Fat crests and a pink lady.

The 3rd and 4th may have been a bit windy but I managed to find enough shelter in some of the net rides on the east side of the site at Billinge. These net rides were sheltered from the worst of the stiff westerlies by higher ground, including the hill summit, and tree/shrub cover provided the additional shelter required. Unsettled conditions can produce interesting birding with some birds being held up or forced down by the weather and others battling through and the only way to find out is to get out there. 

The first bird caught on both days was a Song Thrush and the greyer tones and slightly smaller size of both suggested they were of continental origin. There were a decent number of Goldcrests present and 19 were ringed over the two sessions. Many of the Goldcrests were carrying quite a bit of fat with 8 weighing 5.8g or more and the two heaviest birds weighed in at 6.3g. Birds in this weight range are carrying more than enough fat to fly to southern England in a single non stop night flight and some may even go on to winter in France. Interestingly, a recovery report showing a movement of one of this autumn's Goldcrests came through just the other day, it was ringed on 2nd September and found dead 18 days later in Hampshire, 267km SSE of Billinge. Full details of this and some other recoveries will be posted in due course.

A Stonechat that suddenly appeared on a fence line on the 3rd was the first of the autumn but it didn't linger and quickly moved on. There was a bit of movement overhead despite the strength of the wind and showed how strong the urge to migrate can be. Meadow Pipits and Chaffinches were the most numerous species on the move but a few Lesser Redpolls were also heading south and 4 were caught. One of the Lesser Redpolls had a bit of a pink flush to some of the breast feathers and it almost had me thinking it was a male for a second, but on further examination it was obviously an adult and didn't have any pink in the cheeks or on the rump, concealed or otherwise, which ruled out the possibility of it being a male.

It isn't always appreciated that adult female Lesser Redpolls can have pink feathers on the breast and or rump in addition to those that are more commonly present on the cheeks. However, the pink, when present, is never quite as strong or as extensive as it is in adult males and is usually only noticeable at very close range (generally arms length or less). It is all too easy to rely on the sexing criteria that are given in Svennson and forget some of the other literature that has been produced and younger ringers may not even be aware of some of it. A very useful paper on the subject was published back in 1981, link here: M. Boddy (1981) Ageing and sexing British lesser redpolls, Ringing &Migration, 3:4, 193-202, DOI: 10.1080/03078698.1981.9673780 

Adult female Lesser Redpoll. The pink centres to some of the breast feathers aren't as obvious in the photograph as they appeared in the hand but you can still see they are there.

A side view of the same adult female Lesser Redpoll. 

One of the other Redpolls that was caught was interesting for not having a red poll. There was a slight amber cast to some of the feathers of the fore-crown but it was only very slight. This pigment variation is fairly uncommon but individuals like this do crop up from time to time although the poll is usually a bit more yellow or amber than it was in this case. While this is a first year bird it is trait that I have seen in adults too and I suspect it is more common in females, although it obviously makes sexing birds very difficult outside the breeding season.

Lessser Redpoll without a red poll 03/10/17

The amber coloured cast to the poll is there but it was very slight and barely noticeable in this individual.

One thing that has been a feature of late September and now early October has been a general lack of Blackcaps and Chiffchaffs. There seems to have been a slightly earlier and more complete departure of these two species, and Blackcaps in particular, with fewer late birds coming through or lingering compared to the last couple of autumns. The more unsettled weather and lack of easterly winds have almost certainly played a part so it will be interesting to see if this trend continues through the remainder of the autumn.

So an interesting couple of mornings and well worth the effort even though the combined total was a relatively modest 46 birds. Species totals (retraps in brackets) for 3rd & 4th October were: Goldcrest 19; Blue Tit 3; Great Tit 2 (1); Coal Tit 3; Chiffchaff (1); Song Thrush 2; Robin 1; Dunnock 2 (1); Chaffinch 6; Lesser Redpoll 4; Reed Bunting 1.

Sexing Goldfinches: easier said than done.

My previous posts on this subject are still attracting a lot of interest and my original photographic guide (link here) has been viewed thousands of times. When I put that guide together I was dealing with birds that had been caught in autumn and winter and consequently were not of known sex. However, that post illustrated the problems that can be encountered when trying to sex birds from the extent of the red mask, appearance of the lesser coverts and the colour of the nasal hairs. Around a third of the birds couldn't be sexed on plumage with a sufficient degree of certainty as they had one or more feature that was intermediate in appearance or they had what appeared to be contradictory plumage features.

