2021 marked the twenty seventh full year of banding at Zuma Canyon (established in 1994), located in Malibu. The year was, without a doubt, interesting for both birds and the bird banders. 2021 was especially challenging for birds as the effects of the Woolsey Fire of late 2018 and the ongoing drought continued to impact breeding and species ratios.
In 2021, we caught fewer birds on average. The annual average number of birds encountered (including caught, banded, recaptured, escaped birds, and unbanded releases) within the past 5 years (2016-2020) was about 1,073 birds. 2021 saw only 690 birds encountered, a decrease by about 35.7%. This was especially felt during the summer months, when catching over 10 birds was considered a victory.

Woolsey Fire Impact: 2018 and Beyond

“Presently, we are following the recovery of the avifauna post-Woolsey fire. How will recovery proceed? How long will it take for individual species to reach pre-fire numbers? Will new opportunistic species appear? Will some species not return? Other questions will undoubtedly come up.“

Walt Sakai, Master Bander
Annual Report of 2021 Activities

Even though the fire occurred three years prior, the events of the Woolsey Fire are still being felt. I have been told stories of trees falling down after sustaining fire damage and native vegetation being burned away. In fact, visit Zuma today and you can still see areas where the fire had charred the bark of surviving trees. The implications of the fire (coupled with the persisting drought) has led to increases and decreases of species numbers.
For instance, the Wrentit (Chamaea fasciata), a bird favoring vegetated areas, has seen a major decline post-Woolsey Fire. In prior years, the Wrentit consistently ranked the #1 most abundant species with around 200 birds encountered per year on average. In 2021, they numbered only 7 individuals, #18 on the list.
A similar, albeit less dramatic, trend can be seen with the California thrasher (Toxostoma redivivum), who numbered at around 15 per year on average pre-fire. In 2021, only 5 were encountered and their vibrant songs were seldom heard throughout the canyon.
Woodpecker numbers overall fell post-fire, but have gradually increased since 2020. 2021 saw 5 Nuttall’s Woodpeckers(Dryobates nuttallii) and 1 Acorn Woodpecker (Melanerpes formicivorus), an increase by 4 individuals from the previous year. As the master bander Walt Sakai noted in his 2021 Annual Report, this was likely due to woodpecker use of dead fire damaged trees, which woodpeckers favor.
Other examples of this change can be seen in other species as well. Pre-fire, the ratio of Bewick’s Wrens (Thryomanes bewickii) to House Wrens (Troglodytes aedon) was 2.56:1. The ratio has been 1:1.52 since the fire.
However, 2021 also saw some rises in species abundance. Sparrow and finch numbers were considerably higher than in years previous as early succession vegetation began to grow. Migrant species such as the Gambel’s white-crowned Sparrow (Zonotrichia leucophrys gambelii) and Golden-crowned Sparrow (Zonotrichia atricapilla) have continued to have numbers moving in the right direction. The Lazuli Bunting (Passerina amoena), a relatively rare bird at Zuma, saw an increase in abundance in 2019, numbering 45 encounters. Since then, none have been reported as the species tends to favor areas that had recently burned.

Since the Woolsey Fire, some vegetation has been able to grow back (though the drought doesn’t make doing so any easier). While Zuma is, for now, not the lush green landscape it once was, there is still hope for the native (and non-native) plant species that are rebounding. And while the number of bird species caught in 2021 isn’t that great either, the future is promising.

Drought Impact: Breeding and Feeding

In 2021, Zuma got 15.85 cm (6.24 inches) of rain, about 58% less than the longtime average recorded at the Downtown Los Angeles weather station. Throughout the whole year, especially in the summer and fall months, Zuma was incredibly dry. Vegetation was sparse and almost nothing was left in flower by July. Mornings were very slow, with hardly any birds being caught in the nets for the first few hours. Having more than 3 birds to process each round was almost unheard of.

During the summer months (June 5-August 28, 2021 cycles), the average number of birds caught in nets was about 11 individuals. This average began to increase in the fall and winter months (September 11-December 18, 2021 cycles), at 37.5 birds as the average. Nonetheless, the year was difficult for birds and disappointing for us banders. There was little evidence of CP/BP (cloacal protuberance/brood patch), which would indicate a breeding bird. Bird songs that normally filled the canyon were absent in the first few hours we banded.
Because there were so few plants still in flower (only elderberry, tree tobacco, mustard, Jimson weed, and chaparral mallow by June), resident hummingbird species became a regular in the nets. From the years 2019 and 2020, the average number of Anna’s hummingbirds (Calypte anna) caught each year was 24. 2021 saw 40 Anna’s, an increase of 167%. The Allen’s hummingbird (Selasphorus sasin) saw 44 birds in 2021, an increase by about 130% for the same year range.

Positives of 2021

Despite the numerous negatives that came with banding in 2021, there were also a fair number of successes. For instance, the first Brewer’s Sparrow (Spizella breweri) was banded at our Zuma Canyon station in late August. The fifth Acorn Woodpecker (Melanerpes formicivorus), third Dusky Flycatcher (Empidonax oberholseri), sixth Northern Rough-winged Swallow (Stelgidopteryx serripennis), fourth Black-throated Gray Warbler (Setophaga nigrescens), and third Western Bluebird (Sialia mexicana) were banded as well in the station’s 27 year history.

As of 2021, a total of 107 species have been encountered at Zuma within the past twenty seven years of the station’s existence. 241,157 birds have left the bander’s hand with a shiny metal band around their leg― a souvenir that will provide crucial data about the bird’s movement, body structure, breeding status, and more… if they are to be caught again.

2021: A Banding Year in Photos

Photos used with permission from Amy Worell, Aaron Gomperts, and Walt Sakai.