Thursday, July 30, 2009

Bird Food

By Susan Benson,
CNHM Director of Education

Earlier this spring, when school groups were visiting the Museum, white boards were set up outdoors to “feed” ants in order to teach about ant intelligence. After two days of feeding the ants, I noticed a robin, almost appearing as if it was trying to run me out of the area. The following day, there were significant scratch marks that were made by a small “implement” that I assume must have been the robin, having eaten the peanut butter. Every day thereafter, I saw the robin, and later, the peanut butter would be scraped clean. This morning after the rain, I was watching five robins in the Museum yard and began thinking about birds and their food.

Natural foods that birds eat include insects, worms, grubs, berries and other fruit, tree sap, buds of trees and shrubs, nectar, nuts and seeds, fish and small animals or other birds, eggs, or dead animals.

Sometimes it is surprising to discover what some birds eat. For example, ruby-throated hummingbirds feed on the nectar of mostly red or orange flowers. However, they will also catch insects in midair such as gnats, mosquitoes, fruit flies, or small bees. Hummers will also pull them out of spider webs, and sometimes eat the spider as well. Hummingbirds also take insects attracted to tree sap or pick small caterpillars and aphids from leaves. A red-winged blackbird is believed to eat a diet of up to fifty-seven percent plant seeds, twenty-six percent insects, thirteen percent grain.

Birds have high body temperatures and high metabolic rates so they eat more food ounce for ounce, in proportion to their weights, than do most other vertebrate animals. Larger birds generally eat less in proportion to their body weight than do smaller birds each day.

The smaller a bird is, the more time it needs to spend feeding. Eagles may go without food for several days without ill effect, but the tiny chickadee needs to feed regularly throughout the day in order to survive. The bird with the widest variety of diet ever recorded is the ruffed grouse. Its food is known to include 518 kinds of animals and 414 different plants.

Birds digest their food very quickly. Some small birds like the chickadee eat almost constantly, especially during the winter. Diurnal birds feed most heavily in the morning and late in the afternoon.

Clues can be taken about what a bird eats by observing the type of beak or bill the bird has. Thin, slender, pointed beaks such as those found in warblers are found mainly in insect eaters that use their beak to pick insects off leaves, twigs, and bark. Beaks which are flat and wide at the base are found in birds such as flycatchers, which catch insects in flight. These birds also often have whiskers at the corners of their beak which widens the mouth opening, allowing more successful capture of prey. Woodpeckers have a chisel like beak for pecking holes in trees. Mergansers, adapted for fish eating, have sharp tooth-like edges on the bill to hold fish tightly. The fringed edges of a mallard bill strain plants, seeds, and small animals from water. Cardinals, grosbeaks, finches, and sparrows have a thick, cone-shaped bill good for cracking seeds all year long. When seeds are scarce they eat insects.

Whatever birds may eat, they continue to be a source of enjoyment for humans. It is estimated that over sixty million people in the United States feed birds in their back yards. Birds play an important role in balancing healthy ecosystems, and certainly contribute to our human economy. Sadly, many people are not aware that ten percent of our 852 bird species of North America are endangered or threatened. It is impossible to imagine what our lives would be like without them.


For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.

Thursday, July 23, 2009

Crows

Nature Watch

By Susan Benson,
CNHM Director of Education

For the past two weeks, I have been greeted daily at home by a lone crow. This is a continued surprise to me, because crows are social birds, more often observed in groups than alone. Was it injured? Looking for food? A young crow? All were questions I asked. In fact, young crows often assist their parents in raising the young for several years. One crow family can contain up to fifteen individuals with youth from as many as five combined years. In the winter they gather together in very large groups to sleep in communal roosts. Crows are considered highly intelligent animals, known for their impressive counting skills and use of tools.
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Experiments with captive common, or American crows have proven the birds have excellent puzzle-solving abilities, can count up to three or four, have good memories, and can quickly learn to equate certain sounds or symbols with food. Known to eat the shells of clams, mussels, and mollusks, crows have learned they can eat more easily by picking the shells up, flying with them to a greater height, and then dropping them to rocks below. Herring gulls and crows were seen practicing this technique at the same time, but while the gulls dropped the mollusks onto the mud, crows figured out quickly that aiming for a rock worked better.

