Credits & licences

This guide is built on public datasets and on media under a Creative Commons licence or in the public domain. Below, first where the data come from — the checklist, the family tree, the measurements, the habitats and the distribution maps — and then the full list of photographs and recordings, giving the author, the licence and the source page for each file. Nothing is used under a no-derivatives (ND) licence.

Where the data come from

The guide rests on a handful of public datasets. They are gathered here, with what each contributes and on what terms.

• AviListCC BY 4.0

  The sequence and arrangement of orders, families, genera and species. AviList is the global checklist that since 2025 has been maintained jointly by the major lists — the IOC list, Clements and BirdLife — so that there is one list instead of three. This guide follows version 2025b.

• B10K and the PhyloCode

  The clades above the level of the order, shown in the tree and in the side menu. They follow the family-level genome tree of the Bird 10,000 Genomes project (Stiller et al. 2024) and carry names established under the PhyloCode — a system that names a branch of the tree rather than a rank.

• AVONETCC BY 4.0

  The wing length and weight of every species. Eleven measured traits for all 11,009 bird species in the world, built from measurements of 90,020 individual birds in museums and in the field (Tobias et al. 2022). The wingspan is estimated from the wing length; how that is done is explained further down.

• GBIFCC BY 4.0

  The distribution maps. GBIF gathers records from museums, ringing stations and observer networks into one searchable whole; the maps in this guide draw the density of those records, not a drawn range boundary.

• IUCN Red List

  The status of each species, from least concern to critically endangered. The category appears in the summary box and colours the badge.

• Wikimedia CommonsCreative Commons

  All photographs and most of the recordings. Every file is CC0, public domain, CC BY, CC BY-SA, CC BY-NC or CC BY-NC-SA; no-derivatives (ND) licences are not used. Author, licence and source page are listed per file below.

• xeno-cantoCreative Commons

  The open archive of bird sounds, built by volunteers. Most recordings in this guide were made there and carry an XC number, including those that arrived by way of Wikimedia Commons. Only recordings under CC0, CC BY, CC BY-SA, CC BY-NC or CC BY-NC-SA are used.

Readers' photographs

Anyone with a Creative Commons-licensed photograph of a free-living wild bird that the guide still lacks can submit it. The rules and the form are on a page of their own. Submit a photograph

Which birds are in the guide

The country decides the guide, not a map window: it covers the birds of Mexico, Guatemala, Belize, Honduras, El Salvador, Nicaragua, Costa Rica and Panama, with their own islands, such as Cozumel, the Revillagigedo Islands, Guadalupe Island, Cocos Island and the Bay Islands. The birds of Clipperton are not included.

The guide covers one thousand four hundred and eighty-seven species: every bird that occurs regularly in one of these eight countries, plus the introduced species that have established themselves and the vagrants recorded there from time to time. The maps show a larger window, so the southern United States with Florida, Cuba, Jamaica and part of Colombia appear too; their birds are in the guide only if they also occur in one of the eight countries. The islands of the Caribbean have a guide of their own. Every species receives the same full text, map and naming, however common or rare it is.

Measurements: wing, weight and wingspan

The wing length and weight in each bird's summary box come from a single source: AVONET, a dataset of eleven measured traits for all 11,009 bird species in the world, built from measurements of 90,020 individual birds in museums and in the field. One source for every species, so that two birds in this guide can genuinely be compared. Wing length is the ringer's measurement: from the carpal joint — the bend halfway along the wing — to the tip of the longest primary. The weight is the mean of the birds weighed; a bird's weight varies a great deal over the year, so one figure says more here than a range from another source.

The wingspan is not in AVONET, nor in any other series of measurements: it is hardly ever taken from a living bird, and the figures in the handbooks are estimates that differ from book to book — by twenty per cent in the case of the roller. This guide therefore estimates it from the measured wing length, using a ratio calibrated per family. That ratio varies widely: in a swift, which is almost all hand, the wingspan is 2.6 times the wing length; in a grebe, with its long arm, 4.5 times. A check leaving each species out of its own calibration gives a median error of four per cent, with four in five species within ten per cent. Hence the c.: it is an estimate, and the guide would rather say so than print a precise-looking figure that the next handbook contradicts.

