{"id":392,"date":"2011-06-05T14:16:32","date_gmt":"2011-06-05T18:16:32","guid":{"rendered":"http:\/\/web.colby.edu\/mainebirds\/?p=392"},"modified":"2011-06-05T14:26:56","modified_gmt":"2011-06-05T18:26:56","slug":"review-of-kaufmans-field-guide-advanced-birding-eastern-bluebirds-and-tree-swallows-bird-hormones","status":"publish","type":"post","link":"https:\/\/web.colby.edu\/mainebirds\/2011\/06\/05\/review-of-kaufmans-field-guide-advanced-birding-eastern-bluebirds-and-tree-swallows-bird-hormones\/","title":{"rendered":"Review of Kaufman’s Field Guide: Advanced Birding; Eastern Bluebirds and Tree Swallows; Bird Hormones"},"content":{"rendered":"

In 1990, Kenn Kaufman\u2019s Peterson Field Guide: Advanced Birding was published.\u00a0 This book discussed the identification of difficult groups of birds like winter loons, scaup, medium-sized terns, hummingbirds and Empidonax flycatchers.\u00a0 The book was peppered with Kaufman\u2019s own pen-and-ink drawings.\u00a0 The guide was meant to be a supplement to a field guide.<\/p>\n

Now over two decades later, a greatly revised edition has been published. \u00a0\"\"<\/a>It is fundamentally a different and better book than the first edition.\u00a0 The new edition is still best used as a companion to a standard field guide.<\/p>\n

The number of groups of confusing birds Kaufman covers is greatly expanded over the first edition.\u00a0 Informative photographs are included within each group in lieu of the line drawings of the earlier edition.<\/p>\n

One of the greatest strengths of the new edition is the 140 pages of introductory material, compared to only 19 in the first edition.\u00a0 In this new edition, Kaufman offers a list and extended explanation of 13 principles of field identification.\u00a0 A couple are \u201cAlways use multiple field characteristics\u201d and \u201cConsider the condition of the bird\u2019s plumage\u201d.<\/p>\n

He then has an excellent section on feather tracts of birds and molting.\u00a0 A sequence of photographs on the movement of feathers on an opening wing of a House Finch is brilliant.\u00a0\u00a0 In the folded wing, all the feathers one sees are greater coverts, tertials and the tips of the primaries.\u00a0 As the wing unfolds, the other feather tracts become exposed.<\/p>\n

Kaufman then presents sample illustrations of some birds (some at rest and some flying) to indicate the different feather types.\u00a0 For each example, a photograph and a line drawing of the bird showing the feather tracts is shown.<\/p>\n

Kaufman compares two schools of thought on field identification of birds.\u00a0 One school relies on \u201cgeneral impressions of size and shape\u201d, shortened to the acronym of giss. The other extreme is the fine detail approach where very close study of feathers, bill color and shape and other structures is required to yield a field identification.<\/p>\n

In his coverage of the various problem groups, Kaufman uses both types of information to permit field identification.\u00a0\u00a0 For identification of swallows on the wing, Kaufman suggests watching swallows without using binoculars.\u00a0 One can become familiar with the slight differences in flight behavior and the appearance of distinctive marks from varying perspectives.\u00a0 The giss method can work here.<\/p>\n

But for gulls, Kaufman advocates the fine detail approach, pointing out that the color of various feathers in the wings, tail and mantle are needed to be sure of an identification.<\/p>\n

Eastern Bluebirds and Tree Swallows<\/strong><\/p>\n

Tree Swallow and Eastern Bluebird numbers are building in the state as their migration proceeds.\u00a0 It\u2019s time to make sure your nestboxes are in good shape.<\/p>\n

Tree Swallows and Eastern Bluebirds compete for nestboxes.\u00a0 How can you increase your chances of bluebirds nesting on your property?\u00a0 You can take advantage of the fact that Tree Swallows are intolerant of other Tree Swallows nesting within 10 yards of their own nest.\u00a0 So, if you put two nestboxes close together, one will not be used by Tree Swallows and is therefore available for bluebirds.<\/p>\n

Bluebirds need quite a bit more space.\u00a0 Typically, bluebirds will not nest with 200 yards of another bluebird pair.<\/p>\n

People often wonder if they should remove the previous year\u2019s nest from a nestbox.\u00a0 Eastern Bluebirds prefer to reuse an old nest.\u00a0 For Tree Swallows, removing an old nest has no effect on whether it will be used by Tree Swallows in the current year.<\/p>\n

Hormones and spring<\/strong><\/p>\n

In mammals, the gonads (ovaries in females, and testes in male) remain the same size once adulthood is reached.\u00a0 Not so in birds.\u00a0 Because of the demands of flight, the ovary (most female birds only have one ovary) or testes of birds are greatly reduced during the non-breeding season.\u00a0 Why carry around well-developed reproductive structures when those organs are not needed?\u00a0 With increasing daylength, birds start to produce hormones: mainly testosterone in males and estradiol (an estrogen) in females.\u00a0 These hormones cause the testes or ovary to increase greatly in size.\u00a0 The size of a House Sparrow testis increases 500 times in the span of a month or so in the spring!<\/p>\n

The huge increase in testosterone causes the males to become fiercely combative to other males.\u00a0 One behavior common this time of year is to see a male songbird attacking its reflection in a mirror or window. Testosterone levels will decline in due time and the males will become less hyperactive.<\/p>\n

[First published on May 1, 2012]<\/p>\n\n

\n <\/div>\n\n","protected":false},"excerpt":{"rendered":"

In 1990, Kenn Kaufman\u2019s Peterson Field Guide: Advanced Birding was published.\u00a0 This book discussed the identification of difficult groups of birds like winter loons, scaup, medium-sized terns, hummingbirds and Empidonax flycatchers.\u00a0 The book was peppered with Kaufman\u2019s own pen-and-ink drawings.\u00a0 The guide was meant to be a supplement to a field guide. Now over two […]<\/p>\n","protected":false},"author":146,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_s2mail":"","ngg_post_thumbnail":0,"footnotes":""},"categories":[426,1281,430,433],"tags":[],"builder_content":"","_links":{"self":[{"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/posts\/392"}],"collection":[{"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/users\/146"}],"replies":[{"embeddable":true,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/comments?post=392"}],"version-history":[{"count":5,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/posts\/392\/revisions"}],"predecessor-version":[{"id":399,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/posts\/392\/revisions\/399"}],"wp:attachment":[{"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/media?parent=392"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/categories?post=392"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/tags?post=392"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}