What species are in the Eastern and Western bird guides?

States and Provinces east of the Rocky Mountains are covered by the Eastern Field Guide, those in the Rockies and west are covered by the Western guide

The Eastern and Western Guides were carefully planned to avoid dividing states. The Rocky Mountains form a natural biological and climatic division of the continent, and basically any state or Province entirely east of the Rocky Mountains will be covered by the Eastern Guide, while states and provinces in, or west of, the Rockies will be covered by the Western Guide. The only exception to this is the state of Texas, which has such a broad east-west axis that the only practical way to divide these guides was to put the ‘Trans-Pecos’ Big Bend country in the western guide, and the rest of the state in the east.

There is a great deal of overlap in the two guides, with over 650 species in the Eastern Guide and over 700 in the Western. But simply counting species gives a false impression, since many eastern species that are rare in the west are treated only briefly in that guide, and vice versa.


10 thoughts on “What species are in the Eastern and Western bird guides?”

  1. Richard Humphrey

    I am going on holiday in August to Newfoundland and would like to know which would be the best bird field guide to buy. I would like it to cover the less well known species as well as the common ones. Would the Sibley guide be suitable? Is it small enough to carry around?

    UK birder

    1. Hi Richard, The Sibley Field Guide to Eastern Birds would cover all of the species and all of the variations you’re likely to see in Newfoundland, and it’s definitely small enough to carry around at about 7.75″ by 4.75″ by 1″ thick.

    2. My name is Kevin S. Perry/ Pei Kai Wen in Chinese. I am a MBA candidate thru a Free China/ Formosa (Taiwan) Uni named NTU. I was on the phone with a friend of mind and we were talking abour yearlings so i naturally next thought of their migration patt er ns. Is it posdible to get any brochures or literature about this tropic? Please contact me by phone at 586 489 9343 or mail at 145 Welts Mt. Clemens MI 48043. My email is listed above. Thx in advance for any and all contact or feferals.

  2. Hi David,

    I am planning to make a round trip through Alberta and BC next year. For BC and the Alberta Rockies it seems to be obvious that the Western Guide is the right one to choose. The easternmost place I will visit is the Cypress Hills Provincial Park at the boarder to Saskatchewan. What is your impression for this easterly location. Is it really worth to buy both? I know, the alternative would be the complete Guide to birds, which is wonderful, but to big to carry it around all the time, I think.

    Looking forward hearing from you,

    1. Hi Markus,
      The Western Guide should be all you need. It covers the entire province of Alberta, and the Cypress Hills are notable mostly as an eastern outpost for western (Rocky Mountain) species like White-crowned Sparrow. That whole region is great birding and really fascinating biogeographically with a mixture of eastern and western birds. Have a great trip! (and bring plenty of bug spray if you’re going in spring/summer.)

  3. Hi David,
    thanks a lot for the prompt response!
    You’re right, I really love that entire area, even despite of “Canada’s national bird”…
    Looking forward using your guide in the field,

  4. Hello,

    in August I will visit the western part of Canada (covered by Sibleys Western Guide). However, the most eastern area of the trip will be “Grassland National Park). Does it make sense to buy the Eastern Guide additionally?
    Thank you for your help!

    1. Hi Andreas, You should be fine with just the Western Guide there. Grasslands National Park will be prairie (of course), like Montana which is covered in the Western Guide. To find many “Eastern” species you would need to travel north into the Boreal Forest of central Saskatchewan, where you might find a few species that are not included or barely included in the Western Guide.

  5. Dear David,

    I’ll be visiting Texas in april, covering the Austin area and the Big Bend. Should I then buy both guides or is the Eastern one sufficient?


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