In Search of Shelter: Exploring Cozumel's Raccoon Habitats

The Cozumel raccoon, or the pygmy raccoon, is a critically endangered species found exclusively on the Mexican island of Cozumel. This is the only known habitat of the species, which is troubling considering that the island is only around 478 square kilometers in area and there are currently no designated protected areas on the island for this species. Furthermore, due to an increase in tourism and human development on Cozumel Island, the rate of habitat loss has been steadily rising, which is putting this species at greater risk of extinction. Due to its threatened status, this project seeks create a habitat suitability model to determine a protected area that is most suitable for the pygmy raccoon population. 

Pygmy raccoons are native to the island of Cozumel and range data determines that this is the only location that they are inhabiting, so it is necessary to create a protected area on this island. This species prefers to live in a habitat that consists of mangrove forests and sandy wetlands. Mangrove forests provide adequate protection from predators, while sandy wetlands allow for access to crabs, which make up 50 percent of the raccoon’s diet. What is detrimental to the population is habitat loss due to human impact, so finding an area that is at least 5 kilometers from human populations is necessary. The preferred habitat of Cozumel raccoons is at least 1.5 kilometers from roads. Urban development and the expansion of the road system on Cozumel has been fragmenting the natural raccoon habitat, and a very prominent cause of death is due to the raccoons being hit by cars.  

1. Cozumel Raccoon Range
2. Land Cover
3. Human Population
4. Roads

When gathering my data, the first step I took was projecting all data into the Mexico UTM Zone 16N projected coordinate system. This projection is designed for use on the East coast of Mexico, which is my area of focus, so projecting the data in this coordinate system will ensure the least amount of error, which is useful for identifying specific areas for a protected habitat. I used the raccoon range polygon layer as the extent for my raster and vector data layers. I had to convert my population data layer from raster to vector using the “raster to point” tool because I wasn’t interested in population density, but rather in areas that had been inhabited by humans. I then had to convert my population (point) data and roads (line) data from vector data to raster data. This was done with the Euclidean distance tool, which allowed me to create a layer that identified the distance from each road and the distance from each population point. When working with raster data, I set the environment to have a snap raster from the original population raster data (129 m x 129 m) for all layers.

Reclassify

• Human Population: Euclidean distance raster
  • 4 value groups: 0-5 km, 5-7 km, 7-9 km, 9-13 km 

• Roads: Euclidean distance rater 
  • 4 value groups: 0-1.5 km, 1.5-2 km, 2-4 km, 4-7 km 

Con Tool

• Land Cover 
  • Assign a positive value of 1 to the landcovers that were suitable for the Cozumel Raccoons: 14 (wetlands) 
  • Assign the false raster to 0 for all other land covers 

• Human Population
  • Assign a positive value of 1 to groups 2, 3 and 4, which indicates that the distance from human population is greater than 5 km 
  • Assign a value of 0 to the false raster

• Roads
  • Assign a positive value of 1 to values 3 and 4, which indicates that the distance from roads is greater than 2 km 
  • Assign a value of 0 to the false raster

Combining Raster Layers

Using the 3 con layers (land cover, human population, and roads), I used the raster calculator to combine them into one layer. I used an addition equation to combine the 4 layers, which produced a layer with values ranging from 1 to 4, where 1 is the lowest suitability and 4 is the highest suitability. The highest value of 4 is the most suitable habitat, which is indicated by the darkest color on the map.

I used the following criteria when creating the weighted model:

• Roads: 45%
• Land cover: 35%
• Human Population: 20%

Land cover is most important to the species because its preferred habitat is mangrove forest where they have access to plenty of food, such as crabs, fruits, and seeds, and the canopy provides adequate protection from prey. Roads is second most important because the expansion of the road system on Cozumel has been fragmenting the natural raccoon habitat, and a very prominent cause of death is due to the raccoons being hit by cars. Human population is weighted the least because a majority of the human population overlapped with the area that was most concentrated with roads, and I believe that land cover and the dangers of roads are more important for the suitability of the habitat.

To produce a single layer for the weighted model, I used the raster calculator to combine the layers again with the following equation:

(human population * 0.20) + (roads * 0.45) + (land cover * 0.35) 

Finally, I used the reclassify tool to create 4 groups of the resulting values based on the natural breaks that ArcGIS pro provided to represent suitability value. Like the unweighted model, 1 indicates least suitable and 4 indicates most suitable.

The unweighted and weighted suitability models reflect similar areas that would be beneficial habitats for the raccoon population. The map above represents higher suitability areas in dark green (weighted model) and dark orange (unweighted model), and the lighter colors represent unsuitable areas. The most suitable areas can be seen on the north east side of the island as well as the southwest.

As mentioned previously, the range of the Cozumel raccoon is extremely limited. Because there are no protected areas on the island, the species' current habitat is being threatened by urbanization and human expansion due to tourism. Drawing from my suitability analysis, I propose that future conservation efforts focus on three areas on the island that could serve as potential protected areas for this species.

Spatial analysis and mapping were used to identify three primary regions that could serve as potential protected areas for the Cozumel raccoon species. With the information presented in this map, conservation efforts on the island of Cozumel can establish protected zones to ensure that this species is safe from urbanization and human development. The Cozumel raccoon is already critically endangered, so creating a protected habitat will help revive the population and prevent this species from becoming fully extinct.