Raptor and Corvid Use of Utility Poles:

An Assessment of the Efficacy of Perch Deterrents

Presented by: Phoebe R. PratherAdvisor: Dr. Terry A. Messmer

Jack H. Berryman InstituteUtah State University

Previous Research• Man-made vertical structures are believed

to lead to increased: • Raptor and corvid visitation.• Access to habitats.• Availability of perch, nesting, and roosting sites.• Foraging and predation efficiency.

Fragmentation

• Divides suitable habitat.

• Increases isolation of populations.

• Abandonment of sites.

Management Need• Evaluation of effects of human

infrastructure such as power lines on population.

Conservation Strategy

• Retrofitting structures with perch discouragers to deter raptors and corvids from perching.

Study Objective

• Test the efficacy of five types of perch discouragers on reducing the number of perching events of raptors and corvids.

Study Site

• Gunnison Sage-grouse Conservation Study Area, San Juan County, Utah.

Study Site

Discouragers

One Fire Fly Two Fire Flies

Discouragers

Cones(Kaddas)

Triangles

Discouragers

No treatmentSpikes(Mini-zena)

Study (2007-2008) • 7.5 miles of power line with 84 poles.

Methods

• Divided into 14 blocks of 6 poles. – Each block

contained one of each discourager and a control.

– Treatments and control were randomly assigned.

Methods - Surveys• Began mid-January, finish end of April.

• Surveyed twice a day, five days a week.

• Entire line walked once a week.– Evidence of depredation events and

electrocutions.

Methods - Survey Protocol

• Starting point (east or west) randomly selected.

• Alternate routes taken to starting point.

• Five minutes spent at starting point and each mile point.

Methods - Survey Protocol• Observations:

– Species and numbers of individuals within a quarter mile of either side of the powerline.

• Flying, on ground, perched on trees, fences or poles of a different line.

– Species and numbers of individuals perched on the study poles.

• Individual counted more than once if continued down the line perching on different poles.

Methods– Exact positions of birds on study poles.

Results

• No signs of electrocutions.

• One dead grouse on the road.

• Observations of grouse near road.

Results

Golden Eagle 278Common Raven 39Red-tailed Hawk 35Rough-legged Hawk 15Northern Harrier 8Unknown 2Ferruginous Hawk 1

2007

Golden Eagle 230Common Raven 23Rough-legged Hawk 9Ferruginous Hawk 3Bald Eagle 2Unknown 1

2008

2007 Results

Golden Eagles

0

10

20

30

40

50

60

70

1FF control triangles cones spikes 2FF

Treatment

Pe

rch

ing

Ev

en

ts

2007 Results

Cross Arm

05

1015202530354045

control spikes cones triangles 1FF 2FF

Treatments

Per

chin

g E

ven

tsGOLDEN EAGLE

Insulator Cover

05

1015202530354045

control spikes cones triangles 1FF 2FF

Treatments

Per

chin

g E

ven

ts

•Total:•278 perching events.

•Cross Arm: 122•Insulator Cover: 156

2008 Results

Golden Eagles

0

10

20

30

40

50

60

70

80

90

1FF 2FF control cones spikes triangles

Treatment

Pe

rch

ing

Ev

en

ts

GOLDEN EAGLE 2008 Results

Total:231 perching events.

Cross Arm: 112Insulator Cover: 119

Cross Arm

010203040506070

control spikes cones triangles 1FF 2FF

Treatment

Per

chin

g E

ven

ts

Insulator Cover

010203040506070

control spikes cones triangles 1FF 2FF

Treatments

Per

chin

g E

ven

ts

Results

Discussion- Problems

Discussion- Problems

Discussion

Discussion

Conclusions

Acknowledgments

• Advisor: Dr. Terry Messmer

• Funding: – PacifiCorp– Avian Power Line Interaction Committee.– Bureau of Land Management

• Field Technician Erin Colin.

Questions?