The American kestrel is declining in the Northeastern United States. This project analyzes snag habitat in a decimated ash forest. We propose a kestrel habitat dispersal and enhancement plan that utilizes decaying recycled wood.
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INVITING HABITATION Snag Habitat Design for the American Kestrel
Photos by Lainey Everly
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INVITING HABITATION
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CONTEXT
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| OVERLOOK FIELD SCHOOL 2023
| EVA KAHN, JENNY GINN & MATTIE ECKLUND
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| OVERLOOK FIELD SCHOOL 2023
Grasshoppers
LACKAWANNA COUNTY
Larger Raptors prey on kestrels
Crops
Larger raptors
Increased predator populations, including kestrels, help lower the population of ticks by lowering the population of tick carrying small mammals
Small mammals Woodpeckers
Kestrels feed on grasshoppers and small mammals, decreasing their populations and their pressure on agricultural crops
Kestrels
Ticks Humans
27% KESTREL POPULATION DECLINE IN THE
POPULATION CHANGE BY BIRD CONSERVATION REGION (BCR)
APPALACHIAN BCR
POPULATION DECLINE
POPULATION GROWTH
NEUTRAL POPULATION
NORTHEASTERN US
Emerald ash borers
Woodpeckers create holes in snags, which create habitat for kestrels and other nesting birds
Invasive shrubs Snags
The invasive shrub layer contributes to increased small mammal population, impares raptors’ ability to hunt, and humans’ ability to access the forest
Emerald ash borers kill ash trees, creating openings for invasive shrubs to take over
Decreased Tick populations reduces the risk of tick born illnesses for humans
KESTRELS IN DECLINE
Photo
by D o
minic
Shero
ny
The American kestrel is North America’s smallest and most widespread falcon. However, population estimates are declining rapidly in the United States. Scientists are not certain why kestrel numbers are declining so quickly. Changes to habitat and prey populations due to climate change and the use of insecticides and pesticides are potential factors.
Kestrels rely on snags to perch while hunting and nest in the cavities made by pileated woodpeckers (Dryocopus pileatus). There are widespread efforts in the US to increase nesting opportunities by installing artificial nest boxes, which have been successful for kestrels. This work examines snag habitat in a decimated ash forest in Lackawanna County, PA at the Fuller’s Overlook.
It seeks to explore how to utilize excess dead wood to disperse kestrel and small mammal habitat opportunities throughout private property, and to draw attention to the ecological value of snags through aesthetic exploration. The Overlook property could become a kestrel hot-spot and join a network of conservation efforts aimed at helping these charismatic falcons.
12-24”
PROACTIVE CONSERVATION
Kestrel Nesting 9-12”
Jan. Breeding
3-4 oz
Hatching
Fledging Chicks leave nest
Diet:
Feb.
Mar.
Apr.
May
Jun.
Jul
Aug
Sep.
Oct.
Nov.
Dec.
HISTORIC CONDITION
CURRENT CONDITION
FUTURE CONDITION Robinia pseudoacacia
“Prior to European settlement, which began in the 17th century, the region was home to the Susquehannocks, who were some of the first (Indigenous Peoples) to raise crops and have semi-permanent villages.” Matthews, Discovering Place
Banding helps researchers and Kestrel conservation groups study the habits of individual birds.
Varying nest sizes and shapes will allow researchers to study the specific nest conditions kestrels desire most.
Fraxinus pennsylva
Increased raptor presence decreases mammal population, leading to fewer vector opportunities for ticks
Lonicera sempervirens Invasive shrubs like Privet and Honeysuckle take over the midstory, crowding out the herbaceous layer.
Natural standing Ash snags will last 10-20 years
nica
Ash forest supports a mix of native wildlife, including raptors, bats, insects, and small birds and mammals, Plants such as Rubus occidentalis, Lonicera serpvirens, and Rosa Virginia flourish in the native shrub layer. EAB infestation quickly decimates the Pennsylvania Ash (Fraxinus pennsylvanica) forest in less than twenty years, causing canopy loss.
