Sheffield Peregrines DNA Study

by Dr Deborah Dawson, University of Sheffield (This email address is being protected from spambots. You need JavaScript enabled to view it.)

A breeding pair of peregrines has nested on St George’s Church in Sheffield since 2012. A 24 hour live stream web camera allows viewers around the world to observe the life of the Sheffield peregrines as they raise their chicks. The webcam has had over a million views and weekly updates of the highlights are provided via the ‘Sheffield Peregrines’ blog and the twitter account @peregrines2018 throughout the breeding season (February-July). In the Northern hemisphere, birds pair up and start nesting in February-March. In Sheffield, records since 2015 reveal that four eggs have been laid each year, and between two eggs (2015) and three eggs have hatched (2016-2018). Eggs are laid late March, hatching occurs late April and first flights are usually during the first week of June.

Flying high over Sheffield. Photocredit: David Wood, Sheffield Bird Study Group

As adults, male and female peregrines have slightly different plumage patterns, and males are 20-30% smaller than females, however it can be difficult to distinguish between the sexes when observing birds singly or from a distance. As chicks, peregrines are even harder to sex. Even when the brood contains both sexes, sexing based on observation can be impossible. However, peregrines can be sexed using genetic markers and this can be done using DNA obtained from a mouth swab, feather or blood sample.

Mouth swabbing of a St George’s peregrine chick in 2017. Photocredit David Wood, Sheffield Bird Study Group

At the University of Sheffield, we used genetic markers to investigate the sex of a total of eleven St George’s chicks, fledging between 2015 and 2018. Mouth swabs and/or feathers were taken from each chick by members of Sorby Breck Ringing Group. Dr Natalie dos Remedios extracted the DNA from the peregrine samples and performed lab work at the University of Sheffield. Control samples of known sex peregrines were gathered including a known adult male and female, whose sex was based on size, and 42 other individuals that had been sexed by a commercial company (21 males and 21 females). Genomic DNA was extracted from each Sheffield chick and the control peregrines, and the DNA was analysed using genetic markers to sex the chicks. Five sex markers were used to ensure confidence in the sexes obtained. The DNA sexing results matched the sexes of the birds of known sex (sex based on size and those sexed commercially), the sexes of all control individuals also agreed between the five different markers, confirming that all of the genetic markers used were correctly identifying sex in peregrines.

When the, now validated, sex markers were applied to the St George’s chicks, the genetic sexing revealed that all of the eight chicks that hatched in Sheffield between 2015 and 2017 were male. This was an unexpected but interesting result. The probability of the chicks being the same sex 8 times in a row is 1 in 128.

Oh boy, oh boy, oh boy… St George’s chicks, Sheffield. June 2017. Photocredit: Sheffield Bird Study Group

We then DNA sexed the three chicks that hatched in 2018. Of these, one was slightly larger than the other two. DNA-sexing revealed the two smaller chicks were both male, however the larger chick was female – the first female in at least 4 years.

We are keen to sex chicks from other UK nests to see how often other peregrine pairs produce same sex / sex-biased clutches.

Who’s the mummy?

In 2018, we investigated a second question surrounding St George’s peregrines.

The male adult peregrine at St George’s has a metal leg ring but the female adult is not ringed. It has been suggested that the original female parent was in poor condition in 2015 and may have died. If so, a different adult female may be the mother of the 2016-2018 chicks (David Wood pers. comm.).

We amplified the eleven chicks (2016-2018) with a set of autosomal genetic microsatellite markers that allowed us to distinguish between individuals. We then used the genetic profiles of the chicks to reconstruct the parental genotypes and investigate if any change in parent had occurred. We found no evidence to suggest a switch in either of the St George’s parent.

During the first step of the DNA fingerprinting work we tested and validated the marker set in the control peregrine individuals we have already collected. The validated marker set could also be used to assist in DNA-based investigations of wildlife crime, such as studying parentage. It could, for example, be used to investigate if any proposed captive parents of a chick are the true genetic parents, in cases where the real parents are suspected to be wild peregrines, and the chick has been taken from the wild.

We would like to obtain samples from other UK wild peregrines to create a DNA archive and database to be able to compare individuals and their origins. If you are interested or able to assist with this please contact Dr Deborah Dawson This email address is being protected from spambots. You need JavaScript enabled to view it..


For more information:

Sheffield Peregrines DNA Study:

Sheffield Peregrines webcam (live viewing):

Sheffield Peregrines fundraising page:

Sheffield Peregrines Twitter account: @peregrines2018