Chatfield State Park Herp Survey
A Survey of the Reptiles and Amphibians
of Chatfield State Park
Douglas & Jefferson Counties, Colorado
In March of 2007, North American Field Herping Association (NAFHA) members Joe Farah and Dan Baker approached Chatfield State Park’s Senior Ranger, Christina Bradshaw, with a proposal to conduct a volunteer survey of the park’s reptiles and amphibians. No such study had previously been done, and both sides were enthusiastic. Several meetings were setup to establish goals and methods, and it was agreed that an informal survey would be done, and the data would be turned over to the park.
This project was done by Baker and Farah in their free time during the warmer months of 2007. Fulltime jobs and families allowed for usually only one day per week for field study. This amounted to approximately 200 combined man hours during 32 outings to the park. The first day out was April 6th and the final day was Nov 4th. Unfortunately two persons working one day per week for several hours in the field is not enough to thoroughly survey the over seven thousand acres of land and water in Chatfield. There is a paragraph at the end of this report that addresses the unfilled gaps of this project.
* Since the 2007 season, Baker and Farah have made several trips to Chatfield each year in an effort to continue expanding what is known about the park’s reptiles and amphibians. With each visit, new information is added and this survey should be considered a continual work in progress. An updated version of this report that incorporates the latest findings will be made available every few years, or when appropriate.
The actual field work is usually conducted on foot in the form of active searching for any and all reptiles and amphibians. Observations and identifications are made through visual sightings, hand captures, and even audio observations (frog and toad calls). Index cards, notebooks, and GPS units are used to record data in the field and digital photos and videos were taken of many specimens. Sometimes specimens are captured by hand or net and observed and photographed at close range. All attempts are made to minimize stress on the animals and damage to the environment. At the end of each field work day, the details of that day are recorded in a journal and in an MS Excel spreadsheet. Each entry contains specific information about that day, including time, temperature, weather conditions, area surveyed and reptile totals. Only confirmable data is recorded.
Updated Summary of Findings as of November 2009:
This limited survey has so far revealed that Chatfield’s more than seven thousand acres of widely varying microhabitats support healthy populations of at least 15 species of reptiles and amphibians, and possibly several more. The species encountered first-hand during the 2007 survey are: Crotalus viridis (Prairie rattlesnake), Pituophis catenifer (Bull snake), Thamnophis elegans (Western Terrestrial Garter), Thamnophis radix (Plains Garter snake), Coluber constrictor (Yellow-bellied Racer), Lampropeltis triangulum (Milk snake), Chelydra serpentina (Snapping turtle), Chrysemys picta (Painted turtle), Lithobates catesbeiana (Bullfrog), Lithobates pipiens (Leopard frog), Psuedacris triseriata (Chorus frog), Bufo woodhousii (Woodhouse’s toad), and Aspidoscelis sexlineata (Six-lined racerunner).
As of November 2009, two more species were added to the list by Colorado State Park’s volunteer and bird watcher Joey Kellner. They are Ambystoma tigrinum (Tiger salamander) and Heterodon nasicus (W. Hognose snake).
Other species that may occur within the park are discussed at the end of the report.
Below are a few field observations, along with assessments about the situations of the various species made by Baker and Farah. Each species is addressed individually.
Common Name: Snapping turtle
Latin Name: Chelydra serpentina
Status in Chatfield: Common – Widespread
Total Finds as of 2009: 7 (plus several hatched nests)
The snapping turtle is one of the most widespread and successful reptiles in Chatfield State Park. It is also the largest. Despite all of this, snapping turtles are almost never seen in the open, except during the nesting season when females haul themselves ashore to lay their eggs. Occasionally, adults can be seen basking in the spring when water temps are still cold. The cryptic and secretive nature of these massive turtles makes it difficult to assess their numbers in the wild.
*While we may never know exact numbers and distribution patterns of snapping turtles in Chatfield, it is possible to speculate based on what is known about the species in general, and from the limited observations that were made by Baker and Farah starting in 2007.
Snapping turtles are known for their ability to thrive in almost every type of aquatic habitat, from fast moving streams and rivers to stagnant ponds and marshes. They thrive in large open lakes (such as Chatfield's main reservoir), but do equally well in beaver dams along small streams (such as those found along Plum Creek). They are also known to be highly tolerant of pollution and habitat disturbances caused by human activities (Hammerson 1999). Snapping turtles are also not picky about their diet. They are known to eat plant matter, carrion, and just about any living creature they can capture (Hammerson 1999). With this in mind, there is no reason to doubt that snapping turtles are established in every single major body of water in Chatfield State Park. Every pond and lake, along with both the S. Platte and Plum Creek drainages are prime habitat for these impressive turtles.
- During May and June of 2007, Baker, Farah and Kujawa observed at least six large adult snapping turtles basking on logs, swimming in the shallows, or nesting. Four were seen in the largest pond to the east of the Platte River at the very south end of the park.
