Transcript Raptor and Corvid Use of Utility Poles

Raptor and Corvid Use of
Utility Poles:
An Assessment of the Efficacy of
Perch Deterrents
Presented by: Phoebe R. Prather
Advisor: Dr. Terry A. Messmer
Jack H. Berryman Institute
Utah State University
Previous Research
• Man-made vertical structures are believed
to lead to increased:
•
•
•
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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 Sagegrouse
Conservation Study
Area, San Juan
County, Utah.
Study Site
Discouragers
One Fire Fly
Two Fire Flies
Discouragers
Cones
(Kaddas)
Triangles
Discouragers
Spikes
(Mini-zena)
No treatment
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
2007
Golden Eagle
2008
278
Golden Eagle
Common Raven
39
Common Raven
Red-tailed Hawk
35
Rough-legged Hawk
Rough-legged Hawk
15
Ferruginous Hawk
Northern Harrier
8
Bald Eagle
Unknown
2
Unknown
Ferruginous Hawk
1
230
23
9
3
2
1
2007 Results
Golden Eagles
70
Perching Events
60
50
40
30
20
10
0
1FF
control
triangles
cones
Treatment
spikes
2FF
GOLDEN EAGLE
2007
Results
Perching Events
Cross Arm
45
40
35
30
25
20
15
10
5
0
•Total:
•278 perching events.
control
spikes
cones
triangles
1FF
2FF
1FF
2FF
Treatments
Perching Events
Insulator Cover
45
40
35
30
25
20
15
10
5
0
control
spikes
cones
triangles
Treatments
•Cross Arm: 122
•Insulator Cover: 156
2008 Results
Golden Eagles
90
80
Perching Events
70
60
50
40
30
20
10
0
1FF
2FF
control
cones
Treatment
spikes
triangles
GOLDEN EAGLE
2008
Results
Perching Events
Cross Arm
70
60
50
40
30
20
10
0
Total:
231 perching
events.
control
spikes
cones
triangles
1FF
2FF
1FF
2FF
Treatment
Perching Events
Insulator Cover
70
60
50
40
30
20
10
0
control
spikes
cones
triangles
Treatments
Cross Arm: 112
Insulator Cover:
119
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?