Taxonomic Outlines

Systema Naturae 2000 (Subspecies, 29 Apr 2018)

Websites

Birds of the World
Try Wikipedia
Try Wikispecies

General Search Engines

Bing (Images)
Google (Images, Books, Scholar)
Yahoo! (Images)

Scientific Search Engines & Libraries

Biodiversity Heritage Library (BHL)
Canada Institute for Scientific and Technical Information (CISTI)
Entrez, The Life Sciences Search Engine (NCBI)
Index to Organism Names (ION)
PubMed (NCBI)
ZooBank