Tensas gazette., 1909-10-08
MIGRATION OF RATS
marches of Rodents That Have Bos
Observed in Various Countries

Wv u" various countries.
In nearly all countries a season.
movement of rats from houses al
Darns to the open fields occurs \
spring. and the return movement tal,s
place as cold weather approaches. Te
movement is noticeable even in lar
cities.
More general movements of rats 4.
ten occur. In 1903 a multitude 4
migrating rats spread over seven
counties of western Illinois. Thv
were noticed especially in Mercer an
ROCK Island counties. For seven
years prior to this invasion no abno-
mai numbers were seen, and their COZ
ing was remarkably sudden. An ey-
witness to the phenomenon informd
the writer that as he was returning
MS home by moonlight he heard
general rustling in the field near h
ana soon a vast army of rats crossd
the road in front of him, all going
one direction. The mass stretcha
away as far as could be seen in Ia
dim light These animals remaind
on the farms and in the villages n
the surrounding country, and durip
the winter and summer of 1904 wee
veritable plague. A local newsu-
per stated that between March 20 ad
April 20, 1904. F. U. Montgomery
Preemption, Mercer county, killd
3,435 rats on his farm. He caugf
most Of them in traps.
In 1877 similar migration occurrd
into parts of Saline and Lafayete
counties, Mo-, and in 1904 anothr
came under the writer's Observable
in Kansas River Valley. This va
ley for the most part was flooded b
the great freshet of June, 1903, AM
for about ten days was covered wit.
several feet of water. 1t is certai.
that mcst of the rats in the vale,
perished in this flood. In the fall O
1903 much of the district was visited
by hordes of rats. which remained dur.
ing the winter, and by the following
spring had so increased in numbers
that serious losses of grain and poul.
try resulted.
No doubt the majority of the 50
called migrations of rodents are II
reality instances of unusual reproduc
ton or of enforced migration owing tc
lack OF food. In England a general
movement of rats inland from the
coast occurs every October. This Is
closely connected with the closing Of
the herring season. During the fish
ing the rodents swarm to the coast,
attracted by the offal left from clean
ing the herring, and when this food
supply fails they hasten back to the
farms and villages.
In South America periodic plaques Of
rats have taken place in Parana, Bra
zil, at intervals of about thirty years,
and in Chile at intervals OF from If
teen to twenty-five years. These
plaques in the cultivated lands follow
the ripening and decay of the domin-
ant species of bamboo in each country.
The ripening of the seed furnishes for
two or more years favorite food for
rats in the forests, where the animals
greatly; when this food fails
they are forced to the cultivated dis
tricts for subsistence. In 1878 almost
the entire crops of corn, rice and man
dioca in the State of arana were des-
troyed by rats, causing a serious
famine
An invasion of black rats in the Ber-
muda Islands occurred about the year
1915. In a space of two years they
had increased so alarmingly that none
of the islands was free from them. The
rodents devoured everything which
came in their way-fruit, plants, and
even trees-so that for two years the
people we're destitute of bread. A law
was passed requiring every man In the
islands to set twelve traps. In spite
of all efforts the animals increased,
until they finally disappeared with q
suddenness which could have resulted
only from pestilence.-From Biologi-
cal Survey Bulletin 80.