On December 3, Maine Audubon hosted a kick-off celebration for the publication of Peter Vickery’s The Birds of Maine. The two managing editors (Barbara Vickery and Scott Weidensaul) and Peter’s co-authors (Charlie Duncan, Bill Sheehan and Jeff Wells) all participated in this virtual event.
The first half of June is the best time of the year for bird song in Maine. Male songbirds sing insistently, hoping to win the favor of an available female. Males also sing to ward off marauding males from their own territories.
Our sophistication in listening to bird song and our enjoyment have been greatly facilitated by the writings of Don Kroodsma. An emeritus professor at the the University of Massachusetts, Kroodsma has been studying bird vocalizations for over 40 years. In 2003, the American Ornithologists Union hailed him as “the reigning authority on the biology of avian vocal behavior”.
Kroodsma has an insatiable curiosity about bird vocalizations and also a deep passion for his subject. He certainly shares Shakespeare’s observation that “The earth has music for those who listen”. Kroodma’s curiosity, scientific rigor and passion are all on display in his popular books.
In 2005, Kroodma’s “The Singing Life of Birds” appeared to great acclaim. In easily accessible language, Kroodsma takes the reader through many aspects of bird vocal behavior including song learning, dialects, the functions of song, singing by females among others. The book provides thorough training in the interpretation of bird song.
In this book, Kroodsma provides sonograms for many vocalizations. These graphics show the duration of individual notes and their rise or fall in pitch. He argues that hearing by seeing is a powerful tool.
The latest book by Kroodsma has just appeared and it is wonderful as well. The book is titled “Listening to a Continent Sing: Birdsong by Bicycle from the Atlantic to the Pacific). The book is an account of a 70-day cross-country bike excursion he made with his son David in 2003. Kroodsma was 56 years old at the time and David was 24. The book is an engaging mix of travelogue and natural history with a little bit of geology and anthropology for good measure.
Most cross-country cyclists travel from the West Coast to the East to take advantage of prevailing westerly winds to aid their journey. Many cyclists prefer to ride in the afternoon when those winds are stronger and the sun is behind them. However, our duo decided to ride in the opposite direction, despite frequent headwinds. The purpose of the trip was to hear the songs of the breeding birds. The breeding season arrives late in the Cascades and Rockies. An eastward trip would mean they would miss most of the breeding season east of the Mississippi because they would need to be in the Rockies no earlier than mid-June.
As you can imagine, Kroodsma’s early morning trips were slow-paced with frequent stops to listen intently and to record. Kroodsma’s focus was on sound. He had a small pair of binoculars with him but they were only rarely used. He and David heard hundreds of Eastern Wood-Pewees and Western Wood-Pewees but did not see one, by serendipity, until they got to Oregon.
We travel along with the Kroodsmas on an extended field trip, never sure of what we will hear. When Kroodsma does stop to listen, he describes amazing detail and variety in songs that most of us fail to hear. But, we can listen to those same songs and understand the detail Kroodsma discerns.
In the margins of the book, you will find QR codes (those two-dimensional bar codes). Downloading a free QR Reader onto your smartphone, iPod or tablet allows you to quickly play each vocalization that Kroodsma analyzes. With over 371 recordings, many of which are several minutes long, you can be in the Blue Ridge Mountains of Virginia, the prairie of Kansas or in Yellowstone National Park. If you don’t have a QR reader, you can visit ListeningToAContinentSing.com to hear the recordings.
This book provides a delightful, vicarious ride across our country. We stop frequently to appreciate the music of the birds.
In today’s column, I want to alert you to a couple of recently published bird books from Princeton University Press. The first is The Crossley ID Guide to Raptors. This book follows the format of Crossley’s well-received Crossley ID Guide to Eastern Birds. The Crossley guides use photographs rather than paintings or drawings to illustrate the birds. For each species, a composite plate with many images superimposed on an appropriate landscape is presented. This new guide contains 101 photographic scenes with 35 double-facing. Brief, dense text on identification is provided at the bottom of each plate.
