Crossbill Traffic

It's been some years since I've seen or heard a chipper chupper in the Ely10.  On Tuesday me and 25 thirteen year olds were out on the school fields of Soham establishing whether we could measure the  speed of sound (of course we could but not very accurately they discovered).  The distinctive chip of a Crossbill overhead was a pleasant diversion and it flew over low enough to establish that it was a female type.  6 or 7 years ago there was a spell in July and August when I was recording flyover Crossbills most weeks, let's hope that there are a few more before the summer is over.