1st winter female Lesser Kestrel (Falco naumanni), Fraisthorpe, East Yorkshire, October 2019

Identification notes on the juvenile Lesser Kestrel (Falco naumanni), present at Fraisthorpe, East Yorkshire 22nd-23rd October 2019 and quick notes on the separation from the extremely similar Common Kestrel (Falco tinnunculus)

On Tuesday 22nd October, Kevin Groocock’s photographed a juvenile naumanni at Fraisthorpe, East Yorkshire. The following are some notes on this birds identification and subsequent sightings on 23rd October. I was not lucky enough to see it in the field but analysis here is going from Kevin Groocock’s excellent photos online (22nd) and Mark Pearson’s (23rd) that he was kind enough to email over to me.

The first feature that instantly hits you, in Kevin’s photos, is how plain faced this bird is with a sandy-buff overall colouration.

The open and plaintive face, arises from a weak rear eye stripe and lack of a dusky wash to its ear coverts. In tinnunculus the lateral crown stripe is more defined and darker, which gives tinnunculus a more aggressive facial expression. As a comparison, the same rough idea can be applied to Thick-billed Warbler as naumanni and Great Reed Warbler as tinnunculus.

The Fraisthorpe naumanni shows a split moustachial stripe, (note how the moustache has a weak hairline fracture akin to a juvenile nordic peregrine) sitting adjacent to very sandy cheeks and notable sandy lores. The moustache is less pronounced towards its tip. The base of the moustache, underneath the eye, I always feel is more extensive than tinnunculus. In naumanni it shows a blurrier lower edge to the eye, more akin to eyeliner. Which may trick our eye into making the eye look higher and further away from the beak than in common, giving naumanni an altogether more anxious/cute/parrot like expression.

The parrot like expression on the Fraisthorpe bird is exacerbated by the colour of the upper mandible. If you look closely at the base colour of the upper mandible and to some extent the base of the lower mandible it is yellow, akin to an adult Red Kite. This accentuates the small billed feeling as it makes the dark tip appear smaller when compared to the darker/bluer bill base in tinnunculus given them a larger looking darker bill.

In the hand naumanni are altogether more placid, being very reluctant to bite whereas tinnunculus will happily dig into you with their stronger bill.

The orbital skin between the lores and eye itself seems thicker in my opinion in naumanni.

Moving on to the feathers topography. The greater underwing covert pattern have a more rounded shape with isolated dark centers, more akin to tear drops or curved hearts in naumanni. Compared to the rather more acute diamonds or chevrons (that are normally bridged) seen frequently in tinnunculus. There is some overlap in this feature and like all raptors, exceptions to rule do exist, but when applied to a whole suite of other features this helps to support the final ID.

Greater Coverts - basal barring droops and appears to fall short of feather fringing, the two main  horizontal bands throughout the entire length of the GC's created by this barring is saw toothed as these bars don't meet horizontally or wish to touch. Photo JAB

On the upperwing, the basal two bars in the greater coverts droops downwards (look sloppy). As a result, appears not to touch the adjacent feather unlike with the sub-terminal bar, which slurs upwards towards the head. Also, note on how the black in the outer greater coverts can at times be conjoined between the bars, I have seen this more frequently in juvenile naumanni in the hand (see above). In the majority of tinnunculus this barring is usually more regular, with more basal bars prior to the sub-terminal bar, more uniform traverse and squarer bars. Within this juvenile male tinnunculus do show more variation.

Juvenile female Lesser Kestrel (Falco naumanni -photo credit courtesy of Egidio fulco) note sandy rump

From my experience with 1st plumage 1cy /1st summer birds (early 2cy) in the hand from Israel, Italy, Kazakhstan (prior to 1st moult of flight feathers) the barring across the length of the tail feathers inside of the broadest distal tail and is like marbled royal icing. I rarely see this in tinnunculus (some young males for exception) and can see this in pics I have seen, namely Marks Pearson's tail shot inserted into my composition image. I may be hard to discern but i have looked very closely at Kevin's original pics and can make out the ventral side of one of the tail feather nearing the outemost right hand side of the tail appears to be similar to the pattern I can sin photos from the 23rd. In juv female tinnuculus the tail barring squarer and usually more consistent, uniform and regimented.

Age of Fraisthorpe bird: Juvenile - washed out and sandy uniform tips to the majority of coverts and extensive sandy tips with minimal grey tones (which you would see in 2cy autumn + females) to the majority of contour feathers. The rump including upper tail coverts is very extensively tipped sandy and is fresh. The quite well marked primary bases suggestive juvenile female, which is more like male juvenile tinnunculus. Also the pattern of the greater coverts as discussed above is juvenile in its pattern. 

Sex of Fraisthorpe bird: Female - no apparent grey tones in any feather tract, well-marked primary bases and coarse vertical and extensive streaking (on to trousers/belly) throughout vent

*residue seen on bill is most likely mucus from earthworms given they are ploughing large areas of East Yorkshire at moment. 

In conclusion :

The Fraisthorpe bird is a juvenile with a similar tail pattern to an adult female tinnunculus, (very pro naumanni) with a greater covert pattern more akin to a juvenile male tinnunculus, (again pro naumanni with a bird of this age and sex) coupled with the pale claws, a weak facial pattern and bill, sparsely marked dorsal marginal coverts around the carpal are all features that supports the identification of this bird as naumanni.

