In Uncategorized on July 7, 2014 at 1:27 pm

Espie and her brother Hiko fledged from the San Jose City Hall nest in 2007–Clara’s founding year in her territory. Hiko settled at the Fruitvale Avenue Bridge territory and Espie, the East Span of the San Francisco-Oakland Bay Bridge. 

The East Span territory has been used in the post-DDT era since 1983 when a blue-banded pair (peregrines released by SCPBRG) appeared. The male had been fostered into a Napa County eyrie and the female cross-fostered into a San Luis Obispo County prairie falcon eyrie. The female was shot near the nest and while peregrines were seen on the span for several years, breeding was not documented until 1990.

The peregrines preferred a nest site that was a little alcove in “E-2″ the second tower east of Yerba Buena Island about thirty feet below the eastbound roadbed. This north-facing metal box contained enough dirt, gravel, and road debris to support incubation and nesting attempts were made in many of the years after 1990. 

Our observers documented all manner of calamity when the young attempted fledging. Peregrines are clumsy at landing during their first few days on the wing and the East Span of the Bay Bridge offers scant perching structure to a young peregrine. Sometimes they were carried upward on the strong wind out of the north and then clambered for a perch alongside the roadbed and were squashed by a speeding vehicle. Other times they were set upon by gulls and driven into the sea where they drowned.

A unique agreement was reached whereby the young could be moved to a safer fledging environment during seismic retrofitting construction following the 1989 earthquake. We moved young from the bridge for years. The agreement allowed construction to go forward where a state-endangered species was nesting and it was very good for the birds because their young had a 95% chance of drowning if left in place. When the seismic retrofit construction was complete and state-endangered status removed (2009) the agreement to move young expired. 

Today, lands immediately adjacent to the San Francisco Bay probably have more peregrine falcon territories than at any time in history. Their speedy recovery from near-extinction in our state is due first to stopping the use of DDT and then to recovery activities. But the Bay Area population density can only be explained by the appearance of modern structures offering nest ledges on bridges, buildings, and cranes, and the presence of a booming non-native rock dove (pigeon) population. Nest sites average less than 5 miles distance between them in some parts of the Bay Area and this year a sample of 12 nests yielded an average 3.0 young per nest that were at least 25 days of age. 

The peregrine falcon population is robust but I do not think that is a good reason to look the other way when a recent candidate for extinction will very likely fledge its young into the sea. We brought them back from extinction. We put up the nesting habitat. And, we introduced the abundant food source that now sustains them. I think we bear some responsibility to give them a chance at safe fledging and I have fought that fight for years. But what we (those of us who love peregrines) are up against is an agency-wide wildlife non-intervention policy. That policy, coupled with a species that is now abundant, makes it very difficult for us to gain an exemption.

An additional caveat making it especially hard to do the right thing for bridge-nesting peregrines is this: The State Department of Fish and Wildlife established a policy whereby peregrines may not be hacked (released) less than 50 miles from the coast (a protection for snowy plovers & California least terns–a decision based on emotion and not science in my opinion) or, in the habitat of the greater sage grouse. With this policy the State has pretty much eliminated suitable habitat for peregrine releases. Thanks to an accommodation by colleagues at UC Davis, I was able to gain approval for a release site at one of their off-campus animal facilities that was useful for early season peregrine fledging, and I used that site successfully last year.

The end of the story about Espie and her young is this: The old East Span is being dismantled this year so the agencies changed their mind about non-intervention and agreed to allow me to move Espie’s young. But, in a particularly bone-headed move, CalTrans sealed off the favored E-2 nest site in mid-February thus throwing off the breeding cycle. A little later the pair appeared to be making an attempt to nest on a corner gusset plate that anchors a girder to a tower, and finally, quite late in the breeding season, they settled in a cavity low on the E-8 tower. 

Knowing that temperatures would be exceeding 100 in Davis by the time the young were ready to fledge (it is forecast to be 101 today) I cancelled plans to have any part of their translocation. Putting peregrines inside of a box on the top of a roof in 100 plus degree heat just might be worse than fledging from the Bay Bridge. What I do know is that a peregrine tortured with enclosure in a hot box for a week would probably never return to the box for food and quickly starve. It was frustrating to be able to take them but unable to release them in a manner that was up to our standards. Their chances on the bridge? Probably not good either. An industrial area to the south may offer them a perch. A short distance to the north is the speeding traffic of the new east span which is certainly lethal. And then there are the gulls. 

