So here we are at the end of September and autumn is upon us. While the official ‘Constant Effort’ ringing period ended at the beginning of the month, at Cranwich we undertake a couple extra visits during the season. Our aim is to capture the departure of our main study species the Reed Warbler, including any young of the year which tend to leave later than their parents. Saturday morning and we were looking at our last session for the year. It had been a poor year in terms of numbers of birds caught, with each session catching about half of the average total of previous years. The reasons for this are complicated, but we do know that 2015 and 2016 were pretty poor breeding seasons for many of the tit species on site, and the bowl traps we have in the reeds have indicated insect numbers in the reeds are low this year. Coupled with the cool, wet August, means the Reed Warblers also had a tough year. So our expectations for this final session we quite low. We have two ‘sides’ to the nets. 9 nets in total, the ‘wet’ nets require chest waders to access whilst for the ‘dry’ side wellies will suffice.
After the triumph of setting the nets in the dark, with grey light finally filtering through, the first round on the ‘dry’ side was a pleasant surprise with a good handful of birds. A check on the radio to Hazel checking the ‘wet’ side revealed an even bigger surprise… ‘I have just taken 10 birds out of Net 13!’ 10 birds, in the first net! Whoop!
And so started our busiest session of the season! The bulk of the birds were Reed Buntings, and we likely caught them coming out of their roost from the reeds. There were little guys like Chiff Chaffs, Treecreepers and Long-tailed Tits. There were bigger guys like a stunning young female Kingfisher, a Great Spotted Woodpecker and a couple of Blackbirds that if you were to describe them you would have probably written ‘grey birds’. Continental Blackbirds are usually greyer than our UK residents, but in this case it is unlikely they were from foreign shores. Both were still in heavy moult, something most birds would complete before heading off on any kind of migration. It’s more likely these were just two variations of the plumage. There were Blue Tits, and a Great Tit, a couple of Marsh Tits and a species that is becoming more and more common on site, Cetti’s Warbler. Then there was a single Blackcap and a single Goldfinch.
But the golden icing on this autumnal mix was that stunning little yellowy green warbler, with a strikingly bright yellow eyebrow and two bright bars on the wing. That little spite known as the Yellow-browed Warbler. Not the first time we have caught one on site, but certainly the first time we have caught one during our ‘constant effort’ sessions. Over the last few autumns these diminutive warblers have been increasingly visiting our headlands and coastlines, predominantly in the north and east of the country – makes sense given that they breed in Siberia. Most winter in southeast Asia, but it has been an established visitor to western Europe. But more and more they are being found in inland sites, like Cranwich. Last year was a record breaking year for sightings in the UK, and this year looks to be another good year.