The new raptor guide is co-authored by Jerry Ligouri and Brian Sullivan. Ligouri has published a raptor field guide of his own and both men are expert in raptor identification.
To really develop confidence in identifying a bird species, you need to master five views: from above, from below, from head on, from tail on, and from a lateral view (left or right). Crossley and colleagues make sure that views of all of all these perspectives are provided for each raptor. Of course, the plumage of young raptors differs from adults; these different plumages are well covered along with geographic differences. They devote five plates to the Red-tailed Hawk and three to the Rough-legged Hawk.
The book contains 81 photographic plates. The last third of the book provides an account of each species, including a large map of the distribution of each species. Each account follows a consistent format with sections called Overview, Flight Style, Size and Shape, Geographic Variation, Molt, Similar Species, Hybrids, Status and Distribution, Migration, and Vocalizations.
An extremely useful feature of the book is a collection of mystery photos. The authors provide a number of composite plates to test the reader’s identification skill. For instance, one plate gives a number of eagles in flight; a reader needs to decide if each is a Golden Eagle or a Bald Eagle. Similarly, one plate pictures 21 accipiters at all different angles. The challenge is to decide if each is a Sharp-shinned Hawk or a Cooper’s Hawk. A key is provided for each plate, giving the species, age and sex of each mystery photo and a brief explanation. These plates are powerful learning tools. From my experience, they will also give you a generous piece of humble pie!
Thirty-four species are covered including two species of New World vultures, six falcons, and 24 hawks, eagles and kites. The book measures 10×7.5 inches so is really not convenient to carry in the field. Use it as a learning resource and refer to it often.
The second newly published book is The World’s Rarest Birds by Erik Hirschfield, Andy Swash and Robert Still. The scope of the book is based on the Red List of Birds maintained by the International Union for the Conservation of Nature (IUCN). The IUCN Red List is considered to be the most scientifically objective system for classifying species in terms of their risk of extinction. The Red List incorporates six different levels of concern and this new book covers the 197 species listed as Critically Endangered and the 389 listed as Endangered.
The book begins with a description of the types of threats on Red-listed birds. These threats include geological events, fishing, damming, pollution, energy production and mining, climate change, logging, and agriculture/aquaculture.
The coverage of the species accounts is geographic with the world divided into Europe and the Middle East; Africa and Madagascar; Asia; Australasia; Oceanic Islands; the Caribbean, North and Central America; and South America.
Four species are covered on each page with a color photograph, a distribution map, an estimate of population size, a listing of threats to the species and a short paragraph on the biology and population changes. Scattered throughout are descriptions of threatened species hotspots. This fine book is simultaneously fascinating and saddening.
May and June are excellent times of year to introduce people to the birding fraternity. Males are dressed in their best finery. Birds fill the air with their beautiful songs. The frenetic activities of courtship, nesting and feeding young make it easy to observe birds. And, of course, our bird population here in Maine soars as so many migratory breeding birds return from their wintering areas to take advantage of the long days and productive habitats of Maine.
Two bird guides have been recently published that are geared to beginners. A gift of one of these along with the sharing of your enthusiasm and knowledge of birds may hook another person on birds.
The first book has a local flavor. It is written by Jeff and Allison Wells of Gardiner, Maine. Jeff is a Senior Scientist for the International Boreal Conservation Campaign and Allison is the Senior Director of Public Affairs at the Natural Resources Council of Maine. Their book is called Maine’s Favorite Birds and covers just over a 100 of the most common species in Maine. Each species has a short paragraph giving identification features, voice description and size (length and wingspan). On the facing page, one or more color illustrations are presented. The illustrations by Evan Barbour I are life-like, accurate and very pleasing to the eye.
The limited coverage of Maine’s diverse bird fauna in this guide is an asset for a beginning birder. Most of the species a novice is likely to see will be in this guide.
The book ends with a short section on good spots to go birding in Maine and a list of ways a person can take action for bird conservation. Several opportunities for citizen-science are listed.
