Empidonax difficilis
Silhouette: Emily Willoughby · PhyloPic
In 3 days ~20% in a week ~40%
The western flycatcher (Empidonax difficilis) is a small insectivorous bird in the family Tyrannidae. It is native to western North America, where it breeds in the Rocky Mountains and Pacific Coast forests and mountain ranges from California to Alaska and south to central Mexico; northern populations migrate south to Mexico for the winter.
The western flycatcher was recognized as a single species until 1989, when the American Ornithologists' Union split it into two different species: the Pacific-slope flycatcher (E. difficilis) of coastal western North America and parts of the western Rocky Mountains, and the Cordilleran flycatcher (E. occidentalis) of the interior Rocky Mountains, with both species wintering in Mexico. Both species looked virtually identical to one another, with the split being based on differing breeding habitats and apparent differences in songs and calls. The split was recognized until 2023, when the American Ornithologists' Union and International Ornithological Congress again lumped both species due to a lack of consistent vocal, genetic, morphological differences and extensive hybridization across much of their range.
There are... Wikipedia →
| # | City | Country | Daily sighting probability |
|---|---|---|---|
| 1 | Tijuana | 🇲🇽 México | |
| 2 | Vancouver | 🇨🇦 Canada | |
| 3 | San Diego | 🇺🇸 United States | |
| 4 | Toluca | 🇲🇽 México | |
| 5 | Los Angeles | 🇺🇸 United States | |
| 6 | San Francisco | 🇺🇸 United States | |
| 7 | Seattle | 🇺🇸 United States | |
| 8 | Guadalajara | 🇲🇽 México | |
| 9 | Portland | 🇺🇸 United States | |
| 10 | Mexico City | 🇲🇽 México |
With luck
About 10% of wildlife watchers report a Pacific-slope Flycatcher sighting in San Francisco on a given day, based on 8,350 verified sightings from GBIF citizen-science data. It is the 97th most-seen of the 375 birds we can rate there. Over three days the chance rises to about 20%, and over a week to about 40%, if each day is a fresh chance.
September
In that month about 40% of wildlife watchers report a Pacific-slope Flycatcher in San Francisco on a given day, against under 5% in October to March, the lowest months. That is one of San Francisco's driest months, with almost no rain against 110 mm in December.
Between 9 am and noon
Across all the parks we cover, that three-hour window holds the most Pacific-slope Flycatcher 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 21
Of the 21 cities where we can rate Pacific-slope Flycatcher sightings, San Francisco ranks 6th at about 10%. The best odds are in Tijuana (México, about 30%), Vancouver (Canada, about 10%) and San Diego (United States, about 10%).
GBIF citizen-science records
It is estimated from how often the Pacific-slope Flycatcher is recorded against all the birds logged in San Francisco (8,350 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.