Crows have other creative ways to find food. During spring in Norway and Sweden, fishermen make holes in the ice and drop their fishing lines into the water. Hooded crows have been seen flying in, picking up the line, and walking backward, pulling the line out of the hole until they expose the bait or hooked fish to eat. Crows on a remote Pacific island have learned how to use tools. The birds use long, specially chosen twigs to spear the plump grubs that hide deep beneath the bark of rotting logs. Crows will follow adult birds to identify where the nest and eggs are located. Observers have seen crows shaping a stick to place in a hole in a fence post to search for food. They work together in groups called mobs in order to get food.
Crows have a varied and evolved language more extensive than just the “caw” with which we are familiar. They also have the danger calls and a hollow, rattle greeting sound. They can mimic the sounds made by barred owls and other bird species, and they learn to associate noises with events, especially when the events relate to food.
While some might find the results of crow’s adaptability an annoyance because of how they interact with the human world, their resourcefulness can also be highly regarded. Please share any crow observations you have made by Emailing the Museum at info@cablemuseum.org.

For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.

Thursday, July 16, 2009

Bald-Faced Hornets

Nature Watch

By Susan Benson,
CNHM Director of Education

Maybe you have noticed a football shaped nest hanging from a nearby tree, or a new one being built under your roof overhangs, or under your deck or porch. The term "hornet" is often used to refer to many of the wasps that build large, papery nests. The most notable paper wasp in our area is the bald-faced hornet, a species of yellowjacket wasp. These insects have large, black and white, heavy-bodies with white markings on their faces that resemble a bald spot. They adapt well to their environment, showing a remarkable intelligence for an insect so small.

How do they cope with our northern climate changes? Bald-faced hornets are experts at temperature regulation—both heating and cooling. They heat using the best insulation, trapped air. To cool their nest, special workers bring water to the nest, spread it on the nest and then fan it to “air condition.” But how do they make this nest wonder?

The work begins every spring. In each bald-faced hornet colony, it is the females who do the manual labor. Each worker involved in exterior building gathers a mouthful of tree pulp from loose bark, which she works into paper. The paper is made by mixing starch-filled saliva with the wood. The nest is made up of several tiers of cells, or “cartons” and surrounded by a protective layer. Every visit a female makes creates a strip the color of the bark the wasp harvested, which she spreads with her mandibles and legs to dry into paper. As the nest grows throughout the summer, new, wider tiers are added. The wasps must then remove one or more of the inner layers of insulating paper while constructing new sheets on the outside.

Throughout the summer, worker bald-faced hornets guard the nest and collect nectar and arthropods to feed the larvae. Near the end of the summer, female larvae are fed greater amounts of food, allowing them to develop into queens. At the same time, the queen lays unfertilized eggs that develop into male wasps. The males mate with fertile females, and as winter approaches, the wasps die, except for young fertilized queens that hibernate underground or in hollow trees. The nest is generally abandoned by winter, and will most likely not be reused. This is hard work for one season!

Do we need to be afraid of these wasps? Any animal that is feeling threatened will protect itself. Bald-faced hornets do not have a barbed sting, so can deliver a series of painful stings. It is their venom that creates the pain. However, my method when seeing any bee or wasp is to ignore it, stand still, and let it go on it’s way. Many times when we are wearing colorful clothing, we are often mistaken for flowers, and once they discover that we have no rewards, they move on peacefully. However, beware if you disturb their entire nest.

These insects are beneficial as they are pollinators. They drink flower nectar for quick energy while they hunt, while also using the flowers as a hunting ground for smaller insects that are also attracted there. They can be beneficial in gardens since they predate upon insects that damage plants. It is worth taking the time to observe a bald-faced hornet, as you never know what you might have an opportunity to observe!

For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.

