26 October 2015

Did you know that tiny owls are passing through Pittsburgh right now?

Northern saw-whet owls are 7-8″ long, weigh little more than a robin, and have big yellow eyes.  They live in wooded habitats where they’re fierce predators of white-footed and deer mice.  Though small (and cute) they have “attitude.”

From mid October to December saw-whet owls migrate at night from their breeding grounds in southern Canada and the northern U.S. to points south.  Each one travels alone but not very fast.  Individual owls average 10km (6.2 miles) per night and tend to reuse the same route year after year.  Every four years the species irrupts in large numbers.

We know this because of Project Owlnet, a continental network of researchers investigating owl migration, founded by owl researcher David Brinker in 1994.  In 2011 Brinker analyzed 10 years of fall banding data (81,584 owls banded!) and published his findings in The Wilson Journal of Ornithology.   Click here to read the fascinating results.

Pittsburgh joined Project Owlnet in Fall 2013 thanks to ornithologist Bob Mulvihill of the National Aviary.  Each Tuesday, Thursday and Saturday night from mid October to early December — weather permitting — Bob and his volunteers set up mist nets and play the owl’s call from dusk to midnight at Sewickley Heights Borough Park.

Pittsburgh’s not a main migration corridor so there are nights when no owls show up but it’s exciting when they do.  Thursday October 21 was quite a success as Bob wrote on Facebook,

Our second night of owl banding produced our second owl of the season! And lots of folks on hand to be delighted by it! A few Orionid shooting stars, a continually calling Barred Owl, and a couple of coyotes howling in the distance made for another “Who knew urban ecology could be so wild!?” kind of night.

You’re welcome to attend Pittsburgh’s Project Owlnet. Dress warmly (bring a blanket!) and show up any time.  Be sure to read more here before you go!

Now’s the time to see saw-whet owls up close.

p.s. If you can’t make it out to the park you can still support the project by “adopting” a saw-whet owl on the National Aviary website.  Click here to read more.

(photo of owl in hand by Doug Cunzolo, photo of owl face by Bob Mulvihill, photo of Bob Mulvihill with owl by June Bernard)

Throw Back Thursday (TBT):

Broad-winged hawk migration is about to peak in Pennsylvania. Perhaps it already has.

Next on the Hawk Watch docket will be lots of sharp-shinned hawks, showing off their attitude as they fly.  The peaceful camaraderie of the broad-winged kettle is not for them.  Sharpies are just plain ornery!

Read about their attitude in this September 2008 article –>  Ornery

(photo by Steve Gosser)

Broad-winged hawks are on the move.  By the middle of this month their numbers will peak at Pennsylvania hawk watches.

In summer broad-winged hawks are secretive but by late August the birds have finished breeding and are ready to start their journeys to Central and South America.

Unlike most raptors, broad-wings travel in flocks, rising together in thermal updrafts, gliding out toward their destination.  At the bottom of the glide they find another thermal and rise again.  From a distance they look like rising bubbles so the flock is called a “kettle.”   The video above shows them gliding. Click here to read more about kettles.

Thermal updrafts are best over sun-heated land so the hawks avoid flying over lakes and oceans.  As they move south, the flocks grow in size and become concentrated at the northern edges of the Great Lakes and the Gulf of Mexico.  By the time they reach South Texas there are hundreds of birds per kettle and half a million broad-wing hawks per day.

To really see the sky filled with birds, visit the hawk watches at Corpus Christi, Texas or Veracruz, Mexico’s River of Raptors in the last week of September and the first week of October.

The video below shows broad-wings over Corpus Christi.  One kettle contains well over 1,000 birds!

(videos from YouTube. Click on the YouTube logo to see more information about the video)

The nesting season is over for most ospreys in Pennsylvania and some are already on the move.

In early August young ospreys stay close to home and practice their fishing skills under dad’s watchful eye, but it’s likely their mother has already left on migration.  This osprey family in Duquesne, PA is a case in point.

On July 19 Dana Nesiti photographed them when only two had fledged and their activity was still centered on the nest.

When Dana returned on July 25, all three had fledged and competition had intensified for their parents’ handouts.  Below, the youngster at right has food while two others squabble over a fish. The bird on the far left grabbed his sibling by the wing to pull him away. “Give it to me!”

The winner flew off with the live fish.

But now more than two weeks later, the nest is not the focal point and the family will be hard to find.

Ospreys live in family groups during the breeding season but otherwise live alone.  The family starts to break up shortly after the young fledge.  Mom leaves before the kids are independent while dad stays behind to feed them for 10-20 days or more.  When the youngsters are self sufficient they leave, too.  Finally their father departs, 7 to 39 days after his lady left town.

Because they eat live fish North American ospreys don’t dare to linger where the water will freeze.  They spend the winter in Central and South America and the Caribbean, each at his own favorite place.  The adults won’t meet again until they return to their breeding territory.  The juveniles will stay south for two to three years before they come north to breed for the first time.

After this family has left Duquense we’ll see other ospreys passing through but “our” birds will be gone until next spring.

(photos by Dana Nesiti)