23-10-19

I have spoken to numerous people who were present on site on Wednesday 23rd. A number of these folk are Yorkshire birders with a wealth of combined experience including experience with juvenile naumanni abroad. I find it coincidental that they were to rock up to the same site and then find a kestrel sp. showing several pro features of naumanni , including pale claws on a nearby hedge to where the naumanni was originally photographed.

This is where social media has played a massive part in casting a negative air over this amazing sighting. As the photos taken on Wednesday were at a distance, once they are compressed by Twitter it is very hard to make out specific features and make a call on such a tricky identification, so surely the views of the experienced birders in the field should come over the decisions made from poor quality photos, which meant that there were only two other birders looking for this mega rarity on Thursday morning. 

The fact that there were photos from Tony Dixon on the 23rd on Surfbirds showing the bird to have pale claws is evdience in itself.

I would welcome people to contact me to inform be about photographed pale clawed tinnunculus and would happily pay for the rights to use these photos. Many at this time of your may show claws caked in dried mud. Kestrels will be actively following the plough's around at this stage in autumn and baked mud in the sun will look pale, but never the same ivory tones seen in naumanni or vespertinus.

A first glance of the  photos taken on Wednesday the bird looks to be  tinnunculus like and I for one on first seeing them said I would have overlooked this bird at a raptor watchpoint if that had passed me by. The point is, I wasn’t there and MJP pics are of all the same bird and we know light, angle, chromatic aberrations all play a part in tricking the eye. Remember we are not looking at the bird, we are looking at a digital imaged generated by chemicals on a lcd or computer screen. Folk were there watching it.

I’ve tried to illustrate a comparison shot of why I believe the bird seen and photographed on Wednesday is the same naumanni photographed by Kevin Groocock. I didn’t see the bird on Wednesday, and I’m not one to crave a British or Yorkshire tick. I simply want to learn as much about raptors as I can before I leave this planet and celebrate this bird, in mighty Yorkshire!

MJP's shot from 23-10-19 - (easier to see missing/displaced primary greater underwing covert (circled in orange in comparison image) shown in boths birds )

As we are yet to see wing formula from Kevin's photos I can’t compare this feature between the two sightings, hopefully further pictures will emerge soon from Kevin. 

As can be seen above, I have compared feather detail between one of Kevin Groocock’s awesome pictures from Tuesday and Mark Pearson’s photo from Wednesday to show that they are the same bird.

⦁ Primary underwing coverts, circled in orange - quite a crucial area. In both photos you can see one of the inner greater primary underwing coverts seems to be missing or displaced.

⦁ Median underwing coverts, circled in red - two tram lines of rounded dots in the median coverts that appear to match one another.

⦁ Median underwing coverts, circled in green - very similar elongated tear drop pattern, nestled in a buff shaped wedge. With a gap between the outer axillaries and inner greater underwing coverts. With a plain area below the area circled in green.

⦁ Axillaries, circled in purple - appear to be very barred and draw the eye to that area. In tinnunculus the axillaries and greater underwing coverts are usually more triangular and diamond shaped. In tinnunculus the patterning of the whole greater underwing covert and axillary area is quite bold, whereas in naumanni and this bird the axillaries are the most extensively barred contrasting with the sparsely marked greater underwing coverts. See the description of pattern above.

⦁ Carpal coverts, circled in grey - I assume due to the small size of the carpal covert markings they don’t appear very strongly in the flight shot from Wednesday. That said, the ghosting of these feathers is the same rough pattern, and remember the wing is more stretched in this picture, making the markings less distinct.

⦁ Not circled but the smaller markings in the lower flank/trouser/undertail coverts and lesser underwing coverts don’t show up in Mark’s photo from Wednesday due to lower photo quality at that distance. 

⦁ Face/head – looking at Mark’s and other pics I’ve seen from Wednesday the bill base looks pale yellow to me. The moustachial stripe look split and bleeds around base of the lower orbital ring. The cheeks are very pale, contrasting with the moustachial stripe. The birds blaze above the cere is sandy pale and changes colour to a sandy rufous as the orbital ridge starts. The bird has a darker coloured nape/collar and gives it a contrasting almost ringed look to the nape area. Also note how the colour changes as the nape begins to meet the mantle (at the base of the arm) the colour change from a buffish wash to terracotta is evident in both pics at upper side of the area circled in green.

I went to the site on Thursday morning to try and see the naumanni but had two 1cy tinnunculus in foggy conditions at close range, nothing like the bird photographed on Tuesday and Wednesday. 

Same bird as below - note the limited nature of barring in greater underwing coverts in comparison to axillaries. IMO tinnunculus has a less defined transition between GUWC's and the axillaries than naumanni. 

A nice fresh juvenile female Lesser Kestrel (Falco naumanni) - photo credit Egidio Fulco. P10 (outermost) most likely still growing. Many birders watching the bird mentioned how regularly the wing formula would change. I've see a whole host of pics of the Fraisthorpe bird whereby the relationship of P10 , P9 and P7 varies. Interesting that most folk were happy with birds ID from Kevin's original pics without wing formula on show.

Big thanks to Mark James Pearson  (click for link for more on his blog), Johnny Mac, Rob Little, Jo Hood, Tim Jones and the Spurn Bird Obs crew for great discussion, for providing images and insight into what they observed on the 23rd.

I really welcome comments regarding this bird and as ever love to learn.

Eyes to the skies!