. A Distribution and Abundance of Winter Populations of Bald Eagles in Illinois Stephen P. Havera and Glen W. Kruse Illinois Natural History Survey Biological Notes 129, February 1988
RMMCKT62. A Distribution and Abundance of Winter Populations of Bald Eagles in Illinois Stephen P. Havera and Glen W. Kruse Illinois Natural History Survey Biological Notes 129, February 1988
Distribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois  distributionabun129have Year: 1988  linois Natural History Survey Biological Notes No. 129 <1.00 1.00-2.99 I 3.00-4.99 ) 5.00-9.99
RMT1H40MDistribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois distributionabun129have Year: 1988 linois Natural History Survey Biological Notes No. 129 <1.00 1.00-2.99 I 3.00-4.99 ) 5.00-9.99
. Distribution and abundance of winter populations of bald eagles in Illinois. Bald eagle. Illinois Natural History Survey Biological Notes have the greatest influence on the accuracy of bald eagle counts. Fog, rain, snow, and wind not only make it difficult for observers to see and age eagles but such conditions also may influence the activity of eagles, thereby making them less visible. Difficulties in obtaining accurate determinations of eagle numbers in Illinois do not eliminate the value of such counts. The counts can identify important winter areas and document trends in bald eagle popu-
RMRCCH2C. Distribution and abundance of winter populations of bald eagles in Illinois. Bald eagle. Illinois Natural History Survey Biological Notes have the greatest influence on the accuracy of bald eagle counts. Fog, rain, snow, and wind not only make it difficult for observers to see and age eagles but such conditions also may influence the activity of eagles, thereby making them less visible. Difficulties in obtaining accurate determinations of eagle numbers in Illinois do not eliminate the value of such counts. The counts can identify important winter areas and document trends in bald eagle popu-
Distribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois  distributionabun129have Year: 1988  February 1988 Havera and Kruse: Winter Populations of Bald Eagles IS    I 15 29 12 DEC JAN Fig. 18.-Mean numbci of bald eagles counted per invenloiv in ihe Upper Illinois River Region. 197(5-198.5. Seasonal patterns of hald eagle octiirrence in the Central Illinois Rivei Region are ilhistiated in Figure 20. No census tliglits were toiuhuied from mid-
RMT1H3WMDistribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois distributionabun129have Year: 1988 February 1988 Havera and Kruse: Winter Populations of Bald Eagles IS I 15 29 12 DEC JAN Fig. 18.-Mean numbci of bald eagles counted per invenloiv in ihe Upper Illinois River Region. 197(5-198.5. Seasonal patterns of hald eagle octiirrence in the Central Illinois Rivei Region are ilhistiated in Figure 20. No census tliglits were toiuhuied from mid-
. Distribution and abundance of winter populations of bald eagles in Illinois. Bald eagle. linois Natural History Survey Biological Notes No. 129 <1.00 1.00-2.99 I 3.00-4.99 ) 5.00-9.99. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Havera, Stephen P; Kruse, Glen W. [Champaign, Ill. ] : Illinois Natural History Survey
RMRCCH32. Distribution and abundance of winter populations of bald eagles in Illinois. Bald eagle. linois Natural History Survey Biological Notes No. 129 <1.00 1.00-2.99 I 3.00-4.99 ) 5.00-9.99. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.. Havera, Stephen P; Kruse, Glen W. [Champaign, Ill. ] : Illinois Natural History Survey
Distribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois  distributionabun129have Year: 1988  February 1988 Havera and Kruse: Winter Populations of Bald Eagles 1986. However, the mean number of eagles seen per inventory was the most logical method of presenting the data. Upper Mississippi River Region. The Upper Mis- sissippi River Region extends from the Illinois- Wisconsin border southward to approximately Rock Island, Illinois (Fig. 6). This region was surveyed from October through March during the three winters of 1980-1983 and substa
RMT1H3B0Distribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois distributionabun129have Year: 1988 February 1988 Havera and Kruse: Winter Populations of Bald Eagles 1986. However, the mean number of eagles seen per inventory was the most logical method of presenting the data. Upper Mississippi River Region. The Upper Mis- sissippi River Region extends from the Illinois- Wisconsin border southward to approximately Rock Island, Illinois (Fig. 6). This region was surveyed from October through March during the three winters of 1980-1983 and substa
Distribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois  distributionabun129have Year: 1988  Illinois Natural History Survey Biological Notes No. 129 Table 4.âRegions aerially iinentoried for bald eagles by the INHS and the Irequeno, approximate period, and years of censuses in each region. Region Upper Mississippi Riyer (DubuqueâInterstate 80) Upper Central Mississippi Riyer (MolineâKeokuk) Lower Central Mississippi Riyer (Keokuk-Alton, lower 26 miles of Illinois Riyer) Lower Mississippi Riyer (St. Louis-Cairo) Upper Illinois River (Mor
RMT1FMYADistribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois distributionabun129have Year: 1988 Illinois Natural History Survey Biological Notes No. 129 Table 4.âRegions aerially iinentoried for bald eagles by the INHS and the Irequeno, approximate period, and years of censuses in each region. Region Upper Mississippi Riyer (DubuqueâInterstate 80) Upper Central Mississippi Riyer (MolineâKeokuk) Lower Central Mississippi Riyer (Keokuk-Alton, lower 26 miles of Illinois Riyer) Lower Mississippi Riyer (St. Louis-Cairo) Upper Illinois River (Mor