I managed to catch a few birds last summer that I was able to sex from the presence of a brood patch in the case of females or a cloacal protuberance in the case of males. Although the sample size was quite small they threw a bit more light on the plumage features and on the extent of the red mask in particular. These birds confirmed that there is an overlap in the extent of the red mask between males and females and perhaps far more than is generally realised.

Bringing matters up to date I have caught more Goldfinches so far this breeding season than I have ever done before and I have been able to confirm the sex of these birds by checking them for the presence of a brood patch (female) or a cloacal protuberance (male). Being able to handle and photograph more birds of known sex has confirmed that there is a significant degree of overlap in the appearance of some males and females and others are what might be considered borderline. So lets have a look at some of these recent birds.

Z414635 was retrapped and photographed on 16/06/15                   Z414932 was ringed on 16/06/15                   

Z414933 was ringed on  16/06/15                                       Z414934 was ringed on 16/06/15    

Z414921 ringed and photographed 12/06/15.                   Z414888  retrapped and photographed 12/06/15  

The images above show 6 of the 13 adult Goldfinches that have been caught on my last two visits to Crawford. These birds are broadly similar in appearance but having said that there are some differences in the extent of the red mask with Z414934 (middle right) having the most extensive and Z414921 (lower left) having the least extensive, both above and below the eye. All have some greyish or greyish white nasal hairs or greyish feathers at the front of the crown except for Z414934 (middle right). Some readers of this post may be happy to suggest the sex of some or all of these birds and there is certainly no harm in giving it a go. They represent almost half of the birds caught recently so they are not unusual examples by any means.

So what sex are they: well Z414635 and Z414932 (top left & right) are females and both had very good brood patches; Z414933 and Z414934 (middle left & right) are males and each had a bulbous cloaca; Z414921 (bottom left) is a male and also had a bulbous cloaca while Z414888 (botton right) is another female that had a very good brood patch. Had I caught these birds outside the breeding season I would have probably left several unsexed based on the extent of the red mask and colour of the nasal hairs. In fact  Z414635 (top left) was originally ringed on 18/01/15 and I left it unsexed at the time and that was using all the plumage features including the appearance of the lesser coverts. However, I did make a note that I thought it was possibly a male so it was a really useful to retrap this bird and find out that it is a female and that I nearly got it wrong. 

The other feature that is usually checked when using plumage to sex Goldfinches is the appearance of the lesser coverts. The images below show the lesser coverts of the birds above and in the same order.

female                                                                                   female    

male                                                                            male      

male                                                                                               female

Some ringers don't have much confidence in the appearance of the lesser coverts when it comes to sexing Goldfinches but I think they are just as useful as the extent of the red mask. The image of the lesser coverts that stands out to me is female Z414735 (top left) which is quite unusual as it has mainly black lesser coverts with very little in the way of brown fringes. I have never seen a female Goldfinch with so little brown in the lesser coverts before and that, in combination with the extent of the red mask, is why I even thought it may be a male when it was originally ringed in January. The other birds more or less conform to the general rule that females have mainly brown lesser coverts or very broadly tipped brown lesser coverts while those of males are black or mainly black with well defined and usually narrow brown fringes although Z414934 (middle right) has quite broad brown fringes for a male but they are really well defined. It is worth noting that the black portion of the lesser coverts is usually deeper black and glossier in males than it is in females but as with all Goldfinch plumage features there is some overlap.

There is one more confirmed sex bird that I should show in this post to illustrate another variation in the lesser coverts. I used photos of this bird (D954944) in a recent post because it was a control and I mentioned its appearance then. The bird is a male but it had lesser coverts that looked more female like. However, the lesser coverts were mainly a golden-yellow or broadly tipped golden-yellow rather than the usual brown. It was originally ringed on 09/11/14 as an adult but wasn't sexed at that time. I can only assume the unusual appearance of its lesser coverts played a part in the decision not to sex it when it was ringed. Some may see examples like this as a reason to treat the lesser coverts as an unreliable feature but I simply see it as another variation to be aware of.

Male Goldfinch D954944 photographed 27/05/15

I would love to be able to say that I have found a reliable way of sexing all Goldfinches from their plumage but unfortunately I can't. The more I look at the plumage of birds that have had their sex confirmed by other means the more overlap in the plumage features I see. It is far too easy to get overconfident when trying to sex Goldfinches from their plumage and I know I have been guilty of that in the past. I can't give a definitive figure for the proportion of birds that can't be safely sexed on plumage alone as the time of year will make a difference. Autumn birds present more problems than late winter birds as the protracted moult of the head feathers can make a difference to the appearance of the extent of the red and nasal hairs. Whatever the figure is it is likely to be significant and it could be as high as 30%.

