The following offer useful background information on orca whales in general and on the Pacific Northwest population specifically:

• Hoyt, Erich. 1990. Orca, the Whale Called Killer. 2nd Edition. Camden House Publishing, Ontario, Canada. ISBN 0-920659-25-0 (a color illustrated paperback book describing one person's searches for and experiences with killer whales in the Pacific Northwest -- available from the publisher, bookstores or in libraries).
• Ford, John, Graeme Ellis, and Kenneth Balcomb. 2000. Killer Whales: a Study of Their Identification, Geneaology and Natural History in British Columbia and Washington State. 2nd Edition. UBC Press, Vancouver, BC, Canada. ISBN 0-7748-0469-6.
• Minasian, Stan, Larry Foster and Kenneth Balcomb. 1984. The World's Whales. Smithsonian Books, Washington, D.C.
• Hand, Douglas. 1994. Gone Whaling, a search for Orcas in Northwest waters. Sasquatch Books, Seattle, WA. ISBN 1-57061-070-3 (a wonderful blend of research and lore-probing that manages to craft an engaging portrait of these extraordinary creatures -- available from the publisher, bookstores or in libraries).
• Official Orca Survey Field Guide, 2005 (a five-page, plastic-laminated, complete and updated photo-identification guide to all of the Pacific Northwest southern resident community killer whales -- available from the Center for Whale Research, PO Box 1577, Friday Harbor, WA 98250 for US$38.50).
• Orca Survey (a 60-minute VHS videotape featuring an introduction to our study and video footage and sounds of the Pacific Northwest killer whales -- available from the Center for Whale Research, PO Box 1577, Friday Harbor, WA 98250 for US$25).