Common questions

General information and history

You can learn about the terms used in these questions and answers from our glossary.

Location and background

The nest is located in an active water tower on the campus of Charles Sturt University, Orange, New South Wales, Australia. The tower is constructed of concrete and was built in the 1970s to store water servicing the University. The nest box is 35 m (38.3 yds) from the ground.

The water pump for the tower is activated a couple of times per day for about 25 minutes. It sounds very loud on the cams due to the microphones, but the falcons barely notice it.

In 2007 a peregrine pair were seen in and around the campus area and plans were put in place to build a nesting box and install cameras. By early 2008 the falcons were frequently using the box as a feeding post and they started breeding in spring 2008. The first egg was laid on 23 October 2008 with the first hatch on the 1st December.

They are peregrine falcons whose scientific name is Falco peregrinus subsp. macropus. Macropus means ‘large foot’ as Australian peregrines have bigger feet proportional to their size to cope with large, feisty prey such as cockatoos.

The peregrines

The female is Diamond and the male is Xavier. Diamond arrived in 2015 and Xavier in 2016. We can assume that they were at least two years old when they started breeding, so in 2022, they would be at least nine and eight years old respectively.

All female peregrines are a third larger than the males: they are taller and broader across the shoulders. Diamond has more spots on her chest than Xavier and has slightly less bright yellow on her beak, eye rings and talons. She moves more slowly while Xavier is lighter on his feet.

They are here all year and use the box most days. Because of this, the cameras and chat are open all year.

Our first pair 2007-2015 were Swift (female) and Beau (male). They were named by our first sponsor, the Beaufighters’ Squadron, whose mascot is the peregrine and whose motto is ‘Strike swiftly’. After Beau disappeared, Swift, who was rather lame and probably quite old, gradually allowed the box to be taken over by a new female, Diamond.

Diamond and Bula (Wiradjuri for ‘two’) took over the nest in 2015 but Bula disappeared (presumed dead) in 2016 just as the chicks were hatching. Fortunately, Xavier arrived and was the ‘saviour’ of the season as he provided for the family and all chicks fledged.

There is one pair at Ophir about 20 km away and another at Mount Canobolas, about 30 km away. There are occasional visits by strange falcons at the nest, presumably checking out the Concrete Hilton (tower nickname) to see if it is vacant.

Research

The aims of the project are, firstly, to study the behaviour of a peregrine family, particularly during the breeding season, and, secondly, to analyse its diet through images taken of prey brought into the nest box. Data collection ended in August 2021 and will now be analysed and papers written. However, the cameras will remain operational throughout the year to provide an educational focus about peregrines and their behaviour.

Technical information

The nest, ledge and tower cams are Axis models. The model numbers are:

  • Nest cam: 3344.
  • Ledge cam: 3384.
  • Tower cam: P1448.

The box cam (installed 2020) is a Hik Vision, model: DS-2CD2H85G1-IZS.

The nest and box

Peregrines generally nest on cliff tops or on tall buildings (e.g. skyscrapers, cathedrals) so are habituated to a hard nest surface.  It is called a scrape due to the parents scraping away some of the gravel to make it bowl shaped to better hold the eggs in place.

The box is 1.2 m wide; 0.75 m high and 0.65 m deep (3.9 x 2.5 x 2.1 ft).  It is 35 m from the ground.

Peregrines are basically solitary birds and only one, almost invariably, the female, sleeps in the box at night.  The male sleeps nearby, probably in the trees below.

Prey and diet

The falcons’ diet is almost entirely composed of birds, mostly caught on the wing, but they do occasionally take small bats. They also like cicadas when they emerge. Prey not eaten is cached in various tree branches, and occasionally in the box, to be retrieved at a later time.

The most common prey caught is the starling, but they take all types of birds up to the size of pigeons and cockatoos. However, Diamond shows a clear dislike of starlings, preferring parrots and pigeons. On average, females will bring in slightly larger prey than males.

Chicks and juveniles obtain all the fluid they need from the prey they eat, but fledged juveniles and adults will drink water and bathe.

Sources vary from about 70 to 154 g (2.5 to 5.4 oz) daily for an adult falcon. Newly hatched chicks will eat about 80 g (2.8 oz) per day, increasing to about 300 g (10.6 oz) per day when one month old. A juvenile yearling requires about 157 g (5.5 oz) daily. Peregrines can go a few days without food when hunting conditions are unfavourable.

