Pacific Northwest Cooperative Ecosystem Studies Unit (CESU)

Characterizing Spotted Owl Habitat Using LiDAR

Project ID: P17AC01530

Federal Agency: National Park Service

Partner Institution: University of Washington

Fiscal Year: 2017

Initial Funding: $9,886

Total Funding: $9,886

Project Type: Research

Project Disciplines: Biological

National Park: Yosemite National Park

Principal Investigator: Kane, Van

Agreement Technical Representative: Stock, Sara

Abstract: A. Background

This study will use remote sensing techniques to characterize California Spotted Owl (hereafter Spotted Owl) habitat in areas burned by the 2013 Rim Fire and in unburned areas. Yosemite National Park (YOSE) biologists surveyed for Spotted Owls after the Rim Fire in 2014-2016, and anecdotally detected similar numbers of territorial owls in burned versus unburned forests. Reproduction was low across sites, and it is unknown if low levels of reproduction were due to fire, drought, or non-fire-related vegetation characteristics. The research goals are to: formally evaluate whether fire and the three year mega drought have affected occupancy probability, and assess how post-fire occupancy probability correlates with burn severity and other habitat characteristics – some of which will be quantified using LiDAR and other remotely sensed data.

The impetus for this project resulted from recent high-severity fires in and around YOSE that burned large tracts of prime habitat for the Spotted Owl. Current management recommendations identify habitat loss due to large patches of high-severity fire and invasion of a highly competitive congener, the Barred Owl, as significant threats facing the population. In April 2016, the first Barred Owl in YOSE was detected. Investigating owl responses to fire and drought and how YOSE can serve as a refuge for threatened species facing competition from invasive species are essential research questions to inform future land management and listing decisions.

To accomplish this work, we will use airborne LiDAR data that was acquired immediately after the Rim Fire, for the entire extent of the fire. LiDAR data, in conjunction with other forms of remote sensing data, will be used to examine tree structures and canopy cover surrounding owl nest and roost sites to compare with forest structure in the larger area. Previous work by UW for Sequoia National Park and for the Tahoe, El Dorado, and Sierra National Forests suggests that owl nest sites are most strongly correlated with the percentage of canopy cover associated with large (>105 feet tall) trees.
NPS will collect field data in 2017 that includes locations (GPS points) of Spotted Owl roost and nest sites. These data will be used in remote sensing and GIS analyses conducted by UW to help park management understand how fire creates or degrades habitat attributes needed by breeding spotted owls.

This project will test whether cumulative overstory tree mortality from both the fire and the following mega drought is a factor in owl habitat use. In a collaborative effort with the Institute for Bird Populations, similar methods will be used to determine which structures owls are selecting in areas burned by the Rim Fire for comparison with unburned study sites to inform owl management in the Sierra Nevada.

Expected products include: an analysis of remote sensing to characterize roost and nest trees used by Spotted Owls in burned and unburned areas, and a project report and collaboratively prepared manuscript that addresses whether fire affects owl occupancy probability and how post-fire occupancy probability correlates with habitat characteristics derived from remote sensing.

B. Objectives

Investigators from UW and NPS staff will collaborate to accomplish the following specific objectives.

1. Collect new field data on Spotted Owl presence/absence and roost and nest sites within YOSE.

2. Complete an analysis using remote sensing techniques, including LiDAR, to characterize roost and nest trees used by Spotted Owls in areas within the Rim Fire footprint and in areas that are unburned and outside of the Rim Fire footprint.

3. Use annual Landsat images acquired from 2012 to 2017 to map tree mortality using changes in the Normalized Burn Ratio (NBR) and Normalized Difference Vegetation Index (NDVI).

4. Develop a final report (manuscript) documenting the project methods and results that is suitable for submission to a peer-reviewed journal. The report should address whether fire affects owl occupancy probability and how post-fire occupancy probability correlates with habitat characteristics derived from remote sensing.

C. Public Purpose

The project will benefit the public by providing new information to better understand wildlife and ecosystem response to wildfire, thereby improving natural resource management in YOSE and central California. The products will benefit the scientific and conservation communities to help tailor fire and invasive species management strategies to the needs of Spotted Owls, which face threats from severe fires and invasions of the Barred Owl, an aggressive competitor species. A UW graduate student will gain from the real-world, research experiences concerning the resources of NPS provided by this project.

Deliverables: