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Tucson Audubon Society For a time these articles by the Tweits appear in each issue of Tucson Audubon's Vermilion Flycatcher newsletter. They impart useful "tools and tips for beginning and backyard birders," and are archived here. Amateurs
in Ornithology--February, 2001
Amateurs
in Ornithology Our knowledge of the Cactus Wren is an inspiring example especially for those of us who live in Tucson. Anders H. and Anne Anderson lived just south of Rillito Creek, on Kleindale west of Edith Street. Beginning in the early 1930s Anders Anderson, an electrician by training, became interested in the single pair of Cactus Wrens he could watch from the windows of his home. He was soon joined by Anne, a teacher, and before many years passed their observations extended to the Cactus Wrens in their immediate neighborhood. They learned to band and color band so they could identify individual birds to gather and validate information about the many aspects of behavior they observed. In later years they expanded their study to Cactus Wren populations in the Santa Rita Experimental Range and also at Saguaro National Monument (now Park) where they included Curve-billed Thrashers. And, very importantly, they published what they learned in many articles in Condor and finally in their book The Cactus Wren, published by the University of Arizona Press in 1973. To quote Gale Monson in the forward to this book:”...the Andersons’ book [is] unusually valuable and one of real stature in its field.” There are many more examples of the contributions amateurs have made to the field of ornithology. The well loved Bent series of Life Histories of North American Birds was researched and written by Arthur Cleveland Bent, a successful business man. Bent was an enthusiastic amateur ornithologist from boyhood and had already published some of his observations when in 1910 the Smithsonian Institution asked him to continue the series started by Charles Bendire. He had one huge advantage from the Smithsonian’s point of view – he needed no salary! Instead of continuing he started over and spent the next 44 years of his life combining the research of those before him with his own work to produce all but the last volume in this monumental series. Okay, so you are probably not going to make the tremendous contribution of an Anders Anderson or an A. C. Bent, you can still make a significant addition to our knowledge of birds just by carefully observing and writing down the behavior you see at your feeder or in your backyard. Again, look in the Birds of North America series and note the many attributions to (Some Person, pers. comm.); someone observed behavior not previously documented and let the author know, filling one more gap in our knowledge of birds.
Cactus Wrens build nests for two purposes, breeding and roosting. Their bulky, football-shaped nests, woven of grasses and plant stems, are often placed in cholla cacti. These covered nests with an entry in the end provide protection from cold, rain, or even an occasional snow for roosting adults and even more critically for nestlings. A covered nest made of grasses may not seem like much protection, but during a late winter storm a few years ago, Cactus Wren nestlings survived while Curve-billed Thrasher young in open-cup nests died of exposure. A covered nest also protects eggs and nestlings from the hot desert sun. Bulky Cactus Wren nests and the remnants of abandoned ones are easy to find in cholla cacti. Breeding nests are vigorously defended by parent wrens who are present much of the time while raising young. Roosting nests are often not defended and may fall victim to a Curve-billed Thrasher. Curve-bills appear to compulsively tear wren nests apart. This behavior is hard to understand because the thrashers do not reuse the material and the two species usually don’t interact aggressively except around active breeding nests. Cactus Wrens build several roosting nests but they are often not very sturdy and rarely last a season. The “song” of Cactus Wrens, although easy to recognize once heard, is not easy to describe. It is low in pitch, rough and harsh, monotonous, repetitive and often rapid. It is variously described in field guides as “cha, cha, cha, cha;” “chug, chug, chug;” or “chuh-chuh-chuh-chuh-chuh.” Some people say it sounds like a machine gun. It certainly bears little resemblance to the song of a Winter Wren or the bubbling sound of a House Wren. Variations are used in territorial defense, location, pair bonding, and communication with young, but these differences are not obvious to most observers. Cactus Wrens occupy the same territory year-round, though they may enlarge it some in winter when the insect supply is less abundant. In Tucson look for breeding activity sometime in February, eggs in nests in March, and fledging by the end of April. A pair usually has two clutches, and, if food is plentiful and weather cooperative, they may pull off a third. These birds are very easy to watch in your backyard, so enjoy! To learn more about Arizona’s state bird read The Cactus Wren by Anders H. and Anne Anderson, U. of A. Press, 1973. Though it is out of print, there is a copy in the TAS Library, and it is often available where used books are sold.
