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45 Cards in this Set

  • Front
  • Back
four flyways from west to east
Pacific - Central -Mississippi - Atlantic
amount of wetlands
-1800 = 215 million acres contiguous U.S.
-2000 = 99 million (only 46% remains)
of 99 million acres of wetlands remaining
-5.2 million acres estuarine wetlands
-39.0 million acres emergent vegetation, scrub shrub
-49.7 million acres forested
natural causes of wetland loss
human-caused wetland losses
-agriculture, urbanization, open water
-primarily agricultural on freshwater systems
-primarily open water on freshwater systems (canals, port and marina development, erosion control)
specific areas of severe wetland loss
-California - once had 4-5 million acres, now have less than 500,000 acres
-Iowa - once 2.3 million acres, 26,500 in 1980
-Prairie Potholes (N and S Dakota) - had 7 million, now 3 million
-lower Miss. River Valley - only 20% of original bottomland hardwoods remain
wetlands gained
-107.7 million acres
-mostly in East/Central
Reesources Inventory - 4 methods
1. Breeding population size estimates
2. Predicting production
3. Check on last year's production estimates (includes the parts survey)
4. Fall and winter surveys
Breeding Population Size estimate
-aerial surveys begun in 1947, standardized in 1955
-May-June survey of breeding area for pop. and # ponds
-July survey for broods
-cooperative effort between Canadian WS and USFWS (May)
more about Breeding Population Size estimate
-1/4 mile wide transects, 150 feet above ground at 100 mph
-pilot counts to left, observer to right, 1/8 mile strip
-record species, sex, group size of 20 species
-total transect length 85000 miles
-transects 14 miles apart in potholes, up to 60 miles apart in forests
-covers 2-3% total breeding habitat, 3.5 million km2
-some birds missed, so ground routes cover 100 ponds (5 miles long) to correct for count
correction factor
-air:ground ratio
1-air/ground ratio is CF
-creates visibility index
-1.3 for scoters, go up to 10 for green-winged teal
Predicting Production
-Waterfowl Production and Habitat Survey
-since 1950, usually July 12-15
-estimates broods on 2 million km2, # wetlands still holding water, # ducks still nesting
-survey done by plane, observer only covers 1/16th of mile
-no ground truthing
Predicting Population - 4 types of data collected
a. # of class I, Class II, and Class III broods by species
b. mean # ducklings in class II and III broods
c. # paired and single (male and female) ducks by species
d. # of ponds
Check on last year's production estimates
Waterfowl Harvest Survey
-mail questionnaire
-parts survey (Cooperative Parts Collection Survey)
Fall and Winter Survey (Midwinter survey)
-began in 1930s
-fall aerial surveys for snow geese, brants, swans (better because of differences in plumage)
-winter - aerial surveys in Dec. and Jan
-not done by transects, but by water body
-only 1/3 to 1/2 breeding counts, but useful for wintering distribution of birds
-best for geese
Fall and Winter survey attempts to get estimates of numbers in what areas?
-areas with lots of birds
-National Wildlife Refuges, state areas, major lakes and rivers, Gulf Coast, other wintering places
fall flight
-adults in fall + young
-ranges from 80-100 million birds
objectives of annual regulations concerning migratory waterfowl
1. regulate harvest to protect migratory bird populations
2. maintain acceptable pops and reproductive capabilities by recreationa/harvest opportunities
3. prevent crop degradation by migrating game birds
4. distribute hunting opps for migratory birds as equitably as possible along migration routes
5. limit accidental take of nontarget species where confusion might exist
Habitat management for waterfowl - 2 major aspects
1. production
2. wintering
When is predator management justified in wildlife management context?
1. reintroductions or introductions
2. t & e species management
3. intensive harvest of game (private land and economics)
4. subsistence values (north)
5. marginal habitat conditions around small areas
6. when biopolitics get severe enough that something must be done
1930s attitude about predator control
-science as basis for management
-Leopold's work
-still, pred control not really questioned
1950s - 70s
-Post-war Paradigm Shift
-predator control vs. harvest management
-lots of studies
- agencies quit translocating captive animals, went to wild animals
examples of predator control studies
-Isle Royale moose and wolves
-Jackrabbits and coyotes in Curlew valley
-cougar work in ID - Hornocker
-pheasants and predators in midwest
80s and 90s and today
-conflicting goals and management strategies
-what is natural community?
-what role should agency biologists have?
-acceptability of predator control
what do we have to manage?
what is pred-prey controversy?
1. if predators are unchecked, they keep prey numbers low and may even wipe out (pred. pit idea)
2. predation has no real effect because it removes only those individual prey that would have died from other causes
3. predators actually benefit prey populations by selectively culling less fit members
components of predation
-for predation to limit a prey population, preds must keep prey below level it would reach if preds were absent
-for preds to regulate prey pop, food supply, weather, or something else affects prey pop so that it varies despite predators but predation might partially check changes in # of prey
age classes in predation
-random with respect to age (ambush predators)
-disproportionately kill young or old, shift age structure to middle class animals (prey that tire in chase)
what is impact of reducing number of old animals in a breeding population?
-often increases production of remaining females and possibly increases survival of young
prey characteristics to consider when examining predator impact
-is prey irruptive?
-is prey territorial?
when prey numbers increase fast, predation can intensify for two reasons
-functional response
-numerical response
functional response
-predators take more prey per individual
numerical response
-additioonal predators come to feed or predator population increases
-territoriality sets upper limit on numbers in a marsh
-excess move, disperve, starve, likely higher predation
-animals killed by predation likely would not reproduce anyway
-predation largely compensatory
buffer species
-post predators rely on more than 1 prey spp.
-influence of predation on any 1 prey species is function of availability of other prey
-buffering occurs when preds exort more pressure on more numerous prey, less on scarcer prey
predator characteristics that affect impact on prey
-is predator population affected by other factors than food supply, it may be unable to produce numerical response
-social behavior
diminishing returns
-hunting largely self-regulating
-past certain point, hunting unrewarded
-leads to fewer hunters
doomed surplus
-number of animals produced that exceed capacity of habitat to support and keep secure from predators
harvestable surplus
-most animals produce more young than necessary to maintain population
-extra number can be removed by hunting without affecting population
-density dependence
-productivity and abundance have inverse relationship
Opening Day Phenomenon
-most mortality occurs on opening day
-most hunters afield
Threshold of Secutiry
-population size above which some animals are not secure from predators
-carrying capacity concept indicating habitat ultimately decides population size
Durwood Allen - our Wildlife Legacy
harvest management components
-inventory of populations
-identification of population and harvest goals
-development of regulations that allow goals to be met
changes in hunting ideas
before 1980 - largely believed to be compensatory
-1980s to present - evidence that hunting may be additive for some species