Whatever your view is on this subject I hope you find the photographs of known sex birds useful at least. Some blogs and guides only show images of males and females that have very obvious differences in appearance similar to those below. Those birds are not the problem and simply making reference to the variability of the species doesn't show the points of overlap where accurate sexing starts to become more difficult or impossible using the plumage features discussed. I hope this post has gone some way to rectifying that.

I know it is obvious but Z192897 on the left is a male and D725790 on the right is a female. These images are similar to those that are often shown and described in sexing guides but they don't tell the whole story as they are not typical examples of most males and females.

.

Seeing red: yet another post on sexing Goldfinches.

I have caught a few more adult Goldfinches in recent weeks and this has allowed me to add to my collection of photographs of known sex birds. I now have a much better understanding of the variation in the plumage features that are normally used to sex Goldfinches. Although the sample size isn't very big, only 14 birds made up of 9 males and 5 females, it should be reasonably representative of the population as a whole. All of these birds had their sex confirmed by the presence of a good incubation patch  for females and the shape/size of the cloaca for males.

These birds clearly show that there is much more overlap in the extent of the red face mask than is usually described in sexing guides and more than I had shown in my previous posts on this subject. The 14 birds caught this summer have taught me more than the 400+ caught during the autumn and first half of last winter. Four of the five females in my sample had red that extended well beyond the eye and equalled or exceeded that of some of the confirmed males. With that in mind lets have a look at some of the most recent photos. What sex do you think these birds are? - the answers are further down this post.

The colour of the mask varies quite a bit from an orange red through red to a rich crimson but both sexes display the same variation in colour so there is no help there. The colour of the nasal hairs can help but some females have dark grey or blackish nasal hairs like males. Just to confuse matters both males and females frequently have a fringe of white feathers or white tipped feathers at the front of the crown and these shouldn't be mistaken for nasal hairs although it is easy to be distracted by them.

Before I tell you the sexes of the birds shown in the pictures above lets have a look at a photo of a female that fits the description in most guides. In my experience females that look like this seem to be the exception rather than the rule.

If all female Goldfinches looked like this sexing them would be fairly straightforward but unfortunately they are not.

Answers:
1. male
2. male
3. female
4. male
5. male
6. male
7. female
8. female

I hope you find these photos as useful as I have. The stand out birds for me are the female in photo 3 and the males in photos 4 and 5. The photos show that there is more overlap in the extent of the red mask than is often appreciated and described in ageing and sexing guides. In fact there is probably less overlap in the appearance of the lesser coverts compared to all the other features with most females displaying a brown shoulder patch.

Outside the breeding season quite a large proportion of birds will always be difficult to sex with any degree of certainty, even when using every criteria, and I hope my posts and numerous photos have gone some way to show that. Just don't focus on red mask and let that influence you too much as it could just point you in the wrong direction.  And finally the female in photo 3 also had 3 sub-terminal white tail spots dispelling the myth that only males have 3.

Sexing Goldfinches: summer update

My previous post on this subject has proved to be the most popular of my offerings by far; it continues to receive a good number of page views and seems set to remain the most popular post on this blog for a long time to come. The traffic sources indicate that it has been frequently viewed by those with an interest in keeping Goldfinches as cage birds in addition to bird ringers which it was primarily aimed at. There is clearly a lot of interest in this subject which is testimony to the difficulty that can be encountered in sexing a fair proportion of Goldfinches using plumage features alone. 

The fact that bird keepers can have difficulty telling the sexes apart is interesting as they have the ability to observe the birds they want to sex over a period of time whereas ringers only have a very brief opportunity when the bird is ringed and examined prior to release. Most confusion for ringers occurs in autumn and winter and appears to involve more first year birds than adults but that is when most Goldfinches are caught for ringing and first year birds often make up the bulk of those catches. The perceived greater difficulty in telling the sexes apart in first year birds may largely be a function of the sample sizes involved and may not be a real difference between the different age groups. 

