The wren, robin, blackbird, and common chaffinch are the most widespread species, occurring in 90% of the land area. These and the rook, starling, great tit, and blue tit are among the most numerous and commonly seen. Over the period 1997–2007, populations of pigeons, warblers, tits, finches, and buntings have remained stable or shown an increase (there were massive declines during the 1970s). Kestrel, swift, skylark, and mistle thrush have continued to decline due to changes in agricultural practices such as increased use of pesticides and fertiliser. Climate change has also played a role.