64
RICHARD 9. MILLER
the 71 contests the E. amoenus individual was the first to emerge from
the nest box; on 43 occasions an E . amoenus individual entered the
central chamber and fed, while only one E . minimus did so; and the E .
amoenus spent a total of 2 185 minutes outside the nest box while the
E. minimus remained outside for a total of only 983 minutes. In these
and other experiments E. amoenus individuals were consistently more
aggressive and demonstrated their competitive superiority in physical
encounters.
This model also seems to be the best method of describing the pattern
of interaction between the black rat (Rattus rattus) and the brown or
Norway rat (Rattus norvegicus). The earlier arrival of the black rat in
Britain, with the return of the Crusaders during the middle ages
(Matheson, 1939), allowed this species to occupy most of the British
Isles. The subsequent arrival of the brown rat at the begiiining of the
18th century has apparently been responsible for the disappearance of
the black rat from most of the areas it occupied previously. A similar
replacement is occurring in U.S., where the brown rat replaced the
black rat in an area of 1000 sq. miles in southwest Georgia between
1946 and 1954 (Ecke, 1954). The black rat is often arboreal, however,
and in urban areas this allows it to coexist to a limited extent with the
brown rat -the black rat occupies the top stories of buildings, travelling along power lines and rafters, while the brown rat inhabits the
ground level (Southern, 1964).
Relationships between the wood mouse (Apodemus sylvaticus) and
the yellow-necked mouse (A. Jlavicollis) and the wood mouse and the
bank vole (Clethrionomys gkreolus) invite a similar explanation. The
larger yellow-necked mouse occurs entirely within the range of the
more widespread wood mouse, except in northern Europe, but is absent,
from large areas (Southern, 1964). In Britain A . Jlavicollis occurs in
pockets throughout populations of A. sylvaticus, but is more strictly
confined to woodland habitats while A. sylvaticus is also common in
fields and scrub. The habitat preferences recorded for these species in
Europe also confirm this relationship (Grodzinski, 1959). The bank vole
has a much more restricted distribution than the wood mouge in British
woodlands, especially in winter when the ground layer of vegetation
disappears (Evans, 1942; Miller, 1955; Kikkawa, 1964). This seems to
be related to the fact that the bank vole is more active during the day
and would be exposed to greater risk of predation if it did not restrict
its movements to the immediate vicinity of protective cover. There is
thus a relatively large amount of intersection in the spatial elements of
the fundamental niches of these two species in summer when ground
cover is abundant and the bank vole can move more freely, but interference is alleviated by the fact that the two species have different
RICHARD 9. MILLER
the 71 contests the E. amoenus individual was the first to emerge from
the nest box; on 43 occasions an E . amoenus individual entered the
central chamber and fed, while only one E . minimus did so; and the E .
amoenus spent a total of 2 185 minutes outside the nest box while the
E. minimus remained outside for a total of only 983 minutes. In these
and other experiments E. amoenus individuals were consistently more
aggressive and demonstrated their competitive superiority in physical
encounters.
This model also seems to be the best method of describing the pattern
of interaction between the black rat (Rattus rattus) and the brown or
Norway rat (Rattus norvegicus). The earlier arrival of the black rat in
Britain, with the return of the Crusaders during the middle ages
(Matheson, 1939), allowed this species to occupy most of the British
Isles. The subsequent arrival of the brown rat at the begiiining of the
18th century has apparently been responsible for the disappearance of
the black rat from most of the areas it occupied previously. A similar
replacement is occurring in U.S., where the brown rat replaced the
black rat in an area of 1000 sq. miles in southwest Georgia between
1946 and 1954 (Ecke, 1954). The black rat is often arboreal, however,
and in urban areas this allows it to coexist to a limited extent with the
brown rat -the black rat occupies the top stories of buildings, travelling along power lines and rafters, while the brown rat inhabits the
ground level (Southern, 1964).
Relationships between the wood mouse (Apodemus sylvaticus) and
the yellow-necked mouse (A. Jlavicollis) and the wood mouse and the
bank vole (Clethrionomys gkreolus) invite a similar explanation. The
larger yellow-necked mouse occurs entirely within the range of the
more widespread wood mouse, except in northern Europe, but is absent,
from large areas (Southern, 1964). In Britain A . Jlavicollis occurs in
pockets throughout populations of A. sylvaticus, but is more strictly
confined to woodland habitats while A. sylvaticus is also common in
fields and scrub. The habitat preferences recorded for these species in
Europe also confirm this relationship (Grodzinski, 1959). The bank vole
has a much more restricted distribution than the wood mouge in British
woodlands, especially in winter when the ground layer of vegetation
disappears (Evans, 1942; Miller, 1955; Kikkawa, 1964). This seems to
be related to the fact that the bank vole is more active during the day
and would be exposed to greater risk of predation if it did not restrict
its movements to the immediate vicinity of protective cover. There is
thus a relatively large amount of intersection in the spatial elements of
the fundamental niches of these two species in summer when ground
cover is abundant and the bank vole can move more freely, but interference is alleviated by the fact that the two species have different