Westside Wildlife Corridor

Prolog, March 2020

This page is a simple collection of resources pertaining to the Westside Wildlife Corridor that (on one scale) connects the coastal range to Portland's urban natural areas.

Some Questions

What is it? Why should we care? What can we do to protect, improve, and promote the Westside Wildlife Corridor? What are various groups doing? Could a Brand be developed for the concept, useful for their efforts? Shouldn't residents of city know about the Westside Wildlife Corridor (WWC) ?

The corridor exists as a concept, e.g. in scientific literature, biological studies, etc. Could a WWC unit for students be developed? Could a guide be developed for field trips? Biology teachers hopefully know about the corridor — formalizing it could make it easier to justify studying it. Perhaps teachers themselves could develop such materials.

Can we create infographics, maps, and/or posters that feature key areas along the corridor that could be referenced by local journalists and news reporters to help educate the 'general public'?

Can various natural areas and public/private areas be identified as being part of a wildlife corridor, with uniform signage and educational displays? Can we develop a Logo or other branding material to be used corridor-wide?

The Corridor as an Organizing Principle

The wildlife corridor was here before westward settlement. Our parks are mainly set-aside social constructs, and haphazard development has left the corridor fragmented. No one group, NGO, or non-profit is organized around it, per se, but there are many groups involved, as listed in the 'appendix'.

People recognize the importance of, and are concerned about, the future of the corridor. Please see WWRP - West Willamette Restoration Partnership Goals: [LINK].

Wikipedia's Wildlife Corridor page gives a good overview of the subject, and gives examples of regional, sub-regional, and local wild life corridors. [LINK].

The Sky is the Limit

This is potentially no small project. For example, France has constructed 1762 Wildlife passages along its limited-access A-routes (similar to US interstate freeways). There are 600 in the Netherlands. (Google for Wildlife Overpass!) Portland recently constructed a pedestrian overpass crossing West Burnside — but there is no safe passage wildlife! [Wildlife Crossing].

Wildlife Overpass on A52 Route in south France. Photo by J Miller.

Westside Wildlife Corridor concept...

I don't know who (at the city) made these particular graphics.

The Wildlife Corridor (small)
Wildlife Corridor from River View Natural Area Management Plan

Here, more-or-less, is the corridor area. Once in Forest Park, wildlife is connected west to coastal ranges.

Wildlife Corridor in Google Maps, green arcs added by John Miller

Google Terrain is not better than the subtle hill-shading used by regular Google Maps (too 'busy'). The "corridor" is not simply linear, it is a mesh of connected green spaces and riparian areas. Apple Maps seems to have added more 'green' features to its recent release.

Block diagram or schematic of connected areas

See below for a draft conceptual block diagram with the areas connected. Links are guesses only, for mammals.

AP - Adams Park
AUD - Audubon Preserve
BPN - Butterfly Park Naturescape
FP - Forest Park
GHP - George Himes Park (has Marquam Trail)
HA - Hoyt Arboretum
HP - Holman Park
I5 - Gore under Terwilliger bridge and I-5 ramps.
JBNA - Jesse Boone Nature Park
KW - Keller Woods
McP - Macleay Park
MNP - Marquam Nature Park
MP - Marshall Park
MR - Macadam Ridge property
PA - Pittock Acres
PMP - Powers Marine Park
RVC - River View Cemetery
RVNA - River View Natural Area
SCNA - Stephens Creek Natural Area
TF - Private GAP along Taylors Ferry Road and Stevens Creek trib stream
Tual - Tualatin Mts
Tryon - Tryon Creek State Natural Area
WP - Washington Park
ZOO - Oregon Zoo
Terminus: Willamette River?

Connector: Burnside Wildwood Pedestrian Overpass (Fall 2019), but no Overpass for Wildlife?

Wildlife Corridor Graph (showing assumed connections)

The above is only a preliminary topological abstraction to indicate connections. Each line (supposedly) represents some path that wildlife can take to move from one area to another. The final map might have multiple connections between areas, or connections that are used at different times. Is there an inventory of such connections? Who knows, without data/monitoring of individuals? Note that different species have different ranges. Some species can penetrate certain barriers while other cannot, and so on.

Imagine Three Posters (P1, P2, P3)

These could be variations of a common Base Map
  • P1. What was the HISTORICAL corridor, before settlement? (paths of movement)
  • P2. What is CURRENT paths for mammals, amphibians? What are the barriers?
  • P3. What can be done where to IMPROVE the corridor's connectivity?

Sample Questions for a Study Guide in Schools.

Do Deer cross the river? Do they cross/over/under/around Barbur Blvd? Burnside? I-5? We know they cross Taylors Ferry and Terwilliger Blvd Ext.

How about a FAQ for the Wildlife Corridor, as a way of asking/answering some good questions? Some questions may not have good answers! For example:

  • How and where does the urban environment impede the migration of mammmals: Deer, Elk, Raccoon, Coyote, Beaver?
  • What about aquatic creatures (where migration includes spawning): Salamanders, Frogs, Lamprey Eels?
  • And these Fish: Salmon and Steelhead?
  • What could be done to help?

