Geoscience Reference
In-Depth Information
borealis
) and scrub jays (
Aphelocoma coerulescens
), however, extended family
groups defend territories. Male offspring, or occasionally female offspring,
remain in their parents' (fathers') territories (Walters et al. 1988, 1992). Wolves
(
Canis lupus
), beavers (
Castor canadensis
), and dwarf mongooses (
Helogale
parvula
) also defend territories as extended families (Jenkins and Busher 1979;
Mech 1970; Rood 1986).
Although territorial behavior might intuitively appear to help clarify the
problem of identifying home range boundaries, this is not always the case.
The territorial behavior of wolves actually highlights the imprecise nature of
the boundaries of their territories. Peters and Mech (1975) documented that
territorial wolves scent marked at high rates in response to the scent marks of
neighboring wolf packs. In addition, the alpha male of a pack often ventured
up to a couple hundred meters into a neighboring pack's territory to leave a
scent mark. Such behavior changes a territory boundary into a space a few
hundred meters wide, not a distinct, linear boundary. Hence, distinct bound-
aries of territories are little easier to identify than are boundaries of undefended
home ranges.
Animals are territorial only when they have a limiting resource, that is, a
critical resource that is in short supply and limits population growth (Brown
1969). The ultimate regulator of a population of territorial animals is the lim-
iting resource that stimulates territorial behavior. Although population regula-
tion through territoriality has received extensive theoretical attention (Brown
1969; Fretwell and Lucas 1970; Maynard Smith 1976; Watson and Moss
1970), the general conclusion of such theory is that territoriality can regulate
populations only proximally. The most common limiting resource is food and,
for territorial individuals, territory size tends to vary inversely with food avail-
ability (Ebersole 1980; Hixon 1980; Powers and McKee 1994; Saitoh 1991;
Schoener 1981) For red-cockaded woodpeckers, however, the limiting re-
source is nest holes (Walters et al. 1988, 1992). For coral reef fish, the limiting
resource is usually space (Ehrlich 1975). For pine voles (
Microtus pinetorum
),
the limiting resource appears to be tunnel systems (Powell and Fried 1992).
And for beavers, the limiting resource may be dams and lodges. Wolff (1989,
1993) warned that the limiting resource may not be food even if it appears
superficially to be food.
Territorial behavior is not a species characteristic. In some species, individ-
uals defend territories in certain parts of the species' range but not in other
parts. This is the case for black bears (Garshelis and Pelton 1980, 1981; Pow-
ell et al. 1997; Rogers 1977, 1987). Similarly, many nectarivorous birds defend
territories only when nectar production is at certain levels (Carpenter and