Thursday, July 9, 2009

Orbweaver Spiders

Nature Watch

By Susan Benson,
CNHM Director of Education
This week, on most mornings during or after the rain or dew, spiders webs were quite visible. Drops of water highlighted their presence. One spider I observed had built it’s web in what I thought was the most unlikely place, between my screen and storm doors. Who would guess they could catch something in that space? Nonetheless, spiders are amazing with the webs they weave. Orbweavers are best known by their beautiful webs, made at night in many different habitats. They are obviously known by their spiral, wheel-shaped webs, and are enjoyable to observe.

The making of an orbweaver web is an engineering feat, begun as the spider sends out a line on the wind to another object. Once the new line is secured, they drop a line from the center, making a “Y” shape. They then follow with making the “bicycle spokes” with a non-sticky silk. The final spiral is made with a very sticky capture silk. They keep themselves from getting stuck in their own web by traveling on the non-sticky part of the web. Usually the prey insect that is caught in the sticky lines is paralyzed by a quick bite and then wrapped in silk, or if the prey is a more dangerous insect, such as a wasp or bee, they may wrap the insect before biting.

With very poor vision, orbweavers must sit near or in their web to feel the movement of their prey. When caught, the front legs turn the insect while the back legs wrap their victim with silk. Many build a new web every night.

Orbweaver spiders show impressive brain power and web strategies. If researchers vibrate a web at multiple points, and then remove the stimuli, this spider moves to one point to check if an insect is there, and then moves to the next point with only their memory to guide them. Orbweavers have the ability to memorize multiple coordinates in their web. Web construction itself happens mostly at night, also suggesting that a spatial representation exists. That they can build a web using drops of “glue” and heavy gauge silk line as strong strands, followed by sticky inner catching threads is impressive architecture. Imagine building a house without using your sight!

For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.

Saturday, July 4, 2009

Celebrating the Red, White and Blue

Nature Watch
Celebrating the Red, White and Blue

By Susan Benson,
CNHM Director of Education

While enjoying the 4th of July festivities, keep your eyes and ears out for the red, white, and blue observations of three residents of the north woods. The red of the pileated woodpecker, white of the bald eagle, and the tasty blue of the blueberry can be a great part of any northern outdoor experience.
The woody woodpecker cartoons that many of us grew up with are modeled after the pileated woodpecker. The largest of North America’s woodpeckers, its bright red crest, loud ringing calls, and large, rectangular excavations in dead trees announce its presence in northern Wisconsin. Its call is a loud “kuk-kuk-kuk” and its drumming is loud and resonant from far away. Pileated woodpecker’s hollowed-out holes are broad and deep so they can fit their large bodies inside to find carpenter ants, wood-boring beetle larvae, or other insects. They also pry off long slivers of wood to expose their insect food. To go in search of a pileated, look or listen for them in large, older forests made up of mixed deciduous or coniferous trees.
The white head and tail of the bald eagle can be often seen in this area. We often see eagles while they are in flight. These opportunistic hunters get their food, preferably fish or other birds or mammals, by direct capture, scavenging, or stealing prey from other eagles or other birds and mammals. Eagles also can be seen wading in shallow water to catch fish. Young bald eagles can be seen fledging in late July, about 70 to 98 days after hatching. Before this, the young have been practicing flapping for weeks in preparation of their first flight. If one falls from the nest, the parents usually feed it on the ground. The parents encourage the babies to fledge by flying around the nest carrying food. After fledging, they usually stay with their parents for six weeks, being continually fed during this time. The young watch their parents fish, but don’t learn to catch fish for quite a while. The young begin “catching” carcasses on shoreline and then pick up dead fish floating in the water. Immature eagles won’t get the distinguishing white head until they are three to five years old, but still are an exciting sight to see.
For visitors looking for a tasty, blue treat, 4th of July may bring the delicious taste of wild blueberries. This plant grows in acid, sandy soil, so upland slopes and ridges and open woods are places where this plant can be found. A small shrub that grows about two feet tall, it has small, shiny medium green leaves. Their berries are a pale powder blue to black. For those who know what the plant looks like, and can avoid other possible look-alikes such as the blue-bead lily, blueberries can provide an excellent snack while out hiking.
For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.