August 2021 – Discover-Nature

Dead Trees

Trees offer a variety of services for wildlife, whether they are in a forest, a city park, or in your backyard. Trees grow slowly and die slowly. Each year, they flower, leaf out, and grow fruit throughout the spring and summer and then drop leaves and fruit each autumn. Often, one, two or more branches will die each year, even as new ones are being added. As each part of a tree dies, habitat is not lost; it is transformed into use for a variety of wildlife.

White oak snag by Frank D. Laspalluto, 2021

A hole in a tree can be created by a variety of events: branches broken off by weather or animals, trees being impaled by other trees during violent storms, or punctures or cuttings from human activities. Openings offer nesting sites for owls and flying squirrels. Bark at the lip of a hole will start to peel away allowing bats and spring peepers to get underneath for shelter. Small holes invite insects in, and woodpeckers searching for insect prey enlarge the holes. When a cavity becomes large enough to kill the entire tree, it is often used by tree swallows for nesting or as a great place for honeybees to build hives.

Red-shouldered hawk couple in the early morning light at the Venice Rookery, Venice, Florida, Lookout post by Diana Robinson, 2020

Snags are dead trees that remain standing. These offer birds of prey perches while they scan the areas underneath for small animals to hunt. After the snag becomes too weak to stand any longer and falls to the ground, it becomes shelter for numerous species. Mice and chipmunks use small holes to store food, raise young, and hibernate in for the winter. Large hollow logs offer a home for skunks and bobcats. Accumulated bark and leaf litter is a favorite place for toads and black rat snakes looking for a place to lay eggs. Shade provided under fallen logs promotes a damp environment, a favorite place for salamanders.

As wood starts to decay, decomposers move in. Fungi begins the process by breaking down the bark and returning the nutrients to the soil. Millipedes, termites, beetles, and ants all feed on rotting, decaying wood. Opossum, raccoon, robins and nuthatch find a treasure of insects and arthropods to feed on. Earthworms and grubs help to mix all of the droppings around the fallen log into the soil through their tunnel building activities, constantly enriching the soil.

Shelter for two by Lars-Goran Hedstrom, 2015

Dead trees are an important part of a forest ecosystem and can play a beneficial role in any habitat. Consider leaving branches where they drop, or artfully placing them into your own garden habitats. They provide shelter and food for many organisms, creating a rich and diverse community. Species that directly use the wood provide food for small organisms as they break down the wood and are prey themselves for larger animals. They release the nutrients trapped in the wood and enrich the soil in the process. They create shelter by opening new holes and enlarging existing ones for additional plants and animals to occupy. Next time you are out walking, gently turn over a log, and observe this wonderfully changing habitat.

Opossums

A marsupial is a mammal with young that are born not fully developed and are subsequently carried in a pouch on the abdomen of the mother where the young can attach to a teat and complete their development. The most well-known animals in this group are kangaroos, but we also have one species in Illinois, the Virginia opossum, Didelphis virginiana. The opossum is native to Illinois and is common in all parts of the state. The oldest remains found in Illinois date back 100,000 years ago, while worldwide, opossums are one of the oldest known mammals, with remains dating back about 20 million years ago to the Miocene period.

Virginia opossum, Didelphis virginiana by Phil Myers, UMAA 2008

An adult opossum has coarse gray hair covering its body with white facial hair and a long, pointed snout with a pink nose. They are about the size of a house cat with hairless ears and a one to two foot long hairless tail. Their tails are prehensile, adapted for seizing, grasping, or holding, and used for balancing and climbing. The hind feet have no claws, but do have an opposable toe used for climbing and grasping. They can appear fearsome when baring their teeth, having fifty of them, more than any other land mammal. They live in urban or edge habitats, finding shelter in old dens, rock crevices, hollow logs, and under wood or stone foundations.