Bill Thompson’s The Young Birder’s Guide is explicitly designed for kids. A Peterson Field Guide, this book has the standard field-guide size so is portable into the field.
The book begins with the standard material in most field guides: bird identification features, choosing the right optics, birding etiquette, participating in bird counts, ways to help conserve birds and other wildlife, and the importance of habitat for bird-finding.
About 300 species are covered with one page devoted to each species. The top of each account has a photograph or two. A line drawing is provided in the middle of each page. A map is in the lower right with some information in a Find It box that gives the habitat for that species.
The text provided is in three blocks. Look For gives visual identification skills. Listen For provides descriptions of the vocalizations. I particularly like the prominent depiction of the voice because so many beginners do not realize that one’s ears are often more important than one’s eyes in bird identification. A Remember section gives an interesting fact about the species.
Each account also has a Wow! circle of text that gives an amazing fact about each bird.
Thompson writes that this guide is likely not the only guide anyone will need but should be a very fine first guide.
The latest addition to the Peterson Field Guide series is an exciting contribution to moth identification. This guide, Field Guide to Moths of Northeastern North America, is written by David Beadle and Seabrooke Leckie.
I suspect you will be surprised at the diversity of shapes and sizes of all the moths in our area. You have to be enchanted by many of the common names too such as The Beggar, Four-lined Chocolate, Forgotten Frigid Owlet, The Hebrew, Green Marvel, The Laugher and the Slowpoke!
The guide is arranged with identification features and maps for several species on the left pages with excellent photographs of those species on the right.
Most moths are nocturnal and the authors discuss several ways to attract moths where they can be seen and photographed.
A new book on birding with a strong Maine flavor has arrived in bookstores. The book is “How to Be a Better Birder” and the author is our own Derek Lovitch. Derek is a professional bird guide and with his wife Jeannette runs Freeport Wild Bird Supply. Many of the photographs in the book were taken in Maine and many of the examples Derek uses to illustrate particular points were based on Maine observations.
Published by Princeton University Press, this paperback book is about 200 pages long and is a bargain. The book is intended for intermediate to advanced birders who wish to hone their field skills and to better appreciate the ornithological spectacles around us.
The first chapter is on Advanced Field Identification based on what Derek calls the “whole bird and more” approach. This chapter is not a discourse on subtle field marks to distinguish confusing flycatchers, fall warblers or gulls but rather a presentation of an approach that will allow you to identify more of the birds you seen, even those seen from the rear as they fly rapidly away from you!
To become proficient at any activity, we all know the mantra: practice, practice, practice. Derek urges us to really study all the birds we see, including the most common birds around us. He also suggests that a more holistic approach to bird identification may be a more fruitful way to go about the process of identifying a bird. Focus on the whole bird, not just the critical identification feature (the feature that has an arrow pointing to it in the illustrations in some bird guides). This holistic method is the basis of the “whole bird and more” approach to bird identification.
Derek argues that we should not throw out the field-mark approach but rather add to it the admittedly more subjective yet powerful holistic approach. By becoming intimately familiar with birds, we can often recognize them at a glance without seeing a particular field mark. It’s the same process as picking out people you know in a crowd; you just know them when you them.
Derek discusses the value of this holistic approach to the identification of migrating hawks and pelagic birds. He urges us to work on identification of warblers and sparrows by silhouette. Fellow Maine birder Luke Seitz provides some great line drawings of the outlines of different genera of sparrows.
The chapter on Birding by Habitat shows how being a better botanist can make you a better birder. Knowing the particular grasses particular sparrows prefer makes it possible to find Nelson’s Sparrow and Saltmarsh Sparrow in Scarborough Marsh or a Lincoln’s Sparrow at the Dragon Field in Portland.
Birding with Geography gives great advice for finding migration hotspots for birds. Monhegan Island figures prominently in the examples.
In Birding and Weather, Derek shows that knowledge of basic meteorological principles and an eye on the weather map can make us better birders.
In other chapters, Derek discusses birds at night and their identification by using radar images, freely available on the web, and by identifying the distinctive nocturnal vocalizations of migrants.
