. The Canadian field-naturalist. Natural history. 72 The Canadian Field-Naturalist * Vol. 117. 100 200 Metres Figure 2. Location of permanently marked tran- sects on Great Island, Newfoundland. occupied if an egg was found. Burrows were consid- ered empty if all tunnel branches were explored and no egg was found. Exploring burrows longer than an arm's reach required the careful digging of one or more conical access holes until the end was reached. Excavated holes were immediately patched with sticks and soil to ensure their future integrity. To minimize disturbance, adults and eggs were not re
. The Canadian field-naturalist. Natural history. 72 The Canadian Field-Naturalist * Vol. 117. 100 200 Metres Figure 2. Location of permanently marked tran- sects on Great Island, Newfoundland. occupied if an egg was found. Burrows were consid- ered empty if all tunnel branches were explored and no egg was found. Exploring burrows longer than an arm's reach required the careful digging of one or more conical access holes until the end was reached. Excavated holes were immediately patched with sticks and soil to ensure their future integrity. To minimize disturbance, adults and eggs were not removed from burrows. All portions of the island where burrows occurred were included in the measurement of colony area. Colony boundaries and boundaries of vegetation types were measured to the nearest m along tran- sects. Colony and vegetation boundaries outside transects were determined by careful exploration and by measurements taken perpendicular to transect lines. Measurements were taken along the ground and thus include surface contours. Distance and slope measurements taken along transects, as well as during exploration, were used to draw colons areas on a detailed topographic map at a scale of 1:943 with 10-foot contour intervals. The horizontal surface area of the colony was measured on the map with a Koizumi compensating polar planimeter, Type KP-23. Colony areas were divided into sections with similar slopes. Adjusting for slope, the area of individual sections was given by: Cs = AhT2(cosQ)-\ where Cs is the colony surface area, Ah is the area on the map, T is the scale of the map, and Q is the mean slope along the transects or, if measured areas did not fall along transects, the average slope calculated from the spacing of the 10' contour lines. To improve accuracy, each small section delimited on the map was measured three times with the planime- ter, and the mean of those three measures was used to calculate the area. Colony area calculations took into account
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