It doesn't get any easier the more birds you catch either and this has been echoed by other ringers that have got in touch with me. The more birds you handle the more variation you get to see in the extent of the red face mask, appearance of lesser coverts and colour of nasal hairs and the combinations of those plumage features. The one thing that really hinders the refining of the sexing criteria and learning how best to apply them for me is the lack of known sex birds to test them with. I have previously said that I rarely catch Goldfinches during the breeding season when the presence of an incubation patch or cloacal protuberance can be used to confirm the sex of a bird. However I have put in a bit more effort in recent weeks and have managed to catch a few adult Goldfinches. Unfortunately I haven't caught anywhere near enough to see the full extent in plumage variation that is likely to exist but I still think it is worth showing images of some of the birds caught recently.

Confirmed male Goldfinch ringed 15/06/14:

The extensive and bright red mask on this bird is a good example of what a well marked male can look like.

The bird does have a few small white feathers on the front of its forehead otherwise the nasal hairs are black. In my experience it is not uncommon for male Goldfinches to have a few small white feather on the front of the forehead.

The lesser coverts on this bird have quite broad tips to the innermost feathers in particular, however they are gold coloured fringes rather than brown. This bird supports my view that any bird exhibiting such gold coloured (brownish yellow not brown) fringes to the lesser coverts, no matter how extensive, will be a male.

Confirmed female Goldfinch ringed 26/06/14:

The red mask is much less extensive on this bird and only just extends beyond the eye and combined with the greyish white nasal hairs (note some are worn or missing) make this a text book female. This bird also has some small white feathers on the front of the forehead like the male above.

The lesser  coverts on this bird are text book female too and form a brown patch at the shoulder.

The obvious incubation patch on this bird confirmed the sex as female.

Confirmed female Goldfinch ringed 30/06/14:

This bird has a more extensive mask compared to the previous female and clearly extends beyond the eye although nowhere near as extensive as the first male. The nasal hairs are mainly black or greyish black and there are no small white feathers to the front of the crown. The mask is more orange red than red but the colour of the mask can vary in shade and intensity and there is much overlap between the sexes.

The lesser coverts are similar to the previous female although the brown fringes are not quite as broad. However they still give the impression of a brown shoulder patch.

This bird also had a very good brood patch and confirmed the sex as female

Confirmed male Goldfinch ringed 30/06/14:

The red mask extends beyond the eye but not much further than the female above but the red is more crimson. The nasal hairs are clearly all black.

The lesser coverts have a mixture of narrow and broader brown fringes and some of the inner lesser coverts have brown bases. They are probably best described as intermediate between the text book examples of male (mainly black) and female (mainly brown). 

Confirmed male Goldfinch ringed 30/06/14:

This bird has a crimson mask that extends behind the eye. There is even red streak that extends a long way behind the eye where the red meets the black of the crown.

The lesser coverts are mainly black but all have well defined narrow brown fringes and this is quite common in males. It is fairly uncommon to find males with all black greater coverts in my experience although I have caught a few.

If you are wondering I didn't photograph the cloacal protuberance in any of the the males because I was ringing on my own and I just found holding the bird and blowing back the feathers and pointing the camera in the right place far too difficult but the sex of each male was confirmed in that way.  I hope to catch a few more adult Goldfinches this month while there is still the opportunity to confirm their sex and before they start to moult and if I do there may be another post on this subject later this month.

A further update can now be found by clicking here.

Sexing Goldfinches update.

No I haven't had a change of mind about my previous post but I have added the following illustration to it. I have tried to show examples of the head pattern of male and female Goldfinches that I have photographed in the style of the illustrations in Svensson. I may add other material to the post from time to time when items of interest or new information becomes available.

The forecast is looking good for the morning so I hope to have a net up if it is overcast and the breeze is light enough. I did manage to get a net up in the garden in a brief weather window last week and the last bird caught was a cracking adult male Goldfinch and a control.

This adult male has a very rich and extensive crimson mask and the lesser coverts are mainly glossy black although a few have some very fine brown fringes. I will post details of the original ringing detail when we receive them in due course but judging by the ring number it is probably at least 3 or 4 years old.

There appears to have been a bit of turnover in the Goldfinches recently as I have also photographed a ringed bird that I know I haven't caught this winter. I managed to read part of the number on the ring from some of the photographs but couldn't read enough of them to identify the individual. Hopefully it will find its way into a net.

The ring on this fine adult male starts with an X and I haven't retrapped any of that sequence this winter or last autumn for that matter. I wonder where he has been for the past six months?

If I do manage to catch a few Goldfinches in the morning I am sure there will be one or two that will have me scratching my head when it comes to sexing them. Sorry, I know its a bit corny but I couldn't resist using that saying with this photo.......