- May 27th, 2007: Our first observation occurred at about 8:30am when a very large adult was seen basking on a log in a small, murky pond near Plum Creek.
- June 2nd, 2007: Two large snapping turtles were seen basking on the same log as the May 27th sighting (possibly involving the same turtle) at 10:30 am.
- June 3rd, 2007: A female was discovered laying eggs near a pond to the east of the Platte River in the southern portion of the park. When we found her she had already finished digging the nest and was just starting to lay her eggs. The process took about an hour and we estimated that she laid about sixty eggs. The site is a sandy hillside about twenty meters from the edge of the pond and faces south. It was about 9:30 am and just over 70 degrees. At that same time, two additional large snapping turtles were swimming in the shallows at the base of the steep embankment leading up to the nesting site. In late August we found that the nest had hatched successfully. In October a second nest was found about 1 meter from the first. It too had hatched successfully.
- September 16th, 2007: A nest was discovered that had been torn up by a predator and destroyed. One hatchling was found in good health walking close by. This was on the west side of Plum Creek near the southern edge of the park. Currently there is a beaver dam nearby.
In total, seven snapping turtles were seen in 2007. Six were large adults (possibly all gravid females) that were seen basking, swimming in shallow water, or laying eggs in late March through early June.
From the spring through the fall of 2007, We observed the presence of snapping turtles in both the Plum Creek and South Platte drainage systems. Proof of breeding was confirmed in both of these major water systems within the park as well. Although we didn't observe high numbers directly, we expect that they are common in the park.
- September 25th, 2009: Approximately six snapping turtle nests that appeared to have hatched successfully were seen just west of the Platte River in the vicinity of the Audubon Society building.
Common Name: Western Painted turtle
Latin Name: Chrysemys picta
Status in Chatfield: Rare- Localized
Total Finds as of 2009: 16 (approximately)
As of November 2009, Painted turtles have only been observed in two small ponds at Chatfield Park. Unfortunately, both ponds are located next to walking trails that are frequented by people walking with dogs. Both populations are vulnerable to collection and stress from humans and their dogs.
Western Painted turtles were commonly viewed emerging to bask on logs on sunny days between 8:00 and 8:30 a.m. They alternate basking and foraging until dusk. Several were observed each day the ponds were visited and it is likely that the same individuals were being seen repeatedly. Approximately twelve adults were seen along with several juveniles and hatchlings in one pond, confirming that breeding has occurred in recent years. The other pond, near the main reservoir, also had individuals of various ages from young to old.
The fact that this population is restricted to two small ponds that are exposed to heavy human traffic makes them susceptible to extirpation from the park. In order to prevent this, it is recommended that signs be placed at these ponds to inform people about these turtles and to discourage disturbing them in any way.
Additional Remarks: The Painted Turtle is the official “state reptile” of Colorado.
Common Name: Six-Lined Racerunner
Latin Name: Aspidoscelis sexlineata (formerly Cnemidophorus sexlineatus)
Status in Chatfield: Common - Widespread
Total Finds as of 2009: More than 100
The Six-Lined racerunner was the only lizard observed in Chatfield Park during the 2007 survey. They were seen throughout the park and were common in the areas that were heavily studied. All but the wettest areas within Chatfield are suitable habitat for racerunner lizards and they seem to occupy all suitable places in the park. These lizards like open fields such as those found all over Chatfield. They seem to shun the dense vegetation and tree cover found within the riparian zones of the Platte and Plum Creek. Yet even within these zones, individuals were sometimes found in small open areas.
The regions that appeared to contain the highest densities of these lizards are the cacti and yucca-strewn fields found scattered throughout the park. These sandy, open microhabitats provide the perfect hunting grounds for these swift and alert animals. In certain places at certain times, several dozen were seen in the area roughly equal to the size a football field.
The first Six-Lined racerunner of the 2007 survey was a large juvenile found on April 29th in a small, sandy microhabitat along the South Platte River. It was encountered at approximately 10:00 am basking among some rocks in the shady riparian zone along the Platte. The weather conditions were 75 degrees and sunny.
- May 12th, 2007: Seven individuals were seen along the east side of Plum Creek during the afternoon.
- May 19th, 2007: Seven adult racerunners were witnessed in the open, sandy fields along the Highline Canal during the late morning. The weather was sunny and temps were in the low 80’s.
- May 27th, 2007: More than twenty racerunners were seen in the open, sandy fields along the Highline Canal during midday. It was partly sunny and 85 degrees.
- June 2nd, 2007: More than twenty racerunners (perhaps many of the same individuals as previous days) were seen in the fields along the Highline Canal. Conditions this day were sunny, but cooler (approximately 70 degrees).
- June 3rd, 2007: Approximately fifteen were seen around the ponds along the South Platte River. On this day several gravid (pregnant) females were witnessed nesting in a sandy mound near a pond at 9:30 in the morning. Snapping turtles were also nesting here. One female was discovered dead by the survey team (Possibly crushed by a nesting snapping turtle) and was found to contain five fully formed eggs. These were buried in the hillside. Weather conditions were partly sunny and 75 degrees.