Virginia opossum female with babies using tail for support, Didelphis virginiana by Dawn Pedersen, California Academy of Sciences SF

Females give birth to one or two litters each year, the first in mid-winter and a possible second litter in early spring. Young are born about two weeks after fertilization. A newborn, the size of a bumblebee, must crawl to the mother’s pouch where it will attach to a nipple and stay attached for two to three months to complete its development. Up to twenty young, called joeys, are born in each litter, but the female adult only has 13 teats and the remainder of the young do not survive. Young are weaned at about three months. Usually nocturnal and solitary animals, young will often strike out on their own but may return to the family group for the winter.

Virginia opossum adult, Didelphis virginiana by Phil Myers, UMAA

Opossum are omnivores eating a wide variety of food including fruit, grain, seeds, pet food, garbage, carrion, eggs, insects, frogs and other small animals. Ticks, found on many Illinois mammals, are a favorite food item. It is estimated that an adult opossum consumes several thousand annually. Opossum are scavengers, seed dispersers, and a control for small mammal and insect populations. In turn, they are prey for larger birds and mammals.

Virginia opossum juvenile, Didelphis virginiana by Lisa Wright 2007

When threatened, an opossum may respond by hissing, growling, baring its teeth, or playing dead. Playing dead, an autonomic response, occurs when the opossum faints. They lay on the ground with lips drawn back, teeth bared, eyes half or fully closed, saliva drooling, and a foul-smelling liquid excreted from their anal gland. Individuals can be poked, turned over or picked up and carried away with no response. They will recover by slowly regaining consciousness after several minutes or up to four hours. In the wild, their average life span is two years, and the leading cause of death is being hit by a vehicle.

Virginia opossum tail, Didelphis virginiana by Lisa Wright 2007

Opossum are protected under Illinois law as a furbearer. Hunting licenses are available each year with no limits. Permits may also be issued for nuisance animals that may be trapped for removal to another area. Adults are often infested with parasites, but carry none that are known to affect humans. They are rarely encountered or seen, but you may be able to observe them in the evening, especially under bird feeders or where pet food is left outside.

Dangerous Plants

It’s summer and a wonderful time for hiking in fields and forests, observing the plants and animals that live here. But as you are out enjoying nature, there are dangerous plants to be aware of. Some species can also be found in backyard gardens where they may pose a hazard to people and pets. Here are three to avoid.

Poison hemlock, Conium maculatum by William & Wilma Follette, 1992 USDA NRCS

Poison hemlock umbrel, Conium maculatum by Doug Goldman, 2011 USDA NRCS

Poison hemlock stem, Conium maculatum by Doug Goldman, 2011 USDA NRCS

Poison hemlock, Conium maculatum, is native to Europe and North Africa but is widely distributed in North America. The plant can grow to 12′ tall on a hollow, hairy stem, green with dark maroon spots. Flowers form a small, loose, white cluster often mistaken for Queen Anne’s Lace. All parts of the plant, especially the seeds and roots, contain a poisonous alkaloid oil called coniine. When ingested, the oil works as an inhibitor directly on the central nervous system which may lead to failure of the respiratory muscles and death. Eating six to eight leaves may prove fatal for humans. If the oil comes in contact with skin exposed to direct sunlight, a phytophotodermatitis reaction occurs causing severe burns of the area.

Deadly nightshade fruit, Atropa belladonna,
by Peganum 2009

Deadly nightshade, Atropa belladonna, by Joan Simon 2014

Deadly nightshade, Atropa belladonna, another plant introduced to the U.S., has a long history of use in medicine, cosmetics and as a toxin. Plants grow to seven feet tall with purple and green, lightly scented, bell-shaped flowers. All parts of the plant, but most especially the root, contain tropane alkaloids having anticholinergic properties inhibiting the involuntary muscle movements the body depends on for functions including sweating, breathing, and heart rate. The berries are attractive, dark red, cherry-like and sweet tasting. Consumption of 2-5 berries by children and 10-20 berries by adults can be fatal. Only cattle and rabbits seem to have no reaction to the plant’s poison.

