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San Francisco Nest Diary 2010:

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May 27, 2010: Four eggs hatched. Four young were raised to fledging age. Four young (two males, two females) were successfully fledged and are living in the skies above San Francisco, California. I am grateful to the many people who gave up time at work, leisure time, and time from family obligations, to sit with these birds during the time that they fledged from the nest ledge on the 33rd floor of the Pacific Gas and Electric Company headquarters at 77 Beale Street. Careful observers may now see the family of six from vantage points along the Embarcadero near Cupid's Span and the Ferry Building during the next month or so. It has been a terrific year. Thanks for watching. --2010 Nest Diary Entries contributed by Glenn R. Stewart.

May 24, 2010: Three of four young have fledged safely and are living 30 or more stories above San Francisco.

38 Days oldMay 16, 2010: The four San Francisco PG&E babies are 38 days old today. They will fledge (fly for the first time) during the coming week. Males often fledge at 41 days old and females at 43 or 44 days old. (Females are larger, and thus, require a slightly longer period of development). There are many variables to fledging and it can really occur at any time from this day forward. Their nest box is on a ledge that spans the entire southeast face of the 33rd floor of the Pacific Gas and Electric Company headquarters building in San Francisco’s Financial district at 77 Beale Street. The corridor presents the eyasses with a place to practice flying and landing which is a great advantage to them prior to fledging. Several buildings in the immediate area of the nest ledge present roof tops and wide ledges upon which eyasses can make an easy landing. Still, tall buildings with reflective glass present confusing obstacles. A degree of luck is needed during fledging from an urban nest ledge, or from a cliff ledge in the wild. We wish these birds good luck in the coming week, in their quest to be peregrines, living fully on the wing.

BandingMay 7, 2010: At about noon on May 3rd, we banded two males and two females at about 3 weeks of age in the nest on the San Francisco Pacific Gas and Electric Company headquarters building. They wear these VID (visual identification) bands: Females: 32/Z & 54/C. Males: 87/P & 55/P.

ChicksApril 21, 2010: At ten days of age the young begin the second down appears on the youngsters as shown in this picture (these babies are now 13 days old). The young may now survive in the nest for relatively long periods of time without the care of a brooding parent. This allows both adults the ability to hunt for food so that they may together meet the nutritional demands of their growing young.

4 babiesApril 16, 2010: We have four babies that are eight days old now. Food is being captured by the male and delivered to the nest ledge where the female takes the food and feeds bits of it to each youngster in turn. They are thriving. We will see a large difference in the young from week to week now.

2010 HatchApril 8, 2010:Three eggs hatched on Thursday afternoon, the 8th of April. This photo shows one chick clearly visible beneath Lil as she adjusts her brooding posture. Two halves of newly opened eggshells are also visible in the photo. The chicks will grow to full grown with the ability to fly in six weeks.

April 5, 2010: It is hatch week. We expect the eggs to hatch, if fertile, during the early part of this week. When the eggs do hatch, views of the young will be brief. The adults will feed them several times per day but very little food will be consumed at anyone time. Each baby weighs about one ounce at hatching so a tiny bit of food will fill them up and a parent will return to brooding.

March 22, 2010: Approximately two more weeks of incubation remain before hatching begins to occur. Since we know that this pair has hatched fertile eggs in the past, it is likely that they will have the same experience this year—but we are never sure until we see live babies! It is natural for the eggs to be exposed from time to time, so do not be concerned by intervals of five to fifteen minutes when incubation exchanges or incidences of territorial defense take place.

March 17, 2010: The PG&E Falcons laid their 3rd egg on 2 March and began what we call, “hard incubation” because it continues with only brief lapses for 33 or 34 days. A fourth egg was laid approximately 2 days after the 3rd egg and will hatch about a day later than the other three. The female does most of the incubation but the male takes a turn while his mate eats, preens or enjoys some sunshine nearby.