. The Canadian field-naturalist. 75 % Hardwood YOOL? 91^ YOWL? YOGfi? 75% Conifers GO'^-RO? 50 7o Hardwood B0GL^-yV09 75% Conifers 1 All Hardwood. Figure 2. Territorial occupation by Gray Jays of the same area in 1969. BOGL and WO northward by the use of food until we encountered GO and RO, when the latter were promptly attacked and driven back across the terri- torial line. Trespassing birds are aware that they are trespassing, and always give way before an attack by the rightful occupants. In Algonquin Park, Ontario, and in La Verondrye Park, Quebec, it has been found that the territory of e
. The Canadian field-naturalist. 75 % Hardwood YOOL? 91^ YOWL? YOGfi? 75% Conifers GO'^-RO? 50 7o Hardwood B0GL^-yV09 75% Conifers 1 All Hardwood. Figure 2. Territorial occupation by Gray Jays of the same area in 1969. BOGL and WO northward by the use of food until we encountered GO and RO, when the latter were promptly attacked and driven back across the terri- torial line. Trespassing birds are aware that they are trespassing, and always give way before an attack by the rightful occupants. In Algonquin Park, Ontario, and in La Verondrye Park, Quebec, it has been found that the territory of each pair of Gray Jays approximates one quarter of a square mile, or 160 acres. Coniferous forest, particularly spruce, or a spruce-tamarac association, with trees of small to medium size is the pre- ferred forest cover. Pure hardwood stands are utilized for foraging, but there is no record of a defended territory that was not at least 5^0% coniferous. In La \'erondrye Park, where there is continuous coniferous cover over large areas, territories tend to be more often contiguous than in Algonquin Park, where the coniferous stands are frequently broken by hills of Precambrian rock supporting maples and other hardwoods. The only recorded case of an established pair being displaced by another occurred in Algonquin Park between 1968 and 1969. The male GO, mated successively with GL and RO, had occupied the Museum territory since 1964. In the spring of 1968 BOGL appeared as a third bird with GO and RO and remained on the territory in spite of frequent harassment by GO. In October, 1968, a fourth bird appeared, and eventually, as WO, became the mate of BOGL. In December all four birds were using the territory, but GO and RO were seen only rarely, and by the end of the year it was evident that BOGL and WO were the resident pair. Field work during the winter disclosed that GO and RO were occupying the next territory to the north. The diagram- matic sketches, Figs. 1 and 2, are an attemp
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