One of my retirement activities is giving “enrichment” lectures on cruise ships around the world. I’ve lectured on over 20 cruises and ten different cruise lines. Not sophisticated university-level lectures, but “edu-tainment” as the cruise lines call them. They are part of the ship’s activities, especially on “sea days” when the ship doesn’t make a port call and passengers need activities. Besides lectures, there might be bridge lessons, bingo, trivia contests, or opportunities to lie around the pool. But there are always a group of passengers who enjoy the lectures and attend regularly. Ships with European passengers seem to be the most interested in broadening their horizons. Such is the clientele on my favorite cruise line, Silversea. Lots of folks from the U.K., especially England, and a variety of other Europeans seem to prefer that cruise line.
My typical role is to provide six lectures on appropriate natural history topics relevant to the areas the ship visits. So I talk about the subjects like the ecology of the Atlantic Ocean, island biogeography, fish, and of course, birds. The bird lectures are always the best attended. Depending on the particular cruise, I might talk about the birds of the Amazon, the birds of the Seychelles, the birds of Namibia, or, as on most voyages, seabirds, with a lecture entitled “Living on the Wide, Wide, Sea.”
There isn’t much birdlife on the open sea, because much of it is a biological desert. With no runoff from land, there are few nutrients being added to the water, so the food chain has only a meager source of food to build on. That’s why most birds are closer to continents and islands, even if they rarely visit land. There’s just more food near land.
But when there are seabirds, they are fascinating to watch. I point out the “dynamic soaring” that albatrosses and shearwaters use (see video) to remain aloft for long periods of time and the hopping on the water’s surface employed by petrels while feeding, and the drafting that fulmars and gulls use in following the ship. I explain how seabirds can ingest saltwater because they possess a gland to extract the water and expel the salt through their nostrils. I talk about how Northern Gannets with their streamlined bodies plunge-dive at high speed, using powerful neck muscles, a spongy bony plate at the base of the bill, and tissue like tiny bubble wrap cushioning the chest. The nostrils are inside the bill and can be closed to prevent water entry; the eyes are protected by strong nictitating membranes. Check out this video.
Seabirds are mostly dark or black above and light below. They are countershaded, as are many fish, so that they appear to blend into the background of the sky or water to a predator or prey looki
ng at them from above or below. There’s also the story of Mother Cary’s Chickens – petrels who were once thought to be the souls of sailors lost at sea and the Rime of the Ancient Mariner which gives us the saying about having an albatross around one’s neck.
At some point in every voyage, some passenger discovers a land bird on the deck of the ship. I’ve seen herons, kingfishers, nightjars, and owls land, lost and exhausted, on the ship. Usually they recover their strength and fly off again, to who knows where. Or, in the case of the wagtail that visited our ship one day, stayed and foraged for insects until we reached our next port a few days later.
Hopefully, I make the voyage a bit more interesting for the passengers, especially on those sea days when there’s nothing to see on the horizon but waves, and rarely the occasional bird.