sign in sign up
<<
Home , Eastern gray squirrel, Flying squirrel, Northern flying squirrel, Pileated woodpecker

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 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 and build 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 , of living thing Ants and scurry over the bark, fits into a different role or niche in its and beetles burrow into the wood. community. The niche of an 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 and squirrels, , and mon- to eat. skim over the tree- arch butterflies in Minnesota. 13

1) . 2) Male perched on maple tree. 3) Female wood duck in tree hole. 4) Gray 11 . 5) Hairy . 6) Big brown at night. 7) at night. 8) Firefly in the dark. 12 9) Cicada. 10) . 11) Click beetle. 12) Treefrog. 13) Click beetle, magnified. 41 4

1 3

2

Who Lives Where? are different from most has a different niche. But even then, other 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 , 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 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 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 . Or Then everyone has a unique niche. 1) Red needles and cones. 2) Red squirrel. 3) Sugar maple leaves. 4) Bur leaves and 42 Minnesota Conservation Volunteer . 5) Eastern gray squirrel with oak . 6) Wild grape vine with leaves and fruit. 1) squirrel chomping on . 2) Black walnut leaves and fruit. 3) Northern 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 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 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, , and other ev- to go after the same resources at once. Look for gray ergreen trees. They stockpile 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 , 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) .

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. You’ll see that they usually visit dead or same tree without fighting. for spiders and other insects. dying trees. Woodpeckers hammer holes to reach Red-headed woodpeckers are most insects that live beneath bark and within wood. Left Downy Home. A hard-working downy common in the southern half of Minne- alone, many of those insects could damage trees. Some- pair chops wood for two or three weeks sota. They stockpile acorns in tree cavities times people blame woodpeckers for hurting trees, but this to eat in winter. -eating can help keep trees healthy. American three-toed and black-backed Woodpeckers dig nesting holes on the trunk or branches. Af- woodpeckers live in the north woods. Few 6 ter woodpeckers move out, squirrels, wood ducks, , or other people get a chance to see these rare birds.

46 Minnesota Conservation Volunteer 47 Milkweed Patch Milkweed plants grow naturally in open usually placing only one on each plant. 3 places such as prairies, fields, shorelines, When the young hatch, each monarch and roadside ditches. In midsummer, caterpillar will have a milkweed plant to clusters of tiny bloom pale pink, eat. The young will not need to compete orange, or white with a deliciously sweet with each other for food, and that’s good 2 scent. Butterflies, beetles, and other insects because the hungry caterpillars chomp come to sip the nectar. Dragonflies stop on milkweed leaves all day long. to rest on the leaves. Spiders and praying Monarch caterpillars can eat only milk- mantises hunt in milkweed patches. weed. After many generations, monarchs Why is this plant called milkweed? Cut have adapted to milkweed chemicals and a leaf of a common, whorled, or swamp do not get sick from them. milkweed. A thick, white liquid seeps When a caterpillar grows too big for out. (Butterflyweed has none.) An insect its skin, the old skin splits and peels off, biting into a milkweed plant might find uncovering new skin. This happens five its jaws stuck together, and it might be- times. The last time it splits the skin, spins come ill from the powerful chemicals in a silk pad on the plant, and attaches itself to this “milk.” Thisdefense stops most plant- the pad. When it finishes shedding its skin, eating insects and other animals from the caterpillar has changed into a pupa, munching milkweed. But monarch but- also called a chrysalis. During the next two terflies have found a niche with milkweed. weeks, the chrysalis changes into a butter- fly. The monarch has milkweed chemicals 4 Monarch Rules. On a warm, breezy af- in its body, so birds and other animals that ternoon, a female monarch flies over a try to eat it get a nasty surprise. milkweed patch. She lands atop a Like many birds but unlike most other cluster. Taste buds on her feet tell her she’s butterflies, the monarch flies south for on a milkweed plant. Then she uncurls her winter—all the way to mountains in Mexi- strawlike proboscis, pokes it into a flower, co, where it finds another niche. nV and sips nectar. The sweet juice fills her belly. Before flying away to drink nectar of 1 other kinds of flowers, she lays an egg. She puts a little glue on the egg so it sticks to Teachers resources: the bottom of a milkweed leaf. Teachers guide: Each female lays several hundred eggs, www.mndnr.gov/young_naturalists 1) Common milkweed plant with flower. 2) Great spangled fritillary. 3) Female common whitetail dragonfly. More on beetles and other insects: 4) Monarch butterfly. September–October 2014 www.bugguide.net 49