Hummingbird Tit

Great Tit with deformed bill

Bill deformities are widely recorded in many passerines – and with surprising regularity. Few, though, can be as eye-catching as this Great Tit, which has been visiting a garden bird feeder in Brampton Ash for the last month or so.

Great Tit with deformed bill, Brampton Ash, 14 May 2016 (James Singlehurst)
Great Tit with deformed bill, Brampton Ash, 14 May 2016 (James Singlehurst)

Bearing a passing resemblence to a hummingbird, it feeds from a seed feeder that enables its whole beak to enter, allowing it to take a sunflower kernels with relative ease and with apparently no detrimental effect to its health. Identical bill deformities have occurred in other Great Tits (for example, see here) and research by the BTO has uncovered abnormalities occurring in local clusters, suggesting a genetic basis or an effect of shared environmental conditions.

The Stortons Bearded Tits

On 27th October I was pleased to find two Bearded Tits in the main reedbed at Stortons Gravel Pits. Always great to see, especially locally, I was alerted to their presence by the familiar ‘chuwing’ calls coming from the reeds on the southern side before a male and female broke cover and flew a short distance above the reed tops before dropping down out of sight. Not quite the long, drawn-out ‘sweee’ calls I had been hoping to hear while walking round: Penduline Tit has been seen only once in Northants (at Ditchford GP on 22nd October 1983), another is long overdue and October is the peak month … However, Bearded Tit is a fair consolation prize and with those elongated black moustaches set strikingly against that powder blue-grey head, bright yellow eye and russet plumage tones the male is without doubt a ‘looker’.

Male Bearded Tit, Stortons GP, 2nd November 2013 (Bob Bullock)
Male Bearded Tit, Stortons GP, 2nd November 2013 (Bob Bullock)
Female Bearded Tit, Stortons GP, 2nd November 2013 (Bob Bullock)
Female Bearded Tit, Stortons GP, 2nd November 2013 (Bob Bullock)

Although there have been runs of consecutive blank years, Bearded Tits occur almost annually in Northants and any sizeable area of Phragmites is worth checking for them from late autumn and throughout the winter. Occurrences are limited to relatively ‘recent’ history and there are no records during the period 1849 to 1965. Subsequent records average below 1.5 per year. The number of birds making up the records is generally low, with most records comprising between two and four individuals. Exceptionally, however, double-figure flocks are encountered and the highest currently stands at 20+ at Ditchford GP on 12th November 1972.

Bearded Tits, Northants, Distribution of Records by Month
Records reflect month of initial observation, not length of stay. 

The above graph clearly indicates the peak month of occurrence is October, which is when many disperse from breeding areas in both Europe and the UK as indicated by ringing recoveries. That the Stortons pair was trapped and ringed locally on 17th November has sparked debate on the validity of ringing versus disturbance to these birds. One comment made was that ‘a recovery is unlikely’ and, while that may be so for these two individuals, the same argument could be made for all birds which are trapped and ringed.

Male Bearded Tit, trapped, Stortons GP, 17th November 2013 (Simon Hales)
Male Bearded Tit, trapped, Stortons GP, 17th November 2013 (Simon Hales)

Condemning ringing the Bearded Tits is, therefore, as good as condemning all bird ringing. The ringing group at Stortons is active most weekends and traps a broad spectrum of species from Reed Buntings and Cetti’s Warblers to Water Rails and Great Spotted Woodpeckers. Is it a problem if the Bearded Tits are also trapped during the course of a morning’s ringing?

Much of what we know about bird movements, distribution, migration and longevity has come from ringing and, although a recovery may be unlikely, it might be that the Bearded Tits are from a breeding population on a purpose-managed reserve in the UK (e.g. Minsmere, Leighton Moss) and could be retrapped at such a site. Proving our Northamptonshire wintering Bearded Tits come from a UK breeding population on a managed reserve (or elsewhere in the UK) surely strengthens the case for making the wintering site a conservation area, affording it a greater measure of protection from disturbance or development. Secure wintering sites are just as important to the survival of a species as protected breeding habitats. Stortons is one such site as records indicate it has held Bearded Tits on many occasions during past winters. Furthermore there are ringing recoveries in Northants of individuals ringed in Suffolk and Kent (multiple re-traps).

Bearded Tit is classed as ‘Amber’ in terms of its UK conservation status. There are an estimated 630 breeding pairs (BTO) so, in this instance, there is some value in trapping and ringing them if we can learn more about their movements and set aside protected wintering areas accordingly.

Cross-billed Great Tit

Chris Payne trapped this Great Tit with a strikingly malformed bill in Greens Norton recently. It was trapped twice and appears to be coping well with its deformity and maintaining its average weight.

Great Tit with crossbill malformation, Greens Norton, October 2011 (Chris Payne)

 

 

 

 

 

 

 

Such deformities have occurred in a number of passerine species and on Flickr, there is a page devoted to photos of Birds with Deformed Bills. Several possible reasons for such

Great Tit with crossbill malformation, Greens Norton, October 2011 (Chris Payne)

deformities have been put forward, including genetic or developmental causes, injury or disease, although agricultural chemicals and pollutants may also play a part. It is believed that while some birds can adjust to their handicap and may feed by turning their heads to one side others apparently starve or are plagued by numerous parasites, such as body lice according to Passerines with deformed bills (Julie Craves).