Young naturalists 6 ▼ 1 Niches for 4 Everyone 5 Living things find amazing ways 2 to live together. Go outside, find a tree. Lie down top, catching moths and mosquitoes. beside it or climb up to perch on a An owl lands silently on a branch to sturdy branch. Relax, stay quiet, and watch for a mouse on the ground. 8 look around. You might be surprised All these living things form a natu- 3 at what you see. A tree is more than ral community. The tree is part of their 7 roots, trunk, branches, and leaves. In habitat. A habitat may be as small as many ways, a tree is like an apartment a single tree or as big as a forest. The building—home for many creatures. members of a community depend on By Christine Petersen Birds and squirrels build nests on their habitat for food, water, shelter, 9 Illustrations by Vera Ming Wong branches or inside holes. You might and other natural resources. spot a treefrog hidden among leaves. Each kind, or species, of living thing Ants and spiders scurry over the bark, fits into a different role or niche in its and beetles burrow into the wood. community. The niche of an animal Mushrooms sprout from crevices. includes what it eats and when it is As the sun goes down, a whole active, where it sleeps and raises new crew of critters emerges. A rac- young, and much more. 10 coon or an opossum might climb out This story looks at the niches of of a tree-hole den to find fruit and squirrels, woodpeckers, and mon- insects to eat. Bats skim over the tree- arch butterflies in Minnesota. 13 1) Blue jay. 2) Male wood duck perched on maple tree. 3) Female wood duck in tree hole. 4) Gray 11 squirrel. 5) Hairy woodpecker. 6) Big brown bat at night. 7) Barred owl at night. 8) Firefly in the dark. 12 9) Cicada. 10) Raccoon. 11) Click beetle. 12) Treefrog. 13) Click beetle, magnified. 41 4 1 3 2 Who Lives Where? Humans are different from most has a different niche. But even then, other animals because we can live in every habitat has a limited amount almost any habitat. We bottle water of shelter, food, water, and other re- 5 to carry with us and buy food grown sources. Species that try to share ex- around the world. But we have niches actly the same niche will compete. too. You might live in a house, while Imagine a cool autumn morning. 6 your friend has an apartment. Some You wake suddenly as high-pitched people are omnivores, eating all kinds whistles, chirps, and chatter fill the of food from plants and animals. air outside your windows. Two furry Some are vegetarians, eating no meat animals skitter down a nearby tree at all. Some people have more energy trunk and zigzag across the ground. in the morning, and others get going A red squirrel is chasing a gray later in the day and stay active into squirrel nearly twice its size. the night. How does your niche com- The squirrels are competing for pare with that of friends and family? this piece of habitat, or territory. is another way. To stop compet- a rival might find other kinds of Knowing your niche can be a fasci- The red squirrel is fiercelyterritorial . ing, the gray squirrel might move to foods to eat. The rivals might be ac- nating way to understand your role This little rodent defends its terri- another habitat. Or animals can find tive at different times of day or year. in the world. tory against other squirrels, birds, a new niche in the same territory by Even small changes can relieve the and people. using different resources. One of the stress of competition and make it eas- Compete or Share. Many kinds of Protecting a territory is one way to competing species might find a new ier for similar species to live together. living things can share a habitat if each divide up resources. Changing niches kind of place to make its nest. Or Then everyone has a unique niche. 1) Red pine needles and cones. 2) Red squirrel. 3) Sugar maple leaves. 4) Bur oak leaves and 42 Minnesota Conservation Volunteer acorns. 5) Eastern gray squirrel with oak acorn. 6) Wild grape vine with leaves and fruit. 1) Fox squirrel chomping on walnut. 2) Black walnut leaves and fruit. 3) Northern flying squirrel at night. 4) Bitternut hickory branches and leaves at night. 5) Red oak leaf with acorns. 