Chif-Chaff Influx

I noted two Chiff-Chaffs calling at Cromwell Bottom LNR last Friday (16/3/07) my first migrants of the year. Yesterday (21/3/07) it was noticable that several male Chiff-Chaffs were calling along both sides of the canal towpath all the way down from Rawsons pool on the canal and throughout the LNR, at least 8 birds were in residence. In the afternoon I cycled up to Littleborough on the canal towpath. Its was very noticable that Chiff-Chaffs were in evidence in some numbers in the scrub along the twopath as far as Hebden Bridge. After Hebden Bridge I cycled onto Littleborough then up the road to Blackstone edge, down the road through Crag Vale to Mytholmroyd and then back onto the towpath back to Elland. No calling Chiff-Chaffs were heard from Hebden Bridge until I got back on the canal towpath just below Sowerby Bridge. I cycled more or less the same route last week and did not hear a single Chiff-Chaff. Yesterday gave me a wonderful illustration how migrants spread (and how quickly)from the lower Calder valley to the upper end. I am cycling to the upper Calder valley on Sunday and will make note if the Chiff-chaff influx has spread futher up the valley in the intervening days.