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Wildlife Ecology
Updated 17 November 2009
Bolen and Robinson (2003) Ch. 12 - Wildlife and Soils
Ch. 13 - Wildlife and Farmlands
Some Features of Soil - classified by texture -- using amounts of -- sand, clay, silt
- soils help determine plant cover
- page 243 for classification guide for soil texture
- soil type often influences distribution of burrowing animals (sometimes other species too)
- pocket gophers, pine voles -- soil moisture may also play a part
- lead shot accumulating on soil can kill birds, mammals, etc. -- especially in wetlands- hard
bottoms allows pellets to stay more available, while silt-bottoms make it harder to waterfowl
to ingest pellets
- soil pH can influence vegetation in an area; halophytes - plants that can grow in salty soils
- soil nutrients vary - often poor soils are left for wildlife- good soils are farmed; thus,
vegetation is lower in nutrient quality for wildlife
- selenium deficiency causes nutritional muscular dystrophy or “white muscle disease” e.g., mountain goats; iodine-deficient soils caused goiter in deer
Some Influences of Soil on Wildlife
- foxes, woodchucks, bank-dwelling muskrats - all influenced by soil texture
- if soil freezes, can cause problems for wildlife - e.g., - woodcock usually probe for
earthworms in soft, moist soils- must turn to foods in decaying stumps or logs
- far northern areas have permafrost - animals have to adapt to it; often seek areas with
better drainage for dens, etc. (Arctic foxes, arctic ground squirrels)
- glaciated soils sometimes determine distributions of animals - pheasants need areas with
lots of calcium (which is often associated with glaciated areas; but pheasants can also
search out calcium to a certain extent)
- often feathers, hair of animals is analyzed to determine mineral content to get idea of
quality of soil and vegetation
- ruminants (e.g., elk, mule deer, bighorn sheep) - often attracted to salt licks – mineralbearing soils, sometimes associated with saline springs (sometimes disease spreads at
salt licks due to the large congregations of animals there)
- size of animals is sometimes correlated with soil nutrients (raccoons, cottontails; numbers
of quail increase/area with better nutrients-- see other examples pages
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- natural selection in some areas favors pelage color of prey species to match the soil color-helps animals escape predation- so only those that match soil color live to reproduce
A Tropical Paradox
- deforestation = removing the forest
- tropical rainforests support lush vegetation; many areas have been cleared with the mistaken
notion that these soils will support agriculture
- in reality, rain leaches most of the nutrients from the mineral soil, and it is the litter mat with
its nutrients that supports the vegetation; also many nutrients are tied up in the vegetative
matter; furthermore, soils of many tropical regions contain laterites (material rich in secondary
oxides of iron, aluminum, or both) -- when vegetation is removed, soils harden into ironstoneuntillable- can create a wasteland
- species are being destroyed at an alarming rate in tropics
- habitats for overwintering birds are destroyed (many North American songbirds): as are
habitats for monkeys, sloths, jaguars, etc.
Desertification = the spread or intensification of desert conditions in and around arid lands,
involving lessened biological productivity, accelerated soil deterioration, and
impoverishment of human livelihood systems
- can involve sand dunes creeping over better kinds of soil, but usually develops
in time of drought when vulnerable land is abused (e.g., overgrazing, gathering
firewood, deforestation)
- symptoms include:
1. declining water tables
2. salinization of soil and water (gets salty)
3. reduction of surface water
4. high rates of soil erosion
5. degradation of native vegetation
- area around Mediterranean Sea is becoming a desert; areas in Texas,
New Mexico, Arizona, Colorado - in danger
- native faunas seldom contribute to desertification unless human interference
has already initiated the process (e.g., most wild grazing species are nomadic)
Some Influences of Wildlife on Soils
- burrowing animals move and mix soil (ground squirrels, prairie dogs, gophers, foxes, coyotes,
badgers; also earthworms, mound-building ants, termites, some beetles)
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- animal carcasses, fur, feathers - rot and nutrients returned to soil; excreta - enriches soil (can
sometimes kill vegetation if in great concentrations- like at a roost- can change pH of soil, water)
- many animals cache food, vegetation underground - much becomes incorporated into mineral soil
- water impounded by beaver- rich muck and peat left behind when drained (but if soil is submerged
for a long time, may build up hydrogen sulfide which acts on ferrous compounds- get a surplus of
ferrous iron which may injure roots and soil fungi -- so soils may take a while to recover after
draining)
- hooved animals - may compact soil, contribute to soil erosion- usually not a big problem- most
are nomadic- problems may be localized around salt licks, water holes, etc.
