Birds of Peru
By Thomas S. Schulenberg Douglas F. Stotz Daniel F. Lane John P. O'Neill Theodore A. Parker III Princeton University Press
Copyright © 2007 Princeton University Press
All right reserved. ISBN: 978-0-691-04915-1
Peru is one of the richest countries in the world for birds, with 1,800 species. This book is a guide to the field identification of all birds recorded in Peru and in offshore waters within 200 nautical miles of the Peruvian coast.
A field guide can take many forms. We have endeavored to "stick to the basics" and include only information directly relevant to identification. Our intention was to produce a guide that was complete and accurate, yet sufficiently small and portable to be carried close at hand during long days afield. Consequently we have had to jettison, often with great reluctance, much additional information on the distribution and natural history of each species. Additional material on the birds of Peru that did not fit within the covers of this field guide will be incorporated into future publications.
This book includes all species reported from Peru through May 2004, based on specimens in natural history museums, literature records, and unpublished sight records, tape recordings, and photographs. We exclude a few species, often attributed in the literature to Peru, for which we have been unable to confirm a valid record for the country. We have been relatively generous in including species reported from Peru only from sight records, includingsome species on the basis of records that have not been published previously. We encourage anyone who observes a species not previously known from Peru, or known from Peru only on the basis of sight records, to document such records as thoroughly as possible with specimens (with Peruvian governmental authorization), or with photographs, tape recordings, and field sketches and notes, and to publish these records and the supporting evidence.
The classification and nomenclature of birds is under constant review. This affects how many species to recognize for Peru (in other words, whether to "split" or to "lump" geographic varieties into more or fewer species, respectively), the families to which various genera belong, and the sequence of families. We largely follow the classification and nomenclature of the South American Classification Committee (SACC) of the American Ornithologists' Union (http://www.museum.lsu.edu/~Remsen/SACCBaseline.html).
HOW TO USE THIS BOOK
For each species, we present color figures, species accounts, and with few exceptions a distribution map. We include brief introductions to many (but not all) families, and to some genera or species groups. We use these short accounts to introduce species-rich families, or to summarize information that is similar across a group of related species. It often may be helpful to peruse this material, when present, as an aid to field identification.
Each species account begins with English and scientific names of the species. A name is enclosed in brackets () if the species is known in Peru only from sight records, tape recordings, or photographs, but not from a specimen from Peru.
LENGTH The length of each species is given in centimeters and in inches. These measurements, representing the length from the tip of the bill to the tip of the tail, are taken from museum specimens and therefore are only an approximation of the size of a live bird. Nonetheless, they provide a useful index to the size of each species and are useful especially for comparing species that are similar in appearance but differ in size. Note that the length will be influenced both by bill length and by tail length; two species can be of similar length but differ in mass (for example, if much of the length measurement of one species is taken up by lightweight feathers from a particularly long tail). For some species we provide additional measurements, such as wingspan (ws) estimates of species more frequently observed in flight (seabirds, raptors) or bill length in hummingbirds.
GEOGRAPHIC VARIATION An asterisk (*) identifies polytypic species, that is, species with recognized geographic variation (two or more subspecies, across the entire distribution of the species). We do not discuss geographic variation in any detail in this guide, except for instances when subspecies are sufficiently different in appearance or in voice that they might be recognizable in the field.
SPECIES ACCOUNT The bulk of each species account is taken up with notes on the relative abundance, habitat, elevational range, and behavior of each species, and with a description of its voice. Unless noted otherwise, all of our comments refer specifically to that species in Peru. Due to the constraints of the plate-facing format, the text often is terse. We employ a small number of abbreviations:
ca. for "approximately" cf. for "compare to" sec for "seconds" ws for "wingspan"
We also abbreviate the names of months. For some species, especially those with distinctive plumages, we say little or nothing about the bird's appearance. In other cases, we comment on particular features ("field marks") that may be important for identification. We may call attention to similar species, with notes on how these differ or a suggestion to read the account of that species. We usually do not repeat distinguishing characters; these will be discussed under one species or the other, but not under both.
A familiarity with standard ornithological terminology for the parts of a bird is helpful in understanding the species accounts. Please consult the diagrams in figure 5 and accompanying glossary of bird topography.
