Lesson:

The focus of this lesson is on competition in the natural world—how it exists and how nature has evolved to lessen it. While it can be used for any age group, we recommend younger children due to the nature of the activity.

​

Competition is when different organisms in a set area are searching for the same limited resources—i.e. water, food, ample territory. Competition can also occur during mating, where such competition is a clever evolutionary adaptation to strive for the best possible outcomes of offspring; if males compete for the attention of the females, there is a greater chance that healthier, stronger males will stand out and have the best chance at reproducing. In terms of survival resources such as food, water, and habitat, competition, too, weeds out the weaker animals.

 

Balance is key—while competition is necessary for population control and the health of a species, too much logically leads to trouble. As such, there are also evolutionary adaptations to resist over-competition. Fish, for example, is preyed on by a variety of bird species, such as hawks and eagles, herons and egrets, some duck species, alcids (auks, puffins), and many more. For the purposes of keeping this lesson relatively succinct, we will focus on the Bald Eagle, the Atlantic Puffin, and the Green Heron, though we acknowledge the sheer diversity and abundance of fish-eating birds.

 

Below are some unique adaptations that allow each species, while very phenotypically distinct from one another, to be successful fishers.

​

• The Bald Eagle, weighing between six and fourteen pounds, has strong, sharp talons and beak. It relies on its talons to grab fish out of the water in a flyby. Its talons, in addition to being sharp, have rough pads—almost like sandpaper—to prevent the fish from slipping out during flight. In addition, its sharp, hooked beak is used to effectively rip into the fish, as eagles do not swallow their prey whole. In accordance with their size, they typically consume fish that weigh between one and three pounds, though they have been known to catch larger ones before. In short, the Bald Eagle relies on sharp talons and beak to catch prey and tear into later.

​

• The Atlantic Puffin, meanwhile, is only about one pound, which means its fish consumption will be much smaller, most commonly sand lances (sand eels), but also capelins and herrings. The puffin has adapted to have a serrated bill that allows it to catch and store multiple—even dozens of—small fish within a single hunting endeavor without having to return to land to deposit the catch every time. In contrast with the Bald Eagle's sharp talons, the puffin instead has webbed feet, which allows it to swim quickly through the water to catch their prey.

​

• In contrast with both the Bald Eagle and the Atlantic Puffin, which are both pursuit predators, the Green Heron is a stationary one as well as a stalker. Often, the Green Heron can be found crouching in the shallows or slowly stalking their prey, which consists of mainly small fish such as minnows, though they are versatile and opportunistic, meaning they can eat a variety of organisms that come their way. The Green Heron has a long, spear-shaped beak for catching fish and long legs that allow them to stand in deeper water if need be. 

​

From the differences within one overarching similarity of fish-eating, one can see how important diversity is in the natural world. This physiological diversity between these three species allows them to occupy different habitats and consume different species of fish as well as ones of varying sizes so that all fish-eaters aren't forced to compete in one habitat for the same foods.

​

Activity:

Attached below are the rough sketches and photos of the three aforementioned fish-eating species: Bald Eagle, Atlantic Puffin, and Green Heron. Encourage students to color in the sketches carefully in order to examine for themselves the physiological adaptations that allow these birds to be experts in their unique preying methods. Encourage them to ask questions and search for their own answers along the way.

​

Activity Materials:

​