Table 3 Guidelines used for converting the introduced date given in the reference into a whole number.
From: The global avian invasions atlas, a database of alien bird distributions worldwide
Date given | Grouped (converted) date | Rule |
|---|---|---|
1912 | 1912 | Use the four digit number as given |
c.1890 | 1890 | Use the four digit number given |
1777–1778 | 1777 | Use the earliest date in the range |
1930–1940 | 1935 | Use the midpoint of the range |
C18th | 1750 | Use the midpoint of the century |
early C18th | 1710 | Use the date 10 years into the century |
mid C18th | 1750 | Use the midpoint of the century |
late C18th | 1790 | Use the date 10 years before the end of the century |
1800s | 1850 | Use the midpoint of the century |
c.1800s | 1850 | Use the midpoint of the century |
1990s | 1995 | Use the midpoint of the decade |
early 1700s | 1710 | Use the date 10 years into the century |
mid 1700s | 1750 | Use the midpoint of the century |
late 1700s | 1790 | Use the date 10 years before the end of the century |
early 1990s | 1991 | Use the first year of the decade |
mid 1990s | 1995 | Use the midpoint of the decade |
late 1990s | 1999 | Use the last year before the end of the decade |
1980s–1990s | 1990 | Use the midpoint of the two decades |
<1965 | 1964 | Use the date immediately before the date given |
>1970 | 1971 | Use the date immediately after the date given |
