London Peregrine Facts
It is well known that Peregrines are one of the fastest living birds with speeds reached in excess of 180 mph whilst diving. This is achieved by the 'classic' stoop, whereas a bird will thermal to a great height and then dive onto 'prey' below, always another bird.
Having watched them in London for a good number of years, I have only ever seen this once. The fact of the matter is, there is so much 'natural' prey around (feral pigeon) they have no need to hunt this way. On warm days they will thermal, usually around 10.00am to 2.00pm, but this is in common with most other birds of prey, it is often done to mark territories, sometimes pair bonding if 2 birds are up, or simply to to get from A to B with the least amount of effort.
The most common hunting technique is for a bird, usually the Tiercel when they are breeding, to fly to a high vantage point as near to the nest site as possible and simply wait and target a passing bird. A misconception with Peregrines is that they rarely fail, they do, and on some sites in London, it is quite a lot, feral pigeons are not always easy targets. Peregrines have the speed but ferals are very good 'jinkers'.
The well known derelict site of Battersea Power Station is home to around 4 to 500 ferals, and the resident pair of Peregrines simply have no need to hunt elsewhere or go further afield. Peregrines are most active at dawn and will hunt at first light light, which is the norm for most of the pairs in London. On this site more than any other in London, I have watched their hunting method when the Tiercel is hunting off chimneys, the ferals are aware he is there, and go out low to the ground, fast heading south, under the roof tops. In contrast, ferals leaving later or mid dayish fly much more leisurely and gain height straight away, knowing they are less prone to being targeted. In most birds of prey, the female is dominant and larger and with Peregrines it is no different , the female is around a 3rd again larger than the male.
Nocturnal Activities
It is becoming apparent that on some sites and different countries, nocturnal hunting is being observed. America for one, and it has also been noted in France. In London, there is a well established pair, and within their territory is a structure illuminated by artificial light. I have observed this pair hunting in winter up until 10.00pm of an evening and also seen them leave at 3.00am. I have only witnessed this in winter, and always both birds have left their night-time roost spots together.
I collect the prey remains and pellets from this site and send them off for analysis, as well as being able to identify prey that I cannot get to, but can see. Regularly turning up are the weak flyers that move around at night and also winter migrants. These include: Coot, Moorhen, Water Rail, Quail and Redwing. In particular, I have heard winter Redwing passing-over in the dark and looked back to both birds roost spots, and both were gone, opportune feeding in the dark, the advantages with the Peregrines are their incredible eyesight.
Numbers
I know of at least 18 territorial pairs within the LNHS boundaries, as mentioned on the home page. The truth of the matter is, that the figure is very likely higher. For such a high profile bird which hunts mainly at dawn, they can be surprisingly inconspicuous and lazy, sometimes spending 5 hours or more digesting food and not moving from the same position.
In the early days, the closest pairing was around a 3 mile radius, but they are reducing all the time as more pairs and singles are becoming established and filling in the hole, but the downside to this, is that it is starting to cause disruption to established pairs. Single adults are testing pairings regularly. This year alone (2009), I have witnessed it on 4 sites with 2 failing to breed as a consequence. On both of these sites, the falcon was replaced. Without doubt, London has the size, prey, and structures to hold 25+ pairs, long may it continue.