Jim Williams has been watching birds and writing about their antics since before "Gilligan's Island" went into reruns. Join him for his unique insights, his everyday adventures and an open conversation about the birds in your back yard and beyond.

Posts about Bird biology

Red-tailed Hawks mating

Posted by: Jim Williams Updated: April 14, 2014 - 10:44 PM

These are photos of a pair of Red-tailed Hawks mating. I've been watching this pair for about two weeks, ever since I discovered their nesting site. A few days ago I was fortunate enough to be on site and in the right place when their brief mating encounter took place. Both birds are using their wings for balance. The male is on top. The female has raised her tail and pulled it to the left. (Her tail is light, showing a reddish tint). In the first photo the male has his tail (dark rectangle) in its usual position as he mounts the female. To transfer sperm, the male also twists his tail to the left ( second photo) to facilitate contact of his cloaca with the female's cloaca. This particular encounter lasted about five seconds. Development of the egg in the female takes about 24 hours. The female will lay one egg per day until she has a complete clutch of one to five eggs. Incubation takes from 28 to 35 days. If the egg has markings, those are deposited on the shell during its passage through the uterus. Rapid movement through the uterus produces streaks of color, slower movement spots. Red-tailed Hawk eggs are white or buffy, marked with buff, brown, or purple.  

Sandhill Cranes dancing

Posted by: Jim Williams Updated: April 1, 2014 - 5:32 PM

The Sandhill Crane pair being seen west of our home in Orono was dancing yesterday. I watched them for a couple of hours, and got to see two brief dancing bouts. A neighbor told me they nested at this location last year, producing one colt. It disappeared after a week, probable coyote victim. I've heard of nesting in other years, but never have seen the birds after early spring. I intend to be more observant.

Whamo!

Posted by: Jim Williams Updated: March 30, 2014 - 1:43 PM

If you read the interview with David Sibley in last Wednesday's StarTribune you know that in his new book falcons no longer appear after eagles and hawks. In the first edition, as in all other guide books, falcons are grouped with other raptors. Sibley has moved falcons back with the parrot family. He did this because, he explained, recent DNA studies show falcons to be more closely related to parrots than other raptors. In that regard, Rick Fournier of Minneapolis sent me this comment.

The movements of an urban Snowy Owl

Posted by: Jim Williams Updated: March 27, 2014 - 5:06 PM

The Minnesota Snowy Owl that has been tracked by GPS signals since Jan. 26 has moved to a location west of Cosmos,  Minnesota. That is a shift 15 miles west-northwest from its previous site south of Hutchinson. It moved to Hutch from its long-time location in Ramsey, Minnesota, west of Anoka, where it was netted and given its transmitter. This bird is named Ramsey. It is one of 21 Snowy Owls equipped with transmitters by ProjectSNOWstorm, based in Pennsylvania. The project was initiated when the owls began being seen in the eastern U.S. by the hundreds earlier this winter. The owls and the technology came together as a unique opportunity to follow movement of these birds. You can track Ramsey and the other owls at www.projectSNOWstorm.org.

Below is an image (©ProjectSNOWstorm and Google) from the project website showing the movements of an owl located in urban Baltimore. The transmitter on this bird was set to record location every 30 seconds instead of 30 minutes. The illustration shows movements over a two-hour period.

ProjectSNOWstorm will follow the birds as they move back north to breeding grounds. Information is sent to project headquarters via cell-phone technology. The data is downloaded whenever the birds are within range of a cell-phone tower. Yes, there are few if any cell towers in Arctic Canda, but the transmitters can collect and store thousands of pieces of location data for transmission when possible.

You also can use the website to make a contribution to help with financing of the project.

Great Horned Owl and chicks

Posted by: Jim Williams Updated: March 23, 2014 - 10:13 PM

A Great Horned Owl nest holding the hen and two chicks can easily be seen at Silverwood Park in St. Anthony. (Park personnel have established a limit to approach to prevent disturbing the birds.) The hen and her chicks are nesting in the hollow of a broken branch in a large tree very close to a paved walking path, about 30 feet up. Visitors should have no problem locating the birds. Just look for the photographers, ever-present at this unusual viewing opportunity. The young owls appear to be about six weeks old. The male owl often can be seen perched, sound asleep, high in a nearby tree. That bird, as you can see from the photo below (not a very cooperative bird) is much lighter than its mate. Coloration of this species is highly variable. This female has typical adult coloration. The male tends more toward the lighter birds found most often far north. Great Horned Owls can be so light as to resemble Snowy Owls. This one is far from that, but interesting nonetheless. The owls should be visible for several more weeks. Once the young birds leave the nest they often remain in its vicinity. To find them, drive to the park’s most distant parking lot. There is a paved walkway leading between two park buildings. Follow that pathway approximately 200 yards. You might also find interesting the courtship behavior of at least seven Eastern Chipmunks in a tangle of brush and fallen logs immediately to the right of the walkway from the best owl-viewing spot. Friday, they were chasing each other incessantly. The chipmunks are very obvious right under the eye of the female owl. The male owl, the family’s provider, sleeps during the day, hunting at night. Perhaps that explains the mammals’ apparent daytime nonchalance.

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