Now thanks to Tucson’s Kenn Kaufman, who is both a stellar field ornithologist and a master teacher, we have a much more satisfactory answer: Birds of North America--a Kaufman Focus Guide. For a review of this book see the excellent article by Mark Stevenson in the October Flycatcher. Here, we want to comment on some of the features of Kenn’s guide as they relate to beginners. An initial comment has been that this guide is ‘comfortable,’ reminiscent of the original ‘Golden’ guide. It is compact and relatively lightweight. Its maps, illustrations, and text are opposite each other on the same spread. And it uses the “Peterson” system of identifying the critical field marks with pointers. Arrangement is important in any field guide. The most successful field guides have generally used a close approximation of the official AOU Checklist order, the rationale being that birders can use a guide most easily if they already know where within the guide to look for a species or genus. Generally, the further the author has departed from the standard order the less successful the alternate scheme has been. Kenn has departed from AOU order at a number of points. However, what he has done makes sense for beginning birders most of the time. He has often illustrated birds that are somewhat similar in appearance or behavior on the same page regardless of whether they are genetically related. For instance: American Coot, Common Moorhen, Purple Gallinule, and Least and Pied-billed Grebes appear on the same page and directly follow ducks and geese. Small herons and large rails share a page. Greater Roadrunner appears with Wild Turkey and Ring-necked Pheasant following grouse and quail under the heading “Large, long tailed birds.” This one is dicey; these three are usually found on the ground but placing roadrunner with turkey appears far-fetched, and the pictorial table of contents doesn’t clue you here, though the short index does. Kenn’s arrangement is very different, and the best judges of its success will be the beginning birders whom he had in mind while preparing this book. The opening chapter on birding basics is short and to the point. It’s written in language that is easy to understand and enhanced with the obligatory diagram labeling features of a bird necessary to know to use an identification guide. The short section on variation in plumage within a single species is unique in a field guide. It is illustrated with ten different House Finch examples that make his point quite neatly. Within each species account Kenn has included verbal depictions of songs and calls, as many field guides do. Learning to recognize birds by their vocalizations is an integral part of identifying birds. The use of syllables to describe the song or call plus some indication of quality, speed, pitch, and frequency is more or less standard, but until you actually hear the bird they may not make much sense. The syllables are most useful for remembering the rhythm of a song. For instance, once you have heard a Common Yellowthroat sing “wichity-wichity-wichity” you stand a good chance of remembering that rhythm and can confidently identify the bird even though you can’t see it. There are other really useful ones: Bell’s Vireo with its “cheedledee-cheedledeedle-doo?” and of course the famous “Ho-say-ma-ree-ah” of the Greater Pewee. The best approach is to connect the syllables and the descriptions with the voice in the field or on a CD of bird vocalizations. If the syllables are a good memory aid, that’s great, and, if not, devise something that works for you. All in all, Kenn Kaufman’s Birds of North America is ‘comfort food’ for beginning birders. It’s a nice size, attractively and usefully illustrated, and written with you in mind. The TAS Nature Shop has it, and Kenn will be at the November membership meeting to autograph your copy.
