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Conservation of Airspace and Habitat in a Bird Migration Corridor Anna C Peterson 1,2,, Gerald J Niemi 1,2 , Douglas H Johnson 1,3 1 Conservation Biology Program, University of Minnesota 2 Natural Resources Research Institute, University of Minnesota Duluth 3 USGS Northern Prairie Wildlife Research Center Corresponding Author: [email protected] Acknowledgments This research was funded by NOAA’s Office of Ocean and Coastal Resource Management in cooperation with Minnesota’s Lake Superior Coastal Program through Hawk Ridge Bird Observatory, U.S. Fish and Wildlife Service’s Great Lakes Fish and Wildlife Restoration Act, Minnesota Department of Natural Resource’s State Wildlife Grant Program, Encampment Forest Association, and the University of Minnesota Doctoral Dissertation Fellowship Program. Special thanks to J. Green, J. Long, H. Seeland, P. Dolan, J. Bednar, C. Rutt, A. Balogh, R. Atwell, D. Hansen, and S. Burns. Conclusions There are patterns in migratory bird use of below canopy habitat and above canopy airspace In general, permanent residents and migrants differed in habitat use patterns. Perm. residents were influenced by vegetation-type while some migrants were influenced by landscape features such as distance from shore and elevation. Important habitat use variables (physical and vegetation) were highly variable among bird groups, presenting a challenge in the identification of priority use areas. The airspace between the shoreline and first prominent ridgeline (within 8 km from shore) is an area heavily used by all diurnal migrating birds. There is a large morning flight of predominantly songbirds that occurs within the first 2 hours of sunrise. Migratory raptors follow prominent ridgelines and more heavily utilize the airspace near ridgelines in close proximity (< 6 km) to the shoreline. The airspace between the tree canopy and 100 m above the canopy is used extensively by all diurnal migrants, and corresponds directly with airspace where wind turbines and communication towers are found. Companion studies show large shoreline movements by Common Nighthawk at dusk (www.hawkridge.org), and large numbers of nocturnal movements by owls (Evans et al. 2012). Our study provides information on only daytime migratory bird use of the Lake Superior coastal area. Additional work is needed to determine dusk and nocturnal migratory pathway use. Introduction Many boreal forest birds begin their fall migration by heading in a south-easterly direction for reasons that may include avoiding the prairies and exploiting westerly winds. As a result of this trajectory, a significant proportion of these migrants encounter the Great Lakes. To avoid flying over open water, migrants traveling during both day and night follow the Lake Superior shoreline southwest. In addition, many migrants fly over open water at night and head to the nearest coastline at dawn. This combination of factors leads to the concentration of birds along Lake Superior’s north shore. The north shore is a well-known migratory corridor for raptors, and is of high interest for wind development. Objectives: Assess the distribution of fall migrants in the airspace along the north shore of Lake Superior Improve understanding of large-scale landscape effects on stopover habitat selection by migratory birds Provide recommendations for conservation priorities to ensure protection of migratory bird populations Migration movements in relation to the Great Lakes and Lake Superior’s north shore (left); Broad-winged Hawk (top right) and American Robin (bottom right) movement. Evans, D.L., G.J. Niemi, M.A. Etterson. 2012. Autumn raptor banding at Hawk Ridge, Duluth, Minnesota, U.S.A., 1972-2009: an overview. Journal of Raptor Research 46:36-49. Hanowski, J.M., G.J. Niemi, J.G. Blake. 1990. Statistical perspectives and experimental design when counting birds on line transects. Condor 92:326-335. Mageau, M., B. Sunderland, S. Stark. 2008. Wind Resource Development in the Minnesota Coastal Zone. MNDNR Coastal Program. Pp 24. Seeland, H., G.J. Niemi, R. Regal, A.C. Peterson, C. Lapin. 2012. Determination of raptor migratory patterns over a large landscape. Journal of Raptor Research 46(3):283-295. Methods Below-Canopy Habitat Use August through October, 2008-2010, sunrise – 4 hours later Fifteen survey sites, consisting of six 500-meter survey transects (Hanowski et al. 1990) defined by distance to the Lake Superior shoreline (<1, 1-3, 3-6 km) Above-Canopy Airspace Use September through mid-November, 2008-2010 Simultaneous 7 hr. surveys beginning within1 hour of sunrise Twenty-four survey points organized in eight transects (Seeland et al. 2012) at 3 distances perpendicular to the Lake Superior shoreline (~ 2, 5, 10 km) Habitat Use Patterns of bird stopover use varied across taxa and guilds. Linear model adjusted R 2 values show varying influence of physical landscape attributes and vegetation. Permanent residents (all Perm. combined, Red-breasted Nuthatch, and Black-capped Chickadee were influenced by vegetation, whereas Downy Woodpecker, Swainson’s Thrush, Ovenbird, and Cedar Waxwing were influenced by physical attributes of the landscape . Results Photo by Michael Furtman, michaelfurtman.com © Derek Montgomery Photo Ryan Atwell North Shore Migration Study Sites Minnesota, USA Grand Marais Silver Bay Two Harbors Grand Portage Study sites (right); Below canopy survey (top L.) and Above canopy survey (bottom L.). Lake Superior Minnesota Airspace Use Distance from shore – Observations of both raptors and non- raptors per were lower at sites further from the Lake Superior shoreline. Eighty percent of all raptors and non-raptors occurred within 6 km and 8 km of the shoreline respectively. Flight Height – Non-raptors (mainly passerines) heavily utilized the airspace between the tree canopy and 100 m above the canopy. All raptor groups utilized the airspace between the canopy and 100 m above the canopy. Accipiters (mainly Sharp- shinned Hawk) and falcons (mainly American Kestrel) were more often observed flying at lower altitudes than buteos (Broad- winged Hawk, Red-Tailed Hawk, and Rough-Legged Hawk) and eagles (Bald and Golden). Results Timing - Non-raptors were most active during the first two hours after sunrise, raptor activity increased after these two hours. 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.00 0.10 0.20 0.30 0.40 0.50 0.60 Vegetation adj R 2 Physical adj R 2 OVEN BCCH CEDW DOWO RBNU PERM WAREarly BRCR NOFL REVI LONG AMRE LngThr RCKI SWTH BAWW Study Sites Adjusted r-square values from best fit physical (x-axis) and vegetation (y-axis) models compared to illustrate influence on various bird species and groups during stopover. In general, early season and long distance migrants (e.g. Ovenbird, Swainson’s Thrush) were positively associated with distance from shore and with elevation 2 . In vegetation models, early season and long distance migrants were positively associated with northern hardwood vegetation types, whereas permanent resident species (e.g. Black-capped Chickadee, Red-breasted Nuthatch) were negatively associated with this vegetation type. In addition, many migrant groups were positively associated with aspen-birch, black ash, and emergent vegetation types. 0% 5% 10% 15% 20% 25% 30% 35% 1 2 3 4 5 6 7 Percent of Total Hour after Sunrise Daily movement timing during fall migration Raptor Non-raptor Mean Birds per Hour 0 200 400 600 800 1000 1200 1400 1 2 3 4 5 6 7 8 9 Early Season Passerines 0 2 4 6 8 10 12 1 2 3 4 5 6 7 8 9 Bald Eagle Hour After Sunrise
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Conservation of Airspace and Habitat in a Bird Migration ... · Conservation of Airspace and Habitat in a Bird Migration Corridor Anna C Peterson1,2,†, Gerald J Niemi1,2, Douglas

