All sightings and good survey effort for each year is display on an individual map, with months plotted in different colors.

Click on the thumbnail to view the full sized image, or get the printable full map series version (pdf, 15mb).

1978 1979 1980 1981
 
1982 1984 1985 1986
 
1987 1988 1989 1990
 
1991 1992 1993 1994
 
1995 1996 1997 1998
 
1999 2000 2001 2002
 
2003