- soil erosion - more common in areas where animals have been introduced outside of their natural
ranges (e.g., mountain goats released in Olympic National Park; red deer in New Zealand;
domestic cattle in Africa) or where predators have been removed resulting in increase beyond the
habitat’s carrying capacity (Itasca Park in Minnesota- removed wolves, beaver and deer
populations got too high)
- bat guano- makes a kind of “soil” - other organisms can use it-- makes a whole ecosystem inside
of a cave (see page 261)
Fertilization - useful to restore soil fertility and carrying capacity of many habitats, but it is often too
costly-- in future, may be necessary
Ch. 13 begins here - Wildlife and Farmlands
Agriculture: A Brief History (your book mentions 4 revolutions)
1. about 10,000 years ago, humans first domesticated plants – allowed humans to live in one place
-- civilization was founded on agriculture
2. second revolution was the product of exploration and discovery (international commerce – traded
foodstuff, seeds, spices, coffee – crops moved around the world) - began about the 15th century
3. Industrial Revolution - increased crop production
4. Technology - progress in chemistry, genetics, pesticides - more and better crops
What Has Happened to Farms and Farmlands?
- small farms - originally increased “edge” and hence often supported lots of wildlife (rabbits,
bobwhite quail and later pheasant thrived)
- when farms were abandoned and reverted to shrubs, deer were favored
- modern farming - “clean farming” - fewer edges, fewer fencerows - less interspersion and hence
less wildlife habitat; pastures reduced - more cash crops of beans, corn -- have seen great
reduction in quail, pheasant, cottontails; elimination of greater prairie chickens; machinery also
increases death toll of wild species (caught in mowers, etc.)
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- irrigation, pesticides - contribute
- Agricultural Act of 1956, popularly known as the Soil Bank – allowed farmers to enter into
5- or 10-year agreements for retiring land contributing to crop surpluses (e.g., wheat)
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farmers were paid for fallow land, but they had to protect the land with adequate plant
cover); farmers could enroll until 1960 and most agreements (a few exceptions) expired by
1969
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allowed pheasant populations to increase in many places (SD was a prime example)
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some later plans did not require cover, and they were much less successful at increasing
pheasant production
- Food and Agriculture Act of 1965 established the Cropland Adjustment Program (CAP) to
offset surplus crops – farmers agree to plant grasses and legumes instead of crops for 5 or 10
years
-- resulted in a great increase in duck production
- Conservation Reserve Program (CRP) (read 269-270)
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CRP - is part of the “Food Security Act of 1985 ” (the “Farm Bill” of 1985)
- farmers voluntarily remove highly erodible land from farm production for 10 years
under an agreement with USDA
- farmers must maintain permanent cover (cover may include trees, shrubs, forbs, legumes,
and native or introduced grasses-- but vegetation cannot be harvested commercially
(no mowing or grazing usually; however, in recent years during droughts, they let the farmers
take some hay off of some of these fields) ; hunting IS permitted, however
- farmers get payment annually for 10 years and share up to 50% of the cost of
establishing cover (share costs with the USDA)
- bids averaged nearly $ 100 per acre for the first year
- more than 9.3 million hectares of highly erodible croplands were taken out of
production and put into CRP by 1987
- only 6% of farmers said that they would retain the present (i.e., CRP cover)
vegetation conditions if CRP were discontinued in 1995
CRP Program – has provided valuable habitat for all kinds of species – considered a success
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Other Segments of the Food Security Act
- include Swampbuster and Sodbuster provisions
- farmer cannot drain wetlands or plow high erodible lands without losing their benefits
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Amendments in 1990 and 1996 to the 1985 Farm Bill produced additional benefits for wildlife on
private lands:
- Wetlands Reserve Program (WRP) – provides incentives for landowners to make
long-term or permanent restorations to degraded wetlands on agricultural lands
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Wildlife Habitat Incentives Program (WHIP) – assists landowners with habitat
restoration and management activities aimed toward the critical needs of individual species
(e.g., Karner blue butterfly, Indiana bat, Atlantic salmon)
(Other modifications to Farm Bill over the years since our book was written – check internet)
Farm Crops As Wildlife Food
- bobwhites and pheasants - sometimes eat seeds; quail usually do not harm crops very much, but
sometimes pheasants will eat newly sprouted corn and peck ripe tomatoes - economic damage;
- can sometimes have serious crop damage from waterfowl, blackbirds, rodents, raccoons
(blackbirds = grackles, cowbirds, red-winged blackbirds, some include crows and starlings)
(around Lake Erie, lots of corn is damaged by blackbirds--quite a few studies in this area)
- deer - damage soybeans, alfalfa, fruit trees, etc. (in New York, human hair balls are used to repel
deer from fruit trees (fences also used, but expensive)
- geese can die from impacted soybeans in the esophagus (the beans are dry when eaten, then expand
with moisture)
- orchards - pine voles, meadow voles, deer - destroy trees
- scare tactics, chemicals used to repel or kill damaging animals
- aspergillosis - a fungal infection of the respiratory tract of birds exposed to molding crops
- in some areas, the extra food supply from waste corn and other crops allows some populations to
overwinter in areas farther north than where they normally would (called “stopping short”) - more
southern hunters don’t go for this!!