May 30, 2020

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Page 1: Conservation of Airspace and Habitat in a Bird Migration ... · Conservation of Airspace and Habitat in a Bird Migration Corridor Anna C Peterson1,2,†, Gerald J Niemi1,2, Douglas

Conservation of Airspace and Habitat in a Bird Migration Corridor Anna C Peterson1,2,†, Gerald J Niemi1,2, Douglas H Johnson1,3

1Conservation Biology Program, University of Minnesota 2Natural Resources Research Institute, University of Minnesota Duluth

3USGS Northern Prairie Wildlife Research Center †Corresponding Author: [email protected]

Acknowledgments This research was funded by NOAA’s Office of Ocean and Coastal Resource Management in cooperation with Minnesota’s Lake Superior Coastal Program through Hawk Ridge Bird Observatory, U.S. Fish and Wildlife Service’s Great Lakes Fish and Wildlife Restoration Act, Minnesota Department of Natural Resource’s State Wildlife Grant Program, Encampment Forest Association, and the University of Minnesota Doctoral Dissertation Fellowship Program. Special thanks to J. Green, J. Long, H. Seeland, P. Dolan, J. Bednar, C. Rutt, A. Balogh, R. Atwell, D. Hansen, and S. Burns.

Conclusions • There are patterns in migratory bird use of below canopy

habitat and above canopy airspace

• In general, permanent residents and migrants differed in habitat use patterns. Perm. residents were influenced by vegetation-type while some migrants were influenced by landscape features such as distance from shore and elevation.

• Important habitat use variables (physical and vegetation) were highly variable among bird groups, presenting a challenge in the identification of priority use areas.

• The airspace between the shoreline and first prominent ridgeline (within 8 km from shore) is an area heavily used by all diurnal migrating birds.

• There is a large morning flight of predominantly songbirds

that occurs within the first 2 hours of sunrise.

• Migratory raptors follow prominent ridgelines and more heavily utilize the airspace near ridgelines in close proximity (< 6 km) to the shoreline.

• The airspace between the tree canopy and 100 m above the

canopy is used extensively by all diurnal migrants, and corresponds directly with airspace where wind turbines and communication towers are found.

• Companion studies show large shoreline movements by

Common Nighthawk at dusk (www.hawkridge.org), and large numbers of nocturnal movements by owls (Evans et al. 2012).

• Our study provides information on only daytime migratory bird use of the Lake Superior coastal area. Additional work is needed to determine dusk and nocturnal migratory pathway use.