- June 10th, 2007:More than two dozen adult racerunners were seen in the fields to the east of the Platte River in the late morning. Weather conditions were warm (low 80's) and sunny.
- June 14th and 17th, 2007: Several adult and juvenile racerunners were observed foraging in the open, sandy fields around the ponds to the east of the Platte River between 2:00pm and 4:00pm. Conditions were sunny and hot with temps in the high 80's.
- July 7th, 2007: Three adult racerunners were seen in fields along Plum Creek during the late morning. Sunny and 90 degrees were the conditions of the day.
- July 21st, 2007: More than eight individuals were seen along the path from the Audubon society to the Platte River. Conditions were 95 degrees and sunny. These sighting were made at 11:00 am.
- September 3rd, 2007: Labor Day. Two adult and two hatchling racerunners were seen in the sandy hills along Wadsworth blvd. at the western edge of the park. These were the first hatchlings observed of the year. The weather was partly cloudy and 87 degrees.
- September 16th, 2007: One hatchling racerunner is seen in the fields near the Highline Canal at midday. It was sunny and 87 degrees.
- September 22nd, 2007: Two juveniles were viewed in fields along Plum Creek near the Highline Canal at 1:00 pm. Conditions were sunny and it was 80 degrees.
Common Name: Western Yellow-Bellied Racer
Latin Name: Coluber constrictor
Status in Chatfield: Common – Widespread
Total Finds as of 2009: 11
Western yellow-bellied racers are a primarily terrestrial species with abundant suitable habitat in the park. This species is known to prey on rodents, birds, amphibians, snakes, lizards, frogs and even large insects (Hammerson 1999). Eight racers were found in the park this year including one dead on the road. In total, we documented no hatchlings, three yearlings, five adults, and one egg nest this year. The results of our study show the population of racers in Chatfield is currently healthy and they can be commonly seen in the fields and riparian zones throughout the park.
- May 6th, 2007: Air temperatures reached 60 degrees. At approximately 9:30 a.m. we found a yearling racer under a rock on an eastern facing slope. At approximately 11:30 a.m. a large adult was spotted in the open, but quickly fled to the safety of a Yucca plant. This adult had a large scar on its side.
- May 14th, 2007: While road cruising at night, one adult racer was found dead on the road.
- May 16th, 2007: Temperatures were in the high 60’s and low 70’s. One adult racer was found under a piece of tin in an open field near the Highline Canal.
- June 14th, 2007: Temperatures were above 85 degrees. One adult racer in shed was found under a concrete block.
- July 7th, 2007: An adult was found in shed beneath a railroad tie near area where Highline Canal and Plum Creek meet.
- September 3rd, 2007: A racer nest was discovered underneath a large rock with eleven eggs that had all hatched. The nest was on a southeast facing hillside, the rock was buried approximately eight inches in the ground.
- September 16th, 2007: Temperatures were above 80 degrees when two yearling racers were found under concrete slabs in a field near Plum Creek.
- September 23rd, 2009: Temperatures in the mid 70’s. During mid afternoon, a large adult racer was found on the western bank of the Platte River near the Audubon Society. The Racer regurgitated a small adult Thamnophis elegans that had a newborn T. radix in it’s mouth. The T. elegans was still alive, but the little T. radix was dead.
Common Name: Milk snake
Latin Name: Lampropeltis triangulum
Status in Chatfield: Rare - Widespread
Total Finds as of 2009: 5
Milk snakes at Chatfield, like elsewhere, are reclusive and their numbers are difficult to assess. So far, only five occurrences have been confirmed by Baker and Farah. This can be largely attributed to the milk snake’s nocturnal habits and generally secretive nature. We can assume that the population is much larger then the number of animals we have recorded. Our research primarily took place during the early morning and afternoon hours. Since milk snakes are mostly nocturnal, the animals accounted were not exposed until the debris they were under was removed. The snakes were found in several locations, confirming a wide distribution throughout the park. The short grass habitat in which the milk snakes were found is common in Chatfield, leading to the assumption that where one is found there are many more that are not visible.
- May 27th, 2007: The temps were around 65 degrees in the morning and warmed up to the low 80’s in the afternoon. The skies were partly cloudy with a light breeze. There was a short rain shower in the middle of the day. At approximately 11 a.m., under debris, on an eastern facing slope, we found our first adult milk snake. This specimen was just over two feet in length and appeared vigorous and full-bodied.
- June 3rd, 2007: The temps were in the 60’s in the a.m. and warmed up to the low 70’s by midday. The night before, mild rain showers had passed over the park. The adult milk snake was found around 11:30 a.m. in an open field under a piece of buried tin. Its colors where opaque as the animal was near shed. However, it appeared to be very similar in size to the first adult found.