The bird's length does not come from AVONET but from the field guides, checked per species against its source.

• Tobias, J.A. et al. (2022), AVONET: morphological, ecological and geographical data for all birds. Ecology Letters 25, 581–597. CC BY 4.0.

The Red List categories

The status in each species' summary box is the global assessment of the IUCN Red List, as carried by AviList — not a national Red List of any of the eight countries in this guide. A species on a national Red List, or protected under national nature legislation, can be “least concern” globally, and the reverse also occurs. On the cards in the overview the code is shown only for species outside the lowest category: were it everywhere, the threatened bird would be the one that no longer stood out. The IUCN assesses every species against fixed criteria: rate of decline, size of range, population size and probability of extinction. The nine categories, from lowest to highest risk:

LC Least Concern

Assessed and not in any of the threatened categories: usually a widespread and numerous species.

NT Near Threatened

Does not currently meet the thresholds for Vulnerable but is close to them, or is expected to meet them in the near future.

VU Vulnerable

High risk of extinction in the wild: for example a decline of 30 percent or more over ten years or three generations, or fewer than ten thousand mature individuals.

EN Endangered

Very high risk: for example a decline of 50 percent or more, or fewer than 2,500 mature individuals.

CR Critically Endangered

Extremely high risk: for example a decline of 80 percent or more, or fewer than 250 mature individuals.

EW Extinct in the Wild

Survives only in captivity or as an introduced population outside its original range.

EX Extinct

There is no reasonable doubt that the last individual has died.

DD Data Deficient

There is too little information on distribution or population to assess the risk.

NE Not Evaluated

Not yet assessed against the criteria.

• IUCN (2012), IUCN Red List Categories and Criteria, version 3.1, second edition. The thresholds below are the outline; the full criteria are in that document.

The scientific name

At the foot of every species page stands the full zoological name: the species name, followed by whoever first described the bird and in what year. Where that author and year stand in brackets, the species has since been moved to a genus other than the one it was described in — the brackets are not a detail but a rule of the code of nomenclature, and the guide observes it.

The guide follows the arrangement and the naming of AviList. Author, year, the original name and the type locality come from its extended edition, which gives the first description and its locality for every species. The type localities have been shortened and rendered in present-day place names.

GBIF, the database behind the distribution maps and the Red List categories, is sometimes behind on naming or follows a different arrangement; in this guide that is the case for a number of species. The GBIF name then stands after it, without further explanation — enough to find the bird again in other sources.

The meaning of the names has been composed for this guide from the Latin and Greek roots and generally accepted derivations, in the spirit of Jobling's Helm Dictionary of Scientific Bird Names. Some of the names are still waiting for a second, source-based check.

• AviList Core Team (2025), AviList: The Global Avian Checklist, version 2025b, extended edition. — Jobling, J.A., The Helm Dictionary of Scientific Bird Names, cited through the Wikipedia species accounts.

Arrangement and sequence

The arrangement and sequence of orders, families, genera and species follow AviList, the unified global checklist of the birds maintained jointly by the major checklists. Above the level of the order stand clades: those follow the family-level genome tree of the B10K project and carry names from the PhyloCode.

• AviList v2025b
• Stiller et al. 2024, Nature 629, 851-860 (B10K)

Texts

The texts on this site were written for this guide. Factual data on measurements, distribution and status draw on standard field guides and the IUCN Red List.

Typeface

The running text is set in IBM Plex Sans, the headings in Cormorant Garamond and the small labels in IBM Plex Mono — the typefaces of vorstman.com. Only the title of each page is set in Antonio, a narrow, tall grotesque in the spirit of the classic field guide covers. All four are under the SIL Open Font License 1.1 and are served from this site itself, so no request goes to an outside server.

The maker