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To convey the frequently ambiguous nature of taxonomy we sometimes employ brackets in both the

English and scientific names. These brackets indicate relatedness (or traditionally perceived relatedness)

for taxa that fall either into the gray zone of uncertainty or into the realm of proposed new splits (see

Appendix C). If a taxon has a widely used English name, or if its original name is evident from the English

name, we use brackets only in the scientific name, as in Northern Collared Trogon Trogon [collaris]

puella, or Central American Sharpbill Oxyruncus [cristatus] frater; the name in brackets is simply the

chronologically first-named taxon, which may be called the parent species. If the taxon has a potentially

unfamiliar English name we also include the former (parent) English name in brackets, as with Veraguas

[Brown-throated] Parakeet Eupsittula [pertinax] ocularis or Hick’s [Variable] Seedeater Sporophila [corvina]

ophthalmica. We do this also for some relatively recent splits that are widely agreed upon but likely

unfamiliar to many users, such as Gartered [Violaceous] Trogon Trogon [violaceus] caligatus and Morelet’s

[White-collared] Seedeater Sporophila [torqueola] morelleti. Although sometimes a little cumbersome, we

believe that the information provided by this method is preferable to simply dumping a load of new and

potentially confusing names on the reader with no explanation.

Lengths simply give an idea of relative size; note that every species varies slightly to strikingly in length

(most books provide simply an ‘average’ length, which can be quite misleading). Moreover, because area

is a square of length, a bird 10% ‘larger’ (= longer) than another can appear appreciably bigger in the

field, e.g., a bird 10cm long can appear 20% ‘bigger’ than a bird with similar proportions that is 9cm long

(10 × 10 = 100cm², vs. 9 × 9 = 81cm²).

The species account text then covers points relevant to identification (hereafter, ID), which can include

aspects of habitat, seasonal occurrence, abundance, and behavior, as well as the more conventional ID

criteria of plumage, structure, and voice. Similar-looking species often segregate by geography and

habitat, or by season, which can streamline ID vs. looking for minor plumage or structural differences

(e.g., Blue-chested vs. Charming Hummingbirds, Louisiana vs. Northern Waterthrushes, Red-throated

vs. Middle American Ant-tanagers). Habitat descriptions are usually broad-brush, and behavioral notes

are limited to features that can assist with ID.

Sounds can be very helpful for ID. They are notoriously difficult to describe, but at least some

description may help in several ways: 1) to ID a bird from something seen poorly but heard well; 2) to

prompt the memory, including comparison with similar sounds; 3) to tell you what a bird does not sound

like, often helpful when seeking a species—don’t follow up on high lisping twitters if the bird you are

seeking makes low-pitched rattles.

We use accents to indicate emphasis or a point of rising inflection, as in peé-eer; and CAPITAL letters to

indicate loud or strongly emphasized phrases, as in PEE-eer. As a rule, only the most typical and frequently

heard vocalizations are described; almost all species make myriad other sounds, especially in the breeding

season. Sound descriptions are based on the personal experience of Howell unless stated otherwise,

including reference to the online sound libraries of the Macaulay Library (www.macaulaylibrary.org) and

Xeno-canto (www.xeno-canto.org). This section is omitted if a species is typically silent in Costa Rica.

Although many sounds can be found online and on apps, beware of potential geographic as well

as individual variation, not to mention the possibility of misidentified sound files (especially in the

Macaulay Library, whose utility, sadly, is being diluted by burgeoning poor-quality recordings added

by well-meaning eBird users). Moreover, vocalizations on commercial CDs in particular can be of birds

agitated in response to playback vs. birds giving vocalizations more typically heard in the field.

Status: Statements made here should be used in conjunction with the maps. Species are assumed to be

resident unless stated otherwise. Migrants include winter migrants (mainly visitors from North America),

transient migrants (passing through to/from North and South America), summer migrants (visiting Costa

Rica in summer to breed), and simply nonbreeding (nonbr.) migrants that may occur year-round (such

as wide-ranging pelagic species, or shorebirds that may remain in Costa Rica during their first summer

rather than returning north to breed). Understandably confusing to many visitors from the Northern

Hemisphere, the wet summer months in Costa Rica are often called ‘winter’ by local residents—a legacy

from Spanish settlers coming from a Mediterranean climate, where the winters were rainy, the summers

dry and sunny.

Date and elevational ranges are by necessity broad-brush guidelines, and elevation is often simply a

proxy for habitat. Thus, a resident species found at 500–1500m would not be too surprising if encountered

at 350m or 1600m (especially if in similar habitat), but it would be unusual at sea level or 2000m.

Also note that cloud forest and other humid montane habitats occur at appreciably lower elevations on

the volcanoes of the Guanacaste Cordillera than in the Talamanca Mountains, and that many species

inhabiting humid foothill forest tend to occur at lower elevations on the Caribbean slope than on the