One chapter is a case study at Cape May, New Jersey where Derek used the skills and techniques he describes in the book to better appreciate the migration in October.
You have to check out this unbelievably cool website: http://hint.fm/wind/ This site is a dynamic map of the wind direction and strength across the United States. Moving lines indicate the direction the wind is blowing and the rate at which the lines move is proportional to wind speed. This website will be of great use to birders in deciding when a good time to go birding during spring or fall migration. This website provides a tool to put into practice the information Derek Lovitch provides in his book.
The battle of the bird field guides is picking up again. The sixth edition of the National Geographic Society (hereafter, NGS) Field Guide to the Birds of North America has recently been published. This new edition is much improved. It will offer some serious competition to other field guides.
When I began birding, the two available field guides were the ones authored by Roger Peterson and by Chan Robbins. Peterson’s revolutionary arrow system for showing field marks and his fine illustrations were strengths. However, a separate volume was required for eastern and western birds. Robbins’ guide covered all the birds in North America in a single guide. The illustrations were not as good as Peterson’s but it was convenient to have all the birds in one guide.
In 1983, a potent competitor came onto the scene with the publication of the first edition of the NGS Guide. This guide combined the strengths of the Peterson and Robbins’ guides. All of the birds of North America, including the rarities, were covered. Many illustrations were provided for most species, particularly for species like gulls that have a number of different plumages. The NGS guide displaced the Peterson and Robbins guides in my field pack.
As a cooperative effort, the first NGS guide suffered from uneven quality of the prints. Some of the bird paintings were excellent and others were mediocre. But the quantity of information in the NGS guide greatly exceeded the other guides. The NGS guide has been regularly revised with new illustrations added and taxonomic changes incorporated.
In 2000, David Sibley published the Sibley Guide to Birds, displacing the NSG Guide for me and hundreds of other birders. Sibley’s superb artistry and his skill in field identification make his guide an amazing resource. Like the NGS guide, the Sibley Guide covers the rarities as well as the regularly occurring North American birds.
The large size of this guide makes it difficult to carry in the field. To remedy this disadvantage, the publishers offer a pocketsize version for either eastern or western North America. This size reduction results in smaller sizes of the illustrations and some loss textual material. The necessity of having two guides to cover all the North American birds is a drawback.
The Crossley Field Guide published earlier this year is a welcome addition to the field guide universe. This guide is based solely on photographs, arranged as a montage for each species. The text is terse but informative. Like the Sibley Guide, the large format of the Crossley Guide makes it awkward to carry into the field.
The most recent NGS Guide, with Jon Dun and Jonathan Alderfer as the head consultants, is an exciting and attractive upgrade from previous editions. Three hundred new pieces of art are included. I find no substandard illustrations in this edition.
Navigation is easy. Both the front and back covers are folded. Unfolding the front cover provides a visual index of all the birds except for the passerines (perching birds) with the appropriate page to visit. The unfolded back cover has a similar visual index for the passerines. A Quick Find Index of about 160 common names like crane, crow or swift is useful. Finally, there are seven recessed, labeled thumbholes that allow you to instantly get to the sections for Hawks, Sandpipers, Gulls, Flycatchers, Warblers, Sparrows and Finches. Very useful!
The species coverage is exhaustive. This edition provides an illustration and some text on 92 accidental species that have been recorded in North America three times or fewer. Altogether, 990 species are covered.
One more innovation is the inclusion of maps of subspecies for 37 bird species. This information will be of interest to bird listers because some of these subspecies will likely be elevated to full species.
In the final analysis, I am impressed with the sixth edition. I now keep a copy in my field pack.
In a previous column, I sang the praises of eBird, the website maintained by the Cornell Laboratory of Ornithology and National Audubon Society. This site serves as the depository for bird sightings from birders and ornithologists throughout North America and beyond.