Lesser Goldfinches maintain loose colonial groups even when breeding and defend only a small territory around the nest. They appear to be monogamous, at least for one season, and the male defends the female from other males of the species. In southeastern Arizona breeding can occur anytime between January and November, probably depending on rainfall. The female does most of the nest building, but the male feeds her while she incubates and during the first four or five days of brooding. After that both forage to feed the nestlings. Watch a goldfinch on a sunflower seed head. It often clings to the top and systematically removes every seed, eating some, dropping others, but not missing any. Just because goldfinches forage almost exclusively for seeds doesn’t mean that they are vegetarians. Seeds usually harbor a myriad of small insects; e.g., aphids, of which goldfinches partake. Lesser Goldfinches have a very intricate and varied song, combining trills, warbles, and clear notes. Their vocalizations are reported to include mimicry of as many as 39 other species. The mimicked phrases are much less identifiable to most human ears than those of the Northern Mockingbird, but try listening for Verdin and Bewick’s Wren. Those are two of the most frequently imitated. Whether or not you can detect mimicry, Lesser Goldfinches are a pure pleasure to hear. For further information see the Birds of North America, No. 392, by D. J. Watt and E. J. Willoughby on the reference shelf in the Tucson Audubon Library.
Keep watch at your hummingbird feeder. Check for Rufous Hummingbirds stopping for a drink on their way to Mexico from their breeding areas in northwestern North America, or for “broad-tails” on their way south from the Rocky Mountains. Both species are more common in the lowlands in spring migration than in the fall, but both may appear at feeders in Tucson on their way south. The “black-chins” that have zipped around our gardens all summer depart en masse by the end of September or early October. Don’t think that leaving your hummer feeder out will alter this migratory behavior; “black-chins” are programmed to leave and they do, most heading for Mexico for the winter. Many Broad-billed Hummingbirds leave southeastern Arizona in September, but a few males appear to be permanent residents especially in mesquite bosques along the Santa Cruz and Rillito; we see “broad-bills” through the winter in our yard. In the arrival category, some Anna’s Hummingbirds have been in our area through the summer, but others arrive from California starting in mid August and may nest as early as December. In the Tucson area the most noticeable dove migrant is the White-winged Dove. Though a few linger north of the Mexico border for the winter, most are gone from our yards by mid September. It’s interesting to note that while Tucson “white-wings” migrate, those in Las Cruces, New Mexico, stay put for the winter, although Las Cruces is higher and a good bit colder than Tucson. Why this striking difference in behavior between two populations of the same species? There are other changes to note in September. The few remaining Lucy’s Warblers and Brown-crested Flycatchers will be on their way soon, and the bulk of the Elf Owls and Bell’s Vireos will leave by the middle of the month. Purple Martins and Barn Swallows are massing for migration in September. Look for them over areas with lots of insects. You may hear the martins chirping as they gather near their roost sites before dawn. While most birds that migrate are programmed with the right information for the long trip, a few immature birds making their first journey either have an error in their “hard-wired” navigation system or become the victims of an unusual weather event and end up far from where expected. It can be exciting for birdwatchers when, for instance, a warbler from eastern North America is found in southeastern Arizona in September or October. However, it is almost surely disastrous for the bird, which may survive the winter, but will probably not be able to return to its breeding grounds next spring. Davis and Russell’s Finding Birds in Southeast Arizona (TAS, 1999) is a good reference to what birds should be in our area when. Purchase it at the Audubon Nature Shop and keep it handy.
