. Il campo Canadese-naturalista. Storia naturale. 2002 PoTviN, Breton e Rtvest: il doppio conteggio di rilievo aereo 489 aree di studio il doppio conteggio di antenna tecnica di sondaggio è stato testato in Quebec in otto grandi cervi zone di svernamento (25-213 km-), due blocchi di foresta (160 e 475 km-) sull isola Anticosti (zona 20), e 11 zone di caccia (1 600-26 000 km^) sulla terraferma (Figura 1). Deer distribuzione continua nella provincia è limitare- ed a quelle zone. Le zone del sud (4, 5, 6, 7, 8) hanno un misto di agricoltura-foresta paesaggio mentre nord- ern zone (1, 2, 3, 9, 10, 11, 20) sono in gran parte boscoso. Vegetati

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. The Canadian field-naturalist. Natural history. 2002 PoTviN, Breton, and Rtvest: Double-count Aerial Survey 489 Study areas The double-count aerial survey technique was tested in Quebec in eight large deer wintering areas (25-213 km-), two forest blocks (160 and 475 km-) on Anticosti Island (zone 20), and 11 hunting zones (1 600-26 000 km^) on the mainland (Figure 1). Deer continuous distribution in the province is limit- ed to those zones. Southern zones (4, 5, 6, 7, 8) have a mixed agriculture-forested landscape while north- ern zones (1, 2, 3, 9, 10, 11, 20) are largely forested. Vegetation types are mostly deciduous or mixed, except on Anticosti Island which is dominated by boreal forest. During the snow season, deer congre- gate in wintering areas with a dense mixed and coniferous canopy. Winters are milder in the south, with three to four months of snow cover, but severe in the northern and eastern parts of the deer range, with almost six months of snow. Snow depth rarely exceeds 50 cm in the southern zones but can do so for 30 to 70 days on average in northern ones. Methods Aerial surx'ey technique A detailed description of our double-count aerial survey technique can be found in Breton and Potvin (1997). Deer were counted by two observers sitting on the left side of a Bell 206-B (Anticosti) or Bell 206-L (other zones) helicopter. A bubble window- installed in the back door enabled the rear observer to see under and beside the aircraft. The front observer used the front upper, side and floor win- dows. The width of the narrow^ strip plot extended on the left side only from 0° (below the helicopter) to a 45° angle from the vertical. For each observer, the outer boundary was delimited by two reference marks denoted by plastic tape, on the side window and on the bottom of a rod extending outside and perpendicular to the aircraft. Before each sur ey, the helicopter followed a straight hne (road, air strip) so that both observers verified that their viewing a

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