Sexing Goldfinches: a photographic study (updated 18/02/14)

Lets start by stating the obvious - male and female Goldfinches are very similar in appearance. The standard reference that ringers use is the Identification Guide to European Passerines by Lars Svensson although most ringers simply refer to it as Svensson. In the guide males are described as having, on average, more extensive red on the head (or mask as I prefer to call it), black nasal hairs and lesser coverts that are black or brown black, sometimes narrowly tipped brown. While females are described as having, on average, less extensive red on the head (mask), grey or blackish grey nasal hairs and lesser coverts that are broadly tipped brown although occasionally as narrowly as some males. The illustrations give an indication of the differences in the extent of the red mask of males and females and also point out that the nasal hairs in 1Y males can be grey and in 1Y females light grey. Those descriptions and the use of the term 'on average' in particular allude to how slight some of the differences can be and to the fact that there can be a degree of overlap.

Ringers have different opinions on the reliability of the sexing criteria described above or perhaps I should say levels of confidence in them and I have even heard some say that the appearance of the lesser coverts is not a useful feature for sexing. If I had to estimate the general levels of confidence that ringers have for the various features I would expect the extent of the red mask to attract the highest levels, the colour of the nasal hairs would probably attract moderate levels and the appearance of the lesser coverts coming in last and only attracting low levels.

Photo 1. I have tried to show examples of male and female here that match the description in Svensson. If they were all like this they would be easy to sex and I wouldn't be writing this post. Note the red on the male extends well behind the eye and not just past the eye and also ends at a right angle. This differs slightly from the illustration in Svensson but is fairly typical of many males in my experience. The outer row of feathers in the lesser coverts of both birds is almost identical and this is not uncommon but the remaining lesser coverts are very different.

One of the problems we have with Goldfinches is that most of us don't get the opportunity to handle known sex birds to get a better understanding of the variation in the plumage features shown by the two sexes. I for one catch very few during the breeding season when the sex can be established from other features such as an incubation patch or cloacal protuberance. If you are lucky enough to catch Goldfinches during the breeding season the sample sizes are not likely to be big enough to get a full appreciation of the variation plus the feathers will be at their most worn which will affect the appearance of the width of any brown fringes to lesser coverts for example. When I asked a very experienced aviculturist for his opinion on sexing Goldfinches using plumage features his only response was 'hens lay eggs and cocks don't'!

Another problem with Goldfinches is that quite a large proportion have what appear to be contradictory and or intermediate sexing features based on the descriptions in Svensson. Of 92 birds I photographed and described in detail (extent of red mask, nasal hairs & lesser coverts) between 23/11/13 and 20/12/13 almost half (45) had one or more sexing features that I considered to be borderline, intermediate or were contradictory to a greater or lesser degree. I didn't sex or only provisionally sexed 16 of these which is around 17% or roughly 1 in 6 of the overall sample. I don't know what proportion of Goldfinches other ringers leave unsexed but I offer these figures to show how difficult I find it is to sex some of my birds using the criteria in Svensson alone. You may be wondering why I didn't leave more birds unsexed if all of the features didn't always fit on around half of the birds and now that I have reviewed all the descriptions and photographs so am I for a few at least. In the other cases the sex was confirmed from their wing length rather than any of the conflicting plumage characters.

So lets look at some of my 'ambiguous' birds. These are not aberrant individuals and are representative of about half of the birds that I caught in late autumn and early winter 2013. In my comments on each bird I may mention the wing length, general appearance and anything else I noted at the time. BWP gives wing lengths for British birds as 76-82 for males and 74-78 for females but I operate off 76 to 84 for males and 74 to 79 for females.


Photo 2. There are certainly some greyish white nasal hairs and the front row of forehead feathers are white suggesting female. The red mask is very bright and extends a good way behind the eye suggestive of male. The lesser coverts are quite broadly tipped brown, especially the inners which form a brown shoulder patch and lean towards female rather than male. Add to that the bill looks quite small and more female like and the wing length is 76mm. It is a juv (1Y ) not that I think we should let that sway us. I didn't sex this bird although I suspect it is a female but would everyone else agree?



Photo 3. The red mask on this bird extends well behind the eye and instantly suggests male but the nasal hairs appear pale greyish and more like a female. Then to confuse us even further the lesser coverts are almost a uniform brown forming a shoulder patch. If I now throw in that it is an adult, looks bigger billed than the bird in photo 2 and has a wing length of 78 and we are still none the wiser. This bird and the bird in photo 2 are just a couple of examples of why I don't believe considering the age really helps. This bird is a control and I don't have the original ringing details yet.