Introduction Many boreal forest birds begin their fall migration by heading in a south-easterly direction for reasons that may include avoiding the prairies and exploiting westerly winds. As a result of this trajectory, a significant proportion of these migrants encounter the Great Lakes. To avoid flying over open water, migrants traveling during both day and night follow the Lake Superior shoreline southwest. In addition, many migrants fly over open water at night and head to the nearest coastline at dawn. This combination of factors leads to the concentration of birds along Lake Superior’s north shore. The north shore is a well-known migratory corridor for raptors, and is of high interest for wind development.

Objectives: • Assess the distribution of fall migrants in the airspace along

the north shore of Lake Superior • Improve understanding of large-scale landscape effects on

stopover habitat selection by migratory birds • Provide recommendations for conservation priorities to

ensure protection of migratory bird populations

Migration movements in relation to the Great Lakes and Lake Superior’s north shore (left); Broad-winged Hawk (top right) and American Robin (bottom right) movement.

Evans, D.L., G.J. Niemi, M.A. Etterson. 2012. Autumn raptor banding at Hawk Ridge, Duluth, Minnesota, U.S.A., 1972-2009: an overview. Journal of Raptor Research 46:36-49. Hanowski, J.M., G.J. Niemi, J.G. Blake. 1990. Statistical perspectives and experimental design when counting birds on line transects. Condor 92:326-335. Mageau, M., B. Sunderland, S. Stark. 2008. Wind Resource Development in the Minnesota Coastal Zone. MNDNR Coastal Program. Pp 24. Seeland, H., G.J. Niemi, R. Regal, A.C. Peterson, C. Lapin. 2012. Determination of raptor migratory patterns over a large landscape. Journal of Raptor Research 46(3):283-295.

Methods Below-Canopy Habitat Use • August through October, 2008-2010, sunrise – 4 hours later • Fifteen survey sites, consisting of six 500-meter survey

transects (Hanowski et al. 1990) defined by distance to the Lake Superior shoreline (<1, 1-3, 3-6 km)

Above-Canopy Airspace Use • September through mid-November, 2008-2010 • Simultaneous 7 hr. surveys beginning within1 hour of sunrise • Twenty-four survey points organized in eight transects

(Seeland et al. 2012) at 3 distances perpendicular to the Lake Superior shoreline (~ 2, 5, 10 km)

Habitat Use Patterns of bird stopover use varied across taxa and guilds. Linear model adjusted R2 values show varying influence of physical landscape attributes and vegetation. Permanent residents (all Perm. combined, Red-breasted Nuthatch, and Black-capped Chickadee were influenced by vegetation, whereas Downy Woodpecker, Swainson’s Thrush, Ovenbird, and Cedar Waxwing were influenced by physical attributes of the landscape .

Results

Photo by Michael Furtman, michaelfurtman.com

© Derek Montgomery

Photo Ryan Atwell

North Shore Migration Study Sites Minnesota, USA

Grand Marais

Silver Bay

Two Harbors

Grand Portage

Study sites (right); Below canopy survey (top L.) and Above canopy survey (bottom L.).

Lake Superior

Minnesota

Airspace Use Distance from shore – Observations of both raptors and non-raptors per were lower at sites further from the Lake Superior shoreline. Eighty percent of all raptors and non-raptors occurred within 6 km and 8 km of the shoreline respectively.

Flight Height – Non-raptors (mainly passerines) heavily utilized the airspace between the tree canopy and 100 m above the canopy. All raptor groups utilized the airspace between the canopy and 100 m above the canopy. Accipiters (mainly Sharp-shinned Hawk) and falcons (mainly American Kestrel) were more often observed flying at lower altitudes than buteos (Broad-winged Hawk, Red-Tailed Hawk, and Rough-Legged Hawk) and eagles (Bald and Golden).

Results

Timing - Non-raptors were most active during the first two hours after sunrise, raptor activity increased after these two hours.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.00 0.10 0.20 0.30 0.40 0.50 0.60

Veg

etati

on

ad

j R

2

Physical adj R2

OVEN

BCCH

CEDW

DOWO

RBNU

PERM

WAREarly

BRCR

NOFL

REVI

LONG

AMRE

LngThr

RCKI

SWTH

BAWW

Study Sites

Adjusted r-square values from best fit physical (x-axis) and vegetation (y-axis) models compared to illustrate influence on various bird species and groups during stopover.

In general, early season and long distance migrants (e.g. Ovenbird, Swainson’s Thrush) were positively associated with distance from shore and with elevation2. In vegetation models, early season and long distance migrants were positively associated with northern hardwood vegetation types, whereas permanent resident species (e.g. Black-capped Chickadee, Red-breasted Nuthatch) were negatively associated with this vegetation type. In addition, many migrant groups were positively associated with aspen-birch, black ash, and emergent vegetation types.

0%

5%

10%

15%

20%

25%

30%

35%

1 2 3 4 5 6 7

Pe

rce

nt

of

To

tal

Hour after Sunrise

Daily movement timing during fall migration

Raptor

Non-raptor

Me

an

Bir

ds

pe

r H

ou

r

0

200

400

600

800

1000

1200

1400

1 2 3 4 5 6 7 8 9

Early Season Passerines

0

2

4

6

8

10

12

1 2 3 4 5 6 7 8 9

Bald Eagle

Hour After Sunrise