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Christmas Bird Count trends in the Sea to Sky corridor, 2003



Last week the Naturespeak article on Christmas Bird Counts noted that there are now six count circles (each 75 sq. km) within the Sea to Sky corridor. Our latest, Outer Howe Sound, joined the lineup in 2003 after several years of unofficial local counts on Bowen Island. However, the circle for the new riding encompasses the following: Lighthouse Park in West Vancouver to Cypress Bowl; Horseshoe Bay to Lions Bay; Pasley, Bowen, Bowyer, Keats and large portions of Gambier and Anvil Islands. Many islanders contributed to the count, including 19 from Gambier and 30 on Bowen – 62 field observers all told! It is a logistical challenge to pull it all together and Lewis Maingon on Gambier, the co-ordinator, did an admirable job. We thank him for collating their data used for comparative purposes in this review. Unfortunately he is leaving "Utopia" to reside in the Comox area.

For each of the six count areas the number of field observers/total species numbers/total birds counted (shown in brackets) are as follows: Outer Sound (62/97spp/10,346 birds), Squamish (26/72spp/13,681 birds), Whistler (19/56spp/6,611 birds), Pemberton-Mt. Currie (13/52spp/2,133 birds), D’Arcy-Devine (10/38spp/775 birds) and Lillooet (16/59spp/1,774 birds). Species totals include count week sightings.

The co-ordinator of the Lillooet count, Ken Wright, has found direct relationship between the number of species spotted and the number of observers, supported by the above, but it does not correlate with the total number of birds counted, as shown by the Squamish count in particular. An over abundance of one or two species can bulk up the total count, and for Squamish it was Bald Eagles (2,411) and Glaucous-winged gulls and related forms (6,861) that swelled the count.

For the Outer Sound the culprits were the Barrow’s golden eye duck (2,369) and Pine siskin (2,002), while Whistler’s record volume was fortified by yes, more Pine siskins (3,610) and yes again, Glaucous-winged gulls and allies (1,399). Subtraction of these numbers from the total yields a more reasonable blend with the trend of volume recorded for the other four counts.

The Sea to Sky corridor begins on the rich marine front in the Strait of Georgia; enters an outer Howe Sound of diverse habitats; narrows down in the inner fjord to terminate on salmon-endowed Squamish estuary; ascends to the summit divide of the Western Coast Mountains (the Pacific Ranges) at Whistler; descends to the broad Lillooet-Harrison valley floor (a mega fault zone) with intrusims of coastal climate that is the boundary to the Eastern Coast Mountains (the Lillooet ranges); ascends to a low summit divide on the latter at Gates Lake (near D’Arcy-Devine); then extends eastward to the leeward drier aspect on the mountains’ eastside to terminate on the edge of the Interior Plateau at the fault-bounded Fraser Canyon. Sage brush intrudes the scene at Lillooet, and continental climates prevail in this area.

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