A summary of 1821 in birding and ornithology.
| Years in birding and ornithology: | 1818 1819 1820 1821 1822 1823 1824 |
| Centuries: | 18th century · 19th century · 20th century |
| Decades: | 1790s 1800s 1810s 1820s 1830s 1840s 1850s |
| Years: | 1818 1819 1820 1821 1822 1823 1824 |