What have we learnt from the return of the peregrine? Talk by Ed Drewitt, 4 February 2020

With a full house of members at BRLSI, David Goode introduced the speaker, Ed Drewitt, as one of the country’s most knowledgeable peregrine specialists and author of ‘Urban Peregrines’, the first book to highlight the success of this fabulous bird in urban environments. After 18 years of research on the subject and with his amazing collection of photographic images, Ed gave us a fascinating evening.

He described the slow recovery of bird numbers in the 80s and 90s, after years of persecution and the effects of pesticides; and pairs began nesting in urban locations: on churches, rooftops and industrial sites. Today there are 170 pairs of urban peregrines, each location with a group of enthusiasts working hard to protect their interests.

The recovery has not been matched in rural areas which are mostly in mountainous areas in Wales, Scotland and N. Ireland where persecution is more prevalent and the decline in prey species, lapwing and golden plover for example, has reduced their food sources.

Fortunately, the creation of peregrine nesting sites in cities, the introduction of webcams, and positive media coverage such as Springwatch, has led to much better awareness and understanding of the bird. It is hoped that in future there will be fewer cases of persecution.

The most successful peregrine research has been based on ‘colour-ringing’. One leg has a standard metal/number ring, the other a larger colour/letter ring. The colour indicates region; the letters, which can be read without capture, identify individuals. This system has led to increased reporting of individuals.

Thanks to this, ringing stories are now emerging. A disturbing one was of a Bath young female turning up in Norwich where she ousted the female of the established pair before taking out two chicks from their nest, one by one as they hatched. The Bath female is now the established mate of the Norwich male.

Research has shown that cliff-nesting pairs usually stay in the same type of environment, as do urban birds. They have, however, watched a cliff-nesting pair in Clifton Gorge move into central Bristol between one breeding season and the next.

We saw many excellent images of nest sites such as egg laying (with female looking surprised at her egg), feeding of young and fledging (there is an average 50% mortality rate). There were fascinating charts of where maturing birds fly off to. Young males from Bristol and Bath disperse in all directions though predominantly to the N.E. into the Midlands, where peregrine numbers are still relatively small. Females from the same broods also disperse in all directions though predominantly to the N.E., but they fly far further, often more than twice the distance of the males. This not only has the effect of dispersing the species more widely, but reduces the chance of siblings pairing up.

One of Ed’s particular interests is in urban peregrine prey species. Over 100 have been recorded, with feral or domesticated pigeons making up about a third of the diet. The enormous range of other birds includes kingfisher, blackcaps, snipe, starlings, parakeets (in London), woodcock and whimbrel. One Exeter peregrine kills a dozen young buzzards each year. Only 5% of prey are non-avian; bats and squirrels are examples.

Another discovery is that urban peregrines often hunt at night, taking out migrating birds. City lights show up the passing migrants and help to provide peregrines with an easy meal. Remains of little grebe and water rail have been found in nests.
We heard of many other interesting facts about peregrines such as: their notched beaks, which help them slice prey items; their dark hoods, possibly for reducing glare; their caching of prey items for lean times; young males sometimes acting as ‘helpers’ at their parents’ nest for a season or two; wet springs leading to greater chick mortality; and cliff nesters on average laying fewer eggs than urban nesters.

With the establishment of sound research methods and networks, and with increasing numbers of birds to study, Ed expects a great deal more to be discovered about peregrine falcons in the coming years. On this upbeat note he rounded off his excellent talk.

Alice Nissen