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Figures

Figure 1

Platte River drainage in Colorado, Wyoming, and Nebraska

Figure 2

Channel width in this reach of the Platte River west of Kearney in south central Nebraska has been reduced by approximately 90% during the past century and cranes no longer roost there

Figure 3

Sandhill cranes foraging in a native meadow near the Platte River

Figure 4

Chronology and duration of various investigations under the Platte River Ecology Study

Figure 5

The study area

Figure 6

Staging areas of sandhill cranes in the Platte and North Platte River Valleys

Figure 7

Distribution of roosting sandhill cranes by 0.8 km segment of river channel

Figure 8

Home range characteristics of a radio-marked sandhill crane in the Platte River Valley during spring 1979

Figure 9

Principal foods of sandhill cranes during spring on the major foraging habitats

Figure 10

Daily rates of fat deposition by adult male and female sandhill cranes during the spring staging period in Nebraska and utilization patterns

Figure 11

Conceptual model of sandhill crane population energy budget during the spring staging period in Nebraska

Figure 12

Estimated energy and food requirements of the sandhill crane population during the spring stopover period at projected population levels of 350,000 and 450,000 individuals

Figure 13

Migration corridor and confirmed sightings (1950-spring 1980) of the whooping crane in Nebraska

Figure 14

Diet of male and female mallards during winter and spring migration in south central Nebraska

Figure 15

Daily rates of fat deposition among adult male and female white-fronted geese during the spring staging period in south central Nebraska

Figure 16

Distribution of communal roosts of bald eagles on the study area and average number of eagles sighted between bridges based on aerial surveys during the 1978-79 and 1979-80 winters (see Appendix G for additional details)

Figure 17

Occurrence of prey items in egested pellets of bald eagles found at roost sites along the Platte and North Platte Rivers

Figure 18

A diagrammatic sketch of the principal natural habitats of the Platte River Valley and characteristic species of breeding birds

Figure 19

Distribution of roosting sandhill cranes (by percent occurrence) among categories of unobstructed river channel width and predominant vegetation height class on adjacent channel and island banks

Figure 20

Distribution of bald eagles and water fowl during the 1978-79 and 1979-80 winters in relation to availability of open water (Locations are identified in Fig. 16)

Figure 21

Distribution of avian cholera outbreaks in the Rainwater Basin area during spring 1980 and proximity to spring staging areas of sandhill cranes

Figure 22

The major vegetation types on the Platte River floodplain

Figure 23

Mean annual discharge along the North Platte and Platte rivers (North Platte and Overton substations) during 1910-77 period (After Williams 1978)

Figure 24

Historical trends in channel widths along the North Platte and Platte rivers at the North Platte and Overton substations (After Williams 1978)

Figure 25

Average age of cottonwood, red cedar, willow, catalpa, hackberry, and Russian olive in relation to sample site location along the Platte River

Figure 26

Idealized model of the development of woody vegetation

Figure 27

Effects of riverine hydrology on seed germination rates of cottonwood and willow under various storage regimes

Figure 28

Habitat conditions at 3 vegetation study sites

Tables

Table 1

Mean monthly temperature (degrees C) and precipitation (cm) on the study area (mean values from Grand Island, Kearney, and North Platte)

Table 2

Estimates of peak numbers of sandhill cranes on spring staging areas in the Platte and North Platte River Valleys, Nebraska, during 1979 and 1980

Table 3

Home range characteristics of radio-marked sandhill cranes during spring 1978 and 1979 on study area near Kearney, Nebraska

Table 4

Diurnal habitat use by radio-marked sandhill cranes in the Platte River Valley during 1978 and 1979

Table 5

Changes in the availability of waste corn (kg dry wt/ha) on the Platte River study area

Table 6

Habitat types used by feeding whooping cranes during migration through the Great Plains

Table 7

Habitat use by raptors during the 1978-79 and 1979-80 winters in the North Platte and Platte River Valleys

Table 8

Estimated populations of the principal species of birds breeding on the study area

Table 9

Percent of sandhill crane population roosting in river segments of varying width and vegetation characteristics and the percent of river segments in each category

Table 10

Hectares of harvested corn stubble necessary to support the sandhill crane population under various conditions

Table 11

Avian cholera mortalities among waterfowl in certain wetlands of the Rainwater Basin Area during spring 1980 in relation to population size, water area, and density

Table 12

Comparison of radial growth of cottonwood, red cedar, and willow during a period of low mean discharge (1967-70) and a period of high mean discharge (1971-74)

Table 13

Occurrence, establishment, and mortality of seedlings in 17 permanent 1-m² quadrats

Table 14

Means of the environmental and seedling parameters for quadrats included in the upland, raised sandbar, raised sandbar with neww seedlings, sandbar, and sandbar with new seedlings sites

Appendices

Appendix A

Common and scientific names of animals identified in the study

Appendix B

Common and scientific names of plants species on the Platte River floodlpain

Appendix C

Locations of confirmed whooping crane sightings on or near the Platte River, 1912-49

Appendix D

Characteristics of the Platte River at sites known to have been used by whooping cranes

Appendix E

Distribution and abundance of wintering mallards and geese along the North Platte and Platte Rivers

Appendix F

Mean numbers of raptors seen per census along each survey route in the Platte and North Platte River Valleys during 1979 and 1980

Appendix G

Location and characteristics of bald eagle nocturnal roosts and the mean number of eagles censused per roost

Appendix H

Prey items identified from egested pellets of bald eagles at roost sites in the North Platte and Platte River Valleys in Nebraska

Appendix I

Characteristics of river segments within sandhill crane staging areas

Appendix J

Confirmed sightings of whooping cranes in the Rainwater Basin Area, 1950 - spring 1980

Appendix K

Estimated numbers of sandhill cranes using waterfowl production areas (WPA's) in the Rainwater Basin Area of south central Nebraska

Appendix L

Effects of woody vegetation encroachment on abundance and distribution of various species of birds breeding in the Platte River Valley

Appendix M

Summary of the vegetation types on the Platte River floodplain

Appendix N

Average percent cover of the principal species composing the major habitat types on the floodplain of the North Platte and Platte Rivers

Appendix O

Average and earliest years of establishment of cottonwood, red cedar, willow, and other trees along the Platte River as determined by increment tree cores

Appendix P

The relationship between vegetation and soils at selected sites along the North Platte and Platte Rivers

Appendix Q

Definitions of the 12 environmental parameters used to characterize the 71 permanent quadrats in riparian vegetation studies

Appendix R

Use of grasslands by whooping cranes