HAVE QUESTIONS ABOUT FROGS
by Whit Gibbons
October 12, 2008
spawn numerous environmental changes, including excessive rainfall. Almost
no one today believes the once common myth that small frogs sometimes
fall out of the sky during heavy rains. Nonetheless, an abundance of frogs
and toads can be seen hopping around after heavy rains. An autumn with
above average rain in some parts of the country has brought frogs to the
attention of many people. The following are questions people have asked.
Q. I have
seen several different sorts of frogs during recent rainy spells. How
many kinds of frogs and toads are there in the world?
have described 5,645 distinct species of frogs throughout the world and
34 different families. The family of the true tree frogs has the most
species, with more than 850 species described from the Americas, Europe,
Southeast Asia, and Australia. Many are characterized by having expanded
toe tips that aid in climbing and long, thin legs for jumping. A completely
different family of frogs known as the Asian tree frogs, which occur in
Africa, Asia, and Indonesia, has almost 300 species. Although they look
and behave like the other tree frogs, they are not closely related.
true frogs make up another large family of frogs, with more than 830 described
species. The most familiar ones have robust bodies and strong hind legs
and include the well-known bullfrog, several kinds of leopard frogs, and
rare gopher frogs of the Southeast.
common and largest family of toads throughout most of the globe is the
family Bufonidae with more than 500 species. Members of the family are
found on all warm continents except Australia, although since the introduction
of the tropical American cane toad it is now established in many parts
of that country as well. The species of toads differ among and within
countries, but the squat brown insect-eaters commonly seen in gardens
and backyards in most parts of the United States are also found in regions
as diverse as Great Britain, China, India, and Argentina. The rare burrowing
toad of southern Texas, which ranges through Mexico and Central America
to Costa Rica, and the purple frog, a rare burrowing species from India,
are distinctive in that they represent the only species in their family.
Q. I have
lived in three southern states where we seem to have a lot of different
kinds of frogs. Which states and which geographic regions of the world
have the most species of frogs?
A. Of the
more than 5,600 species of frogs known, 107 are found in the United States.
Russia and Canada each have 24 species, compared to 27 in France, 226
in Australia, and 300 in China. All of these are low numbers compared
to tropical regions of South America, where the highest numbers of frog
species are found. For example, Ecuador has 444 species of frogs; Colombia
has 678 species; Brazil has 776.
In the United
States, the humid southeastern states from the Carolinas to Texas have
the greatest concentrations of species. Alabama, Georgia, South Carolina,
and North Carolina all have high numbers of native species, with 30 species
each. Florida now has 32 species of frogs with the inclusion of three
established introduced exotics in the Miami area. Texas has more species
than any other state with 41, in part because of the presence of several
predominately Mexican species along the border.
the large western states from New Mexico and Colorado to California and
Oregon has as many species as any of the coastal southeastern states.
No northern states have as many species of frogs as southern ones. For
example, North Dakota has nine species, and Alaska has only five native
species. Hawaii is the most depauperate of native frogs, having none.
However, a half dozen species of introduced frogs now live in Hawaii,
including species from Japan, Puerto Rico, the U.S. mainland, and tropical
biologists have reasons for concern as many of the world's species are
declining, and several have recently gone extinct. Learning more about
these fascinating creatures is the first step in solving environmental
problems they face.
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