In British Columbia the Marbled Murrelet (Brachyramphus marmoratus) is red-listed (species legally designated or being considered for legal designation as Endangered or Threatened) (CDC 2001) and designated as threatened by the Committee on the Status of Endangered Species in Canada (COSEWIC). The primary threats identified were the loss of nesting habitat through the logging of old-growth forests and mortality caused by gillnetting and oil spills. Identified Wildlife (IWMS) under the Forest Practices Code (FPC) Act lists Marbled Murrelets as a high priority for management within their provincial range. The feeding behaviour of Marbled Murrelets during the breeding season allows for the use of radar to determine population numbers. Pacific Herring and Pacific Sandlance, common prey species of the murrelet, move into coastal inlets in late May; this period coincides with the incubation period for Marbled Murrelets where nest duties and feeding activities are exchanged every 24 hours. During this switchover adult birds can be detected flying to and from the feeding and nesting sites. High frequency radar has been used on the coast of British Columbia, Washington, Oregon and California to determine size and changes in populations in specific drainages and regions. Burger (1997) states that radar surveys provide the only reliable method of estimating Marbled Murrelet numbers in specific watersheds and that only 7-15% of the birds picked up with radar are detected when carrying out audio/visual forest detection surveys. Radar has also been used successfully to determine the presence or probable absence of Marbled Murrelets in forest stands (Hamer et al. 1995; Cooper and Blaha 1998). Cooper and Hamer (2000) state that radar surveys are a more efficient method to determine presence and/or absence, especially when population numbers in a particular area are quite low. The initial goal of the Canadian Marbled Murrelet Recovery Team (CMMRT) as documented in the Part B: Conservation and Management is to down-list the species from Threatened to Special Concern by ensuring that the population (and habitat) on the BC coast does not decline by more than 30% from the current population during three generations (30 years) after 2002 (CMMRT 2002). The long-term goal is to maintain the current population, by providing sufficient Marbled Murrelet nesting habitat at the end of the 30-year period that if maintained in the long-term, would allow the populations to stabilize. In the Recovery Team document (CMMRT 2002) population and habitat objectives for the six conservation regions on coastal British Columbia have been established. The study area for this project is within the Southern Mainland Coast conservation region with a population estimate of 5000-7000 birds. The short-term priorities for this region are to identify and maintain remaining old-growth patches that meet the regional objectives and to conduct radar surveys to determine the populations within the southern portion of the region. The long-term objectives are to protect further areas of suitable stands to help restore sub-populations that are presently below the likely historical levels (CMMRT 2002). The recovery team recommends maintaining 85% of the present population on the Southern Mainland Coast region. Cullen and Manley (2001 and 2002) used radar to assess the numbers of Marbled Murrelets flying into 27 watersheds within the Sunshine Coast Forest District (SCFD) in 2000 and 2001 and stated that Marbled Murrelets appear to nest at much lower densities (birds/ha) in the SCFD than in other area in BC. From their 2-year radar count they found that within the watersheds of Howe Sound, Marbled Murrelets used the available habitat at significantly lower densities than in other areas of the SCFD. In 2000, 8 birds were recorded in Dakota, 7 in Rainy and 1in McNab, while in 2001 no birds were recorded in Dakota and Rainy and 13 were recorded in McNab.
Leigh-Spencer, Sally. 2004. Evaluation of potential road accessible radar stations for the Howe landscape unit. Forest Investment Account (FIA) - Forest Science Program. Forest Investment Account Report. FIA2004MR018