Monday, June 23, 2014

Treefrogs in trees

Gray treefrogs (Hyla versicolor) are often heard calling from trees near and over wetlands.

Recording of the gray treefrog (from the Amphibian Research and Monitoring Initiative)

These frogs are often mistaken for birds because of their musical trill and calling location.
I recently found one calling from a branch in a small tree near a wetland.
Gray treefrog (circled in red) in small tree at edge of wetland
Zoomed in to see gray treefrog sitting on branch

The gray treefrog is found throughout much of Minnesota and can change from mottled gray to mottled green. (Link to MN DNR gray treefrog page).

Gray treefrog in 'gray' phase

Gray treefrog in 'green' phase

Thursday, June 19, 2014

Vernal Pool - Identification and Verification

Vernal pools are small seasonally flooded wetlands that provide vital habitat for many native amphibians and aquatic insects that require fish-free wetlands to survive. (Photos to right show a few examples of vernal pools in northern Minnesota)
Vernal Pool Workshops: History, Identification, and Monitoring in the MN Coastal Zone
 Join researchers from the Natural Resources Research Institute and participate in hands-on workshops investigating 'Vernal Pools' in the region. Workshops are free and open to the public. Participants will be introduced to methods for locating and identifying vernal pools. These workshops will help raise awareness about the value and importance of vernal pools.

Hartley Nature Center - April 26, 2014 10 am - 1 pm (Save the Frogs Day!)
Jay Cooke State Park – May 17, 2014 10 am - 1 pm
Tettagouche State Park – June 7, 2014 12 - 4 pm
Boulder Lake ELC - June 13, 2014 12 - 4 pm
Sugarloaf Nature Center - June 14, 2014 10 am - 1 pm
Grand Marais – June 28, 2014 12 - 4 pm

For more information:

Interested in Vernal Pool Workshops and Volunteering?

Submit vernal pool locations and data

Saturday, May 10, 2014

Finally spring in Duluth!

Spring has finally arrived in Duluth!

Vernal pools (small, temporary wetlands) are almost ice free and wood frogs and spring peepers are starting to breed. Get out and hear the chorus of the early spring breeding frogs - it only lasts a few weeks.

Video of spring peeper calling 
(another spring peeper and chorus of wood frogs in the background)

Spring peeper - with characteristic X on back
Wood frogs in amplexus
Newly laid wood frog eggs

Thursday, April 17, 2014

Citizen Science Frog Monitoring at Hartley Nature Center - April 26

DULUTH, Minn. – Outdoor enthusiasts of all ages are invited to learn about two research opportunities taking place at Hartley Nature Center, April 26 from 10 a.m. to 1 p.m. The Saturday workshop will provide information and hands-on activities for frog monitoring and vernal pool identification and assessment. Presentations and guided walks to vernal pools starting at 10 a.m., 11 a.m. and noon.

“Anyone who is looking for an excuse to hike in beautiful Hartley Park is welcome to join us to learn about data collection for our long-term frog monitoring project and vernal pool status in northeastern Minnesota,” explained Jennifer Olker, scientist at UMD’s Natural Resources Research Institute. Vernal pools are temporary ponds that are vital breeding habitat for many forest creatures. They are not currently protected in Minnesota and scientists lack critical information about them.
Vernal Pool in Early Spring
Workshop participants will learn about Minnesota’s frogs and toads, the current state of amphibians, importance of small wetlands, and how they can help, including two volunteer opportunities: 

Western Chorus Frog and Wood Frog
helping collect data

1) Frog Monitoring Project: conducting surveys at Hartley Park during three periods: April 25 – May 15, May 30 – June 15 and July 5 – July 20

2) Vernal Pool Identification and Field Verification: in Hartley Park and other locations across northeast Minnesota from snowmelt through July. 

Pre-registration is recommended by contacting Jennifer Olker at,, 720-4344 or Ryan Hueffmeier,, 720-4379.

