Frequently Asked Questions

How many peregrines have fledged since they first arrived in Louth?

From 2015 to 2023, the falcon has laid 34 eggs of which 33 hatched. Of these, 28 fledged although 2 had problems and were taken into care.

How long does it take for the eggs to hatch and the youngsters to fly?

Year on year, the time span for the development of the eggs, hatching and fledging are surprisingly regular. You can download the dates from 2015.

Do peregrines attack other raptors?

They certainly attack buzzards if they fly anywhere near the nest site. The peregrines usually work as a pair to bring down the buzzard, sometimes killing it. We have seen this aggressive behaviour in Louth this year, with at least one buzzard being killed.

Download a PDF file that explains this territorial behaviour as witnessed in Exeter, where over 500 attacks have neen recorded

I've been told that the peregrines have a 'runt' that acts as food for the other chicks when times are hard. Is that true?

No. Times are rarely hard for two adult peregrines that are able to hunt for food. Unlike barn owls that spread out their egg-laying and hatching times so as to allow the first-born to predate the younger chick in times of food scarcity, the peregrine times the hatchings so all chicks arrive within a day or two. All are fed, and certainly in Louth, all have developed into juveniles. In 2023, there was a runt that hatched 54 hours after the previous (3rd) hatching. It was so small, it couldn’t be ringed, yet over time it developed to full size and eventually fledged. The picture below gives a comparison of their size at the time of ringing.

Why is the nest tray placed on the north, coldest side of the tower where there is no sun?

The peregrine is used to bleak conditions in its usual mountain or sea-cliff habitat and cold winds don't affect them and the chicks are always brooded when small if the weather is cold. Very little rain falls from the north in the UK so it is the driest aspect to put the tray. The big danger is from the heat of the sun, and the rain that in the UK comes from the west. When the chicks are old enough not to need brooding, they can become over-heated very quickly in the afternoon sun, and the westerly showers can also soak them. The north and east are therefore always the preferred natural sites peregrines choose, and we try to mimic that with the nest tray.

Are the adult birds the same size?

No. As is the case with most raptors, the male is around one third smaller than the female and is called a Tiercel, from the Latin tertius, meaning a third. The female is a Falcon. There are a number of reasons for the size difference – the larger size of the female makes it easier for her to cover the eggs when incubating and makes her more threatening to preditors. The smaller size of the male means he is more agile when hunting prey.

I have seen peregrines in my garden

Unlikely. Peregrines don't catch garden birds on the ground or on bird tables, they are aerial specialists. It's more likely you have seen a sparrowhawk – they do specialise in ambushing small garden birds.

How many eggs does the female lay?

3-4 is the norm, but it can be fewer, and 6 isn't unknown, though extremely rare. For most of the time the falcon will not incubate the first egg. In fact, she will only properly incubate from the third or even the fourth egg. The egg(s) will often be in the tray with no visible signs of the parents, which is perfectly normal, but the adults are not far away.

Do both adults incubate the eggs?

The falcon will do most of the incubating, which lasts about a month, sometimes letting the male have a turn whilst she hunts, feeds and preens during the day, though she incubates during the night. The tiercel does most of the hunting during incubation, and will catch a lot of blackbird-size prey such as woodcock, golden plover, starlings, etc. Sometimes he will hunt at night, using the lights of Louth to illuminate waders that often move around in the hours of darkness.

Why are the injured birds taken to Worksop when there are birds of prey centres closer to Louth?

Peregrines are a Schedule 1 listed species of The Wildlife and Countryside Act. As such, they can only be handled by those licenced to do so and the Raptor Rescue Centre near Worksop is the closest centre to Louth that has a licence to handle and if necessary keep wild peregrines. Birds found in visitor attractions are often captive-bred individuals.

Do the juveniles stay around the nest with their parents?

The parents sometimes tolerate their offspring for a year, but after that, they must look for their own territory. Some do return the following year – At a site in Belgium in 2024, one of last year’s chicks has done most of the feeding. They have footage of the adult female tearing off bits of food, passing it to one of last year’s male chicks, who then feeds it to the current chicks.

What happens as peregrines age?

The maximum life span of peregrines in the wild is thought to be around 16 years (though most fail to reach that age). As they get older, the falcon will not lay as many eggs as she used to.  Some of her eggs won’t be fertile, some of the fertile eggs won’t hatch, and she won’t produce as many fledglings.

Weakness in an aging peregrine will eventually become evident to other peregrines. If the bird has a prime nesting location, a younger peregrine will try to take its territory and will eventually do so. In the spring, the challenge is often a fight. At other times of the year, the older peregrine may disappear (die) before the new one arrives.

What is a ‘brood patch’?

A brood patch is a patch of featherless skin on the underside of birds during the nesting season. Feathers act as inherent insulators, and prevent efficient incubation. Birds have solved this dilemma by developing dedicated brood patches.