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Cougar Corridors of Southern California 

A spatial analysis of Mountain Lion

habitat and corridor suitability

 

The mountain lion (Puma concolor), also known as the cougaris a large cat native to the Americas.

 

Once abundant in Southern California, their numbers have been reduced to just a few thousand animals in the increasingly developed wild lands north and west of Los Angeles. Besides having less total habitat overall, the remaining groups of cats are finding themselves ever more isolated from one another, leading to genetically dangerous inbreeding.

 

A growing awareness about the need for wildlife corridors is leading to efforts among land management agencies, Caltrans, and wildlife advocates to identify the best corridors that can connect the habitats of these (and other animal) populations. The problem is complex and spatial analysis of the problem with GIS software is proving to be an important tool in the effort.

 

This story map presents an overview of the spatial analytic method developed by CorridorDesign.org that identified three potentially important mountain lion corridors. 

 

(Right) This adult male cat (known as "P-22"), seen in the Santa Monica Mountains above Hollywood, is from the smallest of the local groups, thought to number under 100 strong.

(Photo by Steve Winter/National Geographic).

What makes good mountain lion habitat?

Mountain lions are solitary animals which tend to avoid human contact. In the western United States they feed primarily on mule deer and other large prey. Their stalking behavior requires sufficient land cover like forest and shrubland (land cover types that are also preferred by mule deer and other favorite prey). Complex, rugged terrain also serves well as both stalking cover and an advantage during the hunt for the nimble, speedy predators.

 

These factors all contribute to suitability with different weights (expressed below as percentages). While other factors contribute, for the purpose of this analysis we'll focus on these four primary suitability characteristics:

  1. Forest and shrub land cover (30%)
  2. Legal protection status (25%)
  3. Rugged terrain (25%)
  4. Away from human activity (20%)

Forest and shrub land cover 

(30% weighting)

Both mountain lions and their prey tend to prefer forested or shrubby land. These vegetation types provide food sources for mule deer and other prey. Also, both predator and prey rely on this type of vegetation for visual cover. This factor is of vital importance and thus carries the highest weighting at 30% importance.

 

 

California coastal forest and shrubland offer ideal protection for mountain lions and their prey.

  • Areas in cyan are highly suitable with forest and shrub land cover.
  • Areas in orange are agricultural and open areas. Hungry mountain lions will roam into these areas in search of food. 
  • Areas in red are developed lands with high degrees of human activity and will usually (but not always) be avoided by mountain lions. 

Legal protection status

(25% weighting)

Predictably, mountain lions are often sighted in areas afforded legal protection from intense human activity. In the study area, these are typically public lands like national forests and big state parks, as well as other local greenbelts. 

 

Legally protected areas like the Sespe Wilderness in Los Padres National Forest are favored by mountain lions.

 

  • Areas in cyan identify those tracts of land with the strongest conservation focus that limits human disturbance and activity.
  • Areas in orange are largely protected from development, but allow some human disturbance, including fire suppression, mining and logging.
  • Areas in red are places with no known mandate for protection.

Rugged terrain

(25% weighting)

As their very name suggests, stalking mountain lions thrive in areas with rugged terrain. Steep slopes along with abrupt changes in elevation offer the cats both good visual cover and a competitive advantage against their less nimble and slower prey.

 

San Gorgonio Mountain features the type of rugged terrain preferred by stalking big cats.
  • Areas in cyan are highly suitable with steep slopes and abrupt changes in elevation.
  • Areas in yellow are hilly areas with moderate slopes and more gradual changes in elevation. 
  • Areas in red are flatlands that offer little or no advantage to mountain lions.

 

 

 

Away from human activity

(20% weighting)

Roads are an excellent proxy for the presence of human activity. Where there are roads, there are humans. Mountain lions will tend to avoid crossing roads and especially highways, although in Southern California the big cats are often forced to cross roads to get around, as recent events in the news grimly attest.

 

Hard to cross for a mountain lion. The 101 Freeway in Agoura Hills where several big cats have been struck and killed in recent years.
  • Areas in cyan are further than 750 meters from any kind of road.
  • Areas in yellow are between 250 and 750 meters from any kind of road. 
  • Areas in red are less than 250 meters from any kind of road.

The Area of Interest

For the purposes of this exercise, the area of interest is restricted to the rectangular region seen here. The Core Areas 1, 2 and 3 were identified as core mountain lion areas of occupation, which means that they have the most likely high density of mountain lion distribution in the study area. The Santa Susana Hub was established as a critical linkage to the core areas by the National Park Service.

 

(Click a Core or Hub on the map to identify.)

