Colorado Cottontails

Note: Working project, I have additional references and information I'd like to add in the future. Comments or corrections encouraged.

Let's start with the basics. Three species of Cottontail occur in the state. Desert, Mountain and Eastern. In general Cottontails can be found just about anywhere even up to 11,500 feet. If you don't want to read further Colorado Division of Wildlife neatly summarizes what I will attempt to go into detail below. "Mountain cottontails live in the mountains and in the northwest, desert cottontails live in the southwest and on the eastern plains, eastern cottontails live in woodlands along watercourses in the east." (3)

Now to the difficult part. Which species am I seeing? This quote sums the issue up well, "Differences among cottontails in Colorado are subtle, and it can be difficult to separate the 3 species by external characteristics alone.(1)" For certain identification carful examination of teeth, dissection or genetics are required. Despite similarity to our eyes interbreeding is reported rare despite broad areas of sympatry. West of the town of Bellvue (Larimer County) all three species coexist. (1)

So how do we approach specific IDs in this group, habitat and location, and maybe a sprinkle of field marks.

Desert Cottontail: In general this species is found below 7,000 feet in the state. It is found from the foothills east on the plains, in the San Luis Valley as well as lower elevations in the west slope. Desert Cottontail prefer more arid conditions including prairie dog towns on the plains. However don't be fooled by the name, they are found in riparian areas, montane shrubland and pinyon juniper. (1)

Mountain Cottontail: These can occur anywhere over 6,000 feet in the state, even up to treeline. They prefer montane to semi-desert scrubland, but also occur in forest edge, open parkland etc. (1)

Eastern Cottontail: This species is generally found below 6,500 feet in the state. The broadest area of their distribution is in the Platte River Basin, but also the Republican River Basin (Yuma County). They are also possible in the extreme SE of the state. Their distribution on the plains is confined to Riparian areas near major rivers, however the situation is blurred in the Denver metro area. Eastern Cottontail are know to occur north of the palmer divide north to Fort Collins. This would include Douglas, Arapahoe, Jefferson, Denver, Bromfield, Boulder, Weld and Larimer Counties(1). They prefer to be in riparian areas with plenty of cover.

So where can you safely identify a Colorado Cottontail by range. On the plains far away from water, Desert. Anywhere in the southern plains, except the extreme southwest, Desert. The intermontane west above 7,000 feet, Mountain.

Field marks: First use habitat, then supplement with field marks. First ensure you are looking at an adult. This is best done by size and will take experience. Young rabbits have finer fur, small ears to make things difficult. Luckily if there are young, an adult is nearby.

Desert Cottontail: These have long sparsely furred ears, often with visible veins. This an adaptation to keep cool. They are paler overall grayish on the back and often with orange wash on the throat and chest.

Mountain Cottontail: Small rounded densely furred ears and relatively smaller hindlegs. Overall darker in coloration than Desert.

Eastern Cottontail: The darkest of the three species. It has ears that look more like Mountain in shape. Rounded and more densely furred. This is overall the largest of the three species. (2)

Overall good photographs will be needed and many Cottontails will need to be left at the genus level. Especially along the front range.

Select photos from core of each species range (note: the species is quite variable other the range):
Desert cottontail

• https://www.inaturalist.org/observations/16007681 Typical Desert Cottontail in CO note the pale fur.
• https://www.inaturalist.org/observations/68450797 Showing how ears can look rather rounded, but are longer than eastern
• https://www.inaturalist.org/observations/69796728 Showing the extreme on ear size, no other field mark required!

Eastern Cottontail

• https://www.inaturalist.org/observations/3624682 Very classic look small round ears dark color overall
• https://www.inaturalist.org/observations/10031118 Showing very minimal ear fur density

Mountain Cottontail

• https://www.inaturalist.org/observations/68026553 Very similar to Eastern in look. Eastern and Mountain have been considered sister species
• https://www.inaturalist.org/observations/21884375
• https://www.inaturalist.org/observations/63200992 Showing how difficult Cottontail ID is

Select photos from CO (all IDs should be taken with a grain of salt)

• https://www.inaturalist.org/observations/4996902 Eastern along boulder creek
• https://www.inaturalist.org/observations/33995712 Eastern from Lakewood

(1) Armstrong, D. M., Fitzgerald, J. P., Meaney, C. A., & Fitzgerald, J. P. (2011). Mammals of Colorado. Denver: Denver Museum of Nature & Science.
(2) Tekiela, S. (2007). Mammals of Colorado: Field guide. Cambridge, MN: Adventure Publications.
(3) Cottontail Rabbits. (2014). Retrieved February 19, 2021, from
https://cpw.state.co.us/learn/Lists/Wildlife%20Species/DispForm.aspx?ID=27

Posted on February 19, 2021 04:28 PM by nickmoore91