Monthly Archives: September 2017

A common (murre) story of life and death

 

Murres, like other alcids, have round “football-shaped” bodies. Credit: K. Mack

Common Murres (Uria aalge) are one of the most fascinating marine birds in the North Pacific.  As adults, these “footballs with wings” can fly as easily under the water as they can on land.  Murres have been found diving as deep as the continental shelf (~200m), zooming around after forage fish and krill.  Especially during the breeding season, it takes two parents fishing for most of each day to sate the demands of their single hungry chick.  One of the reasons is because parents bring back one fish at a time, and always head in, tail out.

Murres feed their chicks one fish at a time. Credit: J. Dolliver

Fortunately for the parents, young murres leave the colony after a scant three weeks.  Early in the evening, as the sun tips below the horizon, a murre chick will leave the safety of the colony and walk to the edge of the cliff, accompanied by the male parent.  Dad and chick often engage in an extended conversation – it’s impossible to watch and not pretend that Dad is giving his chick a last few bits of advice.

Well heeded!  A murre chick actually fledges before its wings have grown flight feathers.  Essentially a fuzzy tennis ball with winglets, these chicks take a leap into the unknown.  Will they hit the water, or the rocks below?  Turns out that it doesn’t matter.  Although you might think this is a “dinosaur waiting to happen” survival strategy, the worst imaginable (a splat) doesn’t happen.  Instead, young murres bounce on the rocks, pick themselves up and run for the waves, avoiding marauding gull predators on the way.

Once safe on the water, each chick begins calling loudly: Cheep! Cheep! Cheep! If you’re within sight of a murre colony, it’s a sound you can hear from the mainland during the fledging season (July in California and Oregon; August/September in Washington, British Columbia and Alaska).  And it’s a good thing fledglings have a loud voice because they’re announcing their presence to Dad, who returns the call with a guttural: Eh! Eh! Eh! Eh! Eh!

Against all odds, most Dad-chick pairs find each other and swim away from the colony. Credit: COASST

They will spend the next several weeks together, until the fledgling learns to fish.  Of course this is an especially dangerous time: pairs can get separated and storms can make fishing difficult.  COASSTers know that the post-breeding period is the time to expect murres to wash up on the beaches.  And this got us wondering, is there a signal in the beached bird data that might tell us something about how successful breeding was on the colonies?

Where and when, on average, we expect to see adult and juvenile common murres on COASST beaches.

To figure that out, we turned to Rob Suryan, Associate Professor at Oregon State University, who maintains a long-term database on the Common Murre colony at Yaquina Head Outstanding Natural Area, immediately north of Newport, Oregon.  Rob and his team spend the early summer in the Yaquina lighthouse surveying the murre colony and counting the eggs, then chicks, then fledglings.  This gives them a measure of the breeding success of each pair: the average number of fledglings per pair.  Given that murres only raise a single chick, the very highest this number could ever get is 1.0 (if every single pair was successful).  In reality, something above 0.70 signifies a good year.  In poor years, numbers below 0.40 are common.

We reasoned that in a really good year, colonies would produce a lot of fledglings, filling the nearshore with Dad-chick pairs.  And COASSTers might see that signal on the beach as more than the usual number of juvenile murres, because juvenile mortality is always higher than adult mortality.

By contrast, in poorer years, fewer chicks would even reach fledging stage, and adults would likely be stressed and thinner, more susceptible to the ravages of early fall storms.  In these conditions, COASSTers might see relatively more adults.  That is, both relatively more than juveniles, and absolutely higher encounter rates than “normal” years.

Turns out, we’re right! The graphs below show the relationship between breeding success on the Yaquina Head colony (on the horizontal, or X axis), and measures of COASST data (on the vertical, or Y axis). Each point is a different year, colored so you can easily find each one.

Left: the relationship between how many adult murres are found per kilometer of beach surveyed over the August-September post-breeding season in Northern Oregon. The solid line shows that there are more carcasses when breeding success is truly poor, fewer when breeding conditions are good. Prediction confirmed! Right: the relationship between the proportion of all murres found that are juveniles (for math geeks: juveniles/(adults + juveniles)) and breeding success. Again, our prediction – that good years would yield higher numbers of juveniles – is confirmed!

What does all of this mean?  Basically, that beached bird data can stand in as a proxy for breeding success on the colony.  And this is really good news, because most of the murre colonies in the Pacific Northwest are not regularly monitored, either because they are too far from shore to see (like the Yaquina colony), or because the island or spire where the murres nest is literally unscalable.

If you’re a Pacific Northwest outer coast COASSTer, take special care on your late summer and fall surveys – your murre data are showing us that death is part of the life of the ecosystem.

Unsolved Mysteries – September 2017

Gary encountered this metal buoy at Diamond Creek near Homer, Alaska during his first survey in August. We’re wondering where and how this kind of buoy would be used.

Steel buoy found on the Kenai Peninsula, August 2017.

Craig documented this crab trap float fragment in May. Noticing the abundance of variably colorful foam buoys encountered during marine debris surveys made us wonder—do the colors signify anything? Are they painted for easy recognition by the owners?

Colorful float fragment found May 2017, Half Moon Bay Beach, WA.

Ann and Michael encountered this large plastic drum during their August survey of Flat point on Lopez Island, WA. What would this drum have contained?