 

From an analytic standpoint, the goal was to connect the three outlying Core populations with the center Hub area by delineating the paths of most suitable habitat between each core and the Hub.

The analytical model finds the paths of least resistance between the three mountain lion population cores and the hub. 

Finding the paths of least resistance

All of the four factors in this study are used to identify suitable cougar habitat by overlaying the four layers representing each factor and calculating a combined score for each cell. We call this combined suitability surface a “cost surface” for travel. The assumption is that cougars are more likely to travel through high suitability cells – that they would prefer these over lower suitability cells. The computer can then easily compute the path of least resistance between any set of points on the map.

You can see the resulting wildlife corridors for this model. These paths represent the most likely routes that mountain lions will use to travel between the core areas. As such, they represent the areas where attempts at cohesive, contiguous land preservation might be focused. 

 

 

The analysis method and the model outlined in this map journal, while simplified for clarity, provide an excellent starting point for those seeking to carry out similar analyses in their own regions of the world.

The proposed wildlife corridors

Based on all the combined and weighted statistical data from the four layers, the resulting wildlife corridors are seen here. While not an exact trail per se, these paths represent the most likely routes of mating mountain lions attempting to travel between the core areas. As such, they represent the areas where attempts at cohesive, contiguous land preservation should be focused. As we can see from this map, these corridors pass through some pretty densely developed areas.

 

The reality of making these corridors permanently protected is going to be a huge challenge, and the survival of mountain lions in Southern California is by no means guaranteed, even with reliably protected corridors. But the alternative to not trying would be a Southern California with no more wild mountain lions. The analysis method and the model outlined in this map journal, while simplified for clarity, is an excellent starting point for those seeking to carry out similar analyses in their own regions of the world.

Lions in the Santa Monica Mountains

Learn more about the work of the National Park Service to protect the open space which might allow this magnificent species to endure.

Cougar Corridors of Southern California 

A spatial analysis of Mountain Lion

habitat and corridor suitability

 

The mountain lion (Puma concolor), also known as the cougaris a large cat native to the Americas.

 

Once abundant in Southern California, their numbers have been reduced to just a few thousand animals in the increasingly developed wild lands north and west of Los Angeles. Besides having less total habitat overall, the remaining groups of cats are finding themselves ever more isolated from one another, leading to genetically dangerous inbreeding.

 

A growing awareness about the need for wildlife corridors is leading to efforts among land management agencies, Caltrans, and wildlife advocates to identify the best corridors that can connect the habitats of these (and other animal) populations. The problem is complex and spatial analysis of the problem with GIS software is proving to be an important tool in the effort.

 

This story map presents an overview of the spatial analytic method developed by CorridorDesign.org that identified three potentially important mountain lion corridors. 

 

(Right) This adult male cat (known as "P-22"), seen in the Santa Monica Mountains above Hollywood, is from the smallest of the local groups, thought to number under 100 strong.

(Photo by Steve Winter/National Geographic).

Tap for details Swipe to explore

LEARN MORE

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What makes good mountain lion habitat?

Mountain lions are solitary animals which tend to avoid human contact. In the western United States they feed primarily on mule deer and other large prey. Their stalking behavior requires sufficient land cover like forest and shrubland (land cover types that are also preferred by mule deer and other favorite prey). Complex, rugged terrain also serves well as both stalking cover and an advantage during the hunt for the nimble, speedy predators.

 

These factors all contribute to suitability with different weights (expressed below as percentages). While other factors contribute, for the purpose of this analysis we'll focus on these four primary suitability characteristics:

  1. Forest and shrub land cover (30%)
  2. Legal protection status (25%)
  3. Rugged terrain (25%)
  4. Away from human activity (20%)

Tap for details Swipe to explore

LEARN MORE

Tap to go back Swipe to explore

Forest and shrub land cover  (30% weighting)

Both mountain lions and their prey tend to prefer forested or shrubby land. These vegetation types provide food sources for mule deer and other prey. Also, both predator and prey rely on this type of vegetation for visual cover. This factor is of vital importance and thus carries the highest weighting at 30% importance.

 

 

California coastal forest and shrubland offer ideal protection for mountain lions and their prey.

  • Areas in cyan are highly suitable with forest and shrub land cover.
  • Areas in orange are agricultural and open areas. Hungry mountain lions will roam into these areas in search of food. 
  • Areas in red are developed lands with high degrees of human activity and will usually (but not always) be avoided by mountain lions. 

