.--In two earlier papers (Wilson Bull., 75: 42-55, 1963, and 76: 121-137, 1964) I reported that the primary food of Bald Eagles (Halia. eetus leucocephalus) wintering in an area near Savanna, Illinois, was gizzard shad (Dorosoma cepedianum). This fish is extremely abundant in the Missis- sippi River and its backwaters. Small shad (3 to 4 inches long) are especially numer- ous but occasionally larger individuals (up to 12 inches long) are also present. Several portions of the river and the backwaters remain unfrozen, or open periodically, in the winter. Ice conditions and the distribution of open areas were usually stabilized by late December and, at about this time, shad began to appear in large numbers at the open holes. Factors affecting ice conditions were discussed in the above-cited papers. Undoubtedly this area would be unable to support a large population of wintering eagles (up to 267 in February, 1962) without the availability of gizzard shad. Con- tinued studies in 1964 and 1965 substantiated the value of this species as food for eagles. Although other food sources exist, they do not occur in abundance or with the regularity of shad. TABLE 1 SPECIES OF BIRDS OBSERVED FEEDING ON GIZZARD SHAD Auk Vol. 83 Species Number o] observations Common Merganser (Mergus merganser) Bald Eagle ( Haliaeetus leucocephalus ) Herring Gull ( Larus argentatus ) Ring-billed Gull (L. delawarensis) Belted Kingfisher (Megaceryle alcyon) Red-bellied Woodpecker (Centurus carolinus) Red-headed Woodpecker (Melanerpes erythrocephalus) Yellow-bellied Sapsucker (Sphyrapicus varius) Downy Woodpecker (Dendrocopos pubescens) Blue Jay ( Cyanocitta cristata) Common Crow (Corvus brachyrhynchos) Black-capped Chickadee ( Parus atricapillus ) Tufted Titmouse (œ. bicolor) White-breasted Nuthatch (Sitta carolinensis) Cardinal ( Richmondena cardinalis ) Slate-colored Junco (Junco hyemalis) Tree Sparrow (Spizella arborea) Song Sparrow (Melospiza melodia) Many Many SeveraP Several 2 1 1 1 Several 1 Many Several 1 Several Several Several 1 2 Several  5 to 10. In addition, many other birds, and some mammals, wintering in the Savanna area are also dependent upon shad for at least part of their diets. The populations of some species (woodpeckers and passerines) appeared to be more dense in areas of shad avail- ability than in adjacent areas of similar habitat where shad were not available. About 78 per cent (18 species; see Table 1) of the avian species I observed wintering near the open water (scattered over eight linear miles of sloughs) were seen feeding on shad at least once in the months of January through March (1962-1965). Presumably, had my assistants and I directed our attention away from eagles and toward this problem, we would have found shad to represent a significant part of the winter diet of several of these species. Occasionally Common Goldeneyes (Bucephala clanguIa) appeared in the area and, although I never saw them feeding on shad, it is likely that they did so. Remains of shad were found in the proventriculi of two Common Mergansers. Species recorded in the area but not observed feeding on fish were: Red-tailed Hawk (Buteo jamai- censis), Red-shouldered Hawk (B. lineatus), Pileated Woodpecker (Dryocopus pile- atus), Red-breasted Nuthatch (Sitta canadensis), and American Goldfinch (Spinus tristis). Red-tailed and Red-shouldered hawks occurred in the area regularly. The density of these two species, particularly the latter, was higher within this eight-mile area than in any similar stand of deciduous forest I have investigated, including areas ad- jacent to the study area. Although I lack substantiating data, it seems possible that the hawks were attracted to these sites by the high populations of small birds which may serve as prey. It appears, therefore, that the gizzard shad serve as primary producers in the food cycles of many birds wintering in this area. In addition to the birds mentioned, such mammals as opossums (Didelphis marsu- pialis), raccoons (Procyon lotor), mink (Mustela vison), red foxes (Vulpes ]ulva), gray foxes (Urocyon cinereoargenteus), and various mice (Cricetidae; tracks and signs of feeding observed) fed on shad. Most of the species (exceptions being ducks and the Belted Kingfisher) listed in Table 1 fed on the numerous dead shad that were forced up on the beach, frozen into the ice, or dropped on the ice by eagles or crows. Bald Eagles utilized both dead and live shad, but preferred the latter. In most instances the smaller passerines and the woodpeckers fed near the banks. Occasionally, however, individuals fed on the ice at distances up to 200 feet from the shore and cover. The gulls arrived in the area during March and fed on the dead shad that were freed as the ice thawed. During a 10 minute period (1315 to 1325 hours) on 27 January 1965, Alfred Bjelland, Gary Schnell, and I recorded the following birds feeding on shad remains left from earlier feeding activities of eight Bald Eagles and many crows: 1 Red- bellied Woodpecker, 1 Red-headed Woodpecker, 3 Downy Woodpeckers, 1 Blue Jay, several Common Crows, 4 Black-capped Chickadees, 1 Tufted Titmouse, 1 White- breasted Nuthatch, 4 Cardinals, and 10 Slate-colored Juncos. In nearby trees, were a Red-tailed Hawk and a Red-shouldered Hawk. The sky was clear and the temperature about normal; however, the preceding three days had included heavy rain, some sleet, and finally three inches of soft snow. Weston (Auk, 80: 550-551, 1963) reported 11 species of birds feeding on several species of dead fish on 30 March in Iowa. All but two of the species (Ring-billed Gull and Common Crow) recorded by Weston are different from those I recorded. Thus, in the two areas, 27 species of birds have been observed feeding on dead fish in mid- or late-winter. Some of the species I recorded feeding on fish, although present in Weston's area, were not observed utilizing this food source in Iowa. Weston suggested that permanent residents use fish as emergency food; however, it appears to me that shad may represent a regular and substantial portion of the winter diet of several species occurring in northwestern Illinois. Some of the birds involved are not normally expected to feed on foods of this type (e.g., Slate-colored Juncos). It appears that the gizzard shad play an important role in maintaining winter populations of several species of birds and mammals found in northern Illinois. Per- haps similar situations exist in other areas. This factor should be taken into considera- tion during formation of management practices aimed at control of gizzard shad and related forms.--WrLm E. SOUThfIRSt, Department oJ Biological Sciences, Northern Illinois University, DeKalb, Illinois.