Plastic drum found August 2017 on Lopez Island, WA.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Please share your ideas in the comments!

Gooney Birds? Mollymawks? Albatross!

A recent spate of Black-footed Albatross finds along the north outer coast of Washington in May and June got us wondering about these majestic birds.

With a wingspan of two meters (!) or longer, albatross are the largest members of the Tubenose Foot-type Family (Procellariidae). In the North Pacific there are three species: the dark-bodied, dark-billed Black-footed Albatross; the light-bodied, Laysan Albatross with a “smokey eye”; and the larger, Short-tailed Albatross, distinguished from Laysan and Black-foots by an over-sized bubblegum pink bill (plumage of Short-tails varies with age).

What else might a COASSTer mistake an albatross for? Bald Eagles, Brown Pelicans, Great-blue Herons and Sandhill Cranes are all COASST finds with overlapping wingspans. But each of these birds can easily be distinguished by foot-type, and bill size and shape.

All of these large-bodied COASST finds have distinctively different feet.

A long-lived, monogamous bird, albatross begin breeding at age 5-10, and it takes two parents to raise a single chick. New pairs may require a few years of practice to “get it right.  After that, mates meet annually for a long breeding season: courtship and “re-acquaintance time” starts in November, eggs appear before the turn of the year, and chicks don’t fledge until mid-summer!

Like all members of the family, albatross have a keen sense of smell and can literally smell their prey from tens of kilometers away, a talent that suits these open ocean birds. Dinner for an albatross?  Neon flying squid, flying fish eggs (tobiko in sushi restaurants), and a range of small fish and shrimp-like organisms that come to the surface of the ocean at night.

Unfortunately, smelling their way to food puts albatross in harm’s way. Fishing vessels smell like floating restaurants, attracting albatross and their smaller relatives – shearwaters and Northern Fulmars – some of which become entangled or hooked in gear. Marine debris can also be deceptively appealing, as some plastics, after floating in the marine environment, adsorb and emit the same chemical (dimethyl sulfide) used by procellariiforms as a cue to identify prey. Not only that, floating debris can look like albatross prey (could you tell the difference between a squid mantle and a red lighter floating at the surface?). Young birds are especially susceptible. Dependent on their misled parents for food, chicks ingest plastics, filling their stomachs with indigestible objects they cannot regurgitate.

Photo: Claude Gascon. One theory to explain why albatross consume marine debris is prey mimicry. Oblong, ~5cm floating objects in the yellow to red color spectrum are squid mantle look-alikes.

Populations of Black-foots and Laysans number in the hundreds of thousands.  In contrast, Short-tails number less than ten thousand and are listed as “vulnerable” on the IUCN Red List (International Union for Conservation of Nature).

With a body that mimics a glider, albatross have the ability to soar tremendous distances.  Even while breeding on islands in the Hawaiian Island chain (Laysan and Black-foots) or southern Japan (Short-tails), breeding adults regularly visit North American waters.  Laysan’s appear to prefer coastal Alaska, whereas Black-foots fly due west to the Lower 48.

Breeding so far from our shores, and preferring the open ocean, you might think COASSTers would never find an albatross.  Not so!  In fact, Black-foots are among our top 30 species.  Peak Black-foot deposition is in the summer: May through August, just when adults are finishing breeding and chicks are coming off the colonies.  But the annual pattern is “irruptive.”  That is, in some years COASSTers are much more apt to find an albatross than in others.  In northern Washington, 2012 and 2017 were break-out years; in southern Washington, 2003, 2007 and 2012 were big.  The good news is that there doesn’t seem to be any trend towards higher numbers.

Although you’d have to walk pretty far, on average, to find an albatross on the beach, they do wash up regularly. Along the West Coast, Black-foots are about three times more prevalent on Washington outer coast beaches than along beaches to the south in Oregon and California. And Laysans are a truly rare find (photos are scaled to encounter rate). On the Aleutian Islands, the opposite is true.

Across the COASST dataset, albatross species wash up exactly where you would expect them to given at-sea sightings: Black-foots along the West Coast, and Laysan along the Aleutian Islands in Alaska. Although the total body count favors the lower 48 (note only 3 Laysan have been found in Alaska), it’s actually the encounter rate (carcasses per kilometer) that is important.  Remember, there are many more COASSTers along the outer coast of Washington, Oregon and California than there are in the Aleutian Islands!  The photographs in the figure above are scaled to species-specific encounter rate the—the chance of finding an albatross in the Aleutians is about the same as along the outer coast of Washington.

A closer look at Black-foot deposition pattern on the West Coast reveals two distinct aggregations: one associated with the entrance of the Strait of Juan de Fuca (we’re guessing these birds are associated with the Juan de Fuca eddy – an oceanographic feature south of the Strait), and a second larger aggregation surrounding the Columbia River.  Both the eddy and the “plume” of river water exiting the Columbia River into the Pacific Ocean are highly productive locations where a hungry chick or exhausted post-breeding adult can hunt pelagic prey.

When Black-foot encounter rates are broken down into smaller lengths of coastline (half a degree of latitude, or about 55 kilometers), it’s clear that some locations attract many more.

Moral of this story? If you hope to see an albatross on a COASST survey, head to the south outer coast of Washington during the summer and take a stroll along the sand.