The current forest patch is used as agricultural land by the Fuller family
Ash forest replaces abandoned agricultural land
Emerald Ash Borer first detected in Lackawanna County
Artificial snag and mammal habitat installed Nesting cavities drilled into natural ash snags
Early 1900s
Mid 19th - early 20th century
2004
2023
Kestrels choose nests Potential partners, such as Pennsylvania DCNR, capture and band birds for ecological research
2024
Natural ash snags begin to decay and fall Artificial snags persist as habitat
2035
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INVITING HABITATION
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SITE ANALYSIS
| OVERLOOK FIELD SCHOOL 2023
| EVA KAHN, JENNY GINN & MATTIE ECKLUND 0-15% slopes (required for trail maintenance)
>15% slope (retain current condition)
| 11 remaining snags at 4 per acre
| OVERLOOK FIELD SCHOOL 2023
hunting corridor / maintenance pathway
snags The ash forest is thinned to 4 snags per acre, or 96 total snags
1,569 snags are currently in the Overlook ash forest
ASH FOREST
ASH FOREST PLAN
CREATING HUNTING CORRIDORS & DISPERSING SNAG HABITAT site line
OPEN MEADOW AND FIELD
Across the Overlook property, snag material can be used to create a network of ideal habitat for kestrels in open meadows and fields.
SNAG PLACEMENT WITHIN 50ft BUFFER OF OPEN SPACE EDGE
KF AR
M
brush pile
RL OO
ASH FOREST BOUNDARY
mowed area
DEER FENCE
OV E
The dense invasive shrub layer in the forest makes it impossible for raptors to identify small prey on the forest floor. Our forest plan opens up hunting corridors. These corridors were determined using slope analysis (0-15%) to connect remaining snags. These corridors would be mown and lined with ash brush piles, creating an ideal composition of perches, long site lines of the forest floor, and mammal habitat.
OR
D RI
perching snag
LILY
0
500
1,000 ft
LAKE
Cleared dead wood is repurposed throughout the property as snags and brush piles
12’ wide corridor
N HU
TI
NG
R CO
Ashest r froest fo for h
As
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INVITING HABITATION
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CORRIDOR STRATEGIES
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2
1
+
3
4
Corridors are cleared with a skid-steer and made wide enough to maintain with a mower
Building small mammal habitat after clearing reintroduces complexity in cleared corridors. The piles can be monitored for emergence of invasive species
Within the ash forest, the distance between maintained snags is determined by slope and the shortest route between 4 snags within an acre
Downed woody debris from the ash forest can be redistributed across the property as small mammal habitat in open meadows
Native plantings can be paired with small mammal habitat. Rodents aid in the dispersal of seeds
Outside of the ash forest, snags can be made with rot-resistant black locust to increase the longevity of nesting habitat
6 FT 20 FT
CL
EA
OP
EN
RE
DC OR
ME
AD
RID
OR
SI
OU
TS
NS
IDE
OW
TH
EA
SH
FO R
IDE
TH
12FT
EA
SH
FO R
ES
ES
T
1_Northern highbush blueberry (Vaccinium corymbosum) 2_Black raspberry (Rubus occidentalis) 3_Coral honeysuckle (Lonicera sempervirens) 4_Virginia rose (Rosa virginiana)
T
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INVITING HABITATION
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PROTOTYPE ITERATIONS
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3’-0” 8”
15”
12”
SNAG ITERATIONS DECEPTIVELY COMPLEX SYSTEMS
These iterations sought to find the balance between aesthetic interest and functional, ecosystem mimicry. A central goal was to avoid the use of milled lumber and to repurpose wood exclusively from the Overlook property. Sketches, dowel models, digital modeling, and scaled models all aided in our exploration of form and function.
