Vireo cassinii
Silhouette: Caleb Gordon · PhyloPic
In 3 days <5% in a week ~10%
Cassin's vireo (Vireo cassinii) is a small North American songbird, ranging from southern British Columbia in Canada through the western coastal states of the United States, including California, Oregon, and Washington. The Cassin's Vireo moves down Western United States forests in its migration. During its migration in early spring and late fall, it spends the winter in regions from southern Arizona (the Sonoran Desert) to southern Mexico, including parts of Baja California and the Pacific coast of Mexico.
The vireo is 11–14 cm (4–6 inches) long. It has a grayish olive head, back, and flanks, with whitish underparts. One of its distinctive features is the solid white "spectacles" around its eyes, along with white wing bars. These markings set it apart from other similar species like the plumbeous vireo and the blue-headed vireo.
Cassin's vireo is known for its persistent song, which consists of short, rough-whistled phrases of several notes.These phrases are 2 seconds apart and often alternate between ending on high and low notes, creating a "question-and-answer" pattern. The Cassin's Vireo is known to sing for an extensive duration of time. Hearing... Wikipedia →
| # | Park | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Yosemite National Park | 🇺🇸 United States | |
| 2 | Glacier National Park | 🇺🇸 United States | |
| 3 | Jasper National Park | 🇨🇦 Canada | |
| 4 | Sequoia and Kings Canyon National Parks | 🇺🇸 United States | |
| 5 | Banff National Park | 🇨🇦 Canada | |
| 6 | Death Valley National Park | 🇺🇸 United States | |
| 7 | Zion National Park | 🇺🇸 United States | |
| 8 | Big Bend National Park | 🇺🇸 United States | |
| 9 | Cumbres de Monterrey National Park | 🇲🇽 Mexico | |
| 10 | Saguaro National Park | 🇺🇸 United States | |
| 11 | Guadalupe Mountains National Park | 🇺🇸 United States | |
| 12 | Redwood National Park | 🇺🇸 United States | |
| 13 | Grand Canyon National Park | 🇺🇸 United States | |
| 14 | Joshua Tree National Park | 🇺🇸 United States | |
| 15 | Great Bear Rainforest | 🇨🇦 Canada | |
| 16 | Olympic National Park | 🇺🇸 United States | |
| 17 | Grand Teton National Park | 🇺🇸 United States | |
| 18 | Rocky Mountain National Park | 🇺🇸 United States | |
| 19 | Channel Islands National Park | 🇺🇸 United States |
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Toluca | 🇲🇽 México | |
| 2 | Mexico City | 🇲🇽 México | |
| 3 | Guadalajara | 🇲🇽 México | |
| 4 | Puebla | 🇲🇽 México | |
| 5 | Sacramento | 🇺🇸 United States | |
| 6 | Monterrey | 🇲🇽 México | |
| 7 | Portland | 🇺🇸 United States | |
| 8 | Las Vegas | 🇺🇸 United States | |
| 9 | Mesa | 🇺🇸 United States | |
| 10 | Los Angeles | 🇺🇸 United States |
Rare
Under 5% of wildlife watchers report a Cassin's Vireo sighting in Monterrey on a given day, based on 16 verified sightings from GBIF citizen-science data. It is the 156th most-seen of the 207 birds we can rate there. Over three days the chance rises to under 5%, and over a week to about 10%, if each day is a fresh chance.
February
In that month about 10% of wildlife watchers report a Cassin's Vireo in Monterrey on a given day, against under 5% in March to January, the lowest months. That is one of Monterrey's driest months, with about 20 mm of rain against 200 mm in September.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Cassin's Vireo sightings with a recorded time, and about 9 in 10 of them come between 6 am and 6 pm: it is a daytime animal.
6th of 18
Of the 18 cities where we can rate Cassin's Vireo sightings, Monterrey ranks 6th at under 5%. The best odds are in Toluca (México, about 10%), Mexico City (México, about 10%) and Guadalajara (México, under 5%).
GBIF citizen-science records
It is estimated from how often the Cassin's Vireo is recorded against all the birds logged in Monterrey (16 verified sightings), calibrated against known sighting rates. Figures are rounded to the nearest 10% because citizen-science data supports honest approximations, not decimals, and months with records from fewer than five people show "—". How it works.