Photo 4. First impressions suggest male with bright mask extending a good way behind the eye. The lesser coverts are mainly black (shot suffers from over exposure) with just a few having very slight brown fringes also suggestive of male. You may be prepared to excuse the presence of some greyish white nasal hairs and sex this bird as a male (2 out of 3 ain't bad) and then you measure the wing and find it is only 74.5mm and under the normal range for males and therefore almost certainly a female.

Photo 5. The mask is a darker red on this bird but it still extends a moderate way behind the eye and an interpretation of Svensson could lead a novice to consider male. Nasal hairs appear grey which again could be ok for a male if a 1Y and this bird is a 1Y. Then you look at the lesser coverts and they are almost entirely brown and the median coverts even have brown centres and fringes. The wing length is 76 so doesn't quite exclude male. I provisionally sexed this bird as a female if you are wondering.

Photo 6. A similar head pattern and colour to the previous bird with the red extending a moderate way behind the eye. Most of the nasal hairs are dark grey or black but a few appear to be greyish white. The lesser coverts are very different to the previous bird and are mostly black with well defined narrow brown fringes although some of the brown fringes are a bit broader on the innermost (photo not at the best angle). However the wing length of 75mm almost certainly makes this bird a female and it is included to show how much the red can extend and how little brown there may be in the lesser coverts of some females.

Photo 7. The extent of the red is similar to the birds in photos 5 and 6 but is much brighter. Nasal hairs don't get any whiter and more obvious than this. Lesser coverts have moderate and quite well defined brown fringes with the innermost forming a small brown shoulder patch. It is an adult with a wing length of 77mm and I sexed it as a female. It was a retrap and when I checked the original ringing details I had ringed as a moulting adult female in Sept 2012 so at least I was consistent. The red mask can vary from reddish-orange and orange-red to dark red and through to crimson and some even have a mixture of those. The shade of red doesn't seem to relate to age or sex, at least not in any consistent and usable way.




Photo 8. In this bird the head looks male enough although the red doesn't extend as far as some. The nasal hairs are black so male but most of the lesser coverts are a yellowish-brown or broadly tipped yellowish-brown forming a shoulder patch and not what you normally associate with a male and certainly not an adult as this bird is. Throw in it has a wing of 81.5mm and there is no real doubt it is a male. I recorded quite a few birds with yellowish brown lesser coverts or yellowish-brown fringes to the lesser coverts and all of the ones I sexed were males. The yellowish-brown feathers and fringes contrast with the mantle much more than the usual brown lesser coverts but are really difficult to photograph.

Quite a bit of variation in photos 2 to 8 then and hopefully a few eye openers for some of you and perhaps photo 4 in particular given the short wing length. I could have just shown you loads of pictures of very obvious males and females that we could all agree on but what would be the point of that. I think I have read a comment somewhere that gave a figure for the discrepancies in the sexing of birds between ringers (in birds that have been controlled) and if I remember correctly it was quite high. A figure of around 20% comes to mind but I could be wrong although I am sure it was a significant figure. I suspect a lot of these discrepancies come from the notion that the red generally stops level with or short of the rear of the eye in females and only extends beyond the eye in males. Svensson doesn't actually say that but that is how it often seems to get interpreted from his illustrations.

If you haven't already realised this post aims to encourage ringers to think about leaving more birds unsexed or to only provisionally sex them because so many are far from straightforward and there is much overlap in the sexing features. It is much better to sex fewer and get them all right than risk getting a significant proportion wrong as seems to be the current situation. Lets have a look at another bird with that in mind.


Photo 9. The red doesn't extend much beyond the eye. There is some asymmetry with the red extending slightly further on the right side especially near the crown but it is still suggestive of female. The nasal hairs are mainly greyish-white again pointing towards female. The inner lesser coverts have broad brown fringes forming a small shoulder patch although the outers are dull black with narrower brown fringes but generally more suggestive of female than male. The wing length of 78mm is in the overlap between male and female so doesn't help. The black of the rear crown and nape has many brown feathers admixed. This was something I have looked at on all my birds to see if it is of any use in sexing birds as very obvious female types often seemed to have more brown feathers than males which were often all glossy black. Taking all things into consideration as shown above I sexed this bird as female. This bird lost a few small body feathers whilst being handled so I took the opportunity to send them away for DNA sexing. When the results came back I was surprised to find that it had been sexed as a male! So even with my cautious approach I have to admit to getting this one wrong.



