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San Francisco Nest Diary 2009:

Beginning on April first, ALIYAH KOVNER, an intern with the Predatory Bird Research Group at UC Santa Cruz, has contributed the nest diaries. We are grateful for her help! Note that diary entries list most recent events first.

June 12, 2009: Fledging has occurred. Beginning Memorial Day, May 25th an OP on the 22nd floor of an adjacent building and the streets near the corner of Mission and Main in San Francisco were staffed every day by SCPBRG volunteer fledge-watch personnel and SCPBRG staff. Late on 5/27, a search of 33rd floor PG&E perches from our OPs and the nest cam revealed that the tiercel, Hi, was not on the ledge. Proximity of nearby buildings makes observations challenging and we spent the better part of 24 hours searching for him until he appeared in flight about 12 stories above street level in front of the eyrie. His choice of a perch to land on was a bad one—near a gull nest and above a crow’s nest. The crows immediately began to mob him and the resulting frantic flight of escape ended at a plate glass window where he was killed instantly. His sisters fledged on the afternoon of 30 May. Liwa found her way to the ground a day later and was collected unharmed and returned to a PG&E roof the next day. Kiwel was flying well and being fed by parents on various rooftops until she was spooked by workers on the roof of a building where she was perched. She was found later in the day (6/3) on the ground with a broken clavicle and is now recuperating at the Santa Cruz Predatory Bird Research Group facilities with a good outlook for eventual release.

EyassesMay 22: San Francisco: The eyasses of San Francisco are active and restless. They spend hours each day exploring the roof top of the PG & E building, and less time napping. Liwa, Hi and Kiwel also groom themselves frequently as their flight feathers grow in. They are now covered mostly by their juvenile feathers, with awkward tufts of white hatchling down remaining here and there. They will begin to fly soon, as they grow more and more experimental with their strengthening wings.

 

BandingMay 15: San Francisco The brood was banded on the twelfth, and it was confirmed that there are two females and one male. To accomplish this procedure, a group of SCPBRG members came to the top of the PG & E building and approached the nest scrape. During the procedure, the parents circled the building, and loudly objected to the intrusion their nest. Dapper Dan and Diamond Lil made frequent vocalizations, called kakking, to voice their displeasure. The chicks also vocalized loudly but were fairly cooperative in letting the bands be applied. Though wary of Glenn (seen handling the chicks) and the others, there was little way for them to hide and eventually calmed down. To see these moments captured in photographs, visit the online gallery of Glenn Nevill at http://raptor-gallery.com and by viewing the selected photos and videos elsewhere at this SCPBRG site.

The chicks have been named after words for water, wind, and sun from the Coastal Miwok language, in honor of the tribe that was first to inhabit the Bay Area. The male is nicknamed Hi, meaning Sun. (Pronounced 'hee). The two females have been named Liwa ('lee wah'), meaning Water; and Kiwel ('kee well') meaning Wind. The names are also a tribute to our hosts at PG & E for their commitment to securing green sources of energy for northern California utility customers. After the banding was finished, the parents continued to patrol for intruders but soon settled down and returned to the nest, and have been keeping check as vigilantly as ever since. Today, Liwa, Hi and Kiwel, recovered from their human interaction of earlier this week, napped crouched between the nest scrape and a wall to get some shade.

Growing upMay 11, San Francisco: The three eyasses are nearly as large as their parents. Their bodies will soon become more streamlined in appearance as flight feathers emerge to cover their coat of down in the coming two weeks. Already, dark patches of feathers can be seem through the white, where true feather shafts are coming in. Flight feathers are the longest and begin growing first. We can see a “fringe” of flight feathers emerging around the perimeter of the wings.

By now, the chicks have mastered their balance and amble around the nest curiously. When Lil or Dan bring food, the chicks eat as much as possible and soon become drowsy and immobile. This is why the chicks are often huddled together asleep for periods throughout the day. After they have had a chance to digest, they become alert once more and soon the cycle repeats itself. Due to their rapid growth, they need all of this food as their bodies immediately convert in into muscle and bone and other tissues.

FeedingMay 3, San Francisco: The three eyasses are becoming more steady on their feet, although still very wobbly and prone to tumbling over. Now that Lil leaves the nest to hunt for herself, they are left by themselves for short periods of time; during which they groom themselves or nap, sometimes just taking in their surroundings curiously. They never stray from their collective huddle in the middle of the scrape and now appear to be about four times larger than their size upon hatching. Although they were born nearly blind, they have now developed the sharp eyesight characteristic of birds of prey that allows them to stare so intently around the scrape, sometimes straight into the camera lens. At a little over two weeks of age, the chicks have imprinted upon their parents and eagerly await their arrival with food.