RELATIVE ABUNDANCE Relative abundance is a subjective assessment and can vary geographically, but we have tried to present an "average" assessment. Our assessments are based on our experiences with average encounter rates of free-flying birds, within the species-appropriate habitat, elevation, and range. Relative abundances of some species may differ, for a variety of factors, based on other methods of sampling (such as with mist-net capture rates). We use the following terms in ranking relative abundance:
Common: Encountered daily, or almost daily, in moderate numbers.
Fairly common: Encountered daily or nearly daily in small numbers.
Uncommon: Easily can be missed at a site, even during several days of observation, but should be encountered during longer stays of a week or more.
Rare: Residents that are present in such low numbers, or, in the case of migrants, present at such irregular intervals, that they can be missed even in a stay of multiple weeks.
Vagrant: Nonresident; has been recorded once or on only a few occasions beyond the "normal" range; might be expected to occur again, but not with regularity.
Statements such as "poorly known" or "rare and local" should be interpreted as referring specifically to the status in Peru. The species may be better known, or more common, elsewhere in its distribution.
HABITATS Habitat often is an important clue in bird identification. Most species are restricted to a particular habitat or a suite of similar habitats and are not expected to be encountered in other situations. We use relatively few specialized terms to describe habitats; these are described in the section Habitats of Peru.
BEHAVIOR Our notes on behavior are focused on field identification. We pay particular attention to the foraging level in the habitat (ground, understory, midstory, canopy), since such behavior often is "fixed" within a species (although some species may forage at one level but sing or nest at another). We may comment on foraging behavior, especially where differences in such behavior may help to distinguish between species of similar appearance.
ELEVATIONAL DISTRIBUTION Our notes on the elevational distribution of each species reflect both museum specimens and sight observations within Peru. Elevational distributions may vary locally, depending upon a variety of factors, and so occasional deviations may be encountered from the elevational data that we present. Generally, however, the elevational distribution of a species is an important aspect of its biology; learn to pay attention to elevation when in the field.
VOICE Many more birds are heard than are seen. Additionally, there are many instances of birds with similar appearance that are identified more easily by differences in their vocalizations. The way to learn bird vocalizations is through hearing them in the field, or through study of the increasing library of tropical bird song collections (on cassette tapes, compact disks, or DVDs). Our descriptions of the vocalizations of Peruvian birds are "the next best thing."
The vocal descriptions presented here, almost all of which were prepared by Lane, are intended to cover the most frequently heard vocalizations produced by each species. Voices are described using qualitative modifiers and, when possible, phonetic descriptions (based on contemporary American English usage). In the phonetic descriptions, stressed syllables are written in capital letters (e.g., "CHEW"). Notes that are very stressed or abruptly given are followed by an exclamation point ("!"). Sounds that resemble a question in human speech are followed by a question mark ("?"). The relative length of pauses between notes or phrases is indicated as follows: notes that are produced with almost no discernable pause are run together (e.g., "tututu"); a very short pause is marked by an apostrophe (e.g., "tu'tu'tu"); short pauses are denoted with a hyphen (e.g., "tu-tu-tu"); moderate pauses are indicated with a space (e.g., "tu tu tu"); and the longest pauses are denoted by "..." The same punctuation ("...") also is used at the end of a phonetic description if the voice continues in a similar manner for an extended period. Usually we describe the song first, followed by the call; but we reverse this order in some cases, when calls are heard much more frequently or are more characteristic of the species. We use the terms "song" and "call" frequently, although there are many species for which it is difficult to label a particular vocalization as one or the other. Generally, we classify vocalizations that are produced in territorial defense, mate attraction, and pair bond maintenance as "songs." In some cases, the "song" of a bird is not vocal at all, but rather is produced mechanically: guans rattle wing quills during short predawn flights, for example, and woodpeckers drum on resonant substrates. Some species also combine mechanical sounds with vocal sounds in elaborate displays (especially among the cotingas and manakins, as well as other groups). "Calls," on the other hand, are a class of vocalizations containing sounds with many different functions, such as to maintain contact among members of a pair, family, or flock; to warn others of danger; to mob predators; and sometimes in territorial defense. Most species have a wide repertoire of calls, many of which are seldom used.
Some species typically sing in duets. Duets are of two types, antiphonal and asynchronous. An antiphonal duet is one in which the members of the pair produce their respective vocalization in a very orderly manner, many times one answering the other with perfect timing. Often the duetted song sounds like only one individual is singing (particularly with wood-quail and Thryothorus wrens). In contrast, in an asynchronous duet (such as are given by wood-rails, many furnariids, and a few other species) the members of a pair sing in a haphazard fashion, with their vocalizations overlapping in a manner seemingly without order.
