Frog and toad survey: Run #2

We are continuing with our frog and toad call surveys. This week we completed the second run, which is done between May 20-June 5. The summer nights mean that the sun sets later, so we split the run into 2 nights, May 29 and 30, to avoid being out until after 1:00 am.

As expected, the actors in the play have changed a bit. Wood frogs and Northern leopard frogs were done calling. Spring peepers were still calling in a few locations and will be done soon. Boreal chorus frogs were no longer dominating the chorus, but they were still a noticeable presence.

New frogs and toads included American toads, Gray treefrogs, and Cope’s gray treefrogs, for a running total of 7 species for the watershed so far. Our record-setter location this time was Long Marsh in North Oaks, which had 5 species calling: Spring peepers, American toads, Gray and Cope’s gray treefrogs, and Boreal chorus frogs. There was still a full chorus of Spring peepers calling in this location, which was especially nice to hear.

Gray treefrogs were center stage at all locations. Their melodic trill can become quite the ruckus when hundreds to thousands of frogs are calling. They are distinguished from Cope’s gray treefrogs by their call or by their DNA--call is much easier and faster. There is no way to tell the species apart by sight. In a loud constant chorus of Gray treefrogs, it can be difficult to distinguish the Cope’s lower-pitched and faster trill. This is one reason why we indicate the strength of the chorus in data collection. If there is a loud chorus of Spring peepers or Gray treefrogs, it may not mean that quieter species were absent but rather that they were covered up by other calls. Coloration on Gray and Cope’s gray treefrogs can change rapidly as they camouflage with their environment…and sometimes they don’t camouflage; they stick right out as in the photo at the top of this page. These treefrogs can range from creamy white, to gray, to bright green.

See how many species you can detect in the choruses here from last night. Give it a try before you read my description. How would you describe them, and how many different calls do you hear?

Sounds of an early summer evening at Long Marsh in North Oaks and at Tamarack Nature Center:

Long Marsh recording

The calls in this first recording are quieter, so note that you may want to turn down the sound after you listen to this one. If you listened to the calls last time, you’ll hear Boreal chorus frogs (that sound like running your finger down a comb) and Spring peepers (loud single peeps). Add to that the long, steady trill of the American toad, and the loud fluttery trill of Gray treefrogs. In this example, you can hear how the Gray treefrogs are a little way in the distance and a strong chorus. You will not likely hear any Cope’s gray treefrogs standing out with all of the other noise. You will be able to distinguish them in the next recording.

Tamarack Nature Center recording

These calls were recorded at the small wetland area at the entrance of Tamarack Nature Center. Here you can clearly hear the higher-pitched, melodic trill of the Gray treefrog. Listen for another call that sounds similar, but is faster and lower pitched. That’s the Cope’s gray treefrog. American toads come in around 15 seconds with their sustained trill. Boreal chorus frogs are clear and easy to distinguish in this recording also.

We have one more run to do to capture all of the breeding seasons of our frogs and toads. We’ll keep you posted. In the meantime, happy listening!

Dawn Tanner, Program Development Coordinator


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