Based on new knowledge, the ornithologists who study the relationships between bird species are changing their views on the definition of a species. The American Ornithologists’ Union Committee on Classification and Nomenclature has recognized several “new” bird species and changed the scientific or accepted proper (English) names of birds. (Incidentally, the fact that the English names have been officially chosen, is the reason they should be capitalized in print, just as we capitalize the name of towns, rivers and other proper names.) What determines a species is a topic of continuing debate in ornithology. One view looks at failure to interbreed successfully as the defining criteria, while another view looks for populations with well-defined characteristics (behavior, appearance or vocalizations) or geographic boundaries as definitive. Any of these criteria clearly separate American Robin and Rockhopper Penguin as species distinct from each other, but birds such as “flickers” are a much murkier situation. In 1966 we recognized Red-shafted, Yellow-shafted, and Gilded flickers. Later all three were lumped and named Northern Flicker. Recently, the Gilded Flicker was made a separate species again. Yellow-shafted and Red-shafted individuals have a wide zone of interbreeding where their ranges meet, and this clouds the species picture. Possibly this is a species in the process of evolving into two. There are other examples. In the first edition (1966) of Chandler Robbins’ Golden Guide, there is one Screech Owl in North America. In field guides dating from the 1980s and later, there are two screech-owl species, Eastern and Western Screech-owls. These two species of owls, whose ranges divide roughly along the eastern edge of the Rocky Mountains, were recognized, primarily on the basis of the difference in calls. Plumage color varies within each species, with reddish morphs appearing in some areas and darker gray races found in moist dense forest habitats. Some species, that were separate in 1966, were lumped in the 1980’s and then split again later. Baltimore and Bullock’s Orioles were lumped as Northern Oriole and then split again. They were combined because they sometimes interbreed at the western edge of the Great Plains where their ranges meet, but later studies of their genetic material suggest, as most birdwatchers suspected all along, that these are two different species. Another recent example is the “Solitary Vireo,” which is currently recognized as a complex of three species: Cassin’s, Plumbeous, and Blue-headed. They were originally described as individual species, then lumped, and with more knowledge split again. Here, new data has enabled ornithologists to validate what was originally proposed. In the past quarter-century, the use of biochemical techniques to look at genetic material has provided important new evidence for biologists to consider in classifying birds. Does this mean there will be more species of birds in the future? Yes. For instance, gene sequencing provides evidence that the Curve-billed Thrasher is probably more than one species. We may again be referring to “Palmer’s” Thrasher, the name used in the early 1900s for the thrashers in our area. Today, taxonomists can make decisions about what constitutes a species based on a much broader data base than was available just a few decades ago. Not only does this affect birds at the species level but families may be rearranged and birds may be moved from one family to another. The Green-tailed Towhee is probably not a Pipilo towhee at all, and look where vireos have been placed in the new (1999) National Geographic Guide. Heads up! There’s more change to come. Suggested Reading
Mockingbirds are often seen on similar perches as shrikes, so check each gray, black and white bird carefully; mockingbirds and shrikes are easy to confuse at a casual glance. Shrikes perch more horizontally, have a relatively larger head (hence the name), a shorter tail, a black face mask, and a hooked black bill. Our understanding of where shrikes fit into the evolutionary avian picture has changed considerably in the last 20 years. As a result of examination of genetic material, shrikes (and vireos which also have a hooked bill) are now considered to be related to crows and jays. Except for the Loggerhead and Northern, shrikes are found in the Old World, Europe, Asia and Africa. The largest number are in Africa. While many shrikes are brown rather than gray, their plumage patterns are quite similar throughout the world. Shrikes are known for their habit of impaling prey items on thorns or the barbs on barbed-wire fences. They do this because their feet are relatively weak, and they need the prey item held firmly while they tear it apart with their strong beaks. Sometimes food items are stored and retrieved for consumption later. Males may feed some of these items to their mate while she incubates the eggs and broods young. A female shrike starts incubation with a fat reserve of about 30% of her normal weight so she does not have to stop incubating to hunt food for herself. Finding prey items of the size that shrikes catch is unpredictable, so this pattern of using fat reserves and being fed by the male enables shrikes to hatch most of their large clutch of 5-6 eggs. The female doesn’t just sit, she also turns the eggs 6-10 times a day during the average 16-day incubation period. She broods the newly hatched chicks for 4-5 days until they can control their own body temperature. Her mate brings food which she shares with the chicks. After brooding both parents bring food to the chicks. Loggerhead Shrikes have declined in North America over the last 35 years for reasons not clearly understood. The current rate of decline judged by census data is between 1-2% per year. Researchers believe that loss of natural habitat and heavy use of pesticides are major factors. Extinction of these interesting birds would be a real loss to birdwatchers and the ecosystem. References and Further Reading Lefranc, N. A Guide to the Shrikes of the World. Yale Univ. Press. 1997. Yosef, R. “Loggerhead Shrike (Lanius ludovicianus).” The Birds of North America, No. 231. 1996.
