful gourds.  

And Marge Van Tassel took their picture last weekend on a PSO outing.

(photos by Marge Van Tassel)

If you have bluebird nest boxes it’s mighty frustrating — and deadly to the bluebirds — when house sparrows take over.  

Sometimes, hard as you try, you can’t eradicate the house sparrows, but this year you can put them to good use.

Cornell Lab of Ornithology is doing a study on variation in eggshell colors and your house sparrows can help.  Here’s what to do, quoted from Cornell’s NestWatch eNewsletter:

“Because House Sparrows are a nonnative species, they are undesirable inhabitants of nest boxes in North America, but they are an easily accessible study species that can be used to address ecological questions without disturbing native birds.

“Researchers at the Cornell Lab of Ornithology are currently studying House Sparrows to help better understand the enormous variation in eggshell patterns and color. House Sparrow eggs exhibit an extraordinary amount of variation. Eggshell coloration and pattern may vary with available calcium, sunlight patterns, or habitat quality, and are expected to differ seasonally and geographically as well.

“You can help Cornell researchers gather information about the variation in House Sparrow eggs by submitting digital photographs of sparrow clutches so that the degree of speckling, spot size, and color tone of the eggs can be measured. Based on the variation that the researchers observe, they may find support for particular hypotheses about the underlying causes of eggshell color and patterning.

“To photograph eggs, please place them on a white piece of paper next to a coin for scale. Also, clearly write the date and location (town, state, zip code) on the paper next to the eggs before photographing, or include this information in the file name. Email digital photos to Dr. Caren Cooper (caren.cooper@cornell.edu).”

A Note from Kate:  Don’t do this with any native bird eggs!  Make sure you’re dealing with house sparrows before you begin!

(photo of a house sparrow eyeing a bluebird box, by Bobby Greene)

“Prrruurrpp!”   “Prruurrpp! ”

Last week I heard this sound for the first time this year.  It emanates from a low branch or a dense bush, sometimes from the ground.

“Prrruurrpp!”  is the sound of a newly fledged baby robin, begging for food.  The first batch of robins has fledged.

Baby robins always look vulnerable with their short frowning beaks, short tails, short wings and fluff-tufted heads. 

Indeed they are.  They don’t fly well and they make loud noises that could draw unwanted, predatory attention.  But for a baby robin, the noise is necessary.  It tells their parents, “Here I am and I’m hungry.” 

Don’t rescue these baby robins.  Their parents have not abandoned them.  The adults are gathering food nearby, rushing around collecting beakfuls of worms and bugs.  The noise tells them where to deliver it.

If you listen closely you can hear when food arrives.  The “Prrruurrpp!” is replaced by very loud cheeping and then a moment of silence.  Ahhhh!

Though there’s high mortality in the nesting through fledging stage, robins make up for it by laying three to five eggs per clutch and nesting two or three times per year.  The baby robin pictured above is probably from the second or third nesting since he’s perched among summer flowers.

In the end, more than enough baby robins survive to migrate with their parents in the fall.

(photo by Marcy Cunkelman)

Great horned owls are very versatile, the most widely distributed owl in the western hemisphere.  They range from Alaska to Tierra del Fuego and are found in forests, prairies, mountains and deserts, though they avoid the extremes of dense rainforest, hard desert and high Arctic tundra.

Adult great horned owls have no predators — not even humans will mess with them — but the babies are vulnerable.

Here are two baby owls just a couple of weeks younger than the Pennsylvania pair I featured on May 2.  Steve Valasek found them near his home in New Mexico.  Notice that they’re paler than their Pennsylvania relatives, a characteristic of southwestern great horned owls.

These two appear to be alone and one of them is telling Steve to back off.  

Look at those eyebrows! 

But just in case the stare doesn’t work, step back a bit and you’ll see who’s watching nearby!

Don’t mess with me!

(photos by Steve Valasek)

Dorothy laid her first egg of 2011 on Sunday, March 13 at 1:43pm.  Here are three photos of her with her first egg of the season. 

(The colors are a bit washed out. The egg is actually dark rusty red.)

Watch the peregrines at the Cathedral of Learning on the National Aviary falconcam.

(photos from the National Aviary webcam at the Univ of Pittsburgh’s Cathedral of Learning)

Sometimes a bird picks a dangerous place to nest.

In Tampa Bay, Florida a male osprey began building a nest to attract a mate but he chose a railroad signal tower as his ideal location.  It looked good to him, but it was a big problem for the railroad. 

Fortunately volunteers from the Audubon Society of Clearwater Florida had a better idea.  Watch the video to see how they worked with CSX to move the osprey’s nest.

Would the osprey accept the new location?  You bet!   Moving Day was a success.  Here he is perched at his new home. 

Now all he has to do is unpack the sticks. 

Thanks to Bob O’Malley for sending me this happy news.

(video and photo by Bob O’Malley)