These birds are not tagged, so this is unknown, but could be a 2-5 km (1.2-3.1 mile) radius.

The crop is a storage organ which allows birds to quickly ingest food. Crop dropping is when this food is moved from the crop to the falcon’s ‘stomach’ (proventriculus and gizzard) for digestion. They do this by lifting their heads with beak open, sometimes with a wiggle of the neck.

The indigestible material eaten by the falcons (feathers and bones) forms into a solid oval shape called a pellet. This is cast (regurgitated) sometime after a meal.

Yes, sometimes they do. The stones help scour the crop of fat which collects around the stones. The stones are then regurgitated covered in the greasy substance.

Peregrine vocalisations

Listen long enough and you will hear variations in the calls that peregrines make, but there are a few you will commonly hear:

  • Chupping or ee-chup is a peregrine-to-peregrine vocalization most often heard when a peregrine sees its mate and during bonding sessions.
  • A kek-kek-kek sound is an alarm call meaning something of concern is nearby
  • Wailing: peregrines will wail when looking for a new mate, by females when wanting a prey transfer from their mate, and when seeming to feel annoyed.
  • Honking also seems to be an alarm or warning call.

Falcon senses

The eyesight of a peregrine is 8 times better than that of humans and they can spot prey at least 2-3 km (1-2 miles) away.  Their eyes are fixed in the socket which is why you see head bobbing movements to help them focus on an object in the distance.  Having flexible necks assists in this.

Peregrines have three eyelids.  The upper and lower are white and it is the lower one that closes first.  When Diamond stands on the stones, you often can see her with one eye open and the other closed.  This is because peregrines can sleep with one half their brain while the other half remains alert, known as unihemispheric sleep.  The third eyelid (the nictitating membrane) is translucent and moistens and cleans the eye via blinking in a side-to-side motion. It can be closed to protect the eye during flight at high speed.

Peregrines have ears on either side of their head which are basically openings with very little exterior structure other than the auricular feathers covering the opening. Most birds have a hearing range similar to humans but their acuity is better.

Taste and smell are not vital senses for peregrines.  They do not have many taste buds on their tongues and so will eat birds that a human would find unsavoury.  Despite this, Diamond has a very clear distaste for starlings but will readily eat other birds.

Dangers

The peregrines in Orange are apex predators with their greatest risk being accidents. Juveniles are more at risk of accidents while they hone their flying skills and can be preyed upon by cats and foxes if on the ground. There are no large owls in the area. No eggs or chicks have ever been taken by other birds while in the nest, perhaps due to its covered nature.

Courtship

Courtship rituals and scrape building continues throughout the year, but intensifies in July and August. Eggs are laid usually in late August, with chicks hatching in early October and fledging in mid-November. The youngsters often stay around as late as March being taught to hunt by their parents, and do visit the tower nest occasionally.

Peregrines enact pair bonding rituals throughout the year by chupping, bowing and staring at each other for short periods, but the duration increases (15-20 minutes) with the commencement of the breeding season. The male will also begin bringing gifts of prey to the female as evidence of his ability to provide for her and the chicks. Unfortunately, Xavier often brings Diamond starlings initially, but her refusal of them signals him to hunt for tastier, or more nourishing, prey.

Teamwork is a huge component of the peregrines’ parentings skills. They will strengthen their pair bond further by chasing off threats and will hunt co-operatively by one disturbing prey while the other chases it for the kill. They also strengthen their bonds with courtship flights where both fly high in the air and appear to play together with acrobatic flight manoeuvres.

Mating appears to happen most often on the tower roof (or at least, that’s when we hear them!). The female will perch in a convenient place, bow low and call to the male who will land carefully on her back with talons and toes curled inward. She will raise her tail while he lowers his so that their cloacas touch and sperm transferred. Copulation only lasts a few seconds, but they mate frequently and are noisy doing it. Peregrines mate for life but will find another mate if their current one dies.

Sadly, the mortality rate for juveniles in their first year is as high as 60% with accidents while learning flying skills a major contributor. Survival improves with each year of life thereafter, with a general six-year life expectancy for peregrines in the wild. There are exceptions of course, with Diamond and Xavier being prime examples, and wild falcons can live up to 19 years.
Fertility in a female peregrine will decline with age. In effect, fewer eggs will be laid with some being infertile and others not hatching resulting in fewer fledglings.

Eggs, incubation and hatching

Diamond lays her eggs in late August/early September. As her time approaches, she will stay in the nest box more and will have visible contractions when about to lay. She normally has a clutch of three with approximately 48 hours between each egg being laid.

