Roseate Tern Sterna dougallii By: Kayla Classification - Kingdom - Animalia Phylum - Chordata Class - Aves Order - Charadriiformes Family - Laridae Genus - Sterna Species - dougallii

Natural History -

Birds have been around for millions of years. It is believed that they are the closest living relative of dinosaurs. Some scientists believe that feathers evolved from reptilian scales. Birds have a high metabolic rate in order to fly efficiently and at high altitudes.

Because birds can fly they have a big advantage over animals that cannot. The advantage is that if a predator was trying to catch a bird, the bird could fly away but an animal that could not fly would have to run or stand there scared. Of course most birds can fly fast as well so that helps them get away, too.

Also, once a bird gets above everything there is nothing blocking their path, but land animals might encounter some barriers. For instance, in a forest there would be trees everywhere which would be hard to avoid. The reason for their fantastic ability of flight is all because of feathers.

Of course there are a few other things that help birds fly. For example, birds do not weigh that much. In fact the roseate tern only weighs 4 ounces so, that must make it easier for them to fly.

Birds are vertebrates, which are animals that have a backbone. Since they are vertebrates that means they belong to the phylum Chordata. Birds are also warm-blooded mammals, which means that their body temperature stays about the same regardless of the temperature of their surroundings. Cold-blooded animals, on the other hand, change their body temperatures when their environment changes.

Instead of teeth, birds just use their beaks, which have adapted to tearing food. After millions of years of evolution the bird species have adapted to what they eat, where they migrate, where the nest and how they breed. Each species of birds does all those things differently and that results in diversity.

Habitat -

The roseate terns’ habitat is on rocky coastal islands that either have sandy or pebble beaches. They also might live on an open grassy habitat, but very rarely. Their habitat is almost always on the coast, never inland. The biggest nesting site in Maine is Eastern Egg Rock; more than half of the roseate terns in Maine nest there.

Each spring, when roseate terns come back from migrating, they nest on islands along the eastern coast of North America. They stay from about May to September. They really love coastal beaches and inshore waters. Sometimes, roseate terns nest with other terns in colonies. The nest is a hollow scrape that is located in scant vegetation, sometimes also on bare sand. The roseate tern also tries to hide its nest from predators. They use rocks, vegetation or washed up debris as a protective cover.

When they have their nest ready, the roseate terns can then lay theirs eggs. Once the eggs are laid they will hatch in about 21 to 26 days. Roseate terns will usually lay eggs from late May to late July. Some roseate terns will even lay their eggs as late as mid-August.

Present Status -

Federal & Maine: Endangered

Physical Description -

The roseate tern is a small seabird that looks like a small gull. It has a slender body, short legs, and long pointed wings. The roseate tern has blue-gray wings and white feathers. Its head is mostly black. The bill is also mostly black with a little bit of red at the base. During the breeding season, the bill’s base turns pinkish-red. Its legs and feet are bright red-orange. With all these colors, the roseate tern is a beautiful bird.

Roseate terns are closely related to Arctic and common terns. They are also usually found near each other so it can be hard sometimes to tell them apart because they look so much alike. If you would need to tell the difference, one thing to look for would be the tail’s length. The roseate tern’s tail would be longer than the others. Another thing to look for would be the color. The roseate tern would a paler gray than the Arctic and common terns.

The roseate tern is about 33 - 34 cm in length. When it has fully grown, the adult roseate tern has a wingspan of 72 - 80 cm. The deeply forked tail can be about 15 - 17 cm long. An adult tern weighs about 4 ounces.

Diet and Feeding Habits -

The roseate tern is known for its ability to capture fish by diving quickly into the ocean head first. The roseate tern is a carnivore, which means it only eats meat. The roseate tern hunts in saltwater for small fish such as the white hake, juvenile herring, mackerel, cod, pollock, haddock, and its favorite, the sand lance. Every now and then the roseate tern will also have a clam or two.

