1. Golden-cheeked Warbler Population Viability and Habitat Suitability
Within the Balcones Canyonlands Preserve

2. Golden-cheeked Warbler Monitoring
Our permit requires that we protect habitat and conduct long-term monitoring to assess population viability.
Photo by John Ingram
Photo by Gil Eckrich

3. 5-Year Study ( )
Conducted under contract with the U.S. Forest Service/Univ. of Missouri and with BCP partners and many volunteers.
4 key questions:
How many Golden-cheeked Warblers are there on the Balcones Canyonlands Preserve and within individual macrosites?
How do demographics (e.g., density, productivity, survival) vary with landscape and habitat factors?
How viable are these populations?
How do various management scenarios influence viability?
Photo by John Ingram

4. Methods: Intensive Territory Monitoring
Modeled after Fort Hood’s monitoring program
Color-banding
Average >70% adult males banded per plot
Intensive territory mapping
March 15-May 25, visits
Typically 2 people per plot
Average >130 hours/100 acres
Nest monitoring, productivity
March 15-June 15

5. Photos by volunteer Nancy Norman
Resighting
Photos by volunteer Nancy Norman
We enlisted an enthusiastic corps of ~40 volunteers each year to search for banded GCWAs in areas outside the intensive monitoring plots.

6. Point Count Surveys
5-minute surveys on a grid of points with 250-m spacing across the Balcones Canyonlands Preserve
Designed to allow rapid assessment of large areas
Study design includes comparisons with intensive study plots
1,507 points surveyed from

7. Vegetation Measurements Point Count Stations and Nests
5 m radius
11.3 m radius
Canopy cover
Ground cover
Shrub
Grass/forb
Bare (ground, rock, debris)
Litter
Small stem density
Ashe juniper
Live oak
Other oak/hardwood
Other deciduous shrub
Other exotic
Avg juniper height
Avg non-juniper height
Tree DBH
Ashe juniper
Live oak
Red oak
Shin oak
Cedar elm
Other
Slope & aspect

8. Study Results
Predicted Density of male GCWAs
Question 1: How many Golden-cheeked Warblers are there on the Balcones Canyonlands Preserve and within individual macrosites?
Answer: Current estimate is ~2,000 male Golden-cheeked Warblers, with highest densities in the Bull Creek and Cypress Creek macrosites.

9. Caution: GCWAs immigrating from other areas due to habitat loss can “mask” population declines – which emphasizes the importance of documenting return rates

10. Study Results
Question 2: How do demographics (e.g., density, productivity, survival) vary with landscape and habitat factors? Answer: Large tracts of closed-canopy forests of Ashe juniper and oak are critical for GCWA conservation.

11. Study Results
Question 2: How do demographics (e.g., density, productivity, survival) vary with landscape and habitat factors? Answer: More large Ashe juniper trees support higher GCWA densities.
Photo by John Ingram

12. Study Results
Question 2: How do demographics (e.g., density, productivity, survival) vary with landscape and habitat factors? Answer: GCWA density increases with increasing canopy height.

13. Study Results
Question 2: How do demographics (e.g., density, productivity, survival) vary with landscape and habitat factors? Answer: GCWA nest survival tends to be highest in Ashe juniper trees.
Photo by Gil Eckrich

14. Study Results
Question 2: How do demographics (e.g., density, productivity, survival) vary with landscape and habitat factors? Answer: Nest survival increases with higher densities of Ashe juniper trees.

15. Study Results
Question 2: How do demographics (e.g., density, productivity, survival) vary with landscape and habitat factors? Answer: Nest survival is highest on uplands and decreases on steep slopes.

16. Study Results
Question 2: How do demographics (e.g., density, productivity, survival) vary with landscape and habitat factors? Answer: Understory is important for nest survival (and for fledglings!).

17. Study Results
Question 2: How do demographics (e.g., density, productivity, survival) vary with landscape and habitat factors? Answer: Nest survival tends to vary within and among years.

18. Estimated dispersal distances of males (2011-2015)
Study Results
Question 3: How viable are these populations? Answer: The USFS/Univ. of Missouri are currently running the PVA models. However, we do know that adult and juvenile survival, productivity, and dispersal are all critical and need to be as high as possible to ensure long-term population viability.
Estimated dispersal distances of males ( )
Over 90% of the banded GCWA males returning from their wintering grounds are observed on or near the same territory as the previous year.

19. Study Results
Question 4: How do various management scenarios influence viability? Answer: Need to provide large forested tracts of Ashe juniper and oaks with minimal edge, and manage for mature forest with closed canopy and diverse understory.
Photo by Gil Eckrich

20. References
Reidy, J.L., F.R. Thompson, C. Amundson, and L. O’Donnell Landscape and local effects on occupancy and densities of an endangered wood-warbler in an urbanizing landscape. Landscape Ecology (DOI /s ). Reidy, J.L., F.R. Thompson, and L. O’Donnell. In review. Density and nest survival of golden-cheeked warblers varies with plot, forest, and landscape characteristics. Working on two more manuscripts: GCWA adult/juvenile survival Population viability analyses

21. Acknowledgments U.S. Forest Service University of Missouri
City of Austin
Travis County
LCRA
Travis Audubon Society
The Nature Conservancy
Many volunteers!!
Photo by Volunteer Misa Soliz

22. Any Questions? Golden-cheeked warbler fledglings taking a bath
Photo by: John Ingram

24. Study Results
Question 2: How do demographics (e.g., density, productivity, survival) vary with landscape and habitat factors? Answer: GCWA density declines with increasing urbanization.