Eggs are laid in Orange about a week after the Melbourne peregrine lays her eggs. This is because egg laying times are specific to individual sites, geographical areas and biology of that particular female.

Female peregrines usually only begin incubating eggs when the penultimate one is laid, somehow knowing when this is. Delayed incubating is done to ensure the eggs all hatch close together in time to facilitate chick rearing. Both parents incubate during the day, with Xavier particularly seeming to enjoy this role. Only the female incubates at night. At times the eggs will be left uncovered but they are perfectly safe. Incubating is a long vigil and Diamond needs to go out for a stretch and toilet break.

Hatching is a long process for a peregrine falcon chick, taking up to 72 hours from pip (the first small break in the shell) to hatching. If you want to read more about this incredible process, try these links:

Peregrine chicks/juveniles and family life

Chicks must be constantly brooded initially as they cannot regulate their own temperature. This is undertaken primarily by the female while the male will hunt for prey for her and the chicks, but he will take a turn brooding if the female leaves the nest to eat. Once the chicks have developed their second coat of down, they can be left alone while both parents hunt and feed the chicks. Note that each peregrine pair will be different in their allocation of roles. Xavier appears to enjoy incubating and feeding the chicks, but other males are not so willing.

Peregrine chicks are not competitive when it comes to feeding. Sometimes you will see all siblings lined up with each getting a share of food and other times a single chick might present for feeding. The others are not being left out, but are simply full from their last meal. Prey is plentiful around Orange and none of the chicks will go hungry. Eventually the adults will leave whole prey in the nest for the youngsters to learn how to pluck and open prey for eating. The adults remove any leftover prey to keep the nest clean.

No eggs or chicks have ever been taken by predators while in the nest, perhaps due to its covered nature and the structure of the tower. Fledged juveniles are more at risk of accidents while they hone their flying skills and can be preyed upon by cats and foxes if on the ground.

The chicks are named by public vote from a list of gender-neutral and themed names provided by Dr Kinross. Gender identification of juveniles is not a straightforward process. Males initially grow faster than females who then catch up and overtake the males. It is easier if there is a mixed brood, but harder when there is a single chick so gender may not be determined until close to fledging.

No, banding or tracking is not part of the current research project aims and the chances of resighting is very low.

The white down on chicks will gradually be replaced by brown and cream/beige feathers. They have vertical banding on their front feathers (adult banding is horizontal), a pale grey cere and pale yellow legs and talons. They retain this plumage for a year giving them protection as they pass through other peregrine territories as they are readily identifiable as being too young to breed and not a threat.

No. Peregrine chicks instinctively know not to go too close to the edge of the nest.

Chicks exercise their wings a little while still in down, but once the juvenile feathers are through, they will flap their wings vigorously, gaining strength in their breast and wing muscles. Meanwhile the adults will do acrobatic flight and prey transfer demonstrations in front of the nest which encourages the flapping. It is also a prelude to bringing less food around fledging time as an encouragement for the young to leave the nest to get the prey.

Fledging occurs in November and juveniles remain with the parents for a couple of months learning flying and hunting skills. Once they are able to catch their own prey, they leave the area to eventually find and settle in their own territory. A study by Victor Hurley of 127 banded adults showed that females dispersed on average 64 km (range 6-280 km) and males 25 km (range 1.6-90 km). Peregrines become sexually mature at two years of age.

Further reading

Baker, J. A, (2017). 50th Anniversary Edition: The Peregrine. William Collins, London.

Marchant, S. & P.J. Higgins, (1993). Handbook of Australian, New Zealand and Antarctic Birds. Vol. 2: Raptors to Lapwings. Oxford University Press.

Olsen, P. (1995) Australian Birds of Prey: The Biology and Ecology of Raptors, The Johns Hopkins University Press.

Ratcliffe, D. (1980). The Peregrine Falcon. Buteo Books, Vermillion, South Dakota

Sale, R. (2016). Falcons. Harper Collins.

Stirling-Aird, P. (2012). Peregrine Falcon. New Holland, London.

St. John, K. (2021) Outside my Window: A blog of birds and nature with Kate St. John, https://www.birdsoutsidemywindow.org/

White, C. M., N. J. Clum, T. J. Cade, and W. G. Hunt (2020). Peregrine Falcon (Falco peregrinus), version 1.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://birdsoftheworld.org/bow/species/perfal/1.0/introduction