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Signs of Spring Update: April 9, 2001

Today's Report Includes:

Singing Frogs Signal Spring
Let the Frog Chorus Begin!
Way back in January, the chorus began:
"First a third grade student heard it, then a teacher heard it, then nearly everyone heard it!" (wolfnancy@aol.com) January 9, 2001, Petaluma, CA (38.22 N, -122.78 W)

Now people have heard the chorus in another 37 states and 3 provinces, as today's map shows.

"We had a 2-inch snowfall and after it all melted, it sounded like a thousand frogs croaking at dusk. We have three ponds within 1/4 mile from our house. (juliasusan@aol.com) January 28, 2001, Redding, CA (40.52 N, -122.71 W)

"We heard Spring Peepers at our school. They were very loud. We know that Spring is on its way." (mbtunsta@gcs.k12.nc.us) February 23, 2001, Oxford, NC (36.35 N, -78.65 W)

"Heard my first peeper frogs today. I have been out every day but this is the first time they have sung me a song this year. There was one inch of snow on the ground and it was 32 degrees F. so they must have just been happy that the sun was out." (fredroz@sprint.ca) March 26, 2001, St. Catharines, ON (43.10 N, -79.15)

"The ice is melting, and the peepers were heard on the Duck Pond, which is near our school. No peepers on the creek yet. The pond gets more direct sun, and melted sooner." (mes-moone@rondout.k12.ny.us)March 26, 2001 Accord, NY (41.80 N, -74.23 W)

You Think YOU Had a Long Winter!
After spending the winter buried under mud at the bottom of a lake or surrounded by molding leaf litter, it's no wonder frogs are ready to sing in the spring! And if you go outside on a rainy night, you might see them on the move. So, put on your rain slicker and your galoshes and grab your flashlight. You may see frogs traveling from their wintering area to a breeding pond. But, quiet on the set! Once you're near the pond, be sure to tread lightly--any disturbance and the frogs will stop their tune. Stay quiet and they'll likely start up the chorus again.

But What's All the Singing About?
In the breeding pond, just who is doing the singing? Who is listening? And what do the songs mean? Spring Peeper frogs can give us a glimpse into the answers:

Sweet Serenade
Frog expert Madeleine Linck tells us that it's generally the male frog doing the calling during breeding season. (She notes that many modern herpetologists refer to it as "calling.") While females can be vocal (they have a release call), it is only the males that call to attract females. Males get to the breeding ponds first, and will be calling when the females arrive.

Amphibian Advertising
According to Madeleine, the males' calls are known as "advertisement" calls, and they are very specific calls to attract females. The high pitched "peep, peep" call is a classic advertisement call. Madeleine tells us that experts Stebbins and Cohen conclude in their book, A NATURAL HISTORY OF AMPHIBIANS, that the advertisement calls are species identification signals. Only spring peepers will follow the location of a spring peeper chorus. There is also a trill call thought to be for territorial spacing. A trill call tells an intruding male that he is getting too close to another. James Harding, author of AMPHIBIANS AND REPTILES OF THE GREAT LAKES REGION, believes that females may favor males that give louder and faster calls. Which leads us to ask loudly:

Challenge Question #16:
"Why do you think a female might be more attracted to a louder, faster call? Is there some strategy in the call? What might it tell the female about the male?"

(To respond to this question, please follow the instructions below.)

And the Grammy Goes to...
The males will breed when a female approaches closely. Spring peepers have external fertilization, which means that the male will release his sperm as the female lays her eggs. Females lay single eggs or small clusters of eggs. When they are done, it is believed that the females leave the pond. The males stay in the pond for a longer time. You may be wondering:

Challenge Question #17:
"Why do the male frogs stay in the breeding ponds after they have already fertilized a female's eggs?"

(To respond to this question, please follow the instructions below.)

Calling All Frogs!
If you were a frog, you'd have to know the mating call of your kind. So tune your ears and learn the unique calls of these four frogs:

*Note: These sound files are large, so download with care.
All Recordings Courtesy of Lang Elliott Nature Sound Studio

Chorus Frog
(Pseudacris triseriata)

Spring Peeper
(Hyla crucifer)

Spotted Chorus Frog
(Pseudacris clarki)

Pacific Chorus Frog
(Hyla pseudacris)



When you think you know them as well as any frog, you're ready for the Frog Call Quiz:

Challenge Question #18:
"If you were a Spring Peeper, which of the above calls would you listen for, Frog Call A, B, C, or D?"

#A

#B

#C

#D


(To respond to this question, please follow the instructions below.)

Keeping an Eye to the Sky: Predator/Prey
Life in the spring is not just a song for frogs. Right when the first frogs are calling, they also need to keep an eye to the sky. Some of the birds that return close to the time that frogs emerge include the:

  • Sharp-shinned Hawk
  • Broad-winged Hawk
  • Northern Harrier
  • Sandhill Crane
  • Great Blue Heron
  • American Bittern
  • Fox Sparrow
  • Hermit Thrush
  • Red-winged Blackbird
  • American Robin

Some of these birds return north at this time in part BECAUSE the frogs are emerging. For some, the timing is just a coincidence. Do a little research on these birds and try to answer:

Challenge Question #19:
"Which of these bird migrations do you think are timed to coincide with the return of frogs? Give one or two reasons why you think so."

(To respond to this question, please follow the instructions below.)

Why Warm Water? Discussion of Challenge Question #13
Photo Courtesy Thomas L. Conlin.
Last time we heard about the humpback whales in Maui. We asked, "Why do most baleen whales breed and give birth in warm tropical waters even though they travel back to colder waters when the calves are a few months old?"
"Whales give live births so, I think that they would have to be in a warm environment in order to prevent shock so they don't have more difficulty in breathing," wrote Jake R. That's the right idea!

Warm tropical waters provide the whale calves a better chance to survive and grow. Warm waters keep them from getting cold before they have a chance to gain layers of blubber to keep out the chill of colder parts of the ocean. The babies can nurse from their mothers' milk, but warmer waters don't have as much food for adult whales as the colder seas. They go back to colder waters to feast on abundant food sources and gain back the weight they lost on the migration.

Whale Songs: Discussion of Challenge Question #14
"What might be some reasons why Humpback whales sing?"
Brady knows why: "The humpback whales sing because of communication reasons."
It seems likely that humpbacks sing to attract a mate, since the songs are sung on the breeding grounds. You might also be surprised to know that each distinct population of Humpbacks (e.g. North Pacific, North Atlantic) sings its own particular songs! These populations subtly change their songs from year to year, and every humpback within the population changes its songs in the same way.

Humpbacks on the Rise: Answer to Challenge Question #15
Looking at the counts of Maui's whales, we asked: "By what percentage did February 24 whale sightings increase from the year of lowest sightings to this year's number?"
Answer: The lowest count was 558, and the count this year was 952. The increase of 394 whales represents an increase of 70 percent.

Please Report "Signs of Spring" From Your Part of the World!
Report your "Signs of Spring" sightings to Journey North.
Remember to share your sightings of first frogs, earthworms, red-winged blackbirds, barn swallows, emerging leaves, flowing sap, melting ice and other spring events.


How to Respond to Today's Challenge Questions:

IMPORTANT: Answer only ONE question in each e-mail message.

1. Address an E-mail message to: jn-challenge-spring@learner.org
2. IMPORTANT: In the Subject Line of your message write: Challenge Question #16 (or #17 or #18 or #19).
3. In the body of the message, give your answer to the question above.

The Next Signs of Spring Update Will be Posted on April 23, 2001.

Copyright 2001 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form

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