Late August and September have been very slow in terms of the warbler migration through Goleta and Santa Barbara. Initially we hoped this was due to a delay resulting from the incredibly late spring migration, where many species were running three weeks late. However, as numbers continue to remain low, there are always concerns about a potential population crash.
Another likely contributor to the low numbers is lack of
suitable feeding concentration areas. Unlike my native Britain, where birders
look for migrants on islands or more prominent headlands, along most of the
southern California coast, we search for migrants in areas that have insect
infestations that attract large numbers of birds to feed. The traditional
sources of such rich feeding are red-gum eucalyptus groves, mall and business
car parks with Tipuana trees and tamarisk windbreaks. Over the years, many of
the tamarisk windbreaks have simply died or been removed in a misguided effort
to eliminate invasive plants (these particular tamarisks are not the invasive
species in our desert riparian systems). The eucalyptus groves appear to have a
rather low-level of lerpsid infestations this year, rendering them less
attractive to migrants. This has left local birders scouring the parking lots
with tipuana trees, but pickings have been slim here as well.
After catching up with a couple of low-grade rarities in the
Hollister Techpark (see the introductory photo), a couple of miles from my home, my luck started to change
when I held a warbler identification class for the local Audubon Society on
September 13. As I was attempting to locate Yellow, Wilson’s and Orange-crowned
Warblers for the attendees to explain how to quickly identify them from below,
I saw a Northern Parula. This species is probably our commonest spring vagrant
warbler but is a bit rarer in fall and not quite annual. We enjoyed good looks
at a young male and birders who came to chase it ended up finding a second one,
along with a Tennessee, which is probably our commonest fall vagrant warbler in
recent years.
However, the real excitement began on September 15, when a
“Least Flycatcher” was reported from the Santa Barbara Bird Refuge. This is an
infrequent vagrant on the mainland coast of the county, although I have seen
half-a-dozen or more out on the Channel Islands. The initial images were fairly
poor (showing the bird to rather brownish) and several of us felt the bird was
more likely just a Willow Flycatcher. The local recorder who went down to see
the bird was adamant that the bird was not a Western Willow Flycatcher. Alex
Casterlein, one of new generation of hotshot young birders in the state – and
who had just finished a four-year stint at the University of California Santa
Barbara – then texted me that the primary stack might make the bird a candidate
for an Alder Flycatcher – an ultra-rarity with barely 10 records in the state!
Fortunately, a significant number of the local
bird-photographic community, for whom Least Flycatcher would have been a county
bird, were already on the scene and much better images were obtained. These
showed the bird was olive rather than brown-toned and confirmed the bird
consistently showed a narrow complete eye-ring and a contrasting wing pattern,
all consistent an Alder. In addition, all the structural features matched up
well for Alder, such as the slightly shorter bill, more rounded head profile
and longer primary projection.
I headed down in the afternoon but was only able to get poor
quality looks. Fortunately, it wasn’t a life-or-death situation since I had seen
the only other Alder Flycatcher in the county back in 2018. However, I always
like to take advantage of studying difficult-to-identify vagrants so I can be
more ready if I get lucky enough to run into one myself. Therefore, the next
morning I headed back down to the site. The combination of now having my 12x
binoculars and much better lighting resulted in pretty good looks.
After that I decided to follow up on my resolution to check tipus at a different business park in eastern Goleta for warblers. I don’t like this location as much as the Hollister Techpark because the trees are taller and leafier, resulting in a lot of discomfort from “warbler neck”. To minimize this problem, I spent some time using mobbing calls to draw warblers into one the smaller trees. I quickly attracted a small flock of birds but there was nothing beyond the common western warblers.
I decided to walk over to another section of the car park.
The central areas of the carpark had small “islands” that were densely planted
with low bushes. As I approached one of these, I heard a rasping ‘titch’ note
somewhat similar to some calls of a Yellowthroat. The bird flushed out and
landed on the bank surrounding the car park in the open for a good 5-6 seconds
about 60m away. It was immediately obvious it was a young Mourning Warbler! I
had only seen a couple of these previously in the county – the only ones I had
ever seen in California.
Mourning is the eastern equivalent of the western MacGillivray’s
Warbler and rather similar in many plumages. Fortunately, most young fall
Mourning Warblers show extensive yellow in the throat through to the breast and
do not show the complete breastband and hooded-appearance typical of MacGillivray’s.
This was a typical obvious Mourning in this respect. In addition, MacGillivray’s
has a much harder chip note that I am very familiar with as it is a common
wintering bird in Mexico, where I bird a lot. After putting the word out about
the warbler, the car park started to become a bit of a zoo since there were a
lot of out-of-town birders up to see the Alder Flycatcher and Mourning Warbler
itself is hard to see in the state. At that point, I decided to bail and check
out a few other areas on the way home.
Pam Viale kindly provided the photos for this entry.
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