Reptiles, Amphibians, and Fish

Ectotherm Ambassadors

What do reptiles, amphibians, and fish have in common? They are all ectotherms, living in Mesa Verde National Park!

An ectotherm is an animal that does not keep their temperature stable using their own body, but instead uses the environment. This is why you will often find these animals in sunny or shady areas at certain times of the day. Lizards sun themselves on top of a rock in the morning, but cool off under that rock in the heat of the day. While these animals can appear weird, gross, or frightening to some people because of their differences to us, they still require the same things we do: food to eat, water to drink, and a safe place to call home!

 

Look for collared lizards on rocks in open areas, like Wetherill Mesa, in mornings and evenings, as they try to warm up before and after the cool nights.

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Colorful Collars

Perhaps the most beautiful reptiles in Mesa Verde are the collared lizards. They sport stripes, spots, and a wide range of colors across their scaled skin. The bold stripes around their necks give them their name. These colors help them to attract mates and intimidate rivals for territory, but it's also not the most surprising thing about them.

No matter how sluggish they may look, Collared Lizards are predators, and fast ones at that! They eat a wide range of animals, including insects, other lizards, and small mammals like mice, which they hunt with a mouth full of small, sharp teeth. When they spot their prey, they even have the ability to rear up on two legs and run at a rapid pace to be able to catch their dinner, like a little T-Rex!

 

Like most reptiles, rattlesnakes are most often seen in the morning, when they look for areas to heat up as the sun rises. Keep an eye and an ear out when going on early hikes.

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No Touch-y

Snakes are common at Mesa Verde, but only one is venemous: the Prairie Rattlesnake. Other snake species, like the gopher snake, may have similar patterns on their scales, a strategy (called Batesian mimicry) used to confuse predators who will think the harmless snake is a more dangerous relative. If the snake you're looking at has a noisy tail-rattle and wide head - those are giveaways that this is a true rattlesnake, and not a critter you want to be messin' with.

Rattlesnakes are not venemous because they like to bite people. Their venom is primarily for hunting prey, which is mostly made up of small mammals like mice, voles, and chipmunks. Other adaptations they have for hunting are highly sensitive senses of smell and heat detection. In fact, their rattle is a way to warn off potential threats (likely people) so that they don't have to bite anything!

In Pueblo culture, snakes are some of the closest animals to people. They change as they age like people do, shedding their skins as they grow, and keep pests like mice and rats away. They are to be respected, not feared. If you keep your eyes and ears open while hiking, and keep a good distance from any snakes you see, the worst you will walk away with is a cool story!

 

The chorus of toads can be heard on rainy nights in summer as they hop out of their burrows in search of a mate.

NPS/Joshua Peterson

TOAD-ally Cool!

Amphibians are not a common sight at Mesa Verde, for reasons related to how they breathe and reproduce. Many amphibians partially breathe through their skin, which has to be kept constantly wet. All of them can only lay their eggs in water or very damp places. In a dry place like Mesa Verde, how can an amphibian survive?

Red-spotted and Woodhouse's toads have bumpy, dry skin which doesn't need to be kept constantly wet. The toads and Mesa Verde's only other amphibian - the Tiger Salamander, can spend weeks at a time buried under the dirt, waiting for the perfect time to emerge. This is especially true after summer thunderstorms when pools of water form. Toads will lay their eggs in the pools, tadpoles will hatch and develop into toads in a matter of weeks. For this reason, toads are often associated with lightning and thunder in Pueblo culture.

When walking on a damp summer evening, watch your step. You might get the opportunity to enjoy the presence of one of Mesa Verde's rarer residents!

 

The Colorado Pikeminnow is one example of a fish that has disappeared from the Mancos River. By returning the river to it's natural state, they may be able to return one day.

NPS/ Robert 'Rob' Wood

Go Fish?

Mesa Verde doesn't look like a place that would be a great fishing spot. This is true for 99% of the park. But the 1%, located on the eastern side of the park where the park boundary meets the Mancos River is the subject of a lot of work and research to make it a good home for the fish that live there.

Fish found in the river (suckers, pikeminnow, and chubs) are threatened due to changes such as channeling and destruction of riparian habitat made alongside the Mancos River. Such changes cause uncomfortably warm temperatures, soil runoff, and fast currents that prevent the fish from breeding, feeding, and living there, to the point where some have disappeared. With habitat restoration help from park staff and volunters, the hope is to see an increase in the return of native species.

 

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Species Attribute Definitions

Definitions

Occurrence

Occurrence values are defined below. One or more Occurrence Tags may be associated with each Occurrence value.

Present: Species occurs in park; current, reliable evidence available.

Probably Present: High confidence species occurs in park but current, verified evidence needed.

Unconfirmed: Species is attributed to park but evidence is weak or absent.

Not In Park: Species is not known to occur in park.

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Occurrence Tags

Adjacent: Species is known to occur in areas near to or contiguous with park boundaries.

False Report: Species was reported to occur within the park, but current evidence indicates the report was based on misidentification, a taxonomic concept no longer accepted, or other similar problem of error or interpretation.

Historical: Species' historical occurrence in park is documented. Assigned based on judgment as opposed to determination based on age of the most recent evidence.

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Abundance

Abundant:

• Animals: May be seen daily, in suitable habitat and season, and counted in relatively large numbers.
• Plants: Large number of individuals; wide ecological amplitude or occurring in habitats covering a large portion of the park.

Common:

• Animals: May be seen daily, in suitable habitat and season, but not in large numbers.
• Plants: Large numbers of individuals predictably occurring in commonly encountered habitats but not those covering a large portion of the park.

Uncommon:

• Animals: Likely to be seen monthly in appropriate habitat and season. May be locally common.
• Plants: Few to moderate numbers of individuals; occurring either sporadically in commonly encountered habitats or in uncommon habitats.

Rare:

• Animals: Present, but usually seen only a few times each year.
• Plants: Few individuals, usually restricted to small areas of rare habitat.

Occasional:

• Animals: Occurs in the park at least once every few years, varying in numbers, but not necessarily every year.
• Plants: Abundance variable from year to year (e.g., desert plants).

Unknown: Abundance unknown

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Nativeness

Native: Species naturally occurs in park or region.

Non-native: Species occurs on park lands as a result of deliberate or accidental human activities.

Unknown: Nativeness status is unknown or ambiguous.

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List Differences

The Checklist contains only those species that are designated as "present" or "probably present" in the park.

The Full List includes all the checklist species in addition to species that are unconfirmed, historically detected, or incorrectly reported as being found in the park. The full list also contains species that are "in review" because their status in the park hasn't been fully determined. Additional details about the status of each species is included in the full list.

The checklist will almost always contain fewer species than the full list.

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Species attribute definitions

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