Birds in the Burn: Monitoring Response to the 2020 Woodward Fire
June 23, 2023
Written by Diana Humple (Palomarin Program Lead) and Hilary Allen (Palomarin/Point Blue Avian Ecologist)
In the spring of 2021, biologists from Point Blue’s Palomarin Field Station began a study to see how the 2020 Woodward Fire in the Point Reyes National Seashore affected the bird community, and the study is actively continuing this spring and summer. This project is a collaboration with Point Reyes National Seashore and is possible thanks to funding support from the Point Reyes National Seashore Association (PRNSA). We aim to evaluate how birds use the burned areas versus unburned areas nearby during the nesting season. And based on our previous studies, what we are finding so far is not necessarily surprising – but still exciting to observe.
Overview of the Woodward Fire
The Woodward Fire was ignited by lightning on August 17, 2020, and burned approximately 5,000 acres in the center of Point Reyes National Seashore, just west of the park’s Bear Valley headquarters and visitor center. It was declared contained in late September. For the local communities who resided close to the fire, it was an intense time (including for us at Palomarin: see here for a summary of our precautionary evacuation), and especially for the firefighters and support teams from within the park and who were brought in from near and far, and the park’s natural resource managers.
Of course, fire can ultimately produce healthy regeneration of habitats and be a boon for wildlife, even if initially it may be disruptive. In this fire, the burn severity ranged across the gamut, from low to moderate to severe, and the fire burned across all the dominant plant communities in the region (especially Douglas-fir forest and coastal scrub). See this NPS article for more information about this topic.
Why are we studying the bird response to the fire?
Birds are excellent indicators of their environment, in part because they respond relatively quickly to changes in it, including to the structure of the vegetation they depend upon. Studying bird response to fire (as well as to other environmental changes) can provide a window into the broader impacts and a general sense of the recovery (or alterations) of the system. Additionally, the project collaborators all care about the bird populations here and want to specifically understand what impacts them, how they may be changing over time, and – in this case – how they are responding to the new landscape since the fire. Post-fire bird community studies provide opportunities to evaluate responses across a diversity of species.
Point Blue has been studying bird response to fire for decades, including in the coniferous forests of the Sierra Nevada, shrubsteppe habitat of Oregon, and even riparian habitat here in Point Reyes National Seashore from a different fire.
In fact, Palomarin’s current long-term monitoring (banding and point counting) at Muddy Hollow in Point Reyes National Seashore is an extension of that latter effort: through another collaboration with the park in response to the 1995 Vision Fire in Point Reyes National Seashore, Point Blue found variation across habitat guilds in the immediate years after the fire.
This included greater numbers of shrub-nesting species such as Song Sparrows and Orange-crowned Warblers and lower numbers of tree-nesting species such as Pacific-slope Flycatchers and Chestnut-backed Chickadees (Gardali et al. 2001, Landbird response to wildfire in a coastal riparian system).
The response of individual bird species to habitat changes produced by fire is typically quite variable, depending especially on the habitat requirements of a given species (e.g., nesting location: ground, shrub, or tree nester; and foraging guild), the severity of the fire (Roberts et al. 2021, Fire and Mechanical Forest Management Treatments Support Different Portions of the Bird Community in Fire-Suppressed Forests), and the habitats involved.
Although we have surveyed much of this park for birds through a number of collaborative studies – a number of which are ongoing – we lacked extensive pre-burn data available in the footprint of the 2020 Woodward Fire. Therefore, instead of directly comparing bird populations before and after the fire, we conducted surveys across the variety of habitat types that burned (predominantly Douglas-fir forest and coastal scrub) and across the range of burn severity, as well as in unburned areas of similar habitat types.
With this approach, we are able to explore how bird use during the breeding season differs between these burned and unburned areas, and potentially across habitat types and burn severity – as proxies for how birds are responding to this fire.
Given our knowledge of how birds have responded to other fires, we expected to demonstrate extensive use of the burned zone by birds, and to observe the response of certain bird species to the regrowth of vegetation that commonly follows a fire.
It’s been quite exciting to go back to the same study sites and see what the bird use is this spring, which marks the third breeding season since the fire. Point Blue biologists (including the blog authors and colleague Renée Cormier) are predominantly surveying along Sky Trail, Woodward Valley Trail, and sections of the Coast Trail.
Why spring and summer?