The bird we call Northern Cardinal was considered a century ago to be as many as 4 different species but currently is classified as 18 subspecies. Though our Arizona Cardinalis cardinalis superbus is a very bright red, the scientific literature states that there is considerable color variation between males in this group, so "the brightest of them all" probably applies to individual males rather than the entire superbus subspecies. As late winter drifts imperceptibly into spring, breeding activity in birds increases in intensity. One of the easiest backyard species in which to watch breeding behavior is the cardinal. The information presented here is from the Birds of North America account (Halkin and Linville 1999). Most studies of cardinals have been done in the eastern U. S. Are there differences in the Tucson area? Cardinal nests are built in thick vegetation by the female who chews twigs in her bill to shape them before forming them into a cup around her body. The cup is wedged into position between branches, twigs or vines but not attached to them. Egg laying starts an average of 2-3 days after the nest is completed, and 1 egg is laid per day, usually an hour after sunrise, until a clutch averaging 2-3 eggs is complete. Males guard their mates especially attentively at this time, but DNA fingerprinting has determined that 9 - 36% of the chicks in a given nest are still fathered by a different male. Also, occasionally a different female lays an egg, fathered by the male of the pair, in the pair's nest. Successful reproduction, not fidelity, is what is important. Incubation by the female starts after the last egg is laid, and she warms the eggs with the bare skin of her abdomen where feathers have been lost. After 11-13 days the eggs hatch and the pair begins frantically feeding the hungry nestlings. Their weight increases more than 7 fold in the first 8 days. Young birds usually leave the nest 9-10 days after hatching, barely able to fly short distances and with their feathers not yet fully grown. After leaving the nest the young birds are totally dependent on parents for about 3 weeks, hardly moving from their perch on a branch for the first 11 days. After this, association of parents and nestlings is variable; if the parents are ready to start another brood, parental care ends in less than 4 weeks, whereas at the end of the season it may last almost 2 months. Because losses of eggs and nestlings are high, cardinals may start as many as 8 nests in a season. This is possible because cardinals are permanent residents, adapt to a variety of habitats including back-yards, and are omnivorous, eating seeds, fruit, and insects. Cardinals often dominate smaller birds and their close relative, Pyrrhuloxia, at feeders and other food sources. Many cardinal pairs remain together all year either on their territory or in winter feeding flocks. Death or the occasional "divorce" makes space for a "floater," an unpaired bird. Second-year birds pair around the time the winter-feeding flock breaks up. In urban Tucson you are more likely to have Northern Cardinals in your yard than Pyrrhuloxias, but toward the outskirts of town Pyrrhuloxias may be more common. The two species can have overlapping territories without evidence of aggressive behavior. Look for interesting interactions. Individual Cardinals and Pyrrhuloxias have been observed counter-singing to each other (S. R. Russell, personal communication). Barbara Kingsolver writes, "a pair of cardinals and a Pyrrhuloxia couple who nested in adjacent trees, became so confused, when the young fledged and flew to the ground, that they hopped around frantically for a week, feeding each other's kids." (Kingsolver 1995). The "cheer, cheer, cheer" song of the Northern Cardinal is one of the most widely recognized bird vocalizations. Unlike most bird species, both male and female Cardinals sing. The songtypes are very similar and sometimes indistinguishable from Pyrrhuloxia. Enjoy listening in your backyard. References
and Further Reading Halkin, S. L. and S. U. Linville. 1999. Northern Cardinal. Birds of North America, #440. Tweit, R. C. and C. W. Thompson. 1999. Pyrrhuloxia. Birds of North America, #391. Bird questions? Check Birding | General questions? Contact: Tucson Audubon Society | Webmaster: Email This page was updated on 02/21/06 |