Birds of the Seas
Seabirds live their life on the ocean waves. They are true marine organisms, feeding at sea and only coming to land to breed. Ornithologist John Chardine tells us more about them.
As you sail aboard our expedition ship, seabirds are our constant companions, some following us all day. Even thousands of kilometres from land, they are never lost but are where they want and need to be – where the food is. Living their lives at sea isn’t an easy feat. Only about 300 of the 10,000 species of birds in the world know how to survive among the ocean waves.
There are four main groups of seabirds. The first are penguins, second are 'tube-nosed' petrels and cousins like the iconic albatrosses. Third are the cormorants, pelicans and gannets, and fourth the gulls, terns, auks and skuas. With the exception of penguins which live exclusively in the southern hemisphere, the three other seabird groups can be found on the coastlines and adjacent oceans of all seven continents.
Finding Food Among the Waves
Food on the open ocean is spread out over vast distances and is 'patchy' and concentrated in areas of high ocean productivity where algae grow profusely. To find enough food to sustain them, many seabirds cover vast distances using the energy of the wind to effortlessly glide over the waves. Some seabirds can even smell a chemical produced by algae, signalling what might be a good bet for a meal.
Seabirds are at the top of marine food chains and eat crustacea like krill, small fish like herring, and squid. A few species such as penguins and auks are prodigious divers, plunging several hundred metres under water and remaining there for minutes in order to catch their prey.
Nothing to Drink at Sea
Living things need water and a big problem with the sea is that it’s all salt water. Seabirds have evolved a special gland - the salt gland - which strips the salt from their blood. The gland is located at the top of the head just under the skin, and exudes a highly saline solution which drips from the seabird’s bill or from the nose of tube-noses. Given the chance though, penguins will eat snow at the colony to obtain fresh water. We have even seen young penguin chicks catching snowflakes as they fall from the sky – a magical sight to behold!
The Cycle of Life
Building a nest on the ocean is not possible so seabirds have to come to land to breed. Most breed together in tightly packed colonies on the ground or on a cliff. Colonies tend to be on islands or isolated stretches of coastline, free from mammal predators. Some colonies are a long way from concentrations of food, but for many seabirds, this is not a problem because they can fly so efficiently.
Typically, seabirds only lay one egg per year. This is because the parents are unable to bring back enough food from far at sea to feed more than one chick. Some species can rear more chicks because their colonies are closer to where they feed.
Many seabirds return annually to exactly the same place in the colony, and pair with their mate from previous years. Returning to the same spot is a way they find each other. As seabirds are long-lived - 60+ years for albatrosses - they sometimes stay with the same mate for many years, until one of them dies. 'Divorce' also happens where the two go their separate ways and find new mates.
Helping Our Seabirds Survive
Sustaining populations into the future is a big concern. One problem facing seabirds is floating plastic like discarded straws and lighters, which they mistake for food and bring back to their chicks to feed. The plastic takes up space in the chick’s stomach, and the bird eventually dies.
We at Hurtigruten are very aware of this problem and have eliminated single-use plastics from our ships.
Introduced rats wreak havoc in seabird colonies by eating bird eggs and chicks. Rat removal programmes have allowed colonies to recover. Oil pollution, over-fishing, climate change and coastal development are other serious problems facing seabirds. The goal of conservation is to promote healthy populations and to not let any species go extinct, as happened to the Great Auk in the 1800s.
An expedition cruise with us is the best way to see a range of seabirds and to learn more about each of them from the expert Expedition Team on board the ship. They’ll be able to point out different species to you out on deck and you’ll be able to identify them yourself by the end of your cruise. Understanding the incredible ingenuity and skill it takes for these birds to survive and thrive on the ocean will only add to your admiration for them.