Tap for details Swipe to explore

LEARN MORE

Tap to go back Swipe to explore

Legal protection status (25% weighting)

Predictably, mountain lions are often sighted in areas afforded legal protection from intense human activity. In the study area, these are typically public lands like national forests and big state parks, as well as other local greenbelts. 

 

Legally protected areas like the Sespe Wilderness in Los Padres National Forest are favored by mountain lions.

 

  • Areas in cyan identify those tracts of land with the strongest conservation focus that limits human disturbance and activity.
  • Areas in orange are largely protected from development, but allow some human disturbance, including fire suppression, mining and logging.
  • Areas in red are places with no known mandate for protection.

Tap for details Swipe to explore

LEARN MORE

Tap to go back Swipe to explore

Rugged terrain (25% weighting)

As their very name suggests, stalking mountain lions thrive in areas with rugged terrain. Steep slopes along with abrupt changes in elevation offer the cats both good visual cover and a competitive advantage against their less nimble and slower prey.

 

San Gorgonio Mountain features the type of rugged terrain preferred by stalking big cats.
  • Areas in cyan are highly suitable with steep slopes and abrupt changes in elevation.
  • Areas in yellow are hilly areas with moderate slopes and more gradual changes in elevation. 
  • Areas in red are flatlands that offer little or no advantage to mountain lions.

 

 

 

Tap for details Swipe to explore

LEARN MORE

Tap to go back Swipe to explore

Away from human activity (20% weighting)

Roads are an excellent proxy for the presence of human activity. Where there are roads, there are humans. Mountain lions will tend to avoid crossing roads and especially highways, although in Southern California the big cats are often forced to cross roads to get around, as recent events in the news grimly attest.

 

Hard to cross for a mountain lion. The 101 Freeway in Agoura Hills where several big cats have been struck and killed in recent years.
  • Areas in cyan are further than 750 meters from any kind of road.
  • Areas in yellow are between 250 and 750 meters from any kind of road. 
  • Areas in red are less than 250 meters from any kind of road.

Tap for details Swipe to explore

LEARN MORE

Tap to go back Swipe to explore

The Area of Interest

For the purposes of this exercise, the area of interest is restricted to the rectangular region seen here. The Core Areas 1, 2 and 3 were identified as core mountain lion areas of occupation, which means that they have the most likely high density of mountain lion distribution in the study area. The Santa Susana Hub was established as a critical linkage to the core areas by the National Park Service.

 

(Click a Core or Hub on the map to identify.)

 

From an analytic standpoint, the goal was to connect the three outlying Core populations with the center Hub area by delineating the paths of most suitable habitat between each core and the Hub.

The analytical model finds the paths of least resistance between the three mountain lion population cores and the hub. 

Tap for details Swipe to explore

LEARN MORE

Tap to go back Swipe to explore

Finding the paths of least resistance

All of the four factors in this study are used to identify suitable cougar habitat by overlaying the four layers representing each factor and calculating a combined score for each cell. We call this combined suitability surface a “cost surface” for travel. The assumption is that cougars are more likely to travel through high suitability cells – that they would prefer these over lower suitability cells. The computer can then easily compute the path of least resistance between any set of points on the map.

You can see the resulting wildlife corridors for this model. These paths represent the most likely routes that mountain lions will use to travel between the core areas. As such, they represent the areas where attempts at cohesive, contiguous land preservation might be focused. 

 

 

The analysis method and the model outlined in this map journal, while simplified for clarity, provide an excellent starting point for those seeking to carry out similar analyses in their own regions of the world.

Tap for details Swipe to explore

LEARN MORE

Tap to go back Swipe to explore

The proposed wildlife corridors

Based on all the combined and weighted statistical data from the four layers, the resulting wildlife corridors are seen here. While not an exact trail per se, these paths represent the most likely routes of mating mountain lions attempting to travel between the core areas. As such, they represent the areas where attempts at cohesive, contiguous land preservation should be focused. As we can see from this map, these corridors pass through some pretty densely developed areas.

 

The reality of making these corridors permanently protected is going to be a huge challenge, and the survival of mountain lions in Southern California is by no means guaranteed, even with reliably protected corridors. But the alternative to not trying would be a Southern California with no more wild mountain lions. The analysis method and the model outlined in this map journal, while simplified for clarity, is an excellent starting point for those seeking to carry out similar analyses in their own regions of the world.

Tap for details Swipe to explore

LEARN MORE

Tap to go back Swipe to explore

Lions in the Santa Monica Mountains

Learn more about the work of the National Park Service to protect the open space which might allow this magnificent species to endure.

Tap for details Swipe to explore

LEARN MORE

Tap to go back Swipe to explore

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