Voices frequently vary, due to such factors as geographic variation, dialects, individual variation (differences between individuals present at any given site), repertoires (variation between the songs of any particular individual), age- or sex-related differences in song, and the emotional state of the individual bird. Generally, calls are less stereotyped than are songs; and the vocalizations of nonpasserines and of suboscines are more stereotyped than are those of oscines. We often describe discernable geographic variation, although much remains to be learned about variation in the vocalizations of the birds of Peru.
The majority of our vocal descriptions are taken directly from field recordings; only very rarely do we rely on a literature source for a vocal description. We have preferred to use recordings made in or near Peru; we provide brief locality data for recordings that were made outside of Peru and if these voices differ from those of Peruvian populations of that species. The majority of these descriptions are based on recordings by the authors, supplemented by published sound recordings (see Vocal References). Unpublished vocalizations from other recordists are credited in Vocal Credits.
REGIONAL DISTRIBUTION Each species account ends with a note as to whether that species is entirely restricted to Peru ("ENDEMIC") or is known from any of the countries that border Peru (Co, Colombia; E, Ecuador; Br, Brazil; Bo, Bolivia; and Ch, Chile).
We map the distribution of the majority of the species reported from Peru. Species whose distributions are not mapped include those reported only from far off the coast, vagrants known from only a few records, and some extremely local species. For widespread species we show all of Peru, including the 24 political departments (fig. 1) and the major rivers (see also fig. 2). Some species are restricted to only a small portion of Peru; when possible we use larger-scale regional maps to show these distributions in greater detail.
We use shading to connect areas within which we expect a species will be found, even if there are some apparent gaps in the distribution. The maps are color coded to reflect the seasonal status of each species in Peru (fig. 3). Because some species may contain populations that are both resident and migratory, this can lead to some complicated distribution maps. Although migration is an important part of the life history of many of Peru's birds, migration in Peru has not been well studied. Questions remain about the seasonality of some species. In some cases the seasonal pattern of occurrence for a species was unclear, and there is the possibility that some of our assessments may be shown to be incorrect, as Peru's avifauna becomes better known.
The vast majority of birds in Peru are permanent residents, in part of or all of Peru. In such cases a species remains throughout the year in the same areas where it breeds (although there may be very local movements in the nonbreeding season). Areas where a species is resident are shown in light blue.
A handful of species are breeding residents. They breed in Peru but then depart, either leaving Peru completely (Gray-capped Cuckoo, Snowy-throated Kingbird) or vacating the breeding area and migrating to another part of Peru (White-crested Elaenia in part, Slaty Thrush, Black-and-white Tanager). The areas where these species are breeding-season residents are shown in dark blue. The movements away from the breeding grounds represent intratropical migrations, which are discussed below.
Austral migrants are species that breed in temperate latitudes in the Southern Hemisphere from December to February and migrate north during the austral winter. Most such species spend the entire austral winter in Peru, roughly March-October. Arrival and departure periods vary among species and are poorly documented for most species (especially among landbirds). A small number of species (such as Slaty Elaenia) migrate through Peru en route to wintering areas farther north and so are present only for a few weeks each year. There also are species that are known to occur in Peru as austral migrants, but we do not yet know whether they remain through the nonbreeding season or occur only during migration. Species that occur in Peru strictly as austral migrants are mapped in red. We also show in red areas of Peru that are occupied by an austral migrant population, although the same species may be resident elsewhere in the country (e.g., Swainson's Flycatcher, Bran-colored Flycatcher, Tropical Pewee).
In a few cases, such as Tropical Kingbird and Southern Rough-winged Swallow, a resident population is augmented by migrants from farther south. If these migrants are similar (or identical) to the resident population, then migrants can be impossible to recognize as such in the field (except during those rare occasions when a flock is seen clearly in the act of migrating). Therefore, since migrants usually cannot be distinguished from residents, we do not indicate on the map where these austral migrants occur.
Excerpted from Birds of Peru by Thomas S. Schulenberg Douglas F. Stotz Daniel F. Lane John P. O'Neill Theodore A. Parker III
Copyright © 2007 by Princeton University Press. Excerpted by permission.
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