Oregon Spotted Frogs
Rana prestiosa
One of our Red-listed Canadian Species Breeding programs at Mountain View Conservation Centre is the breeding and conservation of Oregon Spotted Frogs. Once in their tens of thousands, this species ranged from the S.W. corner of B.C. down to California, but now their range has shrunk to only 6 colonies in B.C., 4 in Washington, and 24 in Oregon. There are no frog colonies remaining in California and the colonies in Washington and Oregon are very small. It is considered globally imperiled.
Their habitat loss is due to agriculture and housing development, particularly in the Lower Mainland of B.C. where extensive areas of marshy wetlands have been drained and developed. Other threats include agricultural runoff such as nitrates, invasive plant species that clog waterways, and non-native amphibian species such as bullfrogs which eat spotted frogs at every stage of their development.
History of the Spotted Frog Program at the Mountain View Conservation & Breeding Centre.
The Oregon Spotted Frog Recovery Program began in 1999 when it was decided to collect recently-laid eggs in the spring, nurture them in protected facilities while they grew and then release back into the wild in the fall.�
At Mountain View, the recovery program was initiated in 2003 when our new captive breeding facilty received over 800 embryos from the Aldergrove Pond. By the late summer release, we had reared over 500 frogs, surpassing the survivor rates of all other recovery program participants.
2004
Mountain View Conservation expanded our level of commitment to the program and received over 1,200 frog embryos from the Aldergrove Pond and over 1,300 from the pond sire on Seabird Island. The two batches of eggs were kept separate to minimize disease transfer and record specific survival rates. In the late summer over 750 frogs were returned to Seabird Island.
2006
We expanded the program to 10 breeding tubs. The Seabird Island First Nations Band initiated, and participated in, several community projects concerning area wetlands and the Oregon Spotted Frog.
2007
Our breeding program was expanded once again, this time to 20 breeding tubs. The Recovery Planning Team met to review the program’s success and set a goal of raising the number of frog sites in Canada from the current number of 3 to 20. One such site at The Department of National Defense in Aldergrove, was suffering from a Bull Frog infestation. An eradication program was initiated and if successful, the Spotted Frogs could be released
there in 2008.
Mountain View also continued to work closely with the Seabird Island First Nations Band. Their first Conservation Technician, Keena McNeil was funded by the Recovery Team and trained at Mountain View Conservation.
2008
Mountain View raised 2750 tadpoles with the resulting juvenile frogs being released in September back to the wild.
That year, the husbandry program received in 2500 embryos for the head starting program. Mountain View Conservation Center received 1875 to be raised in 30 tanks. It was found from studies done in 2008 that densities under 100/tub dramatically increased the size of the frogs produced and was the basis for the tub densities trialed that year.
In addition to a pureed lettuce diet, the facility supplemented tadpoles with frozen bloodworm. As small scale trial of affinity for bloodworm was conducted in 2008 and it was found, even at low volume, to show a significant increase in the size of the resulting frogs. The amount of bloodworm offered in 2009 was increased, maximizing the effect of the increased protein on overall size.
Overwintering of frogs was trailed over the 2008-2009 winter at Mountain View. This was quite a challenge with the severe winter weather conditions, however of 255 frogs that were trailed overwinter 247 survived. Overall their condition was good and they seem to have lost very little weight. This has confirmed to us that, outside of lack of predation, it is possible for captive raised frogs to overwinter successfully.
In addition Mountain View held a sub sample of eggs from one of the remaining wild populations that are under severe threat from surrounding intensive farming of livestock and crops, as well as adjacent proximity to active mining areas. These eggs will be raised in attempts to provide an assurance population of frogs from this site.
So far our tadpoles are doing great. We received them as eggs in late March. They began hatching in early/mid April and are about half way to reaching the size they need to be to start metamorphosing!
Trapping efforts at our known occupied sites was conducted throughout March. Frogs were trapped at the known wild sites and some of our captive raised frogs made and appearance. We found frogs returning to these breeding areas that were raised in our husbandry program in 2006 and 2007.
2008
In 2008 Mountain View raised 2750 tadpoles with the resulting juvenile frogs being released in September back to the wild. Frogs from 2008 are still reaching adulthood and should show up in future years!
2009
In 2009, the husbandry program received in 2500 embryos for the head-start program. Mountain View Conservation Center received 1875 to be raised in 30 breeding tanks. It was found from studies done in 2008 that densities under 100/tub dramatically increased the size of the frogs produced and was the basis for the tub densities trialed this year. In addition to a pureed lettuce diet, each facility will be supplementing tadpoles with frozen bloodworm. A small scale trial of affinity for bloodworm was conducted in 2008 and it was found, even at low volume, to show a significant increase in the size of the resulting frogs.
