Gull Island

Just a short boat ride from the Homer Spit is Gull Island, a rookery for sea birds.  Gull island is home to more than 15,000 birds during the summer months when they come to nest.  There are eight different species that nest on gull island, including puffins, cormorants and murres.  

There are two species of gulls here.  The larger of the two is the Glaucous winged gull and the smaller is the Black Legged Kittiwake whose wingtips are black in addition to their legs.  Though these birds will scatter before an eagle, using their maneuverability they will often harass the predator from above to distract it from its intended prey.

When stirred up by an eagle or raven trying to hunt or steal eggs they will take off, en masse, swirling around in enormous flocks as the air fills with the sound of their keening.  When they squabble amongst themselves on the rocks, bickering over nest space, it sounds eerily like children screaming.

Islands like this form important habitats for nesting sea birds.  They need safe places to raise their young away from terrestrial predators.  Here they only have to contend with Eagles.  On the mainland they would need to worry about bears, coyotes and other smaller mammals like marmots.

The gulls and cormorants prefer to nest on the rock faces.  They glue bits of grass to the rock with their own feces which gives gull island a rather pungent smell.  Other species nest on different parts of the rock.  Common murres prefer to nest on top of the island, and puffins burrow tunnels into the narrow band of dirt between the grass and the hard rock of the cliff face.

Red face cormorants are in the center with
 murres to the right and  gulls to the left.

Though the gulls put on a spectacular show, most people are interested in the Red Faced Cormorants.  These are a fairly rare bird and are difficult to find in the wild.  Homer is the most accessible place in the world to see these birds whose habitat ranges down the Aleutian change and into parts of Japan.  We get birders from all over the world coming to see the cormorants so they can add something new to their bird lists.

 The two species of gulls are strong fliers and will get food by scavenging and diving to grab small fish off the surface. Other spercies, such as the puffin and the common murre, are excellent divers.  The murre can reach depths of over 600 feet.  Though they are poor and awkward flyers, they maneuver extraordinarily well underwater.  Before they nest, they form giant rafts in the water that can number in the thousands.  As a boat approaches, the murres at the outer edge will begin diving to get away; this begins a domino effect and creates a rippling wave of birds disappearing into the water.

Instead of flying to escape, these murres are diving into the water.

Fab four Phyla part three: Mollusca

An empty butter clam shell.
If you look closely, you can see a tiny snail laying eggs in the center of the shell.

  By many, this would be considered the most delicious of our fab four phyla. Mollusca is filled with edible organisms like clams, mussels, chitons, oysters, snails, octopus and squid.  People routinely go clam digging on the beaches here and there are several oyster farms around the bay as well.  It behooves people to harvest with care though; these animals, though numerous, are not unlimited in number and we can have a detrimental effect on their populations if we harvest unchecked.

A lined chiton, an organism that scrapes algae from rocks.

Mollusks are characterized by a having a strong muscular foot, a soft body, a mantle and usually, a shell.  Of the Mollusks we find on our beaches, it is the exceptions to the rule that people are most interested in.  The mollusks without shells are the flashiest and most interesting,  organisms such as nudibranchs and octopuses.  Nudibranch means "naked shell" and these organisms are commonly referred to as sea slugs.

The opalescent nudibranch.
The feathery cerrata on its back hold  scavenged nematocysts.

Nudibranchs have some truly amazing adaptations and seem to specialize in eating things that no other animals will.  One of our most beautiful nudibranchs, the opalescent nudibranch, eats sea anemones and passes their nematocysts (stinging cells) untriggered through its digestive system, places them on its own back adopts the nematocysts for its own defense.  Other species of nudibranch eat equally difficult prey; animals that are poisonous or seemingly undigestible are preferred by sea slugs.

Two (fully grown) opalescent nudibranchs.
There is a tiny snail just to the left of the nudibranchs.

Our other most popular mollusk, the octopus, is also without a shell.  Octopuses are the smartest invertebrates and are smarter than many mammals as well.  They can solve puzzles, learn from one another and even use tools.  On our beaches we have the giant pacific octopus, which nestles beneath rocks to wait for the tide to return. The ones we have are fairly small, no larger than 6-8 feet across.  As they grow larger, the octopuses will abandon their cramped dens and move out to deeper waters where their large size affords them some protection.  Eventually, over the course of just a few years, they may grow to have 20 foot arm spans and achieve weights of 160lbs.

Tentacles of a giant pacific octopus.
Notice the empty crab shells outside the den.

 The octopus dens on our beaches are fairly easy to spot because the entrances are often littered with the carcasses of their prey; crab, snail and clam shells lie broken and discarded at an octopus den's opening.  Usually we can only see a few tentacles but occasionally we will find a baby octopus under a rock or see one free swimming in the water.  They are extremely curious animals and will often shake 'hands' with you if you touch the water near the entrance of their dens.

Curiously poking around the entrance to its den.

Mollusks are a group of animals deserving of attention.  Not only are they a commercially and economically important group of animals but they are also important for the health of our bays and oceans.  Clams and mussels can filter upwards of 25 gallons of water a day keeping bays clean.  They are also an extremely important food source for both humans an animals.  For example, there is a tiny pelagic (mid water) snail called a pteropod that serves as the main food source for young salmon.  Mollusks are particularly at risk from ocean acidification which occurs as more and more released CO2 is absorbed into the oceans.  The excess of CO2 in the ocean forms carbonic acid which releases more H+ ions into the water and drops the ocean's ph level.  The acidification of the oceans hinders the formation of the calcium carbonate shells formed by nearly all mollusks and, if it continues, could see the collapse of many of the oceans food webs (including salmon that thrive on pelagic pteropods).  This is one of many environmental challenges facing the world today and it is one that is very deserving of our attention.