Winter wreaks havoc on bearded tit numbers

Milder weather and rain this week has started to thaw out frozen marshes and ponds across the region.

But the coldest December since records began has taken a savage toll, not least at the RSPB's Blacktoft Sands reserve, near Goole which has seen one of its key species, bearded tits, decimated.

At the start of the winter, there were between 250 and 300 bearded tits resident on the reserve, 10 per cent of the entire UK population.

Now there are thought to be just 30 to 50 left, perhaps fewer.

Bearded tits can withstand cold weather but the damage was done during a critical two days at Blacktoft Sands in mid-December when the temperature dropped to -10C and reed seed heads were frozen, which meant the birds were deprived of food and starved to death.

Reserve staff tried to help by putting out sunflower and niger seeds for them, but to no avail.

Bearded tits are remarkable in that they undergo a physical change in autumn to adapt to their winter diet.

In summer, they eat insects but in September and October, their gizzards thicken and almost double in weight and they eat large amounts of grit.

This enables them to grind up the tough seeds and vegetable fibres of their winter diet but leaves them highly vulnerable if this food becomes unavailable.

This is not the first time bearded tits have suffered in this way – after the harsh winter of 1947, only four or five bearded tits were left in East Anglia and just a single male in Norfolk.

But they are capable of producing up to four broods a year so can recover quickly from a disastrous spell such as the one they have just endured at Blacktoft Sands.

Other birds have also been hard hit on the reserve, including water rails, while roosting birds of prey have moved to Whitton Sands to avoid predators such as foxes walking across the ice.

Hopefully, bitterns have taken the sprats put out for them on the ice.

Would-be visitors to the reserve are warned that, after nearly six weeks of extreme weather conditions most of the lagoons are still frozen andthere is little to see at present, even on the well-stocked bird tables.

Elsewhere, it now looks as though at least 50 barn owls have been found dead in East Yorkshire, including almost all of the population at the Tophill Low reserve.

Large redpoll flocks, the majority including mealy redpolls from the Continent, have been reported at a number of sites, while up to three Arctic redpolls have been reported with 50 redpolls near Prison Lake, at Hatfield Moors, South Yorkshire, and have been present for nearly a month.

Geese have included eight European white-fronted geese feeding on the hillside at Astley Lake, Leeds while three have been seen along with 31 pink-footed geese near the North Marsh at Flamborough Head.

A flock of 19 pale-bellied brent geese were at Barmston, while five barnacle geese were at Royd Moor reservoir, South Yorkshire.

Up to 80 whooper swans were at North Duffield Carrs, near Selby.

A drake ring-necked duck, a North American vagrant, is still at Cowpen Bewley, Cleveland, and a female at the Nosterfield Nature Reserve, North Yorkshire, while a female lesser scaup is at Boston Park Lake, South Yorkshire.

tealebill48@yahoo.co.uk

CW 15/1/11

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