Timing of bird surveys depends on the specific study goals: for instance, at Palomarin we are studying the bird community as it changes across the year and over decades, and we mist net and band birds year round (for more info see https://www.pointblue.org/about-us/contact-visit-us/). For this Woodward Fire study, we want to know specifically about bird use of the burn zone during the nesting season, which is a critical period because species’ survival depends in part on conditions allowing them to successfully raise young. Although the nesting season begins in March and April for many of our species here, there is a staggered onset of nesting depending on the species, driven in part by staggered arrival times of our migrants returning from the neotropics (with the latest migrant, the Western Wood-Pewee, arriving as late as early May). We therefore want to survey during the peak breeding period: when both year-round residents (such as Wrentits and California Scrub-Jays) and migrant species (pewees and others such as Black-headed Grosbeaks and Swainson’s Thrush) are here and breeding; and when breeding and singing is at its maximum across all species found in our bird community. May and June represent this peak breeding period in Point Reyes National Seashore, and is when we conduct point count surveys – a method that involves covering a relatively long distance and counting birds that are seen and, especially, heard, at specific locations along the way – in the Woodward Fire zone.
What have we learned about the bird community in the Woodward Fire burn zone so far?
We will conduct analyses of this monitoring effort in fall 2023 and so don’t present results to date, but have some preliminary observations to share from the first two years, 2021-2022.
For any of you aficionados of Point Reyes National Seashore’s extensive hiking trails who have been out in the burn zone since it reopened to the public in 2021 (the year following the fire), it may come as no surprise to know that the footprint of this fire is rich with bird life, as well as a generally flourishing and rebounding vegetation community, and a lot of variation across both components.
Birds have been extensively using the burned areas during these first three breeding seasons since the fire (especially starting in 2022), and although our current season is only partially complete, we have been excited to see how that has continued this year. In some areas of what was a mix of forest and scrub, species associated with shrubs, such as Song Sparrows, MacGillivray’s Warblers and others, are finding extensive regrowth of the understory. The Lazuli Bunting, a species known to follow fire and that is not common in west Marin, has been detected at a few locations in the burn zone. In the burned coastal scrub, where there is an abundance of bush lupine growing post-fire, we are finding relatively high numbers of White-crowned Sparrows and Song Sparrows, while some of the other species such as Wrentits are possibly having a delayed return. In some of the more severely burned sections of forest – where the understory is rebounding – bird species that use dead and decaying trees such as Hairy Woodpeckers are relatively abundant, and finding many options for excavating for food as well as nest cavities. In the last few weeks, we have often heard the loud calls of woodpecker nestlings and observed quite a few sticking their heads out of their nest cavities in the trees and begging for food from their parents. Many of these cavities are later used by secondary cavity nesters that do not build their own cavities (e.g., Pygmy Nuthatches, Pacific-slope Flycatchers) but benefit from the activities of these “primary cavity nesters”: the woodpeckers who do the important work of creating them.
Preliminary results show twice as many birds detected within 50 meters of our observers in 2022 than in 2021. Given the continued growth of the vegetation, including a transition from plants initially resprouting at the base before filling in further, this is not surprising. Indeed, this increasing pattern persisted across the habitat guilds: understory nesters such as Spotted Towhees, Swainson’s Thrushes, and White-crowned Sparrows; midstory nesters such as California Scrub-Jays and Black-headed Grosbeaks; and upper canopy nesters such as Steller’s Jays and Chestnut-backed Chickadees (another secondary cavity nester).
In summary, it’s really exciting to see the vibrant use of these sites by our breeding birds! And quite stunning to be hiking around in these burned forests, with the contrast between the bright green vegetation and the blackened trunks of trees and shrubs.
Curious to learn more or get firsthand experience?
For those of you in the region who haven’t yet been, we strongly encourage you to come check out the burn zone! It is super fun to explore the vegetation, views, birds, and other wildlife there. The fire reached some sections of the Bear Valley Trail and some of the spur trails that connect from there up to the ridge (Old Pine, Meadow, and Mt. Wittenberg trails), and those are worth checking out. To get into the areas of moderate and high severity burn – and some of the more impressive transitions – you’ll want to check out the same areas where we surveyed: along the Sky Trail (especially the area south of Old Pine Trail and near Baldy Trail – but some closer areas too), Woodward Valley Trail, and the Coast Trail between Woodward Valley and Sky trails.
Can’t visit or want another way to be transported there? Listen to the audio recording of Mark Lipman recorded in the burn zone in the fall (Mark is collaborating with PRNSA on a soundscape mapping project in the park). Although this is outside the breeding season, when it’s quieter for birds, you can hear there are still plenty present, along with the persistent and powerful sounds of the wind and ocean.
To learn more about this fire and related topics, check out this series of NPS podcasts.