Date: 1/11/25 10:52 am From: Ethan Monk via groups.io <z.querula...> Subject: [EBB-Sightings] Selasphorus hummingbird eBird issues
Hi folks,
For some birds, it is springtime again, and with the first migrant Allen’s
Hummingbirds beginning to be reported in Northern California in the last
couple of days, maybe it is time for a reminder on eBird best practices
when it comes to Selasphorus (Allen's and Rufous) hummingbirds. To cut to
the chase, Selasphorus hummingbirds in 99% of scenarios should not be
identified to species in eBird unless you are looking at an adult male with
optics and can get a solid read on back color.
Ok, obviously there are some ways around that, tail feathers, displays,
etc. but “adult male + back color, only” should be everyone’s rule of
thumb! Allen’s Hummingbirds are quite common breeders coastally, but drop
off rather quickly and are generally scarce to rare east of I-680,
depending on exactly where you are. At the very least, they are vastly
outnumbered by Rufous Hummingbirds in this region, which might be found as
early as February and through June as spring migrants (see e.g. Heindel
1991). Birders that leave the bayshore and head inland to hike in the green
hills, catch a glimpse at a Hammond’s Flycatcher, or whatever in spring are
prone to way overreport Allen’s Hummingbirds, especially in places like Mt.
Diablo where the species is scarce and Rufous Hummingbirds are anything
but. The Contra Costa Breeding Bird Atlas ran for 4-5 years and had (I
believe, but the information is not in front of me) 3 nesting confirmations
of Allen’s Hummingbird on the mountain. At places like Mitchell Canyon,
Allen’s Hummingbirds are reported frequently during the height of spring,
but the fact is that this is likely a pretty darn scarce nesting species
here, that might not nest here every year. To contrast, I’ve seen up to 37
adult male Rufous Hummingbirds in a single morning on the mountain, and 10+
adult male Rufous at a single hummingbird feeder set up in Alamo, to give
you some sort of an idea here.
Allen’s Hummingbirds do exist as breeders in select areas east of I-680,
including an isolated population in the delta which likely hold the crown
as the most inland breeding Allen’s Hummingbirds in NorCal, but rampant
overreporting of this species due to confusion with what are almost
certainly migrant Rufous is so prevalent it is basically impossible to keep
track of these things in eBird.
Ok, if you have made it this far and are thinking “this is so complicated,
I can never remember where Allen’s Hummingbirds are and are not expected” I
have a solution for you! When in doubt, please enter your Selasphorus
hummingbirds as “Rufous/Allen’s Hummingbird” into eBird. That is what
everyone should be doing everywhere, after all. Thank you for reading and
for helping to preserve eBird data quality. Please tell your friends!