Photo10. Another photograph of the male bird shown in photo 9. It was ringed on 24/11/13 and was obvious juv (1Y). It had no OGCs and had replaced all the tertials along with the central and outermost pairs of tail feathers. 

You will notice the bird above also has white sub-terminal spots on the outer 3 tail feathers. When I started photographing every bird I also trawled the Internet for any articles on sexing Goldfinches and came across a Spanish paper by Senar et al (link here) that looked at using the extent of yellow on the primaries and area of the sub-terminal white tail spots as a way of sexing juvenile Goldfinches. One of the things this paper put forward was that all birds with a sub-terminal white spot on T4 and therefore the outer 3 tail feathers could be safely sexed as male. I am not convinced of that but assuming it is correct for now lets have a look at the implications for the other sexing criteria we have been looking at on some of the other birds with 3 tail spots that I have caught.

Photo 11. The red mask is not very extensive on this bird stopping just after the eye and I think most would say female like and therefore contradicts the 3 white spots. The nasal hairs are greyish black although though some seem to have paler tips but certainly lean towards male. The lesser coverts are moderately tipped brown but are quite well defined and do not form a shoulder patch so are ok for male but are probably best thought of as intermediate. I provisionally sexed this bird as a female and largely based that on the limited extent of the red mask but having reviewed all the photos I wouldn't even provisionally sex this bird now. The wing was 77.5mm so that didn't help. If this is a male as the Spanish study suggests what does it say about the extent of red that males can show.

Photo 12. Another bird with 3 white tail spots and therefore a male according to Spanish study. The red extends a good way behind the eye suggestive of male but the nasal hairs are all greyish white and are about as female looking as they could be whichever way you look at them. The lesser coverts look female but are of the yellowish-brown variety rather than the usual brown. The wing was 79mm and too borderline for me to read anything into it so having taken everything into consideration I didn't sex this bird, not even provisionally.

One of the problems I have with the Spanish study is the suggestion that the white sub-terminal tail spots are oval and their area can be calculated by measuring the width and length and using the elliptical area equation π (Length/2) (Width/2). There is nothing wrong with the equation but there is a problem with thinking the tail spots are oval. In my experience it is not uncommon for tail spots to also be rectangular, circular, semi-circular and a variety if irregular shapes. Males may have more tail spots on average than females or they may be bigger in area but I doubt the number, shape and size of the spots have any practical uses that can be applied to sexing birds in the field. I certainly don't think that birds with 3 tail spots are always males from the many examples I have seen.

Photo 13. A few examples showing the variation in shape of the tail spots. It is not uncommon for the tail spots to be shapes other than oval. I hope to retrap some of the birds I have photographed after their next moult to as I am curious to see if the shape and size of the tail spots changes or stays the same. Similarly I will be able to see if the extent of the red mask, colour of nasal hairs and appearance of lesser coverts changes.

I did measure the length of the yellow on the 6th primary and the width and length of the white tail spots for around 100 bird but I haven't drilled the data yet and there wouldn't be much point as I am not confident about the sex of every bird. The yellow on P6 for the bird in photo 11 was 17.5mm and 18.8mm for the bird in photo 12 so both are relatively short, especially the bird in photo 11. The Spanish study is based on a relative small sample of birds trapped over 3 winters and may not have included any birds of the British subspecies. Ideally it needs repeating in the UK with the sex of each bird being verified from DNA or repeating on a good series of skins rather than going off plumage features that we can't always rely on.

Photographing and describing so many Goldfinches has allowed me to get a much better appreciation of the variation compared to just looking at a succession of birds in the hand. You can make comparisons that wouldn't have happened in the field and you are not relying on memory. At one point I had thought there was some mileage in looking at the rear crown and nape (as mentioned above) but even here you can see there is no clear cut difference between the 2 sexes as seems to be the case with all Goldfinch plumage features. While you can make some generalisations about the rear crown and nape of males and females there is a large degree of overlap and the odd exception on top of that.


Photo 14. Variation in the rear crown and nape. The age, sex and wing length is shown with the sex in brackets only being provisional. You really get to appreciate the variation when you can see them side by side like this.

So after all that how do you sex Goldfinches. Well I would have to say very cautiously and only if you look at every plumage feature. I don't think any one feature is better than another as there is overlap in all of them including the extent of the red mask and hopefully I have gone some way to showing that. I would steer clear of sexing any birds with contradictory and borderline features if we want to increase the accuracy of the data and consistency of sexing between ringers.

