Michael Galloway

Associate Biologist

Caltrans, District 11

Environmental Stewardship & Ecological

Studies

michael.galloway@dot.ca.gov

Use of Artificial Burrows by Burrowing Owls at Lonestar West

164 acres: South of State Route 125, North of Brown Field Airport

Mitigation for Vernal Pool and Upland Impacts for Caltrans State Route 11/Otay Mesa East Port of Entry Project

Site Grading (Vernal Pools/Mima Mounds): July 23-August 31, 2012

Mitigation for Burrowing Owls by Artificial Burrow Installation:o Artificial Burrow Locations Randomly Selected Among 205

Installed Mima Moundso 25 Wood Boxes with Wood Tunnelso 25 Plastic Irrigation Boxes with Corrugated Plastic Drainage

Pipeo 25 “Starter Holes”o Installation Occurred from August 29 to September 18, 2012

Lonestar West Mitigation Site

Federal Migratory Bird Treaty ActCalifornia “Species of Special Concern”

• Local Declines in Central and Southern California Breeding Areas• Habitat Loss• Habitat Degradation/Modification• Ground Squirrel Eradication

• Nesting February 1-August 31• At Lonestar West: Egg-laying: March-May, Hatching-Fledging: April-June

CDFW-Protocol Burrowing Owl Surveys:• Breeding Season(April through August): One daylight survey per month

• Outside Breeding Season: One daylight survey (December)

Burrowing Owl

March 18, 2011

March 3, 2015

Burrowing Owl Numbers and Burrow Usage during the Breeding Season at Lonestar West

Burrowing Owl Breeding Activity at Lonestar WestSurvey Year Plastic Wood Starter Hole

Breeding Burrows (# Successful of # Total)Eggs / Chicks / Fledges

Reproductive Success (% Fledglings from Eggs)

2013 0 of 319 / 1 / 0

0 %

1 of 320 / 8 / 2

10 %

00 / 0 / 0 0 %

2014 2 of 427 / 8 / 2

7 %

3 of 847 / 18 / 8

17 %

00 / 0 / 0 0 %

2015 2 of 747 / 6 / 4

9 %

3 of 626 / 13 / 7

27%

00 / 0 / 0 0 %

Survey Year Plastic Wood Starter Hole Average # BUOW per

SurveyAverage # Burrows with BUOW or BUOW Sign

[90% Confidence Interval]

2013 16[11, 21]

13[9, 18]

1[0, 3]

14[9, 19]

2014 19[17, 21]

17[15, 19]

3[2, 4]

17[15, 20]

2015 18[15, 20]

16[15, 18]

0[0, 1]

15[11, 19]

Future Considerations for Burrowing Owl Mitigation

Location of mitigation site near extant populations of burrowing owls and fossorial mammals

At least three to four burrows per individual / pair / family

Armoring entrances in areas where coyotes are present

Buried chicken wire along floors of boxes / tunnels to prevent filling by fossorial mammal digging

Planting of low-lying vegetation on mounds with artificial burrows to 50-150 feet surrounding burrows

Perches??? Monitoring!!! Plan for contingencies

Acknowledgements

CALTRANS: Bruce April, Kim Smith, and Ted Thurston, the Office of Environmental Stewardship and Ecological Studies

SAN DIEGO ZOO INSTITUTE FOR CONSERVATION RESEARCH: Colleen Wisinski, Susanne Marczak, Lisa Nordstrom, and the research technicians

RECON: Meagan Olson and Pete Tomsovic TIERRA DATA: Jim Kellogg, James Lockman, and

Fausto Larios AECOM: Scott McMillan, Lindsey Cavallero, and

Linnea Spears-Lebrun Jeff Lincer, Jeff Kidd, Doug McKinney

USE OF ARTIFICIAL BURROWS BY BURROWING OWLS AT LONESTAR WEST

LONESTAR WEST MITIGATION SITE

164 acres: South of State Route 125, North of Brown Field AirportMitigation for Vernal Pool and Upland Impacts for Caltrans State Route 11/Otay Mesa East Port of Entry ProjectNine Active Burrows Used by Burrowing Owls Directly ImpactedMitigation by Installation of Artificial Burrows:25 Wood Boxes with Wood Tunnels25 Plastic Irrigation Boxes with Corrugated Plastic Drainage Pipe25 “Starter Holes”Artificial Burrow Locations Randomly Selected Among 204 Installed Mima MoundsGrading of Site (Vernal Pools/Mima Mounds): July 23-August 31, 2012Installation of Artificial Burrows: August 29-September 18, 2012

March 18, 2011

March 3, 2015

BURROWING OWLFederal Migratory Bird Treaty ActCalifornia “Species of Special Concern”•Local Declines in Central and Southern California Breeding Areas

•Habitat Loss•Habitat Degradation/Modification•Ground Squirrel Eradication

•Nesting February 1-August 31At Lonestar:•Egg-laying: March-May•Hatching-Fledging: April-June

•Some are Year-Round Residents at Lonestar

CDFW-Protocol Burrowing Owl Surveys:

One daylight survey per month during the breeding season (April through August) and one daylight survey outside of the breeding season (December)

Complex Plastic Wood Starter Hole

Average # Owls

per Survey

Owl Use / # of Artificial Burrows

Year1 16[11, 21]

13[9, 18]

1[0, 3]

14[9, 19]

Year 2 19[17, 21]

17[15, 19]

3[2, 4]

17[15, 20]

Year 3 18[15, 20]

16[15, 18]

0[0, 1]

15[11, 19]Complex Plastic Wood Starter Hole

MoundsEggs / Chicks / Fledges

Reproductive Success (% Fledglings from Eggs)

Year1 319 / 1 / 0

0 %

320 / 8 / 2

10 %

00 / 0 / 0 0 %

Year 2 427 / 8 / 2

7 %

847 / 18 /

8 17 %

00 / 0 / 0 0 %

Year 3 40 / 0 / 2 0 %

50 / 0 / 10

0 %

00 / 0 / 0 0 %

FUTURE CONSIDERATIONS FOR BURROWING OWL MITIGATION

Location of mitigation site near extant populations of burrowing owls and fossorial mammalsAt least three to four burrows per owl individual / pairArmoring entrances in areas where coyotes are presentBuried chicken wire along floors of boxes / tunnels to prevent filling by fossorial mammal diggingPlanting of low-lying vegetation on mounds with artificial burrows to 50-150 feet surrounding burrowsPerches???Monitoring!!!Plan for contingencies

BURROWING OWL BREEDING ACTIVITY AT LONESTAR

BURROWING OWL NUMBERS AND ACTIVITY AT LONESTAR

ACKNOWLEDGEMENTSCALTRANS: Bruce April, Kim Smith, and Ted Thurston, the Office of Environmental Stewardship and Ecological Studies; SAN DIEGO ZOO INSTITUTE FOR CONSERVATION RESEARCH: Colleen Wisinski, Susanne Marczak, Lisa Nordstrom and the interns; Jeff Lincer; RECON: Meagan Olsen and Pete Tomsovic; TIERRA DATA: Jim Kellogg, James Lockman, and Fausto Larios; Jeff Kidd; Doug McKinney; AECOM: Scott McMillan, Lindsey Cavallero, and Linnea Spears-Lebrun