Week 2April 26: San Francisco: The young have grown significantly since hatching one week ago. Diamond Lil can no longer cover them completely, but instead huddles behind them, keeping a watchful eye. They are growing so rapidly that they are barely able to lift themselves and are beginning to look more like birds than their cottonball appearance of newborns. The chicks are wobbly when they do attempt to stand and their undeveloped wings are not yet much help for maintaining balance. The babies are fed several times per day and each time they eat vigorously. Feathers fly from as she prepares the food though the nest appears to remain fairly clear of debris.

New BabiesApril 17: After 33 days of incubation, the first two of Diamond Lil's brood hatched late afternoon on Friday around 5:30 pm, followed hours later by the arrival of the third.
Though it is hard to see through a web cam, the eggs start to move as they get ready to break from the egg. At this stage of development, the chicks are not getting enough oxygen, so their bodies convulse to break into the air sac at the large end of the egg. About two days after this event, the baby convulses again to create small cracks in the shell (or “pip”) for the exchange of fresh air. With the egg partially broken, the chick's task of slowly breaking its way out begins.
The mother can sense these movements, and in the days and hours leading up to chick's emergence, Diamond Lil was anxious. She shifted frequently and watched the eggs carefully. She could be seen making small calls, perhaps in response to the muted chirping emerging from the clutch. Finally, on Friday, the wait was over and the chicks made their way out. Though they emerge pink, squirming and looking more like aliens than baby birds, they soon dried out to reveal the fluffy white down of healthy eyasses. Though they retain parts of the yolk in their abdomen for nourishment, the chicks are already hungry!
The mother kept the vulnerable chicks under her body to keep the pair warm, though they could be seen squirming under her protective form. One egg remains unhatched and unfortunately probably did not survive.
She left the three for small periods of time, to fetch food from Dapper Dan, during which they swayed unsteadily by the still unhatched egg. Returning every few hours with a pigeon or other small bird, Lil carefully fed each hungry chick small morsels. Their appetite can be explained, as these birds go from helpless down fluffballs to fledging adolescents in just 42 days. They have a lot of growing to do, and exciting milestones await as we watch these amazing creatures mature!

IncubationApril 1: Incubation continues and the morning sun has passed the nest for the day. Our San Francisco pair, Diamond Lil and Dapper Dan, have about 15 days more incubation so they are just over halfway there!

4 eggsMarch 17: The fourth egg arrived on March 14th and incubation is now underway. The 4-egg clutch is shown here along with Mom settling in on the eggs. Note that she uses her beak to pull one of the eggs under her as she shuffles her feet to pull in others so that all are held against her body. The eggs may experience brief periods when an Incubating eggsadult does not cover them without being harmed. The female typically does most of the incubating with the male filling in when the female eats or takes other breaks.

Two EggsMarch 10: Between eight and nine in the morning, PG&E falcon camera-watchers held their breath as the falcon stood in her scrape a little bit hunched over. Eventually, she moved to the side to reveal that a second egg had been laid. She used her beak to move the new second egg next to the one that was laid between Saturday night and Sunday morning. Peregrine Falcon eggs arrive at intervals of about 60 hours. The eggshell is added during the two days that precede laying. The “normal” clutch for a Peregrine is four eggs, sometimes three, and rarely, five.

Typically, incubation begins when the third egg is laid. The falcon brings the eggs up to body temperature and keeps them there for 33 days when we expect them to hatch. When a fourth egg is laid to complete the clutch two-plus days after incubation begins, it hatches two-plus days after its siblings. With adequate food, it soon catches up to brothers and sisters in size.

2009 PG&E NestFebruary 19: Around the time of the fall equinox during September 2008, Peregrine Falcons were observed in brief courtship behavior at the nest box on the southeast corner of the PG&E headquarters building at 77 Beale Street in San Francisco. The brief fall visits gave San Francisco falcon watchers hope for nesting in 2009. Falcons appeared at the nest box during the first week of February.

The San Francisco financial district has been considered a Peregrine Falcon territory since the late 1980s. The Santa Cruz Predatory Bird Research Group placed a nest box on the northwest corner of the PG&E highrise when falcons were seen perching there often. Peregrine Falcons first nested on the building in 2003 and have used PG&E and other nest structures each year since then within their territory.