Three Types of Animal Movement
Three Types of Animal Movement
Dispersal of Young
à young animals are pushed out by mature, established, aggressive adults
àcontrol population densities
à often young end p in marginal habitat, experience heavy mortality from predation and accidents
Mass Emigration
à population has peaked due to favorable conditions, followed by unfavorable conditions
à options: emmigrate or starve, hibernate
Migration
à two types of migration:
Latitudinal migration: north-south movements
Altitudinal migration: change in elevation
Latitudinal Migration:
à in the south winter bird densities are high
-northern birds who breed up north come down south for the winter
-insects, fruits, and seeds are more prevalent
à in the spring, sunlight triggers hormones which cause northern migration
à habitat change may ensure a balance of nutrients and minerals
à 24 hours for feeding the young makes babies grow faster?
Altitudinal Migration
àjust move up and down the mountain nd you can get the same effect as the latitudinal migrants
àelk in the Rockys ascend for the spring/summer , go for the cool climate
àwhen snows cut off food they head into he valleys for the winter
Mortality Factors
TWO factors that control the population of a species:
àbiotic potiential
àenvironmental resistance or mortality factors
Mortality factors affecting deer
à starvation
· Winter is critical. Food is extremely limited
· Herbs, mosses, fungi, seedlings, stump sprouts are covered by snow
· Buds, twigs, conifers foliage, are on the menu!
· As population grows, they tend to over browse
· Eat up to the height of rearing up on hind legs
· BROWSE LINE: 5 feet up (sign of trouble)
· Heavy snows can confine and trap the herd
ISSUES: artificially feeding
-if you keep them alive, they will destroy the habitat
-feeding spreads disease
à Predation
Deer predators include: cougars, bobcats, wolves, coyotes, dogs
MN:
wolves kill 15 deer per square mile annually (superior national forest)
6000 of 37000 killed one year.
Hunting up there is light; wolves may be keeping the deer at carrying capacity
2450 wolves in the entire state; impact on deer herd is minute
Wolves do not compete with hunters for the deer they want (big bucks)
Wolves kill deer who are at least 5 years old and in poor health (1971 study)
Hunters kill deer 2 years old or less in good health
When deer populations decline, wolf populations decline
Free ranging dogs are a problem for young deer
à Hunting
Major source of mortality for white tailed deer
Illegal hunting and poaching is a problem in some areas
Deer populate rapidly: herd control (natural and hunting) is required so they don’t ruin habitat
Some people want hunting banned
à Disease
Can be a concern for herd populations
White tailed deer: susceptible to epizootic hemorrhagic disease (viral)
Common in SE US and regions in Canada. (high density, no cure)
àAccidents
Collisions with automobiles is a significant problem
PA: 45K deer/car collisions per year REPORTED (true number is prob twice that!)
Mortality Factors for Waterfowl
Major factors include:
-loss of habitat
-oil and chemical pollution
-hunting
-lead poisoning
-disease
-acid rain
àloss of habitat
WETLANDS
Loss of habitat is a major threat to migratory birds
Fowl breed in wetland areas, small ponds, lakes
(1/2 have been lost to farming/development)
3.8 million acres have been destroyed in LA, Miss, AR in the last 25 years
Wetland losses seriously affects migratory birds
POTHOLES
Duck factory: Manitoba, Saskatchewan, Alberta, Dakotas, W. Mn, NW Iowa
Produces ½ the nations waterfowl
Ducks raised in potholes (1.25-2.5 acres) density of potholes 125 per square mile
(10 million potholes! In Canada alone!)
US potholes are drained by farmers
Subsidized by USDA to produce more corn, soybeans, and wheat
Iowa: potholes reduced by 94% since the 1930’s
Ducks count: in NA from 15 million to 5 million per year
DROUGHT
drought destroys potholes and wetlands!
1 million potholes were dry in the summer of 1988
Total duck population was 66 million, 8 million less than 1987
CARP
Destroy waterfowl habitat
Eradicates duck foods: coontail, pondweed, water milfoil
Lake Koshkonong:
was once blanketed with rafts of canvasbacks (wild celery, pondweed nuts)
19th century: carp introduced
Fish uprooted choice plants: ducks left
Young carp compete with young ducklings for protein rich crustaceans
àOil and chemical pollution
100,000 fowl are killed annually by oil pollution
Why does oil kill ducks?
· Oil mats the feathers, reduces ducks ability to stay warm
· Birds start to death because they cannot swim or fly
· Kidney and liver failure from swallowing oil/water
Chemical Pollution
· Farm chemical runoff pollutes wetlands
· Keterson National Wildlife Refuge: adjacent to San Joaquin Valley
· Toxic selenium causes birth defects in birds
àhunting
14 million ducks killed by hunters each year (US and Canada)
12.7 US
Hunters deposited 3000 tons of lead into our nations lakes, rivers, streams, marshes annually
280 pellets/#6 shot
Average hunter takes 6 shots to kill one duck
1400 pellets for each bird taken
CA: 600,000 pellets per acre Wi: 120,000 pellets per acre
à lead poisoning
Ducks eating shot: killed 2-3% of waterfowl each year (equivalent to all ducks raised in the Dakotas)
Eagles get poisoned from eating the ducks
Heaviest duck mortality along the Mississippi (IL, IN, MO, AR)
US Fish and Wildlife service phased out lead shot starting in 1987
1991 season: lead shot banned in US
1999 season: lead shot illegal in Canada
Advantage:
Steel shot saves the lives of 2 million ducks a year
Disadvantage:
More expensive
Does not kill at a distance of more than 125 feet
Ruins old guns
àdisease
· Botulism
Caused by the toxic wastes of an anerobic bacteria
Most prevalent in the west, has been seen elsewhere
Kills 100K waterfowl in CA and UT
· Clostridium
Thrives in stagnant alkaline mudflats (dead stuff, high temperatures)
Late summer. Extended drought
Ducks eat the contaminated material and become ill
Kills by paralyzing their breathing muscles (limp necks)
· BUGS!
Avian Cholera: Bacterial
Aspergillosis: fungal
Enteritis: viral
àacid rain
The Black DUCK (highly prized along the Atlantic coast)
· NE US, So Canada: plagues by acid rain issues
· Mayfly larva, very important for black ducks, is highly sensitive to Ph
· (mayfly is wiped out) young ducks have no food can they adapt?