Value of hedges

My normal morning walk with Dylan (dog), takes me across the field to the church and then up towards the Downs. Before I reach the Pilgrims Way, there is a footpath with a hedge either side. On the one side it is quite thin, but sufficient to give protection from the wind and a thicker hedge lies on the other side leaving a narrow passageway between. Every morning I encounter birds within these hedges. This morning I counted the different species: blackbird hedge accentor, blue tit, great tit, ;long tailed tit, song thrush, tree sparrow (a first sighting for this area), and robin. If ever there was evidence for the value of hedgerows this is it. However, the single hedges around the fields here never appear to hold so many birds, usually a scattering of tits, robins hedge accentors and yellow hammers will be what you would expect to see, but nothing like the concentration seen within the double hedge.