The Marbled Murrelet – a key species in the Great Bear Rainforest

Publication - July 20, 2010
The marbled murrelet is a small sea bird whose very characteristics make it both a unique species and also a threatened one. While it spends most of its time foraging at sea, it depends on old growth forests for nesting. The body shape that makes marbled murrelet so effective at diving and moving underwater also makes take off and landing very difficult. This means they have specific nesting site requirements and old growth trees with canopy structures provide those requirements.

Marbled murrelets typically nest on large mossy beds in complex and biodiversity-rich forests older than 250 years — in other words, old growth. These forests provide a canopy structure for nesting and have to be within a 30 kilometre (km) range of the ocean. These mossy beds must be high up in the canopy and hidden in order to protect marbled murrelets from predators when they nest. These mossy beds must also be next to an opening in the forest canopy to allow for the special methods by which this bird approaches its nest and leaves it. The murrelet takes off by jumping out of the nest and the free-falls to earth before beginning to fly.

Attribution: to Gu van Viet

Marbled murrelets are very slow to reproduce. They breed only after two to three years of age. Each breeding female usually lays only one egg per year and that has less than a 50 per cent chance of surviving.

Its slow reproductive rate combined with the logging of nesting habitats in old growth forests throughout much of the bird’s range as well as threats at sea (such as oil spills and gill-netting), have resulted in a rapid population decline — approximately 70 per cent loss in the last 25 years alone. For these reasons, the marbled murrelet is now listed as threatened (red-listed) by the British Columbia (B.C.) Conservation Data Centre, and as threatened under the Canadian Species at Risk Act. It is also listed under the U.S. Endangered Species Act.

It is estimated that British Columbia is home to approximately 27 per cent of the global population. The Great Bear Rainforest is home to half of B.C.’s marbled murrelet population.

SOME INTERESTING FACTS

  • Marbled murrelets require a healthy marine and terrestrial environment for survival. This means oil spills, overfishing, logging and mining activities all place this unique bird at risk.
  • Although they spend most of their time in the ocean, marbled murrelets nest in inland areas in old-growth forests that provide canopy-structured trees needed for their nesting habits.
  • Marbled murrelets do not build nests. They make a depression in existing moss in the tree canopy. This is in order to avoid leaving evidence of a nest which ‘edge of forest’ species like ravens, crows and jays look for when hunting.
  • One egg is about a third the size of a marbled murrelet. The chick remains in the nest for about a month.
  • Most chick species feed on regurgitated food from the parents – but not the marbled murrelet. The chick feeds on a whole fish which its parent sometimes flies up to 70 km away to find.
  • Marbled murrelets do not ‘glide’ like most birds. Instead they fly at one speed. When they stop, they just stop and when they take off from their nest they must drop down from the tree.

SOURCES

Burger, A. E. 2002. Conservation assessment of Marbled Murrelets in British Columbia: a review of the biology, populations, habitat associations, and conservation Technical Report Series No. 387. Canadian Wildlife Service, Pacific and Yukon Region, British Columbia. Issued under the Authority of the Minister of Environment Canadian Wildlife Service. 

H.L. Horn, P. Arcese, K. Brunt, A. E. Burger, H. Davis, F. Doyle, K. Dunsworth, P. Friele, S. Gordon, A. N. Hamilton, S. Hazlitt, G. MacHutchon, T. Mahon, E. McClaren, V. Michelfelder, B. Pollard, S. Taylor, F.L. Waterhouse. 2009. Part 1: Assessment of Co-location Outcomes and Implications for Focal Species Management under EBM. Report 1 of the EBM Working Group Focal Species Project. Integrated Land Management Bureau, Nanaimo, B.C. [online] URL: ilmbwww.gov.bc.ca/slrp/lrmp/nanaimo/cencoast/ebmwg_docs/ei02c_report_3.pdf

Piatt, J.F., K.J. Kuletz, A.E. Burger, S.A. Hatch, V.L. Friesen, T.P. Birt, M.L. Arimitsu, G.S. Drew, A.M.A. Harding, and K.S. Bixler. 2006. Status Review of the Marbled Murrelet (Brachyramphus marmoratus) in Alaska and British Columbia. U.S. Geological Survey Open File Report 2006 1387. [online] URL: pubs.usgs.gov/of/2006/1387/

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