- June 10th, 2007: At approximately 11 a.m. the temps were near 80 degrees and a slight breeze was persistent through the afternoon. A neonate milk snake of about twelve inches was found underneath concrete syntopic with an adult bull snake that was in shed. The colors of the juvenile varied in comparison to the adults. The light bands where very white in contrast to the yellow hue of the two adults that were documented.
- May 23rd, 2009: At 12:20 p.m. a very small juvenile and a healthy young adult were found under concrete blocks. The juvenile was “in shed” and looking cloudy blue. Conditons were cloudy and cool.
Common Name: Western Hognose snake
Latin Name: Heterodon nasicus
Status in Chatfield: Rare – Localized
Total Finds: 2
Although never observed by Baker or Farah, credible reports of the Western Hognose snake have come from other park volunteers at Chatfield. This species prefers rather open areas with sandy soils, and the habitat at the south end of the park in between the Platte River and Plum Creek drainages appears suitable. This tract is somewhat large and undisturbed by recreational activities and probably capable of supporting a small population of this species if left in tact.
The only two observations of this species at Chatfield which are being considered confirmed accounts by Baker and Farah were those made by bird-watcher and Chatfield volunteer Joey Kellner. Mr. Kellner has encountered many H. nasicus in the field throughout Colorado and is qualified to identify the species. He also provided photographic evidence of H. nasicus in Chatfield.
- Sept. 8th 2009. Mr. Kellner found a juvenile crawling in the open on the sandy “two track” that is east of the Platte River and south of the main road at Kingfisher Bridge.
- Sept. 16th 2009. Mr. Kellner found a DOR (Dead on Road) specimen at 7pm on the main road just north east of the wildlife viewing area between the campgrounds and Kingfisher Bridge. Photo documentation was provided.
Common Name: Western Terrestrial Garter snake
Latin Name: Thamnophis elegans
Status in Chatfield: Common – Widespread
Total Finds as of 2009: 75 (approximately)
Common Name: Plains Garter snake
Latin Name: Thamnophis radix
Status in Chatfield: Rare – Widespread
Total Finds as of 2009: 6
Garter snakes are common in Chatfield and have been documented from April through October. Two species of garter snake have been confirmed within Chatfield park boundaries, including some possible intergrades. The western terrestrial garter (Thamnophis elegans) is the primary species of garter snake inhabiting Chatfield. Several plains garter snakes (Thamnophis radix) have been observed in the same regions.
We confirmed over twenty adult western terrestrial garters within park boundaries in 2007 and at least twenty juveniles. The garter snake inhabits nearly every environment in the park. This can be attributed to the wide variety of prey these snakes utilize. Common prey includes fish, insects, worms, leeches, snails, amphibians, small rodents and several other small prey (Hammerson 1999). The adaptability of the garter snake should enable both species to continue thriving within Chatfield State Park.
We have limited the garter snake accounts to significant observations due to the abundant populations in the park.
- April 15th, 2007: The first encounter took place near the Plum Creek drainage into the main reservoir. The air temps were in the high 60’s and windy. A large adult female was observed basking on a muddy shoreline.
- April 29th, 2007: The first encounter with a plains garter took place on April 29th. The temps were in the 70’s and the snake was located near a rock pile adjacent to the Audubon society. It appeared to be a large female.
- June 14th, 2007: In 85 degree weather we documented our first of seven suspected gravid Western Terrestrial females.
- June 20th, 2007: Two apparently gravid females were found in 75 degree weather.
- June 23rd, 2007: In 90 degree temperatures we viewed four suspected gravid females.
- July 28th, 2007: A juvenile garter (probably born 2006) was found under a rock a meter from the waters edge on a western facing slope that was an apparent species integrade.
- Oct 2nd, 2007: The final garter observation was north of the dam on the rocky shores of the South Platte River. Temperatures were in the 70’s. At approximately 1 p.m. a juvenile western terrestrial was seen on the west side of the river and shortly after an adult was seen on the east side of the river.
Common Name: Bull snake
Latin Name: Pituophis catenifer
Status in Chatfield: Common - Widespread
Total Finds as of 2009: 10
Chatfield State Reservoir has a strong, healthy population of P. catenifer. Nearly all of the land area is prime habitat for Bull snakes and they are frequently encountered by visitors and by park staff during their periods of peak activity. These large, powerful constrictors can grow more than 2 meters in length (Hammerson 1999). Bull snakes are among the parks most impressive reptiles and are a thrill to encounter in the wild. Most of the encounters by park goers are during May and June when the snakes are highly active throughout the day. The survey found that Bull snakes are not nearly as active during the daylight hours during the hotter parts of the summer (July, Aug, and Sept).
Senior Park Ranger Christina Bradshaw reported seeing several Bull snakes during the spring and summer and included pictures for verification. A woman employed at the horse stables inside the park reported seeing many adults inside the stables, up to six at one time.
