In Other Words
October 21
2021
7
Diggin’ in the Dirt: What Happened to the Tree Frogs?
By Chip Bubl
Oregon State University
Extension Service – Columbia County
The OSU Extension Office is fully re-
opened. Masks still required inside.
The best way to reach me directly is
with the email below.
Will there be an OSU Master Gar-
dener class next spring?
We are actively planning for an
in-person OSU Master Gardener class
starting next February. The class would
most likely be held on Monday, dur-
ing the day, in St. Helens for about 10
weeks. If you think you might be inter-
ested, let us know. Call Sonia Reagan or
myself (Chip Bubl) at (503) 397-3462.
Your statement of interest doesn’t com-
mit you to anything but will give us
some idea if people are ready to return
to in-person classes. If COVID mutates
again, it might have to be a digital-only
class.
What happened to the Pacific tree
frogs last summer?
This question was raised by a
reader who was quite bothered by the
short cycle of tree frog croaking and
thought it needed looking into. I am not
an amphibian expert but it is a question
worth pursuing. Changes in natural pat-
terns can open our eyes to larger factors
in play.
To understand what might have
happened, it is important to know some-
thing about our Northern Pacific tree
frog (Pseudacris regilla). Our frog is a
sub-species of a larger population that
extends from British Columbia to south-
ern California. It is the most common
frog species in our region and one most
of us have seen often. It is small, from
¾ of an inch to 2 inches in length. The
females are larger than the males. Their
overall color can be bright green to a
more subtle brown. But here’s the trick.
They can change color and/or hue inten-
sity to assist their insect hunting or to
escape predation. There are rare cream-
colored variants. All Pacific tree frogs
have a dark brown line that extends from
their snout backwards on both sides of
their head to where their forelegs start.
This is easy to see on green frogs, more
obscure on brown ones.
Our tree frogs have little web-
bing in their feet but extraordinarily
large round toe pads that act like suction
cups and allow them to climb almost
anything. At our home, they often climb
into hanging fuchsia baskets
near an evening light source
that attracts night flying insects,
their favorite food. Some nights
they are quite talkative, oth-
ers, not so much. Other food
includes ants, beetles, mites,
small snails, and other more
land active creatures.
They need water to
breed. That water can be as
small as vernal pools (very
common in some basalt areas
in St. Helens), marshy pas-
tures, edges of ponds, and the
like. Mating is generally the
only time they take to water. The rest of
the year they are on land in a variety of
habitats. It is thought that their ability
to live mainly out of water makes them
less vulnerable to fish or other amphib-
ians that might fancy them. Their major
predators are garter snakes (I have seen
the snakes swimming in vernal pools
eating tadpoles), raccoons, skunks, and
herons. Rough-skinned newts eat their
eggs as do other amphibians.
Tree frogs mate from late Feb-
ruary through June. It is somewhat
weather dependent as they need water
and a bit of warmth to get active. There
are sometimes deafening male choruses
which often start after a rain. These are
“advertisement calls” to females and
probably other males. One year, a per-
son in Warren called me, asking what
she could do about the “irritating” calls
of the frogs. She didn’t think it was fun-
ny when I said, “love them”. I did won-
der why she moved into a rural area.
“krr-r-r-ek!”
There are good descriptions of
male tree frogs head butting or wres-
tling other males to control their terri-
tory, temporary as that territory may
be. When mating, the male climbs on
the back of the female. She releases her
eggs into the water and the male follows
by releasing his sperm on top of the now
floating eggs. Tadpoles follow. The tad-
poles mainly consume algae and other
pond micro-plants.
During dry periods, tree frogs
are mainly nocturnal. They avoid pre-
dation by blending in and staying still
so as not to draw unwanted attention.
That said, I have seen great blue herons
spearing them in pastures, so they do
face challenges.
Back to the first question, why
was their croaking subdued if not com-
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though there is one that is a prob-
lem further south in their range.
Heat could create more disease
pressure. Their response to last
summer is yet to be determined. I
believe these great little frogs are
survivors and will be back strong.
And that is where I have to leave
the question, for now.
Pacific tree frog (Pseudacris regilla)
www.commons.wikimedia.org
pletely silenced for a time this year?
My best bet was that they were late get-
ting ready to mate and then everything
dried up fast. They need ponds nearby
to lay their eggs in, and therefore will
stop calling if those ponds start to dry
up. Also, if it gets really dry, the males
will retreat back to their hibernacula.
They are amphibians, which means they
need to stay cool and moist. So if it’s too
dry, it will be hard to find them outside
of a cool, wet location. While there are
relatives that survive in the intense heat
of the San Joaquin Valley, I don’t think
our Vernonia green friends were physio-
logically prepared for it. Schedules were
scrambled. Timing was off and then it
was 116°F. It stopped mosquitoes dead
in their tracks. Probably other insects
as well. Our chorus tree frogs certainly
haven’t experienced those conditions
much in their evolution here. I couldn’t
find any information about diseases af-
fecting this population in this area al-
Free newsletter (what a deal!)
The Oregon State Univer-
sity Extension office in Colum-
bia County publishes a monthly
newsletter on gardening and
farming topics (called Country
Living) written/edited by yours
truly. All you need to do is ask for it and
it will be mailed or emailed to you. Call
(503) 397-3462 to be put on the list. Al-
ternatively, you can find it on the web at
http://extension.oregonstate.edu/colum-
bia/ and click on newsletters.
Take excess produce to the food bank,
senior centers, or community meals
programs. Cash donations to buy
food are also greatly appreciated.
The Extension Service offers its pro-
grams and materials equally to all
people.
Contact information
for the Extension office
Oregon State University
Extension Service –
Columbia County
505 N. Columbia River Highway
St. Helens, OR 97051
(503) 397-3462
Email: chip.bubl@oregonstate.edu
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