To be sure a bird is a male the red should extend well behind the eye to a length equivalent to or greater than half the width of the birds eye so at least 2mm beyond the eye. Also the red should remain beyond the eye all the way up to where it meets the black crown feathers and must not return back above the eye near the crown as with the bird in photo 7. The nasal hairs should be black or dark greyish black. Lesser coverts should be all black or have well defined brown or yellow-brown fringes (these fringes shouldn't form a brown or yellow-brown shoulder patch). Lastly the wing length must be 76mm or greater.

For a female the red shouldn't extend beyond the rear of the eye or it may just wrap around the rear of the eye by up to 1 or 2mm but if it does it must return back level with the rear of the eye or return above the eye towards the crown similar to photo 7 (it must not stay beyond the eye up to the crown). Nasal hairs should be greyish white or be mostly so. Lesser coverts (excluding the outer row) should be brown or broadly tipped brown forming a uniform or fairly uniform brown shoulder patch. The wing length should be 79 or under.

My version of the head patterns of male and female Goldfinches drawn in the style of the illustrations in Svensson's identification guide.

If features are ambiguous or the bird is in juvenile plumage you may be able to sex some birds on wing length alone <76 female and >79 male but you should record these as being sexed on size.

Adopting this or something very similar will reduce the number of birds that you sex but will improve accuracy and the repeatability between ringers. Even if you are certain of a birds sex but don't think other ringers would necessarily agree then provisionally sex it rather than giving it a confirmed sex. I have left approximately 30% of birds I have ringed this year unsexed or only provisionally sexed them since adopting this approach.

A final word of caution - don't start sexing 1Y birds if the post juvenile moult is not complete unless simply sexing them on wing length <76 female and >79 male. The feathers around the face are the last to be replaced and the post juvenile moult may not be completed until December for birds from the later broods. The extent of the red and the true colour of the nasal hairs may not have fully developed until well into December in these birds. Feather sheaths and debris from feather sheaths can also make nasal hairs look much paler than they actually are and even paler than the example shown below in some cases. This is not always obvious and easily overlooked if you are dealing with a lot of birds and are having to process them quickly. Also juvenile nasal hairs are pale greyish-buff so can give the impression of female if not fully moulted out.

Photo 15. Close-up of nasal hairs showing dusting of feather sheath debris making them appear paler than they really are. This is not the most extreme case I have seen.

Photo 16. The feathers of the face are the last to be replaced in both the post juvenile and adult moult and this can continue well into December. This bird gives the impression of being a female but the red may not have reached its full extent as the feathers behind the eye still seem to show some juvenile spotting. What appear to be greyish white nasal hairs may be that or they may include pale greyish-buff juvenile feathers that have yet to be replaced.

I have stuck my neck out with this post as there are likely to be as many opinions on sexing Goldfinches as there is variation in them. I have even owned up to the odd mistake as it is so easily done. There is clearly room for further study and this post may even prompt some of you to undertake your own or to publish what you already know. Until then I think ringers need to be more confident and comfortable with being uncertain and leave birds unsexed if there is any ambiguity in any of the features they present and the wing length falls in the overlap between males and females. I have learned a lot from my little photographic study and hope you will get something out of it too.

One more photo collage because it is a cracking adult male and to show how extensive the red can be or orange-red as it is in this case. The lesser coverts are also a little unusual on this bird.

Photo 17. An adult male with probably the most extensive red mask I have seen. This bird was originally ringed as an adult male in September 2011.The nasal hairs are a bit short and appear dusted grey because they are still growing and bits of sheath are present. A few of the nasal hairs were still in pin. The lesser coverts have quite well defined yellow-brown fringes although some of the fringes are much broader than you would normally expect with a male and especially an adult. Adult males are usually described as having glossy black lesser coverts with a few sometimes having well defined narrow brown fringes. There seems to be an exception to every rule but I think we can all agree on this one being a male.

and finally...........

Photo 18. Some Goldfinches are always going to leave us scratching our heads.



If you have read to the end of this post you may be interested in the summer update I posted on 4th July 2014. This shows a few birds caught during the breeding season and can be found by clicking here.

A further update posted on 21st August 2014 and showing more photographs of known sex birds can be found by clicking here.

An additional article on sexing Goldfinches posted on 20/06/15 showing photographs of breeding birds can be found by clicking here.