Climbers and Raptors on Cliffs
A very obvious, spectacular bird that rock climbers encounter in Tasmania is the Peregrine Falcon Falco peregrinus, found in Australia as an endemic subspecies F.p. macropus (essentially meaning “traveller with big feet” – the traveller bit being relevant to the early description of northern hemisphere peregrines many of which, unlike ours, migrate). This, almost worldwide species, arguably the fastest self-powered organism on earth, has nested in Tasmania for at least 19,600 years, a date established by carbon 14 dating carcases found in debris stratified under an old nest. It’s pretty well another world record. Peregrines are famous for their tenacious fidelity to nest sites, even particular nest ledges or potholes. In Tasmania they nest almost solely on cliffs. It’s amazing to think that thousands of successive generations of falcons layed maybe 50,000 eggs, hatching 40,000 fledglings eating 100,000 kgs of prey, in exactly the same place.
Peregrines are very widespread in Tasmania and its islands. Inland, one can run into a nest almost anywhere there is a cliff more than 5m high, especially if it faces away from prevailing winds, although coastal cliffs need to be 20m or more. Often a nest ledge is marked by generations of guano but peregrine roosts (resting and/or hunting perches) can also be ‘whitewashed’, as can roosts of other species that use cliffs such as Australian (Nankeen) Kestrels, Masked Owls and seabirds. So, just as climbers would check a route, then so the possible neighbours should also be checked.
Birds have evolved a huge variety of behaviours to protect their nests from competitors of their own or other species and from predators. Some, typically small birds, pretend an injury and lure predators away while others, typically medium-sized birds offer a vigorous, even violent defence. Some, typically large birds, just slip away early on so as not to draw attention to the nest and its these ‘shy’ types that are most prone to leave a nest for critical periods. It’s all about protecting an investment and oneself. Short-lived (usually small) species cannot afford to miss a chance to breed so they are typically persistent while long-lived (usually large) species know they will live to breed another day and don’t put themselves at risk with people. Perhaps too, they have lived long enough to learn people can be very dangerous.
Peregrines and a few other species such as masked lapwings (spur-winged plovers), take an extreme ‘active defence’ approach and aim to intimidate, scare off or if that fails, even physically harm a potential predator. Loud, anxious or ‘angry’ calls and obvious flying in front of an intruder are meant as a warning which if unheeded, can escalate into something more serious. All the while, stress increases as does energy use and risks to the nest from exposure and predators taking advantage of the confusion or even chicks panicking and jumping from the nest. Problems can happen early in the event too – a peregrine suddenly flushed from a nest can break eggs or even knock a chick from the nest ledge – it has all happened. If a nest ledge is visited by people, be they climbers, photographers or researchers, the birds might move the next season and have to use a sub-standard ledge, effecting productivity. Such a shift can happen when a cliff is ‘opened up’ to climbing and the nest ledge happens to be on a route. The problem can be severe where overnight stays are made by climbers on cliffs.
Although on mainland Australia peregrines sometimes use old stick nests, no falcon species builds a stick nest, peregrines instead just scraping a dish in sand and gravel. But, nest care goes to the other extreme and that’s where encounters with climbers are sometimes too common and too long. Climbs at The Bare Rock behind Fingal, Sleepy Bay at Freycinet and the Candlestick at Fortesque Bay are good examples. In Tasmania, peregrines are resident at most breeding sites. At times they might be away for the day or even roost (sleep) at another place but they are rarely out of touch with their nest cliffs. Even in the dead of winter they might give anxiety calls (slow wails interdispersed with “eechup” calls as the falcons reassure each other they are part of a team) if nest cliffs are visited by people. Come August, territories are being consolidated, possessiveness increases and some alarm calls (a harsh, urgent “heck-heck-heck-heck.. “ might be heard (the larger female’s voice being deeper than the male’s), the male, female or both usually flying back and forth with quick wing beats. Most Tasmanian peregrines lay their 2, 3 or 4 eggs in the second week of September at which time they are very excitable. Once the clutch is finished, incubation (about 32 days) starts, done mostly by the female with a few short shifts per day by the male. He stays on defensive lookout through this incubation period making brief hunting forays. If an intruder is spotted he immediately gives alarm calls and his mate will leave the nest to help defend.
Hatching is a time of great excitement for the birds and hunting then starts in earnest by the male with food deliveries of small birds every hour or two of daylight. For a raptor, peregrines have good night vision and can hunt by moonlight if things are desperate, typically foraging over water. This also means night time disturbance can flush them. Once the chicks are about 3 weeks old (1/2 their nestling period) they are large enough to repel most predators such as ravens that might try a nest raid, and the female is freed up to also hunt.
As the nesting process continues the falcons increase their investment. This can translate into becoming more aggressive but it is also more stressful for them, both physically (especially on hot days) and behaviourally. Risks of collisions also increase as nest defence increases with dives and sometimes strikes on intruders as the birds become tired and reckless trying to get rid of the people. In this nestling period the adults are running a fine energy economy and can have little extra to spare.