Today, I want to point out one great resource that the eBird programmers have made available to take advantage of the many records in the database. You can now see occurrence maps for a number of migratory birds in the United States. The maps were created by relating the records of a particular species with 60 variables describing aspects of habitat, climate, and human population size throughout the U.S.. This model predicts the weekly occurrence of a species of interest as an animated map. It’s really cool! Check out the website at http://ebird.org/content/ebird/about/occurrence-maps/
At this point, the animations only cover the lower 48 states. If you click on Lapland Longspur, you will see they move out of the United States during April. That’s because they are migrating to their breeding grounds on the Canadian and Alaskan tundra. They reappear in the lower 48 in September. Similarly, neotropical migrants like the Scarlet Tanager appear on the animation in early April and are mostly gone by the first of October. During the non-breeding season, most Scarlet Tanagers are in Bolivia, Perú or Ecuador. I expect that in the future, the occurrence maps will include all of the western hemisphere.
The Atlas of Birds
Princeton University Press has recently released the Atlas of Birds: Diversity, Behavior and Conservation by Mike Unwin. The book is an overview of many different facets of the biology of birds. The book is 144 pages long in a large format (8.5 by 11 inches). The text is richly illustrated with color photographs and color maps.
The book is divided into seven units. Introduction to Birds provides information on the fossil history of birds and the relationship of birds to the dinosaurs. Brief coverage of feathers, a hallmark of birds, is provided. Next is a section on Where Birds Live, focused on the birds of major geographic areas like Africa or Australasia. The author briefly covers Important Bird Areas, sites identified by BirdLife International that provide vital habitat and resources for birds and hence have high conservation value.
The third section, Birds in Orders, is an efficient catalog of the major groups of birds, from the ratites (ostriches and relatives) to the perching birds. A section on How Birds Live covers reproduction, foraging, coloniality and migration.
The fifth section is called Birds and People. Here the author describes the importance of birds in human diets, in human culture and in simply providing human pleasure.
Birds under Threat discusses extinction and some of the reasons for bird declines (loss of habitat, pollution, introduced species, climate change). The final section, Protecting Birds, focuses on the efforts of BirdLife International, an umbrella group of non-government conservation organizations around the world. The author gives some detail on the efforts to reduce albatross and other seabird deaths. Many of these birds drown from getting hooked on long lines or getting trapped in trawling nets. By using modified fishing gear and using bird-scaring devices to keep birds away from nets and lines, many seabird lives have been spared.
I found this book to be delightful. The text in the book is limited so the coverage of any particular topic cannot be thorough. Nevertheless, the author conveys a tremendous amount of interesting facts with a remarkable economy of words.
The book is laid out in facing page units so you can start reading anywhere. It’s like eating at a smorgasbord. No particular dish will be enough to fill you up but by the end of sampling all the dishes, you have a satisfying meal.
Perhaps you saw the movie The Big Year earlier this fall. Starring Steve Martin, Jack Black and Owen Wilson, this movie is adapted from a book by Mark Obmascik of the same name. The book describes the efforts of three birders to see as many species as possible in North America in a single calendar year.
The current record for a North American Big Year is a whopping 745 species! To amass that total requires a birder to find all of the 660 or so species of birds that occur predictably every year in North America. Then, the birder has to chase as many vagrant species as possible.
A big year on this scale requires the time and the money to embark on sudden trips to south Florida to see the vagrant LaSagra’s Flycatcher or to southeastern Arizona for the rare Aztec Thrush or to south Texas for the unexpected Green-breasted Mango.
The good will and cooperation of other birders is key to a successful Big Year. Most of the rarities a Big Year birder sees will not found by him or her.
John Vanderpoel of Colorado is in the midst of an amazing Big Year. He has already seen 729 species as of this writing. He has a good chance to eclipse the old record of 745 species.
John is maintaining a blog to document his trips and to share photographs of the many birds and other animals he has seen. He also provides a list of birds he has seen and ones he is hoping for.
In looking over his list, he has a couple of regularly occurring species that should be easy to pick up (Eurasian Tree Sparrow and Gray Partridge). He has not seen Brown Jays or Tamaulipas Crows in south Texas yet.
