3. DEFINATIONS
• Ecology is the study of relationships between organisms and their
environment. Wildlife management is largely an application of
knowledge from this science.
• Environment includes all the materials or processes in the
surroundings of an organism or population. This term emphasizes the
abundance, diversity, and complexity of materials and processes, many
of which influence each managed population.
• Environmental factor is any one of the materials or processes in an
environment. Factors may be groups of materials or processes (soil,
food, weather, biotic succession) or may be more specific (temperature,
soil moisture, browse, closure of the vegetation canopy).
• Habitat is the kind of biotic community, or set of biotic communities, in
which an animal or population lives. For example, a marsh is habitat for
a muskrat population. Habitat is not synonymous with cover. Suitable
habitat provides all the habitat requirements of a species for a season
(wintering habitat, ' breeding habitat) or year-round.
4. • Habitat requirements are the various types of foods, cover, and other factors
needed by a wildlife species for survival and reproductive success. Examples
are winter forage and nesting sites.
• Habitat resources are the various acceptable food and cover types that exist in
a habitat. These resources usually vary in quality (as there may be good and
poor forages and secure nesting sites as well as insecure sites where predation
is likely).
• Zoogeography is the study of past and present animal distributions, including
the evolution, spread, recession, and extinction of species.
• Geographic range is the broad area in which a species occurs. Geographic
ranges are usually illustrated by irregularly shaped shaded areas on maps. For
instance, bighorn sheep occur in western North America.
• Ecologic range includes the habitats, within a geographic range, where a
species occurs. For instance, bighorn sheep occur in arid and semiarid
mountain ranges and canyons of western North America.
5. • Ecological Niches: Ecologists commonly use two definitions of niche. One
emphasizes animal functions; the other emphasizes habitat resources.
• Functionally, an ecological niche is the role of a species in a biotic community,
as determined by its geographic and ecological distribution and by the set of
adaptations that separate it from all other species.
• Niche counter-parts: Similar niches in different geographic regions or biotic
communities are termed niche counter- parts.
• Ecological equivalents: Similar niches in different geographic regions or
biotic communities occupied by species termed ecological equivalents.
• Ecological niche is the set of habitat resources (foods, cover types, water, etc.)
used by a species, as determined by its geographic and ecological range and its
adaptations. This definition permits the concept of an empty niche. Habitat
resources may be available but unused because of species extinction or
extirpation and/or because evolution has not produced an appropriate species
to use the resources.
• Competition is mutual use of limiting habitat resources by two animals or
populations. Species having evolved together tend to be ecologically separated,
so that their functional and resource niches do not overlap completely, and
competition is reduced or avoided.
6. Species Biology
• A first requisite for managing a species population is some understanding of its
biology—its habitat requirements, movement patterns, behavior, and patterns
of reproduction and mortality.
• This requires understanding the adaptations that a species has acquired to
enhance survival and reproductive fitness in its naturally associated
environment.
• Animal adaptations have been classified as:
• 1 Anatomical
• 2 Physiological
• 3 Behavioral
A. Instinctive
B. Learned
7. WILDLIFE AND SOILS
• Soil fertility depends on soil structure and chemistry.
• In general, soils that develop in a moist climate are well leached of minerals.
• However, they are highly productive of carbohydrate biomass, usually in forest
vegetation. The comparatively mineral deficient soil and the abundant
vegetative growth result in large potential forage resources with low
concentrations of nutrients.
• Herbivores adapted to these types of vegetation usually feed selectively on
parts of plants in which nutrients are concentrated, such as buds, fruits, or
seeds.
• They may also be adapted to feeding in vegetation resulting from recent
disturbance by fire or wind. When forest vegetation is disturbed, nutrients
previously bound in the standing crop are released and usually are recycled
through the soil into successional vegetation. This process results in
temporarily enriched forage resources, and disturbed areas attract many forest
herbivores.
8. SOIL AND ANIMAL QUALITY
• Numerous studies have related the productivity of domestic animals to soil
fertility.
• Specific soil deficiencies and their effects on livestock have often been
identified.
• Morrow described infertility of dairy heifers caused by a phosphorus
deficiency that developed from soil depletion by intensive cropping practices
(1969). The cows showed poor coats and depraved appetites.
• After supplementing their diet with phosphorus, the average number of
artificial inseminations necessary per conception fell from 3.7 to 1.3.
9. • Wildlife are also affected by soil through nutrition, but they have two
advantages over domestic livestock.
• First, confinement should make livestock more susceptible to problems caused
by soil deficiency or toxicity. Wildlife, on the other hand, are often capable of
visiting more than one soil type, permitting compensation for local deficiency
or avoidance of local toxicity.
• Second, most wild populations have evolved in the areas where they live. If
there are soil problems, we expect wild animals to become behaviorally or
physiologically adapted for avoiding those problems.
• Behaviorally, they may evolve preferences for food items in which soil-
deficient minerals are concentrated.
• Physiologically, wild animals may develop tolerances for mineral deficiencies
in their environment, perhaps by recycling scarce minerals rather than excreting
them.
10. IMPLICATIONS FOR WILDLIFE
MANAGEMENT
• Wildlife are products of the land, and wildlife managers should be concerned
with maintaining and enhancing the fertility of the land. Practices that reduce
soil fertility also reduce its capacity to produce wildlife.
• Some sites and soils are fragile. Their productivities are not inherent in their
parent materials, but depend on soil stability, structure, and organic matter that
occur only after decades or more of biotic succession and soil development.
• Habitat manipulation practices such as prescribed fire or mechanical treatment
of vegetation might reduce soil fertility if carelessly applied.
• Careful application of such practices requires consideration of site factors,
such as slope and aspect, and of soil factors, such as erodibility or the
consequences of destroying organic matter.
• In fragile areas, the season and the intensity and frequency of habitat treatment
can be varied to reduce or eliminate soil damage.
• Soil fertilization has sometimes been used in habitat management. However,
the benefits of applying fertilizers have seldom been measured and compared
with the costs.
11. 1. Soil is our most basic land resource. Soils vary greatly in fertility and
fragility. Any land-use practice that degrades soil fertility also
degrades its ability to produce any organic resource, including
wildlife.
2. Within suitable habitats, wild animals achieve higher quality, and
wildlife populations are larger and more productive on the more
fertile soils. As with all organic resources, the benefits of wildlife
management can be greater on fertile soils than on infertile soils.
3. Human use of the land tends to be most intensive on areas having
the most fertile soils. The intensity of agriculture, forestry, and range
management on the most fertile soils usually reduces the variety of
food and cover resources available to wildlife and makes these areas
less suitable or unsuitable as wildlife habitat.
4. On soils of moderate fertility, extensive agriculture, forestry, and
range management often increase the variety of habitat resources
and improve wildlife habitat.