Migration Barriers and Passages

This section will have both impassable barriers, and where wildlife can penetrate barriers.

  • Can wildlife get under I5 at Terwilliger curves?
  • IOWA Street viaduct -- Marquam Trail
  • 2nd bridge on I5/Barbur, Vermont, Stream comes down ravine.
  • Underpass at SW 26th Way (is near Tryon Creek trib through Marshal park.)
  • Overpass at Fulton Park -- SW Brier Place
  • Culverts under HWY 43 for 7 River View NA streams.

See Habitat Fragmentation and the Theory of Island Biogeography Page 4 - M Houle. See Wildlife corridors and permeability: a literature review , L Henning. Both references below.

Action Items

These action items are in addition to any Goals set forth by WWRP (See Source Documents).

Acquire patches of private land: For example: missing parts of the Stephens Creek Watershed, Macadam Ridge (Riverview Abbey surplus land), and the Lowell Patton property between Boones Ferry and River View Cemetery. (I call this property Jesse Boone Natural Area or JBNA.) There are likely many such areas. Make a List.

Organize cleanup and restoration projects in places outside of parks, but still vital to the corridor.

Develop classroom material for K-12.

Form a stewardship group for Powers Marine Park (links below). There is a small group of people interested only in the dogwood trees in one area. Possibly people directly across the river in the condos and houseboats? Powers Marine Park friends could join the Willamette Restoration Partnership.

List projects that would improve linkage in the Corridor. See Page 22 of Houle's [PDF] for ideas. Re-establish links where migration is constrained by barriers. Does a comprehensive inventory exist? Need it for making Poster #2.

Encourage wildlife-friendly back yards and street scapes in critical areas (As stated by various reports and existing groups).

Crowdsource collection of data about animal movement.


A link appears with each reference, to the source.

  • West Hills Wildlife Corridor (Marcy Houle, 1990) [PDF]
  • WWRP - West Willamette Restoration Partnership Goals [Crude sub page here]
  • WWRP - West Willamette Restoration Partnership [LINK]
  • WWRP - West Willamette Restoration Partnership page on the corridor [LINK]
  • WMSWCD - West Multnomah Soil & Water Conservation District [LINK]
  • Wildlife Habitat Fragmentation [FACT SHEET PDF]

From The Intertwine: Corridors - Connectivity Forum!!

The Corridors - Connectivity Forum minutes from April 28, 2016, are fascinating! [PDF] Look at all the interest! What's the status??

See under Lori Hennings: A brief history of connectivity planning in Metro area...

  • Metropolitan Greenspaces Master Plan (1992)- corridors and linkages are only safe passages for animals
  • 􏰀Regional Conservation Strategy (2012) - need to plan for biodiversity corridors (corridors mentioned over 200 times in document)
  • 􏰀Wildlife Crossings Guidebook (2008) - providing safe passageways for wildlife across roads
  • 􏰀Wildlife corridors and permeability: a literature review (2010) [LITERATURE CITATION]
  • 􏰀Corridor workshops (2010/11) – over 100 participants mapped corridors


  • Need for Intertwine-wide/level coordinator to facilitation conversations and collaboration
  • Need region-wide coordinator; lots going on but efforts are scattered.
  • Need a common vision to identify priorities (will also help with funding).


A link to the source is given at the end of each statement.

APPENDIX A. Urban habitat corridors in Portland Comprehensive Plan

These policies are from the 2035 Portland Comprehensive Plan (June 2016).

Urban habitats are natural and built areas that provide safe, healthy places for resident and migratory fish and wildlife species that live in and move through the city. Maintaining diverse, connected habitat corridors will help fish and wildlife thrive in and adapt to continued human population growth, development, and climate change. Urban habitat corridors also benefit Portlanders by keeping air and water clean and cool, reducing the risks from landslides and flooding, and providing places for people to play, learn, and experience nature.

Urban habitats encompass the city's most valuable and distinctive natural features — the Willamette and Columbia Rivers, streams and sloughs, wetlands, and large forested areas, such as Tryon Creek State Park, Forest Park and the West Hills, Willamette Bluff, and the East Buttes. Other urban habitats are woven throughout the built environment and include street and yard trees, backyard plantings, parks, and bridges that provide opportunities for bird nesting. Enhancing or establishing new urban habitat corridors will involve preserving and restoring existing natural features, creating vegetated connections between tree canopy and greenspaces, and incorporating nature into the design of buildings and landscaping, streetscapes, parking lots, and infrastructure.

These policies support plans, regulations, and investments to restore and reconnect habitat in diverse areas within the city. (See Figure 3-6 - Urban Habitat Corridors. - don't have that yet.)

Policy 3.64 Urban habitat corridors. Establish a system of connected, well-functioning, and diverse habitat corridors that link habitats in Portland and the region, facilitate safe fish and wildlife access and movement through and between habitat areas, enhance the quality and connectivity of existing habitat corridors, and establish new habitat corridors in developed areas.

