A new peregrine falcon nest box is being readied for the nineteenth floor ledge of San Jose City Hall is a sign of the season. Solstice is just around the corner. With it, comes new interest in courtship to begin another breeding cycle.
This nest box will be a slightly new design. As always, it will fill the space between the building and the shortwall, but just one side of the five-foot long box will be filled with sand. The birds always lay in the left side of the box so that is where the sand will be. The other side will be a flat wooden surface.
Researchers in Wisconsin where all peregrine nests are on man-made ledges (there are not cliffs in Wisconsin) discovered that hatchibility of peregrine eggs was improved when the nest substrate was changed each year. We are reducing the area of nest gravel in San Jose to make this job a little more reasonable. For those who think we might be doing them a dis-service, please consider that most nest scrapes that I visit are less than one square foot in area on an otherwise rocky or uneven surface. Our “ledge” will be five feet wide and two feet deep with a twenty four by thirty inch box of course sand (aquarium gravel) that is five and one half inches deep. The new depth of the sand is thanks to 2 X 6 construction vs. 2 X 4 construction. The other improvement is an overhanging roof to increase shade for the incubating female on a sometimes very warm, south-facing ledge.
I expect to install the box in the next week or so after several more coats of paint. No date has been set as this operation is somewhat weather dependent.
This story ran yesterday in papers across the country and Canada. After a couple of years of trying to get good cooperation from state and federal wildlife authorities in Sacramento I was left with the one recourse of going to the press.
The feds were a little demeaning in their characterization of fuzzy chicks that are cute but that nest failure is a natural part of life. We know for a fact that some structures we put up are particularly bad for fledging falcons. They don’t slip and fall–they fly well and land poorly EVERY time they fledge. The problem on the underside of a bridge is that they do not get a second chance. We know that to be the case. I am willing to spend precious program money on the capture, rearing, and release, post-release monitoring (for eight weeks with help from volunteers and collaborators) to give these young a chance at a successful start in life.
The US Fish and Wildlife Service has said no to a permit for that humanitarian act. The interesting thing is that the peregrine falcon is a state of California fully protected bird–only 13 birds are listed. Why is the federal government dictating management strategy to the State? If the State agrees with this management strategy why are developers and construction workers made to accommodate this fully protected species and climbers made to avoid routes with nesting peregrines while bridge fledglings are squandered?
The State and Feds can’t have it both ways. They have an inconsistent management strategy that at times favors peregrines to the great inconvenience of many, and at times completely ignores the well-being of peregrines causing their death.
Our elected officials are very good at asking pointed questions of agency officials. I suggest you ask yours to inquire about the topsy turvy management approach to peregrine falcons–a fully protected species just taken off the California list of endangered species in 2009. Why, we should ask, do they prefer to see them fledge into the sea when I would happily move them to a safe release site.
I approached this nest with permission of the US Fish and Wildlife Service one week after Summer Solstice for the purpose of collecting addled eggs for contaminent analysis. The photo above shows the status of the nest on June 28th 2013. Five eggs remained in the scrape. One intact egg lay beside the nest box. And a seventh egg was found broken on the ledge nearby.
The broken egg contained a mostly developed embryo that must have died during the period when Dan had the entire burden of incubation but left the scrape at least once per day to feed himself. It is the best evidence we have right now that Lil’s eggs were viable but did not hatch because of incomplete incubation. It is likely that Cher’s eggs were not fertile.
When we reached the balcony on the 33rd floor of the PG&E headquarters building at 77 Beale Street, Cher was incubating the clutch of five eggs. She got up, cacked at us, and then left the nest box but flew past the balcony repeatedly cacking and even perched several times on the ledge to voice her displeasure with our intrusion. Here is a picture of her jumping into flight when I aimed my iPhone at her to snap a photo. (I know, I should have brought Glenn Nevill along for better photos).
Disruption of the nest cycle by a new female was disconcerting for nest
camera viewers but is something we should prepare ourselves to see more of
in the coming years. It is evidence of a robust recovered peregrine falcon
population in the San Francisco Bay Area, and across California.
Non-breeding members of the peregrine falcon population, or “floaters,” are
searching for nesting territories. Some are challenging territory owners,
as Cher did, for the opportunity to breed. While we become attached to
individual falcons, we need to remember that fitness to breed is
fundamental to the viability of species. Hard as it may have been to watch,
we witnessed first-hand the selection of the most fit breeders playing out
this year at PG&E. Last year, we saw it happen at San Jose City Hall when
Fernando replaced EC.
One final note… I have often repeated our belief that peregrines know how
long incubation should take and quit when that period expires. When the
Predatory Bird Research Group and others worked to recover the peregrine
falcon population, our work was rigorous. There was rigorous attention to
the husbandry of captive falcons and rigorous attention to the known
timelines of nesting chronology. We knew that incubation was a thirty-three
day period so we always returned to nests where we left dummy eggs (so that
we could hatch the real ones in our incubators) within the 33 day
incubation cycle to foster young. Nest cameras around the world are now
recording the long incubation times of peregrines that far exceed required
incubation periods. It turns out that we did not fully appreciate the
tenacity of the peregrine to defend its nest territory and to incubate eggs
that were long overdue.
These observations bring me once again to a sense of awe for a bird that
hurtles from the sky each day–at hundreds of miles per hour–to crash into
other birds in order to acquire a meal to eat… It is a bird that almost
succumbed to the effects of toxic chemicals that we added to the
environment just a half century ago. A humbling realization.