. The Canadian field-naturalist. 374 The Canadian Field-Naturalist Vol. 105. 1986 1987 Class 1 Class 2 Class 3 Figure 1. Percent frequency of occurrence of composite vegetation stem density classes 1 (*£5 stems), 2 (>5 but ^15 stems), and 3 (>15 stems) for 23 Common Loon broods. Turtle-Flambeau Flowage, Wisconsin. 1986-1987. located site, and because habitat selection is dissimi- lar for nesting and brood rearing. Mean pH (), specific conductance ( umhos). and alkalinity () were similar to levels reported by Zimmer (1979) for lakes with nesting adults. Water clarity did not a
. The Canadian field-naturalist. 374 The Canadian Field-Naturalist Vol. 105. 1986 1987 Class 1 Class 2 Class 3 Figure 1. Percent frequency of occurrence of composite vegetation stem density classes 1 (*£5 stems), 2 (>5 but ^15 stems), and 3 (>15 stems) for 23 Common Loon broods. Turtle-Flambeau Flowage, Wisconsin. 1986-1987. located site, and because habitat selection is dissimi- lar for nesting and brood rearing. Mean pH (), specific conductance ( umhos). and alkalinity () were similar to levels reported by Zimmer (1979) for lakes with nesting adults. Water clarity did not appear to limit adult foraging efficiency, averaging 163 cm for all areas in both years. Barr (1973) stated loon foraging effi- ciency decreased if visibility was < m. High visi- bility in relatively shallow water may provide increased foraging success by Common Loons. Mean water depth was significantly greater (f-test; P = ,fl = 1980) in LBP(x = 217 cm) areas than in EBP (x = 1X7 cm) areas. Similar mean water depths were reported for EBP areas (Mclntyre 1983) and TBP areas (Strong 1(^S5). These water depths probably provide optimum foraging opportunities. Yellow Perch {Perca flavescens) and other small fish are common on the Til- ( and Bever lu72). Mosi small fish in lakes prefer shallow water (Scot) and Crossman 1973). Thus, it would be advantageous for loons to use shallow water areas toi brood real ing and foraging. Loons used areas containing a highei percenl fre quenc) ol occurrence ol vegetation and wood) debris during l BP(549 I than during io\ i foi both seai. Dominant vegetation found in EBP and I BP area included \4yriophyllum / tricularia ipp Potamogeton ipp and Elodea spp. I fable 2). Brood area < onti g aquatu plants, partu ularlj those with high leal dissection (eg Wyriophyllum spp .nui / ah iiLiihi spp. i could potentially support more fi ii and fish pre) items, making these areas mon uitable to (Common I oons < Kre< kei 19
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