May 19th,2007: A small juvenile was found under a piece of concrete along Plum Creek. The snake was discovered at 10:00 am and the weather conditions were 80 degrees and sunny. Remarkably, the same snake was found under the same piece of concrete on May 27th. This time the snake was about to shed its skin (determined by its bluish appearance), so it may have remained in the same place until it was ready to carry out this process. It was roughly the same time of day and similar weather conditions as the May 19th encounter.
May 27th,2007: A larger juvenile (perhaps one year older) was discovered roughly 100 meters away among some rocks. During this encounter the snake appeared to be emerging from a burrow among some rocks as a light rain shower was falling at midday. The temperature was around 82 degrees and it was partly cloudy.
- June 3rd,2007: A very large adult Bull snake was found coiled among a large piece of rusted metal approximately 2 meters from a large pond along the South Platte River. This observation came at 11:00 am on a partly cloudy day. The air temperature was approximately 75 degrees. Rain had fallen the previous night.
- June 10th,2007: Bull snake sightings came to a peak when four snakes were discovered in a short period of time in a small area along the South Platte River. Three of these were large adults and one was a large juvenile. Two of the large adults were found beneath concrete and one adult and the juvenile were found crawling about in midday near some ponds. The weather conditions on this day were sunny and 80-85 degrees.
- October 18th, 2009: Temps were in the mid 60’s and it was sunny. A hatchling Bull snake was found basking at the entrance of a burrow with four newborn Crotalus viridis. The snake was observed from roughly 12:45 to 1:45 pm.
Common Name: Prairie rattlesnake
Latin Name: Crotalus viridis
Status in Chatfield: Rare – Localized
Total Finds as of 2009: 5
According to reports from rangers and other park staff and the observations made by Baker and Farah, C. viridis is present in Chatfield, but in low numbers and in limited places. Much of Chatfield’s land area is open field and is suitable habitat for prairie rattlesnakes and they could potentially be found anywhere in the park, but they seem to be restricted to a narrow slice of land between the S. Platte River and Wadsworth Blvd. This area is dominated by gentle hills with open fields. The grasses here are tall and there are few trees. There are horse stables and trails in the middle of this area and many of the sightings by park staff (along with the only records during the survey) were in the fields and along the roads near these stables.
The 2007 survey only resulted in one first-hand observation of a C. viridis. Because of limited time and manpower, Labor Day (Sept. 3rd) was the only time the area surrounding the horse stables and along Wadsworth blvd. was surveyed. The goal of this day was to locate a rattlesnake and after searching for several hours in the late morning, a young adult of unknown sex was found basking amongst a pile of large rocks. The site was surrounded by long grass fields and was only 20 meters from the paved road leading towards the horse stables. Heavy vehicular and human traffic encircle this field which is only the size of several football fields.
The snake did not immediately rattle although it had nearly been stepped on. It was only after a rock was lifted and then dropped back into place right next to the animal that it begun to rattle, thereby revealing itself. It slowly retreated under a large rock, and continued to rattle for several minutes. A very small creek (only six inches across and 3 inches deep) ran beneath this rock. Conditions that day were calm, sunny, and in the mid-high 80’s F. The C. viridis was encountered at noon. Also on that day, Baker and Farah spoke with one of the workers at the horse stables and received first-hand accounts of both juvenile and large adult rattlesnakes on horse trails and also on paved roads near the stables throughout the warmer months of 2007.
- October 18th, 2009. Four newly born C. viridis were seen basking at the entrance of a burrow with a newly hatched P. catenifer. This was in the sandy hills approximately 150 meters north-west of the horse stables. The hillside was facing south-west. Air temps were in the high 60’s and the snakes were observed from about 12:45 – 1:45 pm.
Common Name: Western Chorus frog
Latin Name: Psuedacris triseriata
Status in Chatfield: Rare-Localized
Total Finds as of 2009: 50 (approximately)
This small and inconspicuous frog can be heard calling in the early spring while air and water temps are still very cold. The first “herp” encountered by Baker and Farah in 2007 was a male chorus frog calling from some willow bushes that were partially submerged in a small shallow pond on April 6th when the air temps were only in the 20's, the water was 42 degrees and it was snowing.
These shy little frogs are easiest to observe in Chatfield Park during the early spring when they congregate in select locations for breeding. Males call from partially submerged vegetation and are somewhat difficult to locate visually. Breeding activity was observed from April 6th to May 19th, but certainly extends, at least a little bit before and after these dates.
Chorus frogs were only seen (or heard) breeding in three small ponds out of the dozen or so within the Park. One of them is a long, narrow, semi-permanent body of water near the main road and bridge that cross the Platte River where it empties into the main reservoir. This is where the male was heard calling in 20 degree temps on April 6th. No chorus frog activity was witnessed at that spot after that date, but the location looks like prime habitat and an excellent breeding site. There are other similar small ponds nearby on the peninsula between "Catfish Flats", the Platte River and the main reservoir that look like perfect habitat for chorus frogs.