. Distribution and abundance of winter populations of bald eagles in Illinois. Bald eagle. February 1988 Havera and Kruse: Winter Populations of Bald Eagles 1986. However, the mean number of eagles seen per inventory was the most logical method of presenting the data. Upper Mississippi River Region. The Upper Mis- sissippi River Region extends from the Illinois- Wisconsin border southward to approximately Rock Island, Illinois (Fig. 6). This region was surveyed from October through March during the three winters of 1980-1983 and substantial numbers of eagles were counted. The floodplain in thi
RMRCCH45. Distribution and abundance of winter populations of bald eagles in Illinois. Bald eagle. February 1988 Havera and Kruse: Winter Populations of Bald Eagles 1986. However, the mean number of eagles seen per inventory was the most logical method of presenting the data. Upper Mississippi River Region. The Upper Mis- sissippi River Region extends from the Illinois- Wisconsin border southward to approximately Rock Island, Illinois (Fig. 6). This region was surveyed from October through March during the three winters of 1980-1983 and substantial numbers of eagles were counted. The floodplain in thi
Distribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois  distributionabun129have Year: 1988  Fig 7 - 1 vpual iivcniie habitat of the L'ppcr Mississi] gion. The seasonal pattern of eagle use of the Upper Mississippi River Region is shown in Figure 8. Annual peak population counts occurred between 2 February and 23 March. Substantial numbers of birds were still present when counts were terminated each spring. The greatest 1-day count was 213 eagles on 23 March 1983. Southern (1964) observed peak numbers of 268 and 225 eagles in this region
RMT1H3AYDistribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois distributionabun129have Year: 1988 Fig 7 - 1 vpual iivcniie habitat of the L'ppcr Mississi] gion. The seasonal pattern of eagle use of the Upper Mississippi River Region is shown in Figure 8. Annual peak population counts occurred between 2 February and 23 March. Substantial numbers of birds were still present when counts were terminated each spring. The greatest 1-day count was 213 eagles on 23 March 1983. Southern (1964) observed peak numbers of 268 and 225 eagles in this region
. Distribution and abundance of winter populations of bald eagles in Illinois. Bald eagle. Peak population counts occurred between 3 Janu- ary and 9 March in this region with the highest count of 53 eagles reported on 20 January 1982. Generally, fewer than 25 eagles were seen on each census in this region. Immature birds consisted of 0 to 50.0% of the eagles observed on individual inventories, and the av- erage proportion of immatures for all eagles seen was 31.8%. The mean number of bald eagles observed per inventory for individual areas is depicted in Figure 19. The downstream portion of thi
RMRCCH34. Distribution and abundance of winter populations of bald eagles in Illinois. Bald eagle. Peak population counts occurred between 3 Janu- ary and 9 March in this region with the highest count of 53 eagles reported on 20 January 1982. Generally, fewer than 25 eagles were seen on each census in this region. Immature birds consisted of 0 to 50.0% of the eagles observed on individual inventories, and the av- erage proportion of immatures for all eagles seen was 31.8%. The mean number of bald eagles observed per inventory for individual areas is depicted in Figure 19. The downstream portion of thi
Distribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois  distributionabun129have Year: 1988  Fig. 21.-Mean number of bald eagles tountecl per inventory at cen.sus areas within the Central Illinois River Region, 1972-1986. Fig. 23.-Mean number of bald eagles counted per Lower Illinois River Region. 1972-1986. 0 to 50.09 of tlie total eagles observed, and the overall proportion of immatiires was 34.79 for all inven- tories. The mean number of eagles inventoried per cen- sus flight is illustrated in Figure 24. ,reas with the most use by ba
RMT1H40JDistribution and abundance of winter Distribution and abundance of winter populations of bald eagles in Illinois distributionabun129have Year: 1988 Fig. 21.-Mean number of bald eagles tountecl per inventory at cen.sus areas within the Central Illinois River Region, 1972-1986. Fig. 23.-Mean number of bald eagles counted per Lower Illinois River Region. 1972-1986. 0 to 50.09 of tlie total eagles observed, and the overall proportion of immatiires was 34.79 for all inven- tories. The mean number of eagles inventoried per cen- sus flight is illustrated in Figure 24. ,reas with the most use by ba
. Distribution and abundance of winter populations of bald eagles in Illinois. Bald eagle. February 1988 Havera and Kruse: Winter Populations of Bald Eagles 13 12. Fall arrival and spring departure dates were simi- lar to those observed in the Upper Central Mississippi River Region. The progression to earlier arrival of eagles observed on aerial inventories during fall in recent years also occurred in this region. The highest counts for each year occurred between 11 December and 8 March and the largest number of bald eagles recorded in this region was 527 on 6 January 1986. Immature eagles acc
RMRCCH3H. Distribution and abundance of winter populations of bald eagles in Illinois. Bald eagle. February 1988 Havera and Kruse: Winter Populations of Bald Eagles 13 12. Fall arrival and spring departure dates were simi- lar to those observed in the Upper Central Mississippi River Region. The progression to earlier arrival of eagles observed on aerial inventories during fall in recent years also occurred in this region. The highest counts for each year occurred between 11 December and 8 March and the largest number of bald eagles recorded in this region was 527 on 6 January 1986. Immature eagles acc