While adult Peregrine Falcons are still present in The Sunbowl area of the Northern Preserve, there is no sign of young, so the temporary climbing restrictions have been removed. All temporary climbing restrictions have now been lifted.
Peregrine Watch volunteers continue to monitor the Bonticou and Millbrook eyries closely, looking for an indication that eggs have hatched. While the birds have been observed regularly at both eyries, the Millbrook pair has been particularly active with several observations of them defending their territory from passing vultures. Once the eggs have hatched, we can expect to see more frequent prey deliveries to the eyries.
Across the country in California, chicks have hatched on the roof of the UC Davis Medical Center. In urban areas, where Peregrine Falcons can often return to the same site yearly, it is feasible in some scenarios to set up cameras to document the progression. In natural areas, such as Mohonk Preserve, Peregrines have more options for selecting an eyrie location and by the time an eyrie has been established, it would be too large of a disturbance to implement cameras for such documentation. While the UC Davis Peregrine chicks hatched much earlier in the balmy California weather than we expect chicks to hatch here in the Northeast, interested viewers can watch the live stream here.
The incubation vigil continues at each of our three Peregrine Falcon nests. Things appear to be continuing on schedule as the males do most of the hunting and sentry duty while the females spend most of their time incubating eggs. Our observers are keeping an eye out for signs that hatching has begun, which will be mainly evident by a notable uptick in the frequency of prey delivery. Even when the young have hatched, the females will stay close to them and to the nest, keeping them warm and protected from danger, and thus we will not see much of the females for at least a few more weeks.
Peregrine Falcons are one of three members of the Falcon family typically found in our area. The other two species, American Kestrels and Merlins, are smaller that Peregrines but share their basic body shape and their fierce nature. While the Peregrine diet consists almost 100% of birds, Kestrels and Merlins have a more varied diet. American Kestrels may be familiar to you as the small raptors perched on utility wires or soaring over farm fields hunting for mice and insects, and they will also eat reptiles and small birds on occasion. Merlins are less familiar to most people and are less common than Kestrels. Much smaller than Peregrines but larger than American Kestrels, Merlins will also hunt small birds and are often seen chasing large aerial insects like dragonflies. Unlike Peregrine Falcons, American Kestrels are cavity nesters and will often readily occupy artificial nest boxes. Merlins share the Peregrine preference for nests with a view, but unlike Peregrines they frequently lay eggs in nests abandoned by other birds such as crows or hawks.
The large areas of open fields in the Hudson Valley are appealing to nesting American Kestrels and we have several active breeding pairs in our area. One nest box on Mohonk Preserve lands is monitored by Research Associate Zach Smith. You can read more about his Kestrel work here.
Things continue to appear quiet at all three of our Peregrine Falcon nest sites as the females keep up their almost round-the-clock incubation vigils. The males will spell them from time to time, taking over incubation duty so that the females can stretch their wings, attend to hygienic needs, or grab something to eat. Most of the observations reported by our Peregrine Watch team, though, are of the adult males bringing in food or fending off enemies. As long as things are going well at the nests, this will continue to be the case for a few more weeks.
In the meantime, check out this absolutely AMAZING video from a nest cam in Sheffield England. The video captures the exact moment that the female lays her 3rd egg! Not only that, but the male comes in shortly after that with prey for her.
We’re seeing behavior changes that indicate that the female Peregrine Falcons have started to lay eggs. The adults won’t start incubating until egg-laying is complete, and this can take several days. There is usually an interval of roughly 48 hours in between each egg, as the female rebuilds her energy supply to produce a full clutch of eggs. A “full clutch” for Peregrines is considered to be four eggs, although in many years the number of eggs she produces will be less than four, and will vary depending on the health and age of the adults and the conditions and resources available to them. Once she has laid her last egg, she will begin an intense incubation vigil that lasts roughly a month. The female will do most of the incubating, protecting the eggs from predators, scavengers, dehydration, and extreme temperatures. Her mate will bring her food and occasionally grant her some periods of rest before she returns to guard duty.
This is a difficult observation phase for our Peregrine Watch team since the activity at the nest is sparse. It takes a lot of patience and careful study of the male falcon’s routine to confirm the transition from laying to incubating eggs and eventually to hatching.
In the video below, taken in Richmond, Virginia, you can see an example of a nest exchange between a male and a female Peregrine. The female is incubating and resting before the smaller male comes to take over. While there is no audio, the two birds are visibly vocalizing as the two confirm their pair bond, and note the male’s careful positioning as he eases into the nest scrape.
3.19.19 — Courtship Behavior
Temperatures are quickly warming up and our days are getting longer, and the Peregrines have noticed. We’re seeing a sharp uptake in breeding activity, as the birds have demonstrated courtship rituals and are zeroing in on the preferred nest locations for the year. Consequently, the Preserve has announced temporary climbing route and boulder problem closures at Trapps, Bonticou and Millbrook cliffs to protect the Peregrines during the crucial breeding season. It may still be days before any of the females lays her first egg for the year, but with all three pairs returning to the Ridge, odds are good that at least one of them will start very soon.
The video below, from a nest cam in Pittsburgh, shows some of the behavior similar to what our Peregrine Watch volunteers are observing. Like many other birds, Peregrine Falcons show a very ritualized courtship behavior. Note the vocalizations and bowing behavior as the birds interact. There are eggs visible in the nest, but the courtship behavior indicates that the female has probably not finished laying.