April 26 is also national Save The Frogs Day, the world’s largest day of amphibian education and conservation action. Poetry and art contests are being held as part of the celebration. Learn more at

The Natural Resources Research Institute’s mission is to foster the economic development of Minnesota’s natural resources in an environmentally sound manner to promote private sector employment.

Tuesday, July 17, 2012

Stories of frog malformations

"Whatever happened to the ‘deformed frogs’ problem?"
This is a question that we get all the time.

I have tried to answer it for Ask NRRI:
The ‘deformed frogs’ problem has not disappeared, even though it no longer makes the nightly news. Although the widespread occurrence of amphibian skeletal malformations has been considered an important environmental issue and researched extensively around the world, causes of these deformities in wild populations have been difficult to pinpoint.
One thing that scientists agree on is that deformities can result from multiple causes and that these causes vary from region to region. Scientists also believe that many of the causes are primarily due to, or exacerbated by, human activities. The major causes of malformations identified so far are chemical contaminants, parasites, and injuries from predators. At any given location, one or more of these factors could cause amphibian skeletal malformations as well as amphibian population declines. Additionally, the causes of malformations at one site may differ from those at another site.
Deformed frogs continue to be found across Minnesota and around the world, although rarely in huge outbreaks like that discovered in 1995 at Ney Pond in Le Sueur County, and other locations around Minnesota. Research continues to resolve uncertainties in the amphibian malformation phenomena.
Malformed metamorphic Northern leopard frog with extra digits (© NRRI/UMD)
Malformed metamorphic Northern leopard frog with missing foot (© NRRI/UMD)

 There is also a new book out by Judy Helgen (Peril in the Ponds: Deformed frogs, politics, and a biologist's quest) which documents how the research on amphibian malformations got started and her efforts to solve this 'mystery'.

 Minnesota Public Radio covered this story this morning on Morning Edition (Deformed Minnesota frogs still largely a mystery 17 years later) and will be covering it again on All Things Considered (sometime between 3 and 6:30 pm). Here's a preview from the Bob Collins News Cut today (7/17/12):
 "Minnesota made headlines around the world in 1995 when school children discovered dozens of grossly deformed frogs in a pond in south central Minnesota. Soon there were more reports of deformed frogs from around Minnesota and other states -- gruesome pictures of frogs with extra legs, or missing legs, or eyes in the wrong place. Everyone wondered if the frogs were a sign that something was wrong in the environment that could also spell trouble for humans. Seventeen years later scientists still have not completely solved the mystery of what caused frogs to develop those deformities. But we do know more about how the investigation unfolded and how the case of the deformed frogs spawned a fight within the Minnesota Pollution Control Agency about whether the agency should even look into the matter. MPR's Stephanie Hemphill will have the story."
There is also an article on frog malformations in the local section of the Duluth News Tribune (printed MPR story).

Wednesday, May 9, 2012

Tadpoles and Marsh Marigolds

Wood frog tadpoles in Duluth are about 10 mm long right now (about the length of my pinkie finger nail). At this size, they are hard to photograph.

To put this development into perspective, on this day in 2011 the wood frog eggs had just started to hatch.

In many wetlands and ditches, marsh marigolds are blooming,

marsh marigolds - look for them in your neighborhood wetland or roadside ditch

wood frogs are still hanging around,
and spring peepers and chorus frogs are calling (and laying eggs).
Spring peeper (adult)
Western chorus frog eggs - starting to develop

Friday, April 27, 2012

Fairy Shrimp

 Fairy shrimp are small crustaceans that live in the same small temporary wetlands that wood frogs use for breeding. These aquatic critters are fascinating to watch as they swim around upside down with their many leaf-like or feathery legs.

I recently found large numbers of fairy shrimp swimming around developing wood frog eggs. There were hundreds of them! I had never seen this before, so I tried to capture some pictures.
15+ fairy shrimp next to wood frog egg mass
close-up of one of the fairy shrimp
To learn more about Fairy Shrimp (and vernal pools) visit The Vernal Pool Association's website (based in Massachusetts).