Two other ponds where chorus frogs were seen to be gathering for breeding were further south along the west side of the Platte River in the "Chatfield Wetlands" area. Here, along the Platte, are two ponds approximately 100 meters apart which are some of the only places in Chatfield where western chorus frogs have been witnessed breeding in substantial numbers. One pond was only around 1-1.5 meters deep at its fullest point of the year. It is heavily shaded by large, mature trees and the pond itself is choked by willow bushes and cattails. There is no stream flowing in or out of the pond and it is isolated from other bodies of water, yet it was crystal clear from spring through fall in 2007. This particular pond appeared to have the most breeding adults in the spring. At least several dozen chorus frogs were seen and heard. These observations were made from late April through mid May during the morning and afternoon hours. This is also the only location where newly emerged frogletts were found in the late July. No eggs or tadpoles were seen during the late spring or early summer, but several attempts were made to locate them. There were also northern leopard frogs breeding in this pond at the same time. The second pond was larger, deeper, and murkier and likely had small fish. This pond is shaded at one end and is otherwise exposed to the sun. The shoreline is made up of mostly round stones and it is connected to the Platte when the river is running high. This pond is also choked with cattails and willow bushes and seems to have fewer breeding chorus frogs during peak season.
After May, the chorus frogs seem to disappear from sight for the rest of the year. They are small, well-camouflaged and difficult to observe during the hot months of the summer. Survey volunteers did not observe a single chorus frog from the end of May until July 21st when three newly metamorphosed frogletts were seen on the shores of the clear, shaded breeding pond.
The three above-mentioned ponds were the only places in the entire park where chorus frogs were observed in 2007. Not a single one was seen or heard in the entire Plum Creek drainage area despite prime-looking habitat. On the opposite side of the park, along the Platte River, chorus frogs were seen at the south end of the main reservoir and also in ponds further to the south. Curiously, they were only seen on the west side of the river and in certain small ponds. It should also be noted that there were none seen in any of the ponds containing bullfrogs, which are a non-native species in Colorado. Unfortunately, bullfrogs occupy almost every single body of water inside the park, except for a few, semi-permanent ponds. Possible explanations for this localization of chorus frogs include: predation by bullfrogs, limited preferred habitat, pollution, and various other possibilities.
This species should be considered vulnerable to extirpation from Chatfield and special care should be taken not to disturb the three small areas where this frog is able to successfully breed. The few limited places they can be found breeding, and the strong presence of bullfrogs in Chatfield make it unlikely that the chorus frog will be able to expand its range within the park.
As of 2009, we have learned that the main reservoir water level will be raised by as much as twelve feet above it’s current level and that it will fluctuate regularly. This would inundate the entire region just north and south of the main road near Kingfisher Bridge and the mouth of the Platte River. Currently, the strongest population of Chorus frogs exists and breeds here. It will be interesting to see how much of their breeding habitat will vanish when the water level rises and to what extent new habitats will be created for them to use.
Common Name: Woodhouse toad
Latin Name: Anaxyrus woodhousii
Status in Chatfield: Common - Widespread
Total Finds as of 2009: 60 adults & 1000’s of larvae and new morphs
The woodhouse toad was the most abundant and widespread native amphibian seen in 2007. They can tolerate dry conditions better than any of the frog species and can be found far away from permanent water. Woodhouse toads happily inhabit every one of the many natural micro-habitats within Chatfield from the sparse, dry, sandy fields to the dense and permanently wet riparian zones. They even thrive around human dwellings and in heavily altered habitats. Woodhouse toads are prolific breeders and opportunistic feeders. Simply put, woodhouse toads are everywhere in Chatfield Park.
In the spring, adult toads can be observed both day and night as they forage for food and look for mates. During and after rains, woodhouse toads emerge in large numbers. Many are killed by cars on the roads within the park, but their numbers are so strong that the overall population is probably unaffected by these deaths. In addition to living in almost any type of habitat, woodhouse toads also breed and deposit eggs in almost any body of water. Tadpoles were found in the shallows of the main reservoir, in Plum Creek, many of the large and small ponds throughout the park, and even in rain-filled puddles on the shoulder of the park’s busiest road. These characteristics and many others contribute to making the woodhouse toad a widespread, common, and successful species in Chatfield State Park.
The first woodhouse toads of the 2007 survey were found at night (9:00 pm) on May 14th. It was raining and the air temperature was about 45 degrees. More than twelve large adults were found while slowly driving the main roads in the southern portion of the park. They were found hopping across the road and also pressed flat against the pavement, possibly soaking up the residual heat. Only one was seen dead on the road as a result of being hit by a vehicle.
- May 27th, 2007: Nine adult toads and one juvenile were seen in the wet fields adjacent to Plum Creek in the morning. One male was found calling in a flooded field at 8:30 am. The temperature was 70 degrees.