Giant hogweed, Heracleum mantegazzianum, a member of the carrot family, is native to Eurasia and was introduced to the U.S. as an ornamental in the late 19th century. This plant typically grows 6′ to 18′ tall with 3′-5′ diameter, deeply-lobed leaves. Stems are bright green with purple splashes and coarse white hairs. Greenish-white flowers, similar to Queen Anne’s Lace produce 10,000 to 50,000 half-inch long seeds per plant. Like poison hemlock, the sap causes a phytophotodermatitis reaction when in contact with skin subsequently exposed to the sun’s UV rays. Initial reactions may be mild including red, itchy skin developing into more severe blisters and burns after 24-48 hours. Scars last several years, and hospitalization for burn treatment is not uncommon.

Poison hemlock, Conium maculatum by Doug Goldman, 2012 USDA NRCS

All three species are considered weeds, found in fields and along forest edges, and may not be actively controlled or removed resulting in widespread distribution. Recently, poison hemlock has become a serious backyard problem in Ohio and Indiana where plants have been spreading rapidly. Causes for the spread are not clear, but the trend is continuing to move westward. Enjoy your nature viewing, but be aware of the plants around you and the secrets they may hold.

Ladybugs

Lady beetles, popularly known as ladybugs, are a beloved and diverse group of insects found in many backyard gardens. Oval to round in shape with a head that is partially covered by the pronotum, the plate covering the thorax, they come in a variety of colors, with or without spots. Identification is made based on spot shapes and patterns. There are about 500 species living in the U.S., most of which are predatory, which makes gardeners love them. Many species have long, slender larvae with dark, spiny bodies that are also predators of garden pests.

Lady beetle aggregation by Richard Droker

Female ladybugs produce upwards of 1000 eggs laid in batches, several times over a period in late spring and early summer. Eggs hatch in five to eight days, and larvae pupate to adulthood in three to seven weeks. Their one-year life span takes them through winter hibernation under logs, buildings, and snow drifts, and in many houses. Gathering in large groups of several hundred to several million, ladybugs can survive up to nine months of cold temperatures, living off fat reserves. They over-winter near their food sources and wake in spring when temperatures reach above 55˚F/13˚C.

Ladybugs live in a variety of habitats, wherever aphids can be found, including forest, meadow, marsh, prairie and backyard gardens. Feeding on soft-bodied insects, they provide natural pest control, especially in our gardens. Both adults and larvae can consume several dozen insects daily. Primary prey include aphids, spider mites, thrips, scale, insect eggs, and small insect larvae. Ladybugs are also considered important for pest control in agricultural areas. About 3,000 ladybugs can protect an acre of fruit trees or other crops.

14-spot Ladybird beetle, Propylea quatuordecimpunctata by Will George

Several non-native species can be found throughout the U.S. Most have been brought here as part of a biological control effort, but they can negatively affect native populations by outcompeting them for food. Several of these introduced species are now considered to be serious pests, especially when inadvertently collected along with grapes for wine production, giving the finished product a sour flavor.

14-spot Ladybird beetle, Propylea_quatuordecimpunctata_larva by Gilles San Martin

In early spring, before aphids hatch, several ladybug species located in the northern U.S. depend on pollen for up to half of their diet. Providing early-flowering species containing a high pollen load can be very beneficial. Several plants can be added to your garden that will help fulfill this need for ladybugs and other local pollinators including heather, red-flowering currant, grape hyacinth, and dandelion.

Convergent Lady-beetle, Hippodamia convergens by Astrid von Wesenbeeck

Ladybugs are considered omens of good luck all over the world. Four of them were carried into space on one of the shuttle missions to test the effects of zero gravity on insects. Results indicate they have no trouble capturing their prey without gravity. They are the official state insect in Delaware, Massachusetts, New Hampshire, Ohio and Tennessee. Check out your backyard or nearby gardens to see these tiny natural wonders in action.