Table 1. Dates and sources of the distribution records used.

Group	t1 (calibration)		t2 (validation)
	Dates	Source	Dates	Source
Vascular Plants	1930–1969	Perring and Walters (1962) +later records	1987–1999	Preston et al. (2002)
Butterflies	1970–1982	Heath et al. (1984)	1995–1999	Asher et al. (2001)
Breeding Birds	1968–1972	Sharrock (1976)	1988–1991	Gibbons et al. (1993)