The marbled murrelet is a small seabird that lives along the Pacific coast of North America. It is known for its distinctive brown and white marbled plumage and its habitat preferences of nesting in old-growth forests near the ocean. The marbled murrelet has some unique adaptations that enable it to fly between its forest nesting sites and its marine foraging areas. In this article, we will examine the flight capabilities of the marbled murrelet and discuss how its anatomy and behavior allow it to be a highly mobile species despite its small size.
Marbled Murrelet Flight Capabilities
The marbled murrelet is classified taxonomically in the family Alcidae, which includes auks, murres, and puffins. Like other alcids, it has short wings relative to its body size which provide high lift and allow it to fly fairly rapidly with fast wingbeats. Its wings have a rounded shape which reduces drag and makes the murrelet energy-efficient in flight.
Some key features of the marbled murrelet related to its flying abilities are:
– Compact, chunky body shape with short tail reduces drag in flight. Average mass is about 6 ounces (170 grams).
– Wingspan of approximately 16 inches (40 cm). Short, rounded wings provide lift.
– Large pectoral flight muscles power wingbeats. Heart and lungs are enlarged to supply oxygen.
– Lightweight, compact bones. Total skeleton is only around 4% of its body weight.
– Feathers structured for waterproofing and flight. Contour feathers shaped to maximize lift.
These adaptations allow the marbled murrelet to fly at speeds averaging 22-45 mph (36-72 km/h) when commuting or migrating. However, it can reach top speeds of up to 75 mph (120 km/h) while diving or evading predators. Overall, its moderate wingspan, muscular flight stroke, and streamlined body make it well-suited for agile flight through forest gaps or over ocean waters.
Flight Between Forest and Sea
A unique aspect of the marbled murrelet’s flight abilities is that it flies regularly between coastal old-growth forests, where it nests high up in the canopy, and the ocean, where it dives underwater to catch small fish and invertebrates. This requires special adaptations to allow the murrelet to take off quickly from the treetops and maneuver through dense forests.
Some behaviors the murrelet uses when commuting between forest and sea include:
– Powerful burst takeoffs to launch from branch platforms high in trees
– Flapping flight and gliding used to navigate through gaps in forest canopy
– Streaking flight low over water using wings for lift and feet for paddling
– Precise landing on rough ocean surfaces using wings for braking
– Water takeoffs assisted by leg paddling to become airborne
The murrelet has high flight metabolism and large flight muscles to power these frequent takeoffs and landings. Its compact body profile helps it avoid collisions in dense forests. This species spends over 90% of its time in flight or diving during the breeding season in order to provision its chick.
Long Distance Migrations
In addition to local flights between nesting and feeding areas, marbled murrelets undergo long distance migrations of hundreds of miles. Migration patterns vary across their range:
– Northern populations are mostly resident year-round near breeding sites
– Central pop’s migrate south to California in winter months
– Some southern populations migrate north to Alaska in summer
These migratory behaviors maximize food availability in different seasons and reduce energy costs. However, the migrations require excellent flight capabilities over long distances.
Some adaptations the murrelet uses during migration include:
– Endurance flying for many hours or days during migration flights
– Flocking together to reduce energy costs from air turbulence
– Orienting using magnetic field detection and visual landmarks
– Making use of wind patterns by gaining altitude and gliding downwind
– Stopping to rest on water and replenish energy reserves en route
The combination of powered flight and gliding allows the marbled murrelet to travel remarkably long distances of over 1,500 miles while migrating.
Evasive Flight from Predators
An important aspect of the marbled murrelet’s flight abilities is evading predators in the air. When threatened, it can perform rapid dives, loops, zig-zags, and other aerial maneuvers. Some key predator evasion tactics include:
– Detecting approaching predators early using keen eyesight
– Instantly taking flight when a threat is noticed
– Accelerating rapidly to top flight speeds up to 75 mph
– Executing tight turns using short rounded wings for agility
– Diving suddenly toward the ocean surface when over water
– Confusing predators by flocking together in tight swarms
The murrelet’s compact shape allows rapid changes in direction. Its powerful flight muscles provide bursts of speed needed to escape. These evasive maneuvers are an important aspect of the murrelet’s flight abilities, improving its chances of survival.
Impacts of Habitat Loss on Flight
An ongoing threat to the marbled murrelet is the loss of coastal old-growth and mature forests where it nests. Deforestation has removed much of its nesting habitat, especially in Washington, Oregon, and California. This loss of nesting habitat has indirect impacts on the murrelet’s flight abilities and behaviors.
Some of the effects of deforestation include:
– Less suitable forest cover for takeoffs and landings
– Longer, more exposed commuting flights between forest fragments
– More frequent predator attacks near forest edges
– Higher energy costs to reach remaining forest nest sites
– Disruption of native forest food webs that provide prey items
By degrading and fragmented the forests where murrelets nest, logging practices have made flight more challenging for this seabird. Preserving remaining old-growth forest corridors is crucial for connecting marbled murrelet populations and enabling successful flight between inland and coastal areas.
Conclusions
In summary, the marbled murrelet has a number of adaptations that enable successful flight and aerial maneuverability. Its compact, streamlined body shape and short, rounded wings provide lift and reduce drag. Powerful flight muscles allow it to commute rapidly between coastal forests and the ocean. The murrelet can reach speeds over 75 mph during evasive flights or migrations spanning hundreds of miles. However, loss of old-growth nesting habitat has negatively impacted its flight behaviors. Overall, the marbled murrelet is a highly mobile species thanks to its specialized anatomy and flying capabilities. Efforts to preserve suitable coastal forest habitat will be important for ensuring the future success of marbled murrelet populations.
References
[1] Nelson, S.K. (1997). Marbled Murrelet (Brachyramphus marmoratus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA. https://doi.org/10.2173/bna.276
[2] Piatt, J.F., Kuletz, K.J., Burger, A.E., Hatch, S.A., Friesen, V.L., Birt, T.P., Arimitsu, M.L., Drew, G.S., Harding, A.M.A., Bixler, K.S. (2007). Status review of the marbled murrelet (Brachyramphus marmoratus) in Alaska and British Columbia.
[3] Cooper, B.A., M.G. Raphael, and D. Evans Mack. (2001). Radar-based monitoring of marbled murrelets. The Condor 103:219-229.
[4] Hébert, P.N. and Golightly, R.T. (2008), At-sea distribution and movements of nesting and non-nesting marbled murrelets Brachyramphus marmoratus in northern California, USA. Marine Ornithology 36: 99–105.