Another stress peak occurs at fledging when chicks are exercising their wings and playing on ledge edges. Any extra stress, especially from a visit to or near a nest ledge, can cause premature fledging where a chick not properly feathered or toned to fly, jumps to ‘escape’. Such a ‘crash-landing’ chick might drown , be injured or be unable to get to a safe roost that night and is be at a heightened risk of predation (eg by a Tasmanian devil). The adults might be distracted with people at the cliff and not have seen where the chick went so their feeding and defence of prematurely fledged chicks, even after disturbance finishes, is compromised.
The defence of peregrines against potential predators other than people (dogs, eagles, ravens etc) usually only lasts seconds, rarely even minutes but their response to people can last hours. That is because they can usually chase off non-human threats easily; not so people. That’s where the prolonged disturbance that rock-climbing sometimes represents can cause problems. I have visited many peregrine nest sites over the years and have encountered climbers at a surprising proportion, sometimes in the middle of nowhere. Quite often the climbers were in situ, persisting despite falcons’ protests because, as they explain, they made such an effort to get to the cliff. Sometimes the route being used is well away from the falcons’ nest but not always, and I have at times (politely) asked climbers to move; usually unsuccessfully. On those unfortunate occasions I have cancelled my research visit (usually why I was there) since the birds can do without the added stress of a visit from me. To put my money where my mouth is, more recently I am developing monitoring techniques that do not require a visit to nests during breeding. On the up-side I have had many peregrine reports from climbers who backed-off on finding the falcons in situ and recent interest in protecting peregrines at The Bare Rock is part of that ethos.
At this spectacular site the whole cliff will be closed until October by which time the peregrine nest location will be confirmed. If it is, as usual, on the Pashendale climb route on the eastern section of the cliff, that section will be closed until the young fledge in December, the closed section boundary being immediately to the east of the western rock overhang. I will monitor the birds’ behaviour in relation to climbers’ activities and we all can review the results of this management option at the season’s end.
Rock climbing in Tasmania utilises a great variety of places and there are many coincidences of climbers and falcons. But really, the issue is pretty easy to deal with if one considers the birds have little choice where they best nest – they are the experts. In contrast, we do have a choice and its just recreation after all.
Although Tasmanian peregrines (including their eggs and nests) are wholly protected by law everywhere at all times, surely the best regulating mechanism in little-known areas is climber ethics. If you get persistent “hecking” calls from a falcon during that nesting period, back off, presuming you can safely. If going to a cliff where it is not known if peregrines are breeding during that breeding period try and design your visit so that you can back off if a peregrine starts defending .
In better-known areas, peregrine nest cliffs can be closed to climbing during breeding (mid August to Xmass) by regulation (if on reserved land) by landowner say-so or by climbers’ policies, codes of conduct and ethics. At small cliff nest sites that are also regular climbing sites (such as at The Bare Rock), stopping climbing during breeding is the obvious option but on very long cliffs spatially restricting climbing might be an option.
Certainly climbers can be a problem for peregrines in some places at some times but a similar but less obvious problem occurs with climbers and eagles. Eagles are notoriously shy nesters, the white-bellied sea eagle Haliaeetus leucogaster and especially the wedge-tailed eagle Aquila audax perfectly fitting the bill of large, long-lived, slow breeders which would rather live to breed another day than put themselves at risk by aggressive defence against people.
In Tasmania wedgies nest only in large, stable, sheltered trees and sea-eagles mainly so with a few nests on cliffs and rock stacks on islands. The key to conserving nesting eagles is obviously keeping disturbance away from nests but part of this is not paying attention to the nest. The eagles seem very self – conscious and the worst thing one can do is gawk at the nest especially if you are above it. Once a nest is noted or if you already know one is nearby, pretend it is not there while staying as far away as possible and staying for as short as possible. In Tasmania, eagles nest anywhere from August to January inclusive with the most sensitive times usually September-November. Nest trees are usually on lee slopes and can be tucked in under or adjacent to cliffs. At high altitudes they are sometimes just off the lips of cliffs, probably to take advantage of turbulence to keep snow off during early spring. Eagle nest can be huge (up to 5m3) and very obvious but not always.
So, before tackling a cliff you are unfamiliar with, maybe do a bit of homework remembering your disturbance can occur during access to your climbs as well as while your there. Many eagle nests are on the State’s Natural Values Atlas or you can inquire of the Threatened Species Section at DPIPWE or, given a bit of warning, the author can help. Again, climbers have reported a number of eagle nests, something which helps with their conservation.
Many very experienced (dare I say iconic) Tasmanian climbers such as Bob McMahon are very familiar with these issues so ask about. Feel free to contact the author if you want to know more and I would love to get your peregrine records be they nests or other. Also, be aware peregrines are not universally popular – over the years there have been a number of altercations between climbers and pigeon fanciers wanting to shoot or trap the falcons so please report problems to the wildlife authorities. Again, Bob has been a Trojan in this regard.
As I’ve written before – these birds are your climbing companions so both enjoy and look after them.