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Birds in the Midst of Change
Great Salt Lake Dynamics
• Natural
• Man caused
Natural Conditions
• Climate: a factor in long term trends
• Annual variation
Historic Lake ElevationsAn Indicator of Climate
Historic Lake ElevationsAn Indicator of the Annual Water Cycle
Lake elevation measurement sites
Anthropogenic Influences on Lake Ecology
• Highlights from history
• Substantive effects
1850Highlights from History
1870188018901900191019201930194019501960197019801990
Substantive Effects:
Diking is responsible for the creation of four distinct ecological units.
• North Arm• South Arm• Bear River Bay• Farmington Bay
Substantive Effects:
Necessary construction to the Southern Pacific causeway in the 1980s has created a salt trap in the North Arm.
Substantive Effects:
Current upstream water consumption reduces the standing lake elevation by an estimated five feet (Arnow 1980).
Substantive Effects:
Of 400,000 acres of lacustrine wetlands 50% are currently under management by state, federal and non-government organizations.
Substantive Effects:
Exotic fish (i.e., carp and gizzard shad) were introduced into managed wetland systems and water storage impoundments.
Substantive Effects:
Nearly 200,000 acres on the periphery of Great Salt Lake are leased properties for mineral extraction and other industrial uses (DSLF 1996).
Substantive Effects:
In addition to mineral extraction, shorelines have been significantly altered by:
• road and railroad construction• WMA diking• power line development• other human activities
Substantive Effects:
The commercial harvest of brine shrimp cysts, and other shrimp biomass, at times exceeds 200,000,000 lbs. annually.
Avian Use and Responses to Change
• Nine examples of GSL species and their response to change.
American White PelicansTwo decades of breeding adults
1963-2000 Gunnison Island White Pelican Breeding Adult Population
0
5,000
10,000
15,000
20,000
25,000
196319641972197319741976198019811982198319841985198619871988198919901991199219931994199519961997199819992000
Bre
ed
ing
Ad
ult
s
Eared Grebes
Great Salt Lake Eared Grebe Geographic Distribution Measured against Lake Elevation
Year Elevation Salinity (%) North Arm
Salinity (%) South Arm
Grebe Pop. North Arm
Grebe Pop. South Arm
1982 4200 26 10.5 Few 1,400,000 1986 4211 17 6 4,000 Few 1987 4210 17 6 3,500 Few 1989 4205 18 10 17,732 30,006 1990 4203 19 13 72,472 84,093 1991 4202 22 13.5 2,830 47,379 1992 4200 25 15 Few 156,210 2000 4202 26 9.5 Few 1,127,300
Tundra Swan
1960-70Swan concentration area
1990s Swan concentration area
Ogden Bay WMA
Bear River Refuge
White-faced IbisStrategic Nesters
1998
1999
2000
2001
California GullBreeding Adult Population
Year Breeding Adults Surveyors 1931 81,700 Behle 1983 80,237 Paul 1992 154,200 Robinette 1994 160,000 Paul/Jehl
Snowy Plover
Snowy Plover, master of dynamic habitats:
• Double brood in optimum conditions
• Long lived ( survival rate 2.7)
• Exploiter of ephemeral habitats
Changes in Distribution and Available Snowy Plover Nesting Habitat 1990-93 at Focal Study Sites, (Paton 1994) Focus Area % Habitat Decline Factor for Decline Howard Slough 56 Re-vegetation Layton Marsh 74.7 Re-vegetation
Wilson’s Phalarope
Annual WIPH Estimates
-
100,000
200,000
300,000
400,000
500,000
600,000
700,000
1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000
Year
The New Horizon:Integrated Conservation