Policy 3.65 Habitat connection tools. Improve habitat corridors using a mix of tools including natural resource protection, property acquisition, natural resource restoration, tree planting and landscaping with native plants, and ecological design integrated with new development.

Policy 3.66 Connect habitat corridors. Ensure that planned connections between habitat corridors, greenways, and trails are located and designed to support the functions of each element, and create positive interrelationships between the elements, while also protecting habitat functions, fish, and wildlife.

You can visit the 2035 Portland Comprehensive Plan on-line here [LINK].

APPENDIX B. West Willamette Restoration Partnership

(From WestWillamette website) To conserve and enhance the forests and natural areas of SW Portland by forming an active coalition of engaged volunteers, community groups, landowners and organizations. We aim to improve conditions supportive of native flora and fauna through good land stewardship, volunteerism and education. [LINK]

The West Willamette Restoration Partnership (WWRP) is a coalition of engaged volunteers, community groups, landowners and organizations working to conserve and enhance the forests and natural areas of SW Portland. Our Partnership supports habitat enhancement and stewardship efforts in southwest Portland’s Willamette River subwatersheds to provide a key link in the wildlife corridor connecting Forest Park and Tryon Creek State Natural Area. [LINK]

The corridor (From West Willamette website) The WWRP project area encompasses an essential linkage of the Westside Wildlife Corridor in SW Portland, a section of the west hills that includes undeveloped natural habitats and streams. We are working to enhance the functionality of this wildlife migration corridor, forming a connection between Tryon Creek State Natural Area in the South and Forest Park in the North. Ultimately, we hope to help maintain a healthy wildlife corridor connecting SW Portland's natural areas all the way to Oregon's Coast Range. [LINK]

APPENDIX C. ArcGIS Story Map by Andrew Addessi

ArcGIS Story

There is an ArcGIS Story Map by Andrew Addessi, Portland State University. The ArcGIS Story has various things: invasive plants, West Willamette Restoration Partnership focus areas, certified backyard habitats, and so on.


APPENDIX D. The Westside Wildlife Corridor on City of Portland website

The Westside Wildlife Corridor is the forested spine of the west hills that provides the green backdrop to downtown Portland. This local target area will help protect remaining natural habitat, protect headwater streams, and create a continuous wildlife migration corridor from Forest Park south along the west hills.

As this target area has not been identified as a regional target, a community survey asked respondents to prioritize the following selection criteria. The results are listed in rank order:

  • Filling in gaps within existing protected areas.
  • Linking to Washington/Forest Park and Tryon Creek natural areas.
  • Buffering existing natural areas.
  • Maintaining a green backdrop to downtown Portland.
  • Providing neighborhood access to trails.

Special Status Habitats: Interior forest, Oak woodlands.

*Special Status Habitats include habitat types that have been recognized by state and federal agencies or organizations as being ecologically important. Portland's Special Status Habitats include "Strategy Habitats" identified in the Oregon Conservation Strategy that are found in Portland: herbaceous wetlands, upland prairie and native grasslands, oak woodlands, interior forests (especially late successional conifer forests), bottomland hardwood forest, and riparian habitat.


APPENDIX E. Miscellaneous Supplements

Cascade Crossroads is a 30-minute documentary film chronicling the story unfolding over and under Interstate 90 just east of Snoqualmie Pass in Washington’s Cascade Mountains. [LINK]

News release for purchase of RVNA -- 147 acres -- mentions the wildlife corridor [Fish Blog LINK]

Particular Watersheds and Natural Areas

There are many, most are listed in the above Block Diagram,

Powers Marine Park

Powers Marine Park consists of 47 acres along the Willamette River. Seven streams from River View Natural Area flow down to and through it (after passing poorly under HWY 43).

Powers Marine on Intertwine 'Old Site': [LINK]. On City of Portland, Parks web page [LINK]

Stephens Creek Watershed

Stephens Creek watershed area in Google Maps, red arrows added by John Miller

Some Stephens Creek Watershed has become a natural area. Downstream from there goes under freeway, along a gore, and down through private property with developers wanting to put houses on it. LiviblePDX?

A 3.5 acre Pacific willow forested wetland at the mouth of Stephens Creek is the most extensive remaining floodplain on the creek.

  • Stephens Creek Stormwater System Plan (2013) [6 MB PDF]
  • Stephens Creek Functional Plan (2005) [PDF]

Other Westside Watersheds

A map of the wildlife corridor should show streams & perhaps watershed boundaries. Boundaries may not be as significant for larger mammals as for aquatic creatures. (?)


WestsideWildlife.org - John Miller registered the domain name through 2020, but there's nothing on it yet. A site could be hosted for free along with John's Time Haven Media websites, or the domain name can be transferred to a trusted party. [LINK]


This page is being compiled/developed by John Miller, of Southwest Portland, for his personal edification, and discussion purposes, and possibly to become part of a dedicated website — WestsideWildlife.org