He is planning to go on a pelagic bird trip in the Gulf of Maine on November 12, hoping to add a Great Skua to his list. He will no doubt chase a Pink-footed Goose in Nova Scotia that has been present for a couple of weeks. A Barnacle Goose was present in Aroostook County in late October but has not been relocated since the snow storm. Perhaps it will reappear, becoming a chase bird for Vanderpoel.
After John’s New England and Nova Scotia trip, he will be standing by to go for rarities wherever they might appear. South Florida, Texas and Arizona are the most likely places for rare species but with birds, you never know. One of John’s rarest birds was a Gray-hooded Gull that appeared at Coney Island!
I encourage you to visit John’s blog at http://www.bigyear2011.com/ and check his progress. It’s fun to vicariously experience his Big Year.
The huge boreal coniferous forest that covers much of Canada and the northern tier of the United States has great ecological significance. For birds, this forest provides breeding habitat for millions of migratory birds of several hundred species. Other birds like Spruce Grouse, Black-backed Woodpeckers, Boreal Chickadees and Gray Jays spend their entire lives in the boreal forest.
Alas, the boreal forest is not immune to the depredations of humans. Industrial development and climate change are obvious threats. The damming of waterways for hydropower has flooded some habitats. Strip-mining and the extraction of oil from tar sands have had profound impacts on both land and water quality. Climate change is leading to melting of the permafrost and the drying up of wetlands.
Humans are unusual among mammals in that we build our houses. Sometimes we use natural materials and other times plastic or other artificial materials that do not occur in nature. Beavers are the only other local mammals I can think of that build substantial houses.
Most birds however are excellent builders, manifested usually in the form of a nest. Some nests are extraordinarily intricate while others are massive.
The excellent skills of birds in building nests are remarkable in at least three ways. First, most of the building is accomplished with the aid of only the bill. The feet may help in holding material and the body itself can be used to mold the shape of the nest but the majority of the work is done with the bill.
Second, birds don’t get a lot of practice. Most birds build a single nest per season and some use the same nest for years.
Lastly, the instructions on how to build a nest appear to be genetically encoded. Birds know how to build a nest although in some species older, more experienced birds seem to build with more skill than first-timers.
The source of most of the information in today’s column comes from a recent book by Peter Goodfellow entitled Avian Architecture: How Birds Design, Engineer & Build. The book is richly illustrated with over 300 color images (photographs and drawings). The text is limited but adequate. The drawings and text allow the author to give the reader a firm understanding of how various nests are made.
The coverage goes from simple nests to more complex, sometimes communal nests. Goodfellow breaks nests into twelve categories and devotes a chapter to each type. The author provides several examples of each type of nest. Examples are drawn from birds around the world.
The simplest nests are called scrape nests. They are built by simply gouging a shallow depression in the ground. Sometimes eggs are laid directly on the ground and in other species, a lining is created in the scrape. Female Common Eiders pluck feathers from their breast to line their simple nest.
The depth of the scrape is critical. For Pectoral Sandpipers nesting on the arctic tundra, the scrape depth minimizes heat loss. Shallow scrapes expose the eggs to wind chill and deep scrapes cause the eggs to lose heat to the permafrost below.
Nesting on the ground is risky so it is no surprise that a scrape nest and the eggs laid within it are camouflaged. The young usually show precocial development so they can leave the nest soon after hatching.
A number of birds nest in holes and tunnels. Some, like woodpeckers, make their own holes and some, like kingfishers, make their own tunnels in riverbanks. Other species are secondary cavity nesters, using either natural or existing holes or tunnels. Such birds may elaborate the holes by adding linings of plant material. A good local example is the House Wren. The Great Hornbill of southeastern Asia provides a remarkable example. The female adds mud to the opening of her nest cavity, essentially sealing herself in with only a slot opening to the outside. She and her young once they hatch are dependent on the male for all their food. The mother may remain cooped up in her nest for two months. The narrow opening to the nest prevents predators like martens from entering.
Aquatic nests are made by only four types of birds: jacanas, marsh terns, grebes and rails. Aquatic nests are immune from attacks by terrestrial predators.
