CaliforniaHerps.com

A Guide to California's
Reptiles and Amphibians




Sounds of
Northern Pacific Treefrog - Pseudacris regilla

(Baird and Girard, 1852)

(= Pacific Treefrog - Hyla regilla)
Click the play button or the speaker icon to listen to an mp3 sound file.


Advertisement Calls


An advertisement call is the most well-known call of a frog. It is produced by a male during the breeding season to attract females of his own species. It can also serve an agressive function to defend his calling site by warning rival males of his presence. Frogs usually make the calls around bodies of water that are suitable for breeding and egg laying. These calls can be heard during the evening and at night, and sometimes during daylight at the peak of the breeding season.

The Northern Pacific Treefrog produces two different kinds of advertisement calls: a two-parted, or diphasic call, typically described as rib-it, or krek-ek, with the last syllable rising in inflection, and a one-part, or monophasic call, also called the enhanced mate attraction call.

(The call of the Baja California Treefrog is known throughout the world through its wide use as a nighttime background sound in old Hollywood movies, even those which are set in areas well outside the range of this frog. The call of the Baja California Treefrog is identical to that of the Sierran Treefrog and the Northern Pacific Treefrog, and it is possible that the calls of all of these species were also used as movie sound effects.)


Diphasic (two-parted) Call

This call is produced during the day and at night, often in large choruses.
This is a 35 second recording of a large group of Northern Pacific Treefrogs calling at night from a pond in Del Norte County. It begins with one frog breaking the silence, then others quickly follow until the chorus rises in volume before it is faded out. This is the typical sound of a large chorus of these frogs, which often continues for more than ten minutes.

This is a 9 second recording of the advertisement call of single male Northern Pacific Treefrog recorded at night near the Columbia River in Klickitat County, Washington. This call is faster and higher in pitch than the Yakima frog.

This is a 4 second recording of the advertisement calls of a single male Northern Pacific Treefrog, recorded at night on the banks of a small pond in Yakima County, Washington. Insects can be heard in the background.
This is a recording of a small group of frogs calling at night in Grant County, Washington.
Waveform and Sonogram
This is a recording of one repetition of the call of a male Northern Pacific Treefrog calling at night in Yakima County, Washington.

The image on the right is a visual representation of this call.

Click on it to see a larger image.

Click here for information about how to read the waveform and sonogram images.

Monophasic (one-part) (enhanced) Call

This call is produced during the day and at night. It is produced at a high rate when a male is approached by a female, and he continues to produce it until he has amplexed the female.

 
This is a 12 second recording of the fast enhanced mate attraction cal of a male Sierran Treefrog. It was recorded at about 9,000 ft. in Alpine County in late June at the beginning of the breeding season when the snow was melting around the breeding pond. Another deeper single-note call is heard along with birds and flowing water.

(This sound is the same as the sound made by the Northern Pacific Treefrog.)



Trilled Encounter Call


The trilled encounter call is a raspy trilled sound. It is an aggressive signal aimed at other males and is used to establish spacing between them at the calling site during a breeding chorus. The encounter call is typically heard during the beginning of the chorus when territories are being established and then later when a male intrudes on the territory of another male either physically or with very loud calling.
 
This is a 7 second recording of trilled encounter calls made by male Baja California Trefrogs, recorded in Riverside County in mid March on a sunny afternoon. The recording starts with some typical advertisement calls, then ends with three trilled calls.

(This sound is the same as the sound made by the Northern Pacific Treefrog.)


Land Call


The land call is a prolonged one-note kr-r-r-ek sound made much of the year, especially when it is raining. Land calls can be heard during the day, often in wooded areas away from water. I have seen frogs produce this call while they were sitting high on a tree branch as well as when they were on the ground.
Northern Pacific Treefrog
This is a 17 second recording of land calls of a single Northern Pacific Treefrog during daylight in October on a wooded trail, King County, Washington. An airplane is heard in the background.

This adult frog was found as seen here about 10 feet up in a tree producing the land call one afternoon in Thurston County, Washington.






Release Call


The release call is made by a frog when another male frog attempts to clasp its back in amplexus. A frog will also produce this call when it is grabbed across the back by a human, and probably also when it is grabbed by other types of predators.
 
This is a 5 second recording of 3 release calls produced by a male Sierran Treefrog in breeding phase as it was grabbed across the back. (The frog was not harmed.) Recorded in Alpine County.

(This sound is the same as the sound made by the Northern Pacific Treefrog.)

Short Videos
Northern Pacific Treefrog Sierran Treefrog
A male Northern Pacific Treefrog calls while floating on a pond in the Cascades Mountains of Washington on a sunny Summer day. This is the two-part advertisement call.

A male Sierran Treefrog makes the one-part or enhanced call from the edge of a small temporary snow-melt pond at 8,600 feet elevation in Alpine County. This species is identical in sound and appearance to the Northern Pacific Treefrog.
Sierran Treefrog Sierran Treefrog
In this short video we see three adult male Sierran Treefrogs make their encounter call. These calls were elicited by making a raspy noise near the frogs as they were sitting on the water in calling position. The call of each frog is slightly different. This species is identical in sound and appearance to the Northern Pacific Treefrog. A male Sierran Treefrog makes a few advertisement calls, until a second frog between him and the camera, makes a raspy trilled encounter call. The first frog responds with his encounter call, but when the second frog continues, he then turns to face his aggressor and charges toward him, continuing to make his encounter call. The second frog changes his call to a faster one part call. Finally they both stop, and the first frog sucks in his throat sac and dives underwater. This species is identical in sound and appearance to the Northern Pacific Treefrog.
Northern Pacific Treefrog Habitat  
In this short video you can hear some land calls and see a couple of loations in Washington where the land calls are being made. (And you get an idea of how hard it is to find a land-calling frog in such dense vegetation.)  


You can listen to more recordings of Northern Pacific (Pacific) Treefrogs on this cd:

Carlos Davidson - Frog and Toad Calls of the Pacific Coast - Cornell Laboratory of Ornithology

cd cover

and on the cd that comes with this book:

Lang Elliott, Carl Gerhardt, and Carlos Davidson - The Frogs and Toads of North America - Houghton Mifflin Harcourt.

book cover



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