Illinois Natural History Survey Reports

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ILLINOIS
NATURAL
HISTORY
SURVEY R e p o r t s
Winter 2005
No. 382
I N S I D E
Evaluation of Growth,
Survival, and Thermal
Selection Differences
among Genetic Stocks
of Muskellunge
2
SPOIL: The Springs of
Illinois
4
Soybean Virus
Transmission by
Rootworms
5
Species Spotlight:
Least Weasel
6
Naturalist’s Appren-tice:
Scientific Illust-ration—
Draw a Least
Weasel
7
Continued on back page
Illinois has a new animal immi-grant—
the nine-banded arma-dillo
(Dasypus novemcinctus).
This quirky, armor-plated mam-mal
actually is native to the New
World tropics. It first was docu-mented
in the U.S. in the Rio
Grande Valley of southern Texas
in 1849. At the beginning of the
twentieth century the armadillo
was restricted to Texas, but it has
been steadily moving northward
and eastward. Escaped animals
established a population in
Florida that also has spread.
Natural dispersal has been aug-mented
by people intentionally
and inadvertently transporting
armadillos to new places. Over-all,
the species has expanded its
Was That an Armadillo I Just Saw?
range 4–10 km/year, which is
considered rapid for mammals.
By 1954 the armadillo’s range
included southern Oklahoma, all
of Louisiana, and southern Ar-kansas.
In 1972 the armadillo
also occupied parts of Missis-sippi,
Alabama, and Georgia and
there were outlying records in
Colorado, Kansas, Missouri, and
Tennessee. By 1995 it was es-tablished
in most of Oklahoma,
southern Kansas, Arkansas,
southern Missouri, western Ten-nessee,
Mississippi, much of Ala-bama
and Georgia, and southern
South Carolina, and individuals
occurred as far north as Nebr-aska.
The species’ northward
expansion will be limited by the
severity of winter weather since
armadillos can’t hibernate. Its
predicted range covers areas with
mean January temperatures
greater than -2°C and includes
southern Illinois to about 39°N
latitude (running across the state
just north of Alton and south of
Effingham).
There had been sporadic oc-currences
of armadillos in Illi-nois
since the 1970s, but a flurry
of recent sightings prompted us
to begin a survey (supported by
the Illinois Wildlife Preservation
Fund) in 2003. We mailed a
questionnaire to 135 individuals
knowledgeable about southern
Illinois’ fauna, including Illinois
Department of Natural Resources
(IDNR) district heritage biolo-gists,
wildlife biologists, and for-esters;
conservation police offic-ers;
Nature Preserves Commis-sion
field staff; and state park
superintendents. Surveys were
also addressed to the person or
agency responsible for animal
control in 22 southern Illinois
= > 1 record
= 1 record
The nine-banded armadillo (Dasypus novemcinctus), a recent Illinois
immigrant. Photo by Michael Jeffords, INHS Office of the Chief
Armadillo sitings records, 1999–2003.