Wildlife Survival

 

Ecology of Populations: the study of how populations interact with their environment

Genetic Diversity: is a measure of the variety of different versions of the genetic code within an individual species

Population: a group of individuals of the same species
Communities: two or more populations of different species in the same area


Abundance is the number of species in a population and Diversity is the number of different species in a communtiy.

Ecosystem: a community plus its abotic factors ex. soil, rain, temperatures
Biosphere: the part of the earth that contains living species.

Population dispersion can be random, uniform and clumping (where individuals flock together) like plants that grow together in a region that suits their requirements for life, fish that swim together to avoid predation and birds that migrate in groups.

Two types of reproductive growth:

  • K-Selected - matures and reproduces slowly. High parental care.
  • R-Selected- matures early and has many young. Little if any parental care.

 

Population Growth

  • Biotic Potential- maximum growth rate of a population given unlimited resources in the environment. A female human can have up to 20 children!!

Abiotic (non-living: soil, water, air) factors are density-independent. Adverse weather, floods, droughts, extreme temperature change will kill off species with no special preference towards animal density. In other words more animals are not killed JUST because the population is crowded.

Biotic Factors (living factors) are "density dependent" factors. These are stresses in a population that kill off animals BECAUSE they are densely packed. Examples of a higher risk of death include limited food availability, parasites and pathogens (microscope organisms like bacteria, viruses) the denser the population.

Know how these additional factors will affect a population:

- sex ratios, age structure (relative proportions of individuals of each age), natality (birth rates), mortality (death rates), immigrations and emigration.


~Activity: Turkey Trouble, How Many Bears Can Live in This Forest?


Carrying Capacity- the maximum number of individuals a given environment can sustain.

  • Know the major limiting factors (any resource that is in short supply) that could influence the population size of a species. Examples could be space, food, or water.

Population curves

  • J-curve- unrestricted, exponential growth. This spells trouble for the environment and the ultimate health of the population because of course nothing can grow forever. Have you seen human population growth curve? It looks exactly like a J-curve!!!!
  • S-curve- logistic growth, arthimetic growth and often density-dependent. The growth rate is slower as the size of the population approaches the carrying capacity and the population eventually becomes stable.

~Activity: Carrying Capacity, Oh Deer!

 

Invasive species

Exotic organisms are aliens introduced into habitats where they are not native.

Invasive organisms can be thought of as biological pollution. There are more than 6,000 alien species in the United States.

            Plants
                        Purple Loosestrife
                        Garlic Mustard
                        Multiflora Rose
                        Japanese Knotweed/Bamboo
                        Water chestnut
            Animals
                        Zebra Mussels
                        Starlings
                        Hemlock Woolly Adelgid
                        Asian Longhorn Beetle

                       Pond Hopping Snakehead fish, Brown Tree Snake (poisonous, 10' long bird eating snake in Guam), Mankind!

Specific traits of invasive species that allow them to outcompete native species:

  • the ability to grow and reproduce more rapidly than native species
  • early sexual maturity
  • the ability to disperse young widely
  • tolerance of a broad range of environmental conditions
  • no natural preditors in new habitat


~Activity: World Travelers


Extinction

~Natural Extinction: Massive ecological extinctions (dinosaurs at the end of the Cretaceous period and two thirds of all marine life at the end of the Permian period) were caused by natural causes, perhaps triggered when large asteroid struck the earth.

We are now in a sixth mass extinction, but its rate is much faster. By the year 2050, we could lose 1/3 to 2/3 of all the species on the Earth. The first five mass extinctions took 10 million years on average to repair by natural evolution. The next one will take a lot longer to recover from because humans are distroying the topography, landscape AND the habitat in which the plants and animals lived.
Habitat Destruction: The biggest reason for the current increase in extinction is clear cutting land.
Habitat Fragmentation: Habitat fragmentation divides populations into isolated groups that are vulnerable to catastrophic events. It also limits population so that an insufficient number of animals exist to cushion it from inherited inbreed diseases or ailments.

Passenger Pigeons plunged from hundreds of millions to zero. Moa of New Zealand. The bison came within a few hundred rifle shots of extinction.

Hunting and Trapping

  • Survival versus recreation
  • Regulated hunting and endangered species
  • Harvesting of animals and population ecology.

Over harvesting (hunting and fishing) is responsible for depletion or extinction of many species.

Passenger Pigeons plunged from 2 to 3 billion to zero. Moa of New Zealand and the Dodo bird are now extinct. The bison came within a few hundred rifle shots of extinction.

What valuable commercial products were overhunted/fished in our region?

  • beaver
  • mink
  • deer
  • turkey
  • sturgeon
  • trout
  • Be able to explain the role of hunting and trapping for game species and the ripple effect on other species

Migration

  • Animal Migration, seasonal or periodic movement of animals in response to changes in climate or food availability, or to ensure reproduction. Migration most commonly involves movement from one area to another and then back again. This round-trip, or return migration, may be of a seasonal nature, as in the spring and autumn migrations of many birds. Or it may require a lifetime to complete, as in various species of Pacific salmon that are born in freshwater streams, travel to ocean waters, and then return to the stream where they were born to breed before dying. Animal migration is becoming more risky because of loss of habitat in the case of birds or global warming in the case of salmon.
  • Activity: Great Bird Migration and Hidden Hazards

Endangered Species

Extirpated Species: species no longer found in New York but living elsewhere
            Wolverine (1840)
            Elk (1830)


Endangered Species: Species whose population is dangerously low. Highest rate are in freshwater ecosystems
            Gray Wolf (once extirpated in 1890)
            Cougar (once extirpated in 1908)
            Shortnose sturgeon


Threatened Species: Populations of species that border on becoming endangered unless action is taken
            Canadian Lynx (1890)
            Bald eagle


Successful Comebacks: Back from the brink of disaster!
            Turkey
            White Tailed Deer
            American Beaver
            Peregrine falcon
            (Bald Eagle)
            Osprey, California Condor from captive breeding

Characteristics common to endangered species:

  • Large body size
  • Requires very large or small territory
  • Slow to reproduce
  • Doesn't tolerate human interference well
  • Picky eaters
  • Tasty or has other desirable trait to humans (feathers for hats in the case of snowy egrets)
  • Low tolerance for a range of environmental conditions

~Assignment

  • Name 3 Endangered or Extinct Species and describe the reasons for their population fall.