lar to the 198895 average. Ducks preferred areas
We flew 37 surveys aerial surveys over Eagle
Areas B, C, and CD most in fall, with highest den-
River Flats from April to November 1995 with a
sities in Areas B and CD.
single-engine, fixed-wing aircraft using standard
USDI methodology. 1995 was a wet year in upper
A comparison of air and ground counts on the
Cook Inlet, so ponds were full most of the season.
same survey dates in fall was made to develop a
Fall weather was mild, which delayed migration
correction factor for birds missed from the air, and
through upper Cook Inlet. Numbers and species
to obtain a more accurate species composition of
of waterbirds counted on ERF were similar to
ducks. There were no statistical differences
other years, dominated by dabbling ducks and
between counts of geese and swans from the air
Canada geese, particularly in fall. Utilization of
and ground, but there was a statistical difference
standard study areas within ERF by waterbirds
between duck counts. Biases associated with the
was recorded and presented by season.
airground comparison probably make the counts
Other marshes in upper Cook Inlet were sur-
unreliable for airground corrections. The ground
veyed in 1995 to compare to ERF. These included
counts do provide reliable counts for species com-
Palmer Hay Flats, Goose Bay, Susitna Flats, Trad-
position.
ing and Redoubt Bays, and Chickaloon Flats. We
conducted 25 surveys from April to May. More
Haugen, R.K. (1995) Climate and tides. In Inter-
than 90% of the waterbirds counted were found
agency expanded site investigation: Evaluation of
on marshes other than ERF during the season.
white phosphorus contamination and potential treat-
Waterbirds concentrated on broad intertidal mud
ability at Eagle River Flats, Alaska (C.H. Racine and
flats in marshes other than ERF, Goose Bay, and
D. Cate, Ed.). CRREL Contract Report to U.S.
Palmer Hay Flats, where this habitat type is poorly
Army, Alaska, Directorate of Public Works, FY94
represented. Species composition of waterbirds
Final Report, p. 187200.
was similar on all areas. Numbers by species and
Meteorological elements and tidal inundations
area are presented by season.
are the major driving forces for physical and bio-
logical processes within ERF. In May 1994 a mete-
Eldridge, W .D., and D.G. Robertson (1998)
orological site was installed at ERF next to the
Waterbird utilization of Eagle River Flats and
EOD pad to provide baseline data for ongoing
Upper Cook Inlet: AprilOctober 1997. In Inter-
investigations. Comparisons between ERF and the
agency expanded site investigation: Evaluation of
Anchorage climatic record (Anchorage airport)
white phosphorus contamination and potential treat-
showed that daily maximum temperatures were
about 1C lower at ERF and minimum tempera-
ability at Eagle River Flats, Alaska (C.M. Collins and
tures 2.3C lower. A comparison of mean daily air
D. Cate, Ed.). CRREL Contract Report to U.S.
Army, Alaska, Directorate of Public Works, FY97
temperatures between the ERF main site at the
Final Report, p. 722.
EOD pad and an ERF coastal meteorological site
had a 5.3C difference, showing that air tempera-
Waterbird utilization of Eagle River Flats (ERF)
was monitored during spring, summer, and fall
ture variances within ERF are greater than the
1997, with 36 aerial observations. Numbers of
ERF/Anchorage differences.
waterbirds, identified to species or species group,
A historical analysis of Anchorage temperature
were recorded by study area and pond number
and precipitation from 1917 to the present was
within the study area, and by four major habitat
done to compare the normalcy of the weather dur-
types. ERF became snow and ice free earlier than
ing the ERF project on a monthly basis. The ERF
in 1996, experienced extremely dry conditions
field seasons of 1993 and 1994 can be character-
during summer, and experienced normal water
ized as normal except that May 1993 was more
levels in fall, with a relatively early freezeup.
than one standard deviation warmer and wetter
Numbers of swans in spring and fall were similar
than normal, and August 1994 more than one
to 1996 but considerably lower than the 198895
standard deviation warmer and drier than nor-
average. Numbers of geese were similar to recent
mal.
years. Duck utilization of ERF was minimal in
A program for the development of tidal tables
spring 1997, but normal for summer, despite the
was obtained from NOAA and adapted to predict
low water levels. Duck migration in fall 1997
past and future periods of tidal inundation of ERF.
exhibited a strong peak in early September rather
A table of predicted tides high enough to flood
than the protracted series of peaks normally
ERF for the months of May through October is
observed, but the mean number for fall was simi-
given for the period 19941997. Additional tables
44
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