2 Squirrel Niches Five species of tree squirrels live in Minnesota. Trees are part of their niche. Squirrels scamper and leap through the treetops, using branches like highways to stay away from hungry predators. Several kinds of squir- rels may share a habitat in the city or the country. How do 3 they avoid competing? By choosing different tree species, squirrels can avoid competition. Gray squirrels like big, old trees. Fox squir- 4 rels are common in oak woods in the southern third mer. A single gray squirrel will bury of Minnesota. Red squirrels can turn up anywhere, hundreds of acorns in the ground be- but they are most common in northern evergreen fore the snow falls. It digs them up again forests. Northern flying squirrels live there too. in winter, when other foods are hard to find. Southern flying squirrels live in southern Every year, squirrels forget some of their stored Minnesota forests. 1 food. Buried seeds and acorns sprout into tiny new Squirrels find tree holes in which to trees. This helps the natural forest community. make their nests. If a squirrel can’t find a Fox and gray squirrels climb trees to gobble cozy hole, it builds a warm nest by put- sweet fruit. Red and flying squirrels eat mushrooms. ting leafy twigs on branches and pil- Squirrels also hunt insects and take bird eggs or ing on more leaves, twigs, and grass. chicks from a nest. Each species eats a slightly differ- ent mix of foods. That way, nothing is used up. Favorite Foods. Squirrels like to eat nuts and seeds from oak, maple, hickory, and Time Sharing. Different squirrel species have different black walnut trees. Red squirrels prefer schedules, or “time niches.” This way, they are less likely 5 seeds from pine, spruce, and other ev- to go after the same resources at once. Look for gray ergreen trees. They stockpile seed cones and red squirrels in early morning and late evening. to eat later. Fox squirrels eat acorns and Fox squirrels get a later start and are busy in the mid- black walnuts, which they might stash dle of the day while other squirrels rest. You’ll have in a tree hole or under fallen leaves. Gray to stay up late to spot a flying squirrel. They wake squirrels have a taste for acorns. These meaty up at dark and spend the night gliding between nuts begin to drop from oak trees in late sum- trees in search of food. 44 Minnesota Conservation Volunteer September–October 2014 45 4 5 1) Pileated woodpecker. 2) Yellow-bellied sapsucker. 3) Hairy woodpecker. 4) Downy woodpecker. 5) Red-headed woodpecker. 3 6) Northern flicker. animals might move in. In this way, wood- to make a deep nest hole hidden under peckers open up more niches for other a branch or a broken tree stub. To keep creatures in the natural community. squirrels and other predators from finding their eggs or nestlings, they carry away all Hairy or Downy? A woodpecker flies the chips and sawdust. between two trees and perches upright on the side of a branch. Its black and white More Woody Niches. Pileated wood- feathers, or plumage, create a beautiful bold peckers, Minnesota’s largest, build nests pattern of spots and bars. If you have a bird high in tall trees. These crow-size birds 2 book, it will show two species that fit this visit standing or fallen trees to find nests of Woody Niche description—hairy and downy woodpeck- carpenter ants. ers. They often use the same trees and eat Northern flickers find insects by prob- Makers a similar diet of beetles and moth cater- ing into the ground with their long bills. What’s that sound in the distance? pillars. To tell the species apart, notice the They eat more ants than any other birds It’s like someone is beating a fast rhythm bird’s size and which part of the tree it uses. do. To find ants in winter, they fly south. on a snare drum. If you are outdoors, the A downy woodpecker is not much big- Like flickers, yellow-bellied sapsuckers noisemaker is probably a woodpecker. Minne- ger than a sparrow. It usually hunts on go south for winter. In early spring they re- sota has nine species of woodpeckers. This wood- small branches. The hairy woodpecker turn. They wind around trees as they drill land bird’s large bill, strong neck, and thick skull is as large as a robin. It looks for food on holes to drink sap. work like a jackhammer to drill holes in trees. large branches or the tree trunk. Because Red-bellied woodpeckers rarely land on 1 Which trees do woodpeckers visit most often in of this small difference in eating habits, the ground. They scoot along tree trunks your yard or neighborhood park? Watch for a while both a downy and a hairy can feed on the and branches, peering under loose bark to find out.