The architecture of an aquatic nest usually includes aquatic plant materials that float dues to airspaces within, thus keeping the eggs above water. Some aquatic nests are fixed to the shoreline while others float in deeper water.
Cup-shaped nests are the most common type of nest. A strong cup with a lining provides protection for the eggs and chicks. The nest is anchored strongly, usually with spiders’ silk. Most cup-shaped nests are located above the ground.
The Ruby-throated Hummingbird attaches gray lichens to the outer wall of its nest. The nest looks like the broken base of a branch of the tree on which it sits.
Domed nests combine characteristics of cup-shaped nest and cavity nests. The entrance hole is an important architectural consideration, minimizing predator risk and the chilling effect of the dominant winds.
The book covers so much more: mound incubators that use the heat of composting material, platform nesters, colonial nesters and others. The text is easy to understand and can be shared with children. This book provides a great entry to the wonder of birds.
In 1990, Kenn Kaufman’s Peterson Field Guide: Advanced Birding was published. This book discussed the identification of difficult groups of birds like winter loons, scaup, medium-sized terns, hummingbirds and Empidonax flycatchers. The book was peppered with Kaufman’s own pen-and-ink drawings. The guide was meant to be a supplement to a field guide.
Now over two decades later, a greatly revised edition has been published. It is fundamentally a different and better book than the first edition. The new edition is still best used as a companion to a standard field guide.
The number of groups of confusing birds Kaufman covers is greatly expanded over the first edition. Informative photographs are included within each group in lieu of the line drawings of the earlier edition.
One of the greatest strengths of the new edition is the 140 pages of introductory material, compared to only 19 in the first edition. In this new edition, Kaufman offers a list and extended explanation of 13 principles of field identification. A couple are “Always use multiple field characteristics” and “Consider the condition of the bird’s plumage”.
He then has an excellent section on feather tracts of birds and molting. A sequence of photographs on the movement of feathers on an opening wing of a House Finch is brilliant. In the folded wing, all the feathers one sees are greater coverts, tertials and the tips of the primaries. As the wing unfolds, the other feather tracts become exposed.
Kaufman then presents sample illustrations of some birds (some at rest and some flying) to indicate the different feather types. For each example, a photograph and a line drawing of the bird showing the feather tracts is shown.
Kaufman compares two schools of thought on field identification of birds. One school relies on “general impressions of size and shape”, 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.
In his coverage of the various problem groups, Kaufman uses both types of information to permit field identification. For identification of swallows on the wing, Kaufman suggests watching swallows without using binoculars. One can become familiar with the slight differences in flight behavior and the appearance of distinctive marks from varying perspectives. The giss method can work here.
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.
Eastern Bluebirds and Tree Swallows
Tree Swallow and Eastern Bluebird numbers are building in the state as their migration proceeds. It’s time to make sure your nestboxes are in good shape.
Tree Swallows and Eastern Bluebirds compete for nestboxes. How can you increase your chances of bluebirds nesting on your property? You can take advantage of the fact that Tree Swallows are intolerant of other Tree Swallows nesting within 10 yards of their own nest. So, if you put two nestboxes close together, one will not be used by Tree Swallows and is therefore available for bluebirds.
Bluebirds need quite a bit more space. Typically, bluebirds will not nest with 200 yards of another bluebird pair.
People often wonder if they should remove the previous year’s nest from a nestbox. Eastern Bluebirds prefer to reuse an old nest. For Tree Swallows, removing an old nest has no effect on whether it will be used by Tree Swallows in the current year.
Hormones and spring
In mammals, the gonads (ovaries in females, and testes in male) remain the same size once adulthood is reached. Not so in birds. 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. Why carry around well-developed reproductive structures when those organs are not needed? With increasing daylength, birds start to produce hormones: mainly testosterone in males and estradiol (an estrogen) in females. These hormones cause the testes or ovary to increase greatly in size. The size of a House Sparrow testis increases 500 times in the span of a month or so in the spring!
The huge increase in testosterone causes the males to become fiercely combative to other males. 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.