The adjacent Carmanah Creek and Walbran Creek watersheds are found along the southern portion of the west coast of Vancouver Island. The mountains here are less steep than farther northwest along the coast. Carmanah Mountain on the west side of the site is 1052 metres in height.
Western Hemlock dominates the forest in the lowest vegetation zone, although Sitka Spruce forms a narrow belt adjacent to the ocean. Western Redcedar at lower elevations and Yellow Cedar at higher elevations are common tree species, while Amabilis Fir, Shore Pine and Red Alder also occur.
This and three other forested sites in British Columbia have been identified as IBAs for breeding Marbled Murrelets (a nationally threatened species) even though it is still uncertain whether these are the best Canadian sites for the species. Given the state of the information at this time (early 2001) it appears that these sites are probably amongst the highest quality sites, but others may be equally as good, or better. Since the species is very difficult to survey, the habitats and favoured breeding areas are poorly known. The IBA includes the whole of each watershed because Marbled Murrelets may breed in both low and high elevation areas, although most researchers believe that lower elevation forests are preferred.
In 1990, surveys were conducted on Vancouver Island that used visual and auditory detections to assess Marbled Murrelet activity in an area. In 1990, researchers recorded over 70 detections of Marbled Murrelets in the Carmanah valley. This and other previous studies suggested that the area was an excellent location for the species.
Radar surveys have been used in many watersheds along the west coast of Vancouver Island in the late 1990s. These radar surveys are thought to be more accurate than the detection surveys as they record all the birds flying into a watershed at dawn. There is still uncertainty over whether all birds detected are using the associated watershed, but most are believed to be. Since parts of the province with less steep topography can not be surveyed as accurately using the radar survey method (since birds do not concentrate at river mouths as much and can fly over lower-lying watershed divides) the radar survey results from the Carmanah Walbran are thought to not fully represent the numbers of murrelets present. In 1995, a maximum of 146 birds were recorded on a radar survey in the Carmanah section of the site. In addition, high amounts of inland activity and high numbers of the birds at sea suggest that it is one of the better sites for Marbled Murrelet.
The first two nests (as opposed to nestlings) of Marbled Murrelets in Canada were found in the Walbran Valley in 1990 and 1991.
Most of this IBA is within the relatively recently designated Carmanah Walbran Valleys Park. The upper ends of the Walbran Creek watershed are not in the park however and thus may be logged. Some parts of the site have already been subject to logging.Catégories ZICO Habitats Usages Menaces Potencielles ou Existantes Status de Protection
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