- June 2nd, 2007: A pair of woodhouse toads was found in amplexus at the outlet of a beaver dam along Plum Creek. This was taking place in approximately two inches of water at 9:00 am. Temperatures were in the high 60's and it was a sunny morning.
- June 3rd, 2007: A small juvenile was found half-buried in sand in an open field along the Platte River at 7:30 am. The morning was 60 degrees and sunny.
- June 10th, 2007: Many hundreds of woodhouse tadpoles were seen in some puddles that had formed along the main road through the park near the Platte River crossing. The several puddles were only 6 inches or so deep and approximately 1 meter wide and several meters long. There is no shade in this location. Also on this day, several hundred tadpoles were seen in the shallows of the main reservoir west of the "catfish flats". One male was also heard calling along the shore in this location. These observations took place between 7:00 am and 9:00 am. The morning was sunny and the air temperatures were in the 70's.
- June 20th, 2007: Two adult woodhouse toads were found on the trails near the "Chatfield Wetlands" along the Platte River around 9:00 pm on a calm, 75 degree night.
- July 7th, 2007: Many thousands of newly metamorphosed woodhouse toads were seen along Plum Creek. Hundreds of tadpoles were also seen in a beaver dam along Plum Creek. Water levels in Plum Creek were very low that day and several adult and larger juvenile toads were found in the creek itself. Weather conditions were hot (around 90 degrees) and sunny. The observations this day were made between 9:00 am and noon.
- July 28th, 2007: A large adult woodhouse toad was captured hopping about on a small island in the Platte River at the southern end of the Park. This encounter took place at around 10:00 am on a cloudy day with air temperatures in the low 70's.
- August 26th, 2007: At approximately 10:00 am, three juvenile woodhouse toads were found out in the open along the sandbars in the low-running Plum Creek channel. Conditions were sunny and in the low 80's.
- September 22nd, 2007: Four newly metamorphosed toadletts were found at the output of the beaver dam along Plum Creek where a pair was seen in amplexus on June 2nd. They were observed foraging at noon. The day was sunny and 80 degrees.
Common Name: Bullfrog
Latin Name: Lithobates catesbeianus
Status in Chatfield: Common - Widespread
Total Finds as of 2009: More than 60 adults and 1000’s of larvae and new morphs
Bullfrogs are the largest amphibian in Chatfield State Park and arguably the most common. The adaptability of this introduced species has allowed them to out-compete many of the native amphibian species. Bullfrogs appear to emerge later in the year than Colorado’s native amphibians. They are fiercely territorial and known to eat most things that can fit in their mouth including amphibians, snakes, small mammals and even birds of suitable size.
Bullfrogs can deposit more than 20,000 eggs in one breeding season (Hammerson 1999). Most native fish find the eggs and larval stage of the bullfrog to be unpalatable. This perfect storm of increased offspring and reduced predators, along with their adaptability to human modified environments will continue to diminish the park’s native herp populations.
We have documented countless bullfrogs from May through November. Tadpoles were observed through the summer, often basking in the shallows of several large ponds along the South Platte drainage system. Bullfrogs can be found in every permanent body of water in the park in several different stages of development. Numbers are difficult to quantify but at least tens of thousands are present in different stages of development in the park. Due to the abundance of encounters we have limited specific accounts to our first and final observations.
- May 19th ,2007 On our first observation, temperatures were in the high 60’s when we arrived at the Audubon society entrance and in the low 80’s around 11 a.m. when we left. More then ten adult and juvenile bullfrogs were observed amongst cattails from the floating footbridge; at the western most pond, no tadpoles were observed.
- November 4th,2007: Our final observation was in a heavily shaded oxbow, approximately three feet deep, eight feet across and twenty feet long near the South Platte River. We found young bullfrogs living with crayfish, adult northern leopard frogs and several small fish, one of which appeared to be a game fish.
Common Name: Northern Leopard frog
Latin Name: Lithobates pipiens
Status in Chatfield: Common - Localized
Total Finds as of 2009: 14 adults and 100’s of new morphs
The northern leopard frog is a “species of concern” in Colorado. Many factors have reduced populations including habitat destruction, water contamination and non-native species introduction. In 2007, Baker and Farah documented several small populations of northern leopard frogs from April through November within Chatfield park boundaries.
These frogs can be found in several riparian habitats along the South Platte River and Plum Creek drainage systems. They have been found cohabitating several seasonal ponds with the much smaller chorus frogs. However, leopard frogs are seldom found sharing habitats with the larger bullfrog. Bullfrogs are reluctant to populate the shallower pools of clear water and small weed-choked streams suited for leopard frog breeding. This may contribute to the leopard frog population’s resilience in the face of the larger invasive species.
Predators of the Leopard frog in Chatfield include adult bullfrogs, snapping turtles, garter snakes, raccoons, predatory fish such as largemouth bass and birds of prey such as herons. We have observed adults primarily in early spring and in early fall. Juveniles were mostly documented during the summer. Hundreds of newly metamorphosed juveniles were viewed radiating from the seasonal ponds in late summer during several days of frequent rains.