15”
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SNAG ANALYSIS AND DESIGN
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| EVA KAHN, JENNY GINN & MATTIE ECKLUND
ECOSYSTEM OF A SNAG
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TRANSPECIES HELIX SNAG
COMPLEXITIES OF SPECIES USE AND CAVITY TYPES
Each snag offers unique habitat opportunities for a range of wildlife. Variations in height, diameter, branch structure, wood hardness, and state of decay allow for different kinds of cavities to be formed by different animals. The nesting cavities created by the Pilleated woodpecker are most relevant to kestrels. When the woodpecker is ready to nest, it will build a cavity
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NATURAL SNAG CAVITY TYPES
1:3 MODEL OF SNAG DESIGN ITERATION
that is long and narrow, providing hidden cover for its young while they grow. After the woodpeckers vacate the nest, kestrels or other raptors like screech owls have the opportunity to move in.
Woodpecker foraging
Mammal habitat
Insect habitat
Bird nesting
This model uses Pennsylvania Ash wood found on site to reconstruct a natural snag. The design emphasizes the attractive twisting form of a natural snag, with smaller pieces that spiral around a main trunk. Each piece of wood varies in diameter, with the largest generally laying closest to the main trunk and the smallest diameters on the outside. The form swells out in the center,
DESIGNED SNAG CAVITY TYPES
mimicking the shape of a traditional nest box. Cavities and entrances of varying size exist in this center area. Two pieces have holes designed to accommodate mason bees or other beneficial insects.
Woodpecker foraging
Mammal habitat
Insect habitat
Bird nesting
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INVITING HABITATION
TOOLS
1_ Chainsaw (felling a snag) 2_ Splitter (splitting the log) 3_ Router (carving the internal nest cavity) 4_ Power drill (attaching nest to snag) 5_ Hammer and chisel 6_ Auger (digging the hole) 7_ Shovel (digging the hole) 8_ Post hole digger (digging the hole)
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PROTOTYPE ASSEMBLY
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MATERIALS
MODEL A: NEST BOX SNAG
1_ Dead ash log (the nest) 2_ Standing tree (Robinia pseudoacacia; artificial snag post) 3_ Hinges (opening the nest for maintenance) 4_ Rocks (securing the footing) 5_ Hook and loop fastener (closing the nest) 6_ 4” and 2” screws (attaching wood to snag)
MODEL A: NEST BOX SNAG
After spliiting the log, use the dremmel to carve out a 12”x4”x2” cavity into the flat side of the piece.
Use a hammer and chisel to clean up the cavity. Chisel through one of your two pieces to create the kestrel entry way.
Attach the two halves of the ash wood together using small hinges. The nest can now be opened for maintenance.
Sort cut pieces by length and diameter. The largest pieces will make up the first layer of the helix.
Arrange pieces such that there are varying sizes of cavities in regards to their openings, depths, and heights.
MODEL B: TRANSPECIES HELIX SNAG
Fell a tree for the snag trunk. There are many kinds of trees that make a good snag, but Robinia pseudoacacia is a particularly good choice because of its prevalence and rot resistance.
Cut pieces of ash wood of varying diameters, ranging in length from 8” to 18”. Select the straightest pieces with the fewest nobs.
| EVA KAHN, JENNY GINN & MATTIE ECKLUND
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MODEL B: TRANSPECIES HELIX SNAG
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NEST BOX PROTOTYPE
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| EVA KAHN, JENNY GINN & MATTIE ECKLUND
1_Kestrel Nest Box 2_Kestrel Nest Box, Closed View 3_Kestrel Nest Box, Open View 4_Kestrel Nest Box, Inside View
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HELIX SNAG PROTOTYPE
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| EVA KAHN, JENNY GINN & MATTIE ECKLUND
1_Transpecies Helix Snag 2_Transpecies Helix Snag, Full View 3_Transpecies Helix Snag, Detail One 4_Transpecies Helix Snag, Detail Two
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SNAG RAISING
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1_ Aerial View of the Snag 2_ Making Progress 3_ Finishing Touches
| EVA KAHN, JENNY GINN & MATTIE ECKLUND
1_ Open Meadow 2_ Full View of Planted Snag 3_ Perches on Top of Snag
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