19 September 2012

Swanderings abroad

Being large, white and usually occuring in large fields or water bodies, swans are an 'obvious' part of our countryside. In winter there can be large concentrations of birds, especially at WWT (Wildfowl & Wetland Trust) reserves, mainly comprising of the migratory Bewick's and Whooper Swans.
Our other swan species, the Mute Swan is seen in the UK all year round. Around 124,700 Mute Swans have been ringed in the UK and Ireland and from recoveries it's obvious that the majority of Mute Swans are sedentary. Once a bird finds a mate and a territory it remains faithful to the site and rarely moves more than 5km.

Mute Swan - Jill Pakenham

I received a phone call recently regarding a Mute Swan that had wandered into a John Deere tractor shed at Ringwood, Hampshire. It was very thin and in heavy moult so had to be taken into care but the signs are looking promising of a full recovery. Thankfully this bird was ringed and this ring hinted to its origins staight away. It was wearing a German ring from the Helgoland Ringing Scheme! It will be interesting to know when it was ringed, to see if the sea crossing had anything to do with its poor condition.

You will be used to seeing maps on the Demog blog but the BTO are now able to produce them on our 'recoveries summaries by species' online ringing reports section of our website. The map below is from the Mute Swan page which shows how special a German Mute Swan recovery is.

Mute Swan recoveries. Ringed in Britain or Ireland; Found in Britain or Ireland

11 September 2012

What happened to the Pied Flies?

Many nest recorders (www.bto.org/nrs) and ringers (www.bto.org/ringing) have reported low breeding success among the populations of Blue and Great Tits that they have been monitoring during the 'summer' of 2012, with bad weather and a related lack of invertebrate food taking their toll at a number of sites. Migrant Pied Flycatchers have similar habitat preferences and diets, but breed slightly later - Peter Coffey from Merseyside Ringing Group summarises the season as experienced by his study population.

Upper Valley

"What a strange year for my Pied Flycatchers in Denbighshire! It started so well with the earliest record of a female nest-building on 14th April, followed by the first egg on 25th April (site record – 24th April). Four more clutches were started on 28th/29th April but then almost nothing until a late rush between 9th-13th May. Numbers of nesting pairs were slightly below average but nothing to worry about.

Then all hell broke loose! 36% of Pied Flycatcher nests were predated at the egg stage, compared to the norm of 5%. Chief suspects were Weasel and Wood Mouse; smears of blood on the inside of two boxes suggest the females were taken.

The surviving nests achieved remarkably good success considering the weather with 85.7% of chicks fledging. As the size and frequency of caterpillars in the food diminished towards the end of the season it was not surprising that weaker chicks in later broods perished.

Four very late nests were probably re-lays by females that had lost their first clutch (one female had been ringed earlier at a nest that was subsequently predated). By any standards their fate this year was abysmal – 19 eggs converted into 9 chicks of which only one fledged! It was a combination of egg predation (again), addled eggs and chick death. It reduced the overall chick/fledging success rate to 81.2% and the egg/fledging success rate to 49.2%.

Pied Flycatcher male

My RAS work also suffered. Early predation occurred before I’d had a chance to trap sitting females and it’s often a struggle to trap males at late nests – they’ve started their moult and can be disinterested! So imagine my joy when I trapped the only male seen at any of the late nests – and it was a control (not ringed locally), my only one of the season!"

Thanks for Peter for letting us know and for the photos.

03 September 2012

Strange Swallow

Ringers are well aware that unusual bird movements or bird moult can hint at something yet to be discovered. While ringing in his Nottinghamshire garden Adrian Blackburn has caught over 700 Swallows this year, with most of them being juveniles but with some adults also. One of these was wearing a Spanish ring but more interestingly one bird seemed to be both adult and juvenile at first glance.

Juvenile Swallow

Unfortunately this Swallow was unringed (so origin unknown) but the most remarkable thing about this bird is that it was a juvenile that was going through its main moult into adult plumage, and replacing its wing feathers! British Swallows normally do this in Africa so a bird moulting in Nottinghamshire is was very unusual. The 'old' juvenile wing and tail feathers were much browner compared to the new growing feathers and this hints that this bird has been in a sunny location so unlikely to be in Nottinghamshire.

Swallow with older brown feathers and new blue feathers

Could this bird have hatched in Iberia and moved North to the UK instead of South to Africa (similar to reverse migration) or did this bird hatch in the far North and started moult before reaching its wintering grounds? Hopefully this bird will be captured again by a ringer further on in its journey and start to answer some of these questions.

Swallow tails with older feathers but replaced blue rump feathers

Thanks to Adrian Blackburn for letting us know and for the photos.