Whilst I agree with what melodious said, if a ringer had caught this individual and claimed it was a marsh tit, I think they'd be wrong. Identifying can be over complicated. Ringing obviously helps with i.d. of difficult to separate species, but unless you are ringing, you have to draw a line somewhere when identifying a species. This individual has all the hallmarks of willow and ticks every box of old school identification. Human error can effect everyone incl me. These photos are too good and the individual is too cooperative for there to be any doubt regardless of what someone holding it might claim.
In reply to Robbo:
Wasn't arguing with the identification, Ribbo, actually agreeing with it. Just giving a snippet of information from a scientific study I'm working on in case any readers found it of interest. As it's a scientific study we have to go with the best evidence presented. So if what an observer thinks and what a ringer thinks are different we can't ignore that; there are records of hybridisation between to the two species for example.
In reply to melodious:
Agreed. Of course, there also has to be a risk that records of hybridisation are wrong due to mis-identification, esp pre-ringing and close studying. I certainly am happy to accept it does happen, but the risk is there.
Worth noting that the bill spot feature was first proved by RSPB Science Officer and ringer Richard Broughton using caught birds and museum specimens. It then started being used by birdwatchers. During the same study he showed two features previously used for identification were completely unreliable (presence of a glossy cap is sex, age and individually variable in both species, there is complete overlap in bib size) and one only works (with caution) reliably at certain times of year (wing panel). While I very much doubt the work I'm doing will overturn anything Richard found I do have to keep a very open mind and the bird i mentioned is a case in point; everything seemed to fit Willow except the bill spot (including wing length which was a mm outside the known range of Marsh, now that's an easy measurement to get wrong!) but bill spot is by far the most reliable visual feature! So if any stray feathers drop out if it's caught again we are definitely looking to do DNA analysis on them; we have had a least one mixed pair locally though no young were produced.
Bull necked appearance and lack of obvious white cheek.
Neck size is also variable (sex, individual, moult, health, plus posture can make it difficult to assess). The two colour division on a Marsh Tits cheek is the only other reasonably and consistently reliable feature feature for field identification according to Broughton. However tail length gradation is used by ringers and, providing the bird isn't in moult or the tail damaged, can be seen in good quality photos and may, at times, be doable in the field.
*melodious* you're a mine of willow tit information, thank you! I'm taking notes! Where are you studying them for your research? I noticed there was a callout for people to take part in a willow tit survey near me, and I really wanted to participate, but they were looking for people who had experience of doing BTO surveys before, which I don't have. (I don't think they would be very impressed by the fact that I am participating in the tawny owl survey!!) As you can tell from this thread, I'm not exactly experienced with willow/marsh tits either. I've only done botanical surveying, which is very different. Those plants stay nice and still!
I'm intrigued by the idea that marsh and willow tits can hybridise. Has that happened with a pair of definitively identified birds? From what you say, it sounds like it has?
In reply to Kiera:
Hi Kiera. Birds of the Western Palearctic gives two instances of confirmed Willow x Marsh Tit hybridisation in Europe (plus also Willow x Coal Tit). What perked my curiosity initially, however, was a mixed pair in Barnsley, South Yorkshire in 2008 (written up in Atlas of Breeding Birds in the Barnsley Area 2006-2011). Behaviour suggested the Willow Tit was male and the Marsh Tit female. After building a nest together it came as a surprise when the male then re-mated with a Willow Tit. There has been as least one other instance locally (in north Derbyshire) of Willow and Marsh Tits 'interacting' closely together but nothing more is known in that case. Interestingly both these occasions involved areas where Marsh Tit would not normally be found so it might be because the Marsh Tit, finding itself alone, sought the nearest company it could find. With both species becoming rarer, and their ranges more fragmented, perhaps this kind of thing will happen more often? I see from another post that you are Sheffield based; that's where my study is! Our team could certainly show you the survey ropes, just not sure how to get contact details to you via this platform (no private message facility?). Perhaps via Sheffield Bird Study Group? If you are keen then let me know on here, I'll let SBSG know that you want to get in touch with our team and they could pass your details along to us.
I have a cunning plan! I have an email address that I only use for junk mail - if you email me on there, I can pick up your details and then email you back from my actual address. It's owlpost1977 at gmail dot com. I have only just joined SBSG last week and don't have my membership details back yet, so this is the best way for now - otherwise we may sow seeds of consternation and confusion!
Totally different (and obviously much larger species), so may not be relevant at all - but I recently saw a black swan quite happily cosying up to a flock of whooper swans. I was curious, so I did a bit of digging and it seems that black swans can sometimes interbreed with other swan types under similar conditions to those you describe - and even with geese. In this case, they are naturalising escapes, but I guess the principle of a scarcity of mates is the same.
I would love to know if there are broader studies of the impact of dwindling and fragmenting native bird populations (habitat loss, climate change?) on incidence of hybridisation.
I'm not far outside Sheffield too at Kiveton Park where we have a few Willows and send my sightings to SBSG and know David Wood.
Also get the occasional Marsh Tit too.
There is a messaging system on here melodious will check it out for you when back on laptop.
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