TO READ THE BEST FROG BOOK EVER WRITTEN?
June 30, 2013
of the United States and Canada" (2013; Johns Hopkins University
Press) by C. Kenneth Dodd Jr. arguably stands as the best modern reference
book ever written on this important group of amphibians. The term "frogs"
includes the common toads with which everyone in America is familiar,
and the book covers pretty much everything scientists have learned about
their biology. The comprehensive coverage of the ecology, reproduction,
diet, and conservation of the 100 native U.S. frog species (which includes
the 27 found in Canada) is excellent.
982-page book has almost 400 color photos of frogs, toads, and treefrogs
as well as the eggs, tadpoles, and habitats of many of them. Range maps
show the distribution patterns of the naturally occurring species plus
those of six "established nonnative species" that are now
firmly entrenched in one or more states.
6,800 living species of frogs are known today, so the paltry 1.7 percent
of the total number of the world's species that are found north of Mexico
might seem insignificant. But as with many groups of animals, some of
the most in-depth ecological research on frogs has been done by scientists
in the United States and Canada. Consequently, a thorough summarization
of this nature constitutes not only a major literary undertaking but
also a significant contribution to the field of herpetology.
says in the introduction of his book, "Frogs are now at greater
peril worldwide than at any time in recent geologic history." The
same can be said about many other groups of free-living animals including
turtles, sharks, and monarch butterflies. One progressive step in the
conservation process is a synthesis of what is known about the life
history and ecology of particular groups of organisms in prescribed
places. The author is to be commended for doing an admirable job on
behalf of the frogs and toads of the United States and Canada.
the status of six frog species that arrived in the United States without
an invitation. For half of these frogs from other countries that have
found a U.S. home, Hawaii is the only state where they have become established.
Ironically, Hawaii is also the only state with no native frogs whatsoever
(even Alaska has three native species). Other invasive species include
the greenhouse frog, which is native to Cuba but found throughout most
of Florida and parts of Georgia, Alabama, Mississippi, and Louisiana,
as well as Hawaii. Cuban treefrogs, first reported in Florida in 1931,
are now established in the Florida peninsula and have been sighted in
Savannah, Houston, and other isolated cities where they might have arrived
via horticultural shipments, motor homes, or boats on trailers. The
African clawed frog, first introduced to U.S. laboratories in the 1930s
for pregnancy tests and 40 years later in the pet trade, are totally
aquatic. Populations are now established in California and Arizona.
How these various nonnative species might negatively affect other frogs
or, especially in Hawaii, even other animals is still being investigated.
conservation, the book has an important and sobering assessment in the
last two pages, a section titled "Index of Potential Stressors."
References to scientific studies are given for a total of more than
100 natural and commercially produced chemical contaminants that have
been suspected or documented to have negative impacts on frogs when
they are introduced into natural habitats. The author states that frogs,
"with their unprotected eggs, aquatic larval development, [and]
permeable skins ... are being saturated by a host of lethal and sublethal
toxic substances." Some, such as DDT, lead and mercury, are not
surprising to find on the list. Others are chemical names listed in
various pesticide and herbicide products found in garden sheds. Not
all have been proved to be detrimental to frogs but each bears supporting
research to find out if we should be concerned. We may not have as many
frogs as other places, but we certainly want to keep the ones we've
you have an environmental question or comment, email