Date: 6/3/25 10:42 pm From: Andy Engilis via groups.io <aengilisjr...> Subject: Re: [centralvalleybirds] Late Spring Migrants— observations in Yolo County
Hi Zane, nice summary. I just returned from 8 days in Arizona and indeed there were lots of migrants moving through there, many late. We had numerous Hermits, Townsend, pewees, and Olive-sided Flycatchers in many desert habitats
On May 31, along the Colorado River (Palo Verde Ecological Reserve, we had numerous migrants moving through. I suspect we will continue to see birds trickling through into mid-June, many probably too late to breed.
Andy
Andrew Engilis, Jr.
Curator
Museum of Wildlife and Fish Biology
University of California, Davis
(530) 754-8813
<aengilisjr...>
https://mwfb.ucdavis.edu/
________________________________
From: <centralvalleybirds...> <centralvalleybirds...> on behalf of Zane Pickus via groups.io <zanep987...>
Sent: Tuesday, June 3, 2025 9:58:18 PM
To: <centralvalleybirds...> <centralvalleybirds...>
Subject: [centralvalleybirds] Late Spring Migrants— observations in Yolo County
Hi Birders,
There has been much discussion amongst birders throughout California about how late spring migration has been this year. This certainly was noticeable in the Central Valley. While some have noted the slow start to spring and the relatively poor showing of migrants in April, things seemed to pick up in May. Now we have reached what is typically the tail end of migration, and yet I continue to see exciting numbers of migrants for the late date. I felt it worthy to report the following observations of notably-late migrants that I have both personally observed and seen reported in the past week in Yolo County.
Hermit Warblers: Prior to this week there were no June records of this species for Yolo County. Julian Johnson observed one yesterday at the Putah Creek Riparian Reserve for a new late spring record. That record was quickly broken this morning when Julian and I had a singing male in a riparian patch at the Yolo Bypass Wildlife Area (YBWA). I see that Sean Smith also reported a female Hermit in Davis today on eBird. Perhaps more will be found in the coming days. There are very few June records for the Central Valley overall.
Townsend’s Warblers: Usually gone by the last week of May, I have observed Townsend’s Warblers at nearly every passerine birding stop I have made in the past week, including three individuals this morning in random willow riparian patches at the YBWA. Others have observed additional Townsend’s Warblers in the county in the past week along Putah Creek and elsewhere.
Black-throated Gray Warbler: Sean, Julian, and I had a female at the Cache Creek Settling Basin on 6/1. There are just a small handful of June records for the county.
Western Sandpiper: A healthy-appearing adult was photographed at the YBWA on 5/31 by Joo Tan, which looks to be the latest spring record for the county.
Purple Finch: Not known to nest in the county, Joshua Greenfield reported two birds, including a singing male, on Rayhouse Road in the Coast Ranges on 5/29. These could either represent the latest spring migrants or a potential first breeding record for Yolo County.
Migrants of other various other species that tend to straggle into June (Willow Flycatcher, Western Wood-Pewee, Western Tanager, Swainson’s Thrush, and Black-headed Grosbeak, to name a few), all continue to be reported in Yolo County daily. One intriguing theory for the late spring is how mild the temperatures have been for the time of year. In Yolo, we have only reached temperatures of 100F for two days (last weekend), far below the run of hot weather that usually occurs by June in the valley. Perhaps there are other factors at play as well, but the lack of hot days to get birds moving north may well be playing a role in migrants passing through later than expected.
Regardless, spring migration is still very much underway and I encourage everyone to get out and see what you can turn up in your local patches!