Observers may ride a bicycle or walk out the bike path on the new East Span to view the birds on E-8 (count 8 towers from the island). Some folks report getting quite close to Espie and her mate while they are perched on the new span. The young should be fledging any day now. Personally, I do not want to witness the calamity.

(Post Script: We withheld information about the E-2 nest location because the area was closed due to bridge construction activity).

Central Asian Falconry

In Falconry Observations on April 22, 2014 at 3:43 pm

An image from Dennis Keen's Central Asian Falconry website.

An image from Dennis Keen’s Central Asian Falconry website.

I write today to share an extraordinary resource about the practice of Kazakh falconry that has been researched, written, photographed, and most importantly lived, by the former UC Santa Cruz student, Dennis Keen. Dennis is in his fifth year of studies in Central Asia. He is a Fulbright Scholar and has completed a Stanford Master’s degree. His website is a collection of his current observations of culture plus historic knowledge of the ancient art of falconry including interviews with an elderly Kazakh falconer who is the repository for generations of falconry knowledge. It is a fascinating read for anyone with a curiosity about lands and cultures beyond our own and especially about those who have hunted with goshawks, falcons and eagles over millennia.

You may learn more about the work of Dennis Keen here:

Borrowed from the website: Central Asian Falconry, by Dennis Keen

Borrowed from the website: Central Asian Falconry, by Dennis Keen

Three Eyries

In Eyrie Visits on April 20, 2014 at 9:57 pm

We sit and look at eyries. In this case, one coastal nest, one Santa Cruz Mountains nest, and, one urban nest. Observer colleagues and I try to nail down hatch dates so that I can return to band at the right time.

There is little activity at the nest when falcons are incubating but there is plenty to entertain the patient watcher. The Coast. Backs to the ocean, we watched the eyrie as the sun slowly made its way over the top of the cliff that we watched. An osprey soared over from time to time and red-tailed hawks too. Whimbrels probed the sand at water’s edge. All the while a peregrine that we believed to be the female preened her plumage and the sun eventually illuminated her cliffside perch. For three and one-half hours the nearby eyrie appeared to be vacant. The peregrine made no move toward it. In fact, she never left her perch until an adult peregrine flew past traveling north. She followed making some half-hearted jabs at the passerby and then returned to her spot in the sun. (It is wonderful to see so many peregrines in the world!) Finally–and for just five seconds–the head of an adult peregrine that we believed to be the tiercel was visible above the protected ledge we had been watching intently. Five seconds out of four hours. Ah, incubation underway… We waited another half an hour and then packed up gear after a lovely morning on the coast.

The Santa Cruz Mountains. Many pairs of peregrines (more than 10) now make their home in this coast range. My friends–dedicated falcon watchers–found this pair several years back and have seen the pair at two different eyrie locations. They hiked the mountainous trails this year until they had a view of the nest site at eye level from quite a distance across the canyon. They sat staring at the ledge they believed to be the eyrie for two hours until they detected a movement and discovered they had been staring at a falcon’s tail feathers the whole time! They watched for four and one-half hours and saw her leave the nest only once and for just a few moments. They could hear the tiercel call from a distance. Again, no food going in so we assume eggs are still under incubation.

The urban site. Here, our peregrines use an old raven’s nest on the side of a building in an industrial area. Heat waves from a building in the foreground confuse the view. The tiercel wears a band that I hope to be able to read when I visit to band the young because access to the immediate area of the nest is only possible at the time of banding. We want to identify him. Staring at a building through a powerful spotting scope can sometimes draw the police, and it did. The officer who got the call happened to be a birder and so was fascinated by what he found–a happy ending to an initially tense situation. My friends stayed on until four and one-half hours in, the falcon left briefly and returned with some cached food dangling from one foot. When she landed on the edge of the nest, one tiny white head popped up informing us that at least one hatchling was in the nest. I’ll add that site to my calendar for banding!

We sit and watch nests. The world goes by and the peregrines tell us their story.


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