United States Department of Agriculture, Forest Service
Pacific Southwest Research Station
Sierra Nevada Research Center
Effects of prescribed burning in the spring on avian communities
The Research:
Fire is a natural disturbance that can have an overwhelming influence on vegetative structure, biodiversity, productivity, and species composition in a given
area. Fuels management programs implemented in ecosystems where fire is
an integral component many mimic natural processes to some degree, but are
often characterized by parameters that are different from those of the historic
fire regime. Landscape changes resulting from forest management practices
such as timber harvest and fire suppression in addition to private property
and air quality concerns make burning in the spring desirable for meeting fuel
management goals. On the other hand, spring coincides with a number of
important wildlife activities such as the breeding of forest birds.
Alterations to habitats as the result of fire may influence abundance and
diversity of bird populations within a given area. Forest litter, shrubs, ground
vegetation, logs, and snags are habitat features most affected by low intensity fire. wildlife associated with these features may be reduced temporarily.
Specific habitat features do not generally occur evenly across a given area but
are patchily distributed. Patchiness or heterogeneity is generally associated
with high biodiversity and fire generally increases heterogeneity across the
landscape. Avian populations are monitored through a standardized census
method consisting of a 1,000 meter timed transect.
Snags are an important aspect of forest structure for wildlife and provide nest
and roost sites for a wide variety of cavity-nesting birds and mammals. Fire
and snags have a complex relationship as fires may result in the consumption
of snags, while at the same time live trees may be killed. Snags are chosen at
random at each study site and followed through the course of the study to
determine availability as well as natural fall rates and changes associated with
burning. Those snags that are actually used by breeding birds are also followed
and their features compared to those of random snags.
This study seeks not only to understand how birds respond to a changing
landscape, but also to integrate forest management practices with research.
Through this integration, we can gain not only a better understanding of the
natural world but make informed decisions about fire management.
USDA Forest Service
Pacific Southwest Research Station
Sierra Nevada Research Center
Photo: D. Drynan
Our Mission:
Sierra Nevada Ecosystems are
complex and our knowledge
of them is incomplete. As a
result, the long term outcome
of any given land and
resource management strategy
is uncertain. We will provide
assistance to land managers
and policy makers by
addressing this management
dilemma through targeted
research, emphasizing an
integrated, ecoregional
approach to examine
particular physical, ecological,
and socio-economic issues,
across a range of appropriate
spatial and temporal scales
specific to each issue.
This unit will represent the
collective research expertise
and interests of scientists
located in Fresno, Davis
and Albany as well as other
scientists within the Pacific
Southwest Research Station.
With a full spectrum of
research, from long term,
fundamental research
to short-term, tactical
applications, this Center
is intended to support
conservation, restoration,
and sustainable utilization of
the lands within the Sierra
Nevada ecoregion.
USDA Forest Service
Pacific Southwest Research Station
Sierra Nevada Research Center
For further inforamation contact:
Dr. Kathryn Purcell, Research
Ecologist
Dr. Peter Stine, Program Manager
Dr. Jim Sedell, Station Director
Pacific Southwest Research Station
Objectives:
• To monitor population changes in bird populations and species composition in
response to prescribed fire.
• To determine the effects of burning in the spring on breeding efforts of forest birds
• To compare habitat features selected by breeding birds in response to prescribed
burning with consideration for variability associated with habitat heterogeneity
• To discover how site fidelity and plasticity in habitat selection may influence the
response of breeding birds to disturbance
• To better understand the process of habitat selection within a changing landscape
Application of Research Results:
We have not found large changes in bird communities related to burning nor were
any species clearly restricted to burned or unburned areas. Approximately half of the
species examined did not show a response to fire. Changes in bird populations that
we found were generally within the range of population fluctuations related to other
biotic and abiotic factors in the absence of fire. Additionally, we cannot ignore the
fact that without prescribed fires, wildfires will be more intense with greater potential
for negative impacts. Thus attempts at fire exclusion do not ultimately benefit those
species that have negative responses to fire. Within this context, there is little concern
about negatively affecting populations with prescribed fire with the exception of species with low abundance or restricted ranges.
Based on results from this study, we recommend protection of preferred snags, in particular, large ponderosa pines along with the continued reintroduction of fires as an
ecological process. Forest management strategies that affect tree species composition,
tree mortality, and tree size will affect snag-nesting species. Our results suggest that
forest managers can improve availability of useable snags by retaining large trees (both
living and dead), and preferred species.
The greatest net loss of snags occurred on sites after long periods of fire exclusion
and thus protection of preferred snags may be warranted in these areas if snags are
limited. While the characteristics of nesting snags did not affect nesting success, we
did find lower nesting success for cavity nesting species immediately following prescribed fire applications.
For open-cup nesters, nesting success was altered by fire for 3 of 5 targeted species.
Changes in daily nest survival probabilities due to fire were related to changes to
nest site vegetation and only occurred within 1 year of burning. Brood parasitism by
Brown-headed Cowbirds increased following fire as long as 6 years postburn. These
results are consistent with increased visibility of nests and/or nesting behavior following prescribed fire.
Location:
The study is at 1024 to 1370 meters (3,200 to
4,000 feet) in Blue Canyon located in the Sierra
National Forest. It is part of the Kings River
Administrative Study Area.
Albany Location:
800 Buchanan Street
Albany, CA 94710
Mailing Address:
P.O. Box 245
Berkeley, CA 94701
Phone: 510-559-6300
Fax: 510-559-6440
Davis Location:
2121 Second Street
Suite A101
Davis, CA 95616
Phone: 530-759-1700
Fax: 530-747-0241
Photo: K. Bagne
Fresno Location:
2081 E. Sierra Avenue
Fresno, CA 93710
Phone: 559-323-3200
Fax: 559-297-3355