The roseate tern is a consumer, which means it eats other organisms for food. It usually carries only one fish at a time but if the fish are small enough then it can carry a couple more. If the roseate tern cannot catch any fish for some reason, then it will try to steal fish from other terns.

The roseate tern will forage fish as far as 20 km from its colony. But usually they will only forage about 10 - 16 km from its colony.

Causes of Endangerment -

Between about 1870 and 1880 the roseate terns were in serious danger of becoming extinct in the northeastern part of the United States because people were hunting them for their feathers. Then, they would use the feathers as decorations on hats.

The roseate tern’s population has fallen by about 75% since the 1930’s. On November 2, 1987 the roseate tern was designated endangered in the United States.

Gulls steal the roseate tern’s eggs, their young, fledglings, and sometimes even adults. Gulls also take over colonies established by terns. Humans also don’t help much either, because of the use of beaches some of nests get destroyed. The Migratory Birds Act protects terns by making it illegal to capture, kill or take individuals, nests or eggs.

The roseate tern might have competition with other terns, for instance with the common tern for good nesting sites. The roseate tern is sensitive to disturbance by humans such as recreational use of beaches.

In North America, the roseate tern’s population is small because there are not very many places for them to nest. There are not many places because of the use of beaches and that’s where the roseate tern loves to nest. Since the roseate tern eats fish, any pollution in the water could make them sick or even kill them. Also, fishermen catch a lot of fish and then there aren’t enough fish for the roseate terns to eat.

The roseate tern cannot survive in the winter weather that Maine has so it heads down to northeastern South America where it is warmer. First they will spend a day at sea to get food but when they return to the beaches to make their nests they become easy prey for predators that catch them for food.

Personal Essay -

How does diversity strengthen an ecosystem? Well, if there wasn’t diversity there wouldn’t be much of an ecosystem in my opinion because an ecosystem is a group of organisms that interact with one another in their environment.

Diversity also has a good amount to do with the food chain. It helps keep a good balance with everything. To keep a good balance there can’t be too much of one animal because too much can be a bad thing. Of course there can also be a problem if there is too little of one animal.

The roseate tern, for example, likes many different kinds of fish. In fact it eats mostly fish. If there was only one type of fish and it got extinct, then it would be hard for the roseate tern to adapt to eating something else. Because of diversity, though, the roseate tern has nothing to worry about because it has many other types of fish to eat.

Before this expedition, I knew what diversity was but I never knew how important it was to our ecosystem.

My point is that diversity is important. One way or another, no matter who or what you are, it affects you. If for some reason cows were to become extinct and we wouldn’t have milk or beef, we would not become extinct because we have other things to eat. We have diversity.

Bibliography -

1. Lahonaton Audubon Society.   http://www.nevadaauducon.org/BirdSites/SpeciesClass.htm. (February 26,2003)

2. Roseate Tern Factsheet. March 1,2003.  http://www.dec.state.ny.us/website/dfwmr/Wildlife/enspec/rotefs.html. (March 10,2003)

3. Watkins, Patricia et al. Life Science. Orlando, Florida: Harcourt Brace Jovanich.1989.

4. “The Anatomy of Flight.” Zoobooks. Aug. 91: pg. 7-8.

5. Audubon. 2003. http://www.audubon.org/bird/species/roseate-tern.html.(February 26,2003)

6. Scott, Shirley et al. Birds of North America. Washington D.C.: National Geographic Society. 1983.

7. Endangered Species:Roseate Tern. 2003. http://exn.ca/ mini/endangered/rosetern.cfm.(February 26, 2003)

8. Roseate Tern. May 15, 2003. http://www.cws-scf.ec.gc.ca/hww-fap/hww-fap.cfm?ID_species=39&lang=e(March 23,2003)

9. Endangered Species Roseate Tern. December 6, 2002. http://www.atl.gc.ca/wildlife/roseate.(February 27,2003)

10. “Bird.” Britanica Junior Encyclopedia. 1975.