In recent years, the Northern Leopard frog has been reportedly declining in Colorado and throughout it’s range across the U.S. Front Range populations are known to have disappeared, although the reasons why are not definitively known. If the Platte River and Plum creek populations of Leopard frogs at Chatfield are to remain strong, they must be monitored and care must be taken to ensure that adequate breeding sites, over-wintering sites and summer foraging habitats are maintained.
- April 29th, 2007: The first experience with northern leopard frogs this season. Baker and Farah arrived at the park at approximately 8 a.m. and the temperatures were in the low 70’s and warmed to around 80 degrees at noon when we left. The calls of N. leopard frogs and chorus frogs attracted us to some seasonal shallow ponds void of fish with clear water and thriving vegetation throughout. We waded into the pond and an adult male was calling from heavy brush. When threatened, he dove approximately one meter to the bottom of the seasonal pond and froze in place for over a minute. We continued to observe and witnessed several adults swimming approximately .5 m under water. We captured several adults and identified them as males.
-July 21st, 2007: Temperatures were in the 90’s and the weather was sunny with a light breeze. Hundreds of newly metamorphosed juveniles were viewed radiating from the seasonal breeding ponds near the Audubon society entrance. This followed several days of frequent rains.
- Aug. 26th, 2007: Approximately six juvenile leopard frogs were seen along the edges of a shallow, weedy stream that runs parallel to Plum Creek. This was in the late morning.
- Nov 4th, 2007: Our final documentation of a N. leopard frog was in a heavily shaded oxbow approximately one meter deep, three meters across and seven meters long, near the South Platte River. Temperatures reached the high 60’s. We observed an active adult northern leopard frog living amongst young bullfrogs, crayfish, and several small fish.
- April 19th, 2008: An adult male was found calling in the presense of a large L. pipiens egg mass. He appeared to be calling from over the submerged mass and fending off other males that approached. This was in a flooded marsh on the west side of Plum Creek at the south end. Cattails dominate the vegetation and the water is slow-moving and clear, not stagnant. Nearby is a large pond with Bullfrogs.
Common Name: Tiger salamander
Latin Name: Ambystoma tigrinum
Status in Chatfield: Unknown (rare – localized?)
Total finds: 1
Chatfield has abundant suitable habitat for Tiger salamanders, but none were seen by Baker and Farah since the survey began in 2007 and reported sightings are rare. This species may be more common than it appears, or it may only exist in low numbers and in limited locations due to pressure from game fish, bullfrogs and other predators. Many temporary and small semi-permanent pools were examined in the spring in an attempt to locate breeding adults and larvae, but none were seen. The only confirmed account is from park volunteer Joey Kellner.
- Oct. 12th 2008. At 5:38 am, Mr. Kellner was driving south on the main road just past the horse stables (Towards Kingfisher bridge and the Platte River) when he spotted an adult crossing the road. The specimen was photographed and released.
Other Species of Possible Occurrence
Because of limited time and manpower, it is likely that several species of reptile and amphibian occur in Chatfield, but were not observed during the 2007-2009 survey. These include, but are not limited to:
Sceloporus undulatus (E. fence lizard), Nerodia sipedon (N. water snake), Thamnophis sirtalis (Common garter snake), Tantilla nigriceps (Plains black-headed snake) and Eumeces multivirgatus (Many-lined skink). Other possibilities include the occasional, Phrynosoma hernandesi (Short-horned lizard), Spea bombifrons (Plains spadefoot toad), and Liochlorophis vernalis (Smooth green snake) which have been recorded near the park.
We expect that as the survey continues in 2010 and beyond, one or more of the above-listed species will be documented in Chatfield State Park.
This study is the first of its kind and has initiated the process of documenting the reptile and amphibian populations at Chatfield State Park. Although many valuable observations have been recorded thus far, we recognize that much work remains before a complete picture of the park’s reptiles and amphibians will begin to take shape.
While several areas have been explored thoroughly, there are many areas of the park that have not been thoroughly searched. The majority of time was spent surveying the areas in and around the riparian zones of Plum Creek and the South Platte River. These areas are less frequented by park visitors and also contain the highest abundance and diversity of reptiles and amphibians in the park. Going forward, we plan to survey areas of the park that have not been sufficiently studied.
As we move into 2010 and beyond, we will continue to expand our knowledge and improve our data collecting techniques in hopes that this information can be used by future enthusiasts to further study the park’s reptiles and amphibians. Finally, we would like to thank Christina Bradshaw for her enthusiastic support of this project.
Hammerson, Geoffrey A. Amphibians and Reptiles in Colorado,Second Edition.
Niwot, Colorado 80544: University P of Colorado, 1999. 484
Fellers, Gary M. Standardized Protocol for Surveying Aquatic Amphibians,
Davis, California 95616: Division of Environmental Studies, 1995. 5-6
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