The amount of bloodworm offered in 2009 was increased, maximizing the effect of the increased protein on overall size. Overwintering of frogs was trailed over the 2008-2009 winter at MVCS. This was quite a challenge with the severe winter weather however of 255 frogs that were trailed overwinter 247 survived. Overall their condition was good and they seem to have lost very little weight.
This has confirmed to us that, outside of lack of predation, it is possible for captive raised frogs to overwinter successfully. In addition, Mountain View is holding a sub sample of eggs from one of the remaining wild populations that are under severe threat from surrounding intensive farming of livestock and crops, as well as adjacent proximity to active mining areas. These eggs will be raised in attempts to provide an assurance population of frogs from this site.
2011/12
- In our aquarium at Mountain View, we have four frogs who are 2 and 3 years old. We are hoping they will mate to produce egg masses. When that happens, the egg masses will be moved to another aquarium. When they hatch; we will have tadpoles, which will gradually change (or metamorphose) into froglets. Finally they will change into frogs. Some will remain with us, and some will be returned to the monitored populations in the wild. Prior to release, the frogs will be caught, counted, measure, weighed, and injected with a tag just under the skin. The tag indentifies the frog and helps with ongoing research of this species. There are frogs out in their natural habitat that used to be here at Mountain View! The released frogs have laid eggs and produced offspring. We are working toward a stable population in the wild.
In 2009, we built a wetland in our Conservatory in order to maintain a captive breeding program here at Mountain View. Our plan for 2012 is to breed our frogs and place the resulting tadpoles out in our wetland, so that we can monitor their progress over the following years. That way, we can help design better ways to build sustainable populations here in B.C., and offer assistance to the programs in Washington and Oregon, and build up a shared library of information on the health and progress of the Oregon Spotted Frog.
Click here to Donate: Adopt an Oregon Spotted Frog
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WILD STATUS:
Endangered
LIFE SPAN:
Unknown, but thought to be about 5 years.
WILD POPULATION:
Canada: 108 adults resulting in 54 breeding pairs US: approximately 1000 adults
DISTRIBUTION:
The Spotted Frog’s range has shrunk to 3 colonies in British Columbia, 4 in Washington and 24 in Oregon.
SIZE:
4cm to 10cm in length from snout to rump.
HABITAT:
Live in flood plain wetlands associated with permanent water bodies and prefer the warm, shallow edge of marshes to lay their eggs. They also use temporary ponds like the ones created from spring rains. The frogs prefer ponds that are exposed to sunlight that will keep the water warm.
REPRODUCTION:
Frogs reach maturity when they are 2 or 3 years old.
DIET:
Adult frogs eat mostly invertebrates such as beetles, flies, spiders and water striders. They are ‘sit and wait’ predators, remaining motionless in the water or on the shoreline, until something wanders by that looks tasty.
Tadpoles are grazers, eating algae, decaying plant mater and detritus.
In our captive breeding program the tadpoles are fed cooked pureed kale. The froglets dine on small pinhead crickets until they are released.
INTERESTING TIDBITS
- Medium size frog with black spots that have a lighter centre located on their head and back.
- Adult frogs are green, brown or reddish brown while Juvenile froglets are brown or olive.
- Two dorsolateral folds which are usually lighter in color appear as stripes along the back.
- The eyes are set in such a manner that it looks like the frog is looking right at you.
- When on land the frogs crouch close to the ground rather than sitting up straight like most red-legged frogs.
- Tadpoles begin to change into froglets in July and by August over 95% have morphed into frogs.
- The frogs are sensitive to nitrates which are common by-products of fertilizers. Water that would be considered safe for human consumption is not safe for these little frogs.
- Frog larvae and eggs are food sources for insects; but once the tadpoles form their greatest enemy is the bull frog. The bull frogs feed on the spotted frog at all stages of its life. There is an infestation of bull frogs in the lower mainland. Bull frogs are not indigenous to this area and are often released by people into the wild when they are no longer wanted as pets.
- Prior to releasing the frogs from our recovery program, they are caught, counted, measured, weighed and injected with a tag just under the skin. The tag identifies the frog and helps with the ongoing research of this species.
- The species name prestiosa means “precious” in Latin.
Native to B.C., these rare amphibians will soon become extinct if we cannot find a way to successfully breed and protect them.
It wouldn’t be possible for Mountain View Conservation to continue its programs without your donations! Please continue to support this extremely important work.You can help now!
Click here to Donate: Adopt an Oregon Spotted Frog
Or Click the Canada Helps logo and donate securely online.
You will recive a Tax Receipt immediately.
Thank you!
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