This paper will examine four species of birds in an effort to ascertain which species may be considered generalist / opportunistic and which species are specialist depending on specific climate or with a narrow niche preference. In order to providers with accurate information the writer will examine the environmental preference of these specific species, their diet, population growth and biome that provides the perfect living conditions for their species. The four species being examined today are the American Robin, the Wood Stork, Great Blue Herron and the Double Crested Cormorant.
The American Robin's diet consists of a wide variety of berries earthworms and insects, and they are found throughout North America. Communities or Robins are found in several biomes, including forests edges, woodlands, grasslands, tundra and forests regenerating from recent fires, they are also found in populated urban areas since human development provides areas for them to forage. Although the Robin is a migratory species some of them have adapted to the cold and spend their entire lives in the colder regions of Northern America and Southern Canada.
Although some American Robin is capable of adapting to several environments their diets are not so widespread in the summer they feast on insects and earthworms, while in the winters their diets mainly consists of berries. It is often hard to determine whether or not a species fall in the category of generalist or specialist because of their behavior and eating patterns, however it could safely be said that the American Robin is a specialist and their eating habits has proven this and also because they are migratory.
The Double Crested Cormorant is widely distributed being found in egions with bodies of water that will support their diet of mainly fish however crustaceans, insects and amphibians are known to be consumed by them. The biomes that provide them with the best living conditions would be the temperate costal waterways, freshwater rivers and lakes and other marine waters The fact that they consume over 250 species of fish which is readily available in regions with abundant rainfall has aided in the rebound of their population.
The Double Crested Cormorant falls within the category of generalist [opportunistic. In the United States he Wood Stork is found mainly in the southern regions along the coastal areas. Their food supply which includes a range fishes, frogs, mollusks, snails and insects can be found in coastal areas, tidal waters, marshes, swamps, streams and mangroves. The to provide them with food supply year round. Although their diets are made up of several types of items they mainly come from the waterways and as such their distribution is not widespread, making the Wood stork a specialist species.
The Great Blue Herron was made for survival; they are very adaptive and can be found in a ide variety of areas within the United States. Their diets include both vertebrates and invertebrates, insects, fishes and even other birds. They also consume small mammals and amphibians which can be found in forests or waterways. These birds can also endure the cold winters therefore many biomes support their habitats. The Great Blue Herron would be considered an opportunistic species since they are widely distributed and very adaptive to climate and diet.
In concluding I would like to say that most species don't fit easily into one category making it harder to identify hether or not they are specialist or generalist, as in the case of the Robin who is widely distributed, however they are confined based on what they eat and weather conditions.