Erosion, Sedimentation, and Wildlife
- estimated that more than 6 billion tons of solid erode each year from nonfederal lands in US
- eroded soil often gets into aquatic environments- silt makes the water turbid- many species cannot
tolerate it and die or leave; cuts light and affects plant life --often see an increase in carp and
spotfin shiner (considered “rough fish”) and decrease in walleye and other game fish usually of
better food value
Agricultural Chemicals and Wildlife
- DDT, Aldrin, Dieldrin-- get into food chains --kill many species
- species often develop resistance to chemicals if used long enough
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- DDT use banned in US; but still manufactured here and exported to other countries
- many insecticides are not species-specific
- in some areas, pest management is going toward combination of chemical, cultural, and biological
methods (use natural predators, grow certain things together; use pheromones to lure pests; use
sterile males)
Insecticides, herbicides, fertilizers – read pages 280-288
Farming For Wildlife
- shelterbelts-windbreaks - protect against soil erosion; offers cover for many species; offers
corridors between monoculture crops; more “edge”
- value of shelterbelts to wildlife depends on:
a. species of food and cover plants selected
b. the density and arrangement of plants within shelterbelt
c. width of shelterbelt
d. the right-angle orientation of the shelterbelt in relation to prevailing winds
- odd areas - food patches left unharvested; odd corner that does not drain well - offer habitat
- roadsides - could be managed more for wildlife-- in some areas, farmers are encouraged not to
mow them until after pheasants, quail have nested; roadsides can offer better habitat for these
species if sowed to grass-legume mixture
- caution - if roads are heavily used, lead may accumulate and harm the species that live there-- so
management is often favored in less-used areas
- tillage - many farmers plow in fall after harvest; exposes land to erosion and may form a hardened
plow pan (compacted layer) just beneath bite of plowshare; not good for soil or wildlifeit also plows under any waste crops that wildlife could eat
- conservation tillage - minimum tillage or stubblemaking- do not plow; plant next spring
in the old plant debris; however, more herbicide may be necessary--- results in better
water infiltration, less erosion, reduced runoff, save on fuel costs; also seems to allow more
wildlife to use the area; however, in some areas, the birds (or other species) harm crops in
the area
- late mowing of hayfields is encouraged so that game birds can nest (or leave unmown islands
around nests)
- in some areas, prescribed burning of stubble allows better access to the waste corn or other crop
by wildlife
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Important farm wildlife species: bobwhite quail, ring-necked pheasant, cottontail rabbit
Order Galliformes - chicken-like land birds: forage on ground for seed, insects
(mainly non-migratory)
Family Phasinidae - quail, partridge, pheasants
1. Bobwhite quail - abundant in brush, abandoned fields, and open pinelands, but avoids
deep forests: in winter, found in flocks (coveys) of up to 30 birds:
(a forest edge species): winter ice storms- die offs
- males white face: females yellow face:
- has a small home range (about ½ mile diameter): 40 acres is a management
area for quail: small fields are very good for quail- they do well when
fields are a mosaic of habitat
- eat seeds, especially ragweed, foxtail, grain
(some insect matter in early summer)
2. Ring-necked pheasant – introduced into U.S. from Asia in early 1900’s (or late 1800’s)
- common in open woods and farmland in brush, hedgerows, shelterbelts,
and cornfields: roost in trees:
- feeds on waste grains (especially corn), seeds, berries (some insect
matter in early summer)
Fall plowing-
- many studies have been done on pheasants (your book mentions some of
detrimental to both quail them): level of calcium in the soil seems to be quite important- southern
and pheasant- turns
limit of distribution coincides with edge of glaciation-soils high in calcium
under waste corn and
are typical of glaciated soil
other grains
- high temperatures and high humidity also seem to be less than ideal for pheasants
- farmland-good to have woodlots and fencerows and small fields (patches)
- often nest in grass- roadsides, pastures, etc. - nest around June and broods
are off by about July 4- so early mowing disturbs nests (farmers are advised
to mow after broods hatch) (or to grow a fast-growing crop that can be
harvested before nesting)
- sometimes large numbers are turned loose in the fall for hunters
Mammal:
3. Cottontail rabbit - most important small game animal in Ohio: habitat of brushy areas,
strips of forest with open areas nearby, edges of swamps, weed patches:
will use brushpiles, shelterbelts, fencerows
- herbivorous- many wild plants, woody plants in winter: will eat corn,
wheat, soybeans too
- will nest nearly anywhere