Date: Fri, 21 Sep 2001 07:19:12 -0400 Reply-To: Maryland Birds & Birding Sender: Maryland Birds & Birding From: "Magnusson, Nancy C." Subject: Article: "Where Have All the Birds Gone" MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" I thought this might be of interest to this group as well. -----Original Message----- From: kgrosz@state.de.us [mailto:kgrosz@state.de.us] Sent: Tuesday, September 18, 2001 7:42 AM To: VA-MD-DE-Bugs@yahoogroups.com Subject: re: [VA-MD-DE-Bugs] Hickory Horned Devil diet VA MD DE Buggers: Sorry, here's the article: Garden Check - Up-To-Date Information for Delaware Gardeners 10 August 2001 Cooperative Extension University of Delaware College of Agriculture and Natural Resources Where Have All the Birds Gone? Ever wonder about an insect's preferred cuisine? Not likely, unless, of course, the critter in question is an uninvited guest chewing on your prize rose. Yet Dr. Doug Tallamy, University of Delaware professor of entomology and applied ecology, is concerned. In a recent study he found that insects largely ignore the leaves of non-native plants, opting instead to eat the foliage of native species. But with non-native plants increasingly choking our native growth, the insects' food supply is disappearing rapidly. At issue is the availability of insect food, a fact on which the entire food chain rests. Why should the disappearance of insects concern people who spend millions every year getting rid of them in the garden? Because plants are at the base of the food chain, and insects feed on plants. If insects disappear, so do the creatures that depend on them. In fact, more than 90 percent of insects are restricted in their diets, because they do not have the enzymes required to digest the leaves of non-native plants, sometimes referred to as exotics. It's simple: fewer plant food sources, fewer insects, wildlife vanishes. Over several months this year Rebekah Baity, an undergraduate researcher in the UD College of Agriculture and Natural Resources, and I began to measure the amount of leaf area eaten by insects on more than two dozen plants and trees. The research site is 10 acres of long uncultivated farmland in Chester County, Pa., where non-natives - specifically, oriental bittersweet, autumn olive, Japanese honeysuckle and multiflora rose - have crept into unmowed fields once inhabited by native plants. In evaluating the food preferences of native insects, we found that the insects consumed 239 square centimeters of the leaves on black oak, a native American tree, as compared to 12 square centimeters of Norway maple, a highly invasive species rapidly spreading throughout eastern North America. Although a number of studies have been conducted on ecological problems caused by non-native plants, the focus has been on the economics of unchecked invasion and the biological threat of displacing native plants. I believe this is the first study to quantify the effects of non-native plants on the food supply of insects and relate it to the food supply of birds as well as the ultimate consequence to ecological balance. Fast-growing non-native vines such as bittersweet, Japanese honeysuckle and climbing bushes such as multiflora rose can actually strangle a healthy tree - even huge ones. All plants vie for sunshine for photosynthesis, yet vines have an advantage. Before long, the tree weakens, first losing its ability to bear leaves, seeds and fruit, then declining to the point that a wind or ice storm finishes it off. The result is a loss of plant food for insects and protein and shelter for birds. Bird studies conducted over the past decade reveal that native bird populations are in decline. Until now, however, the findings seemed to indicate that the decline was the result of a loss of habitat, both in the tropics and the United States. The multiflora rose is an example of a shrub introduced into this country as an ornamental plant. This rose offers excellent nesting sites and berries for birds to forage in fall, so marketers purposely appeal to people who want to encourage wildlife into their yards and gardens. But now this aggressively growing bush has overtaken creek banks and roadsides all over the United States, effectively choking out native plant species. Yes, multiflora rose does provide nesting and berries for winter-feeding birds, but what is overlooked is that native birds also nest in native plants. More important, when raising their young in the spring, birds depend upon a supply of insects and larvae to feed the hatchlings. If the insects are eliminated, so are future generations of birds. And the problem is not limited to Pennsylvania. Multiflora roses are among the many non-native plants that now dominate much of the American countryside. Unchallenged by insect pests from their homeland, this exotic shrub grows wild, crowding out plants native to North American open areas and forests, upsetting the balance of nature. When people see green open spaces, they think nature has taken over. What they don't recognize is that the fields of green in many parts of southeastern Pennsylvania and Delmarva peninsula are overrun with 90 percent non-native growth. A green field in which the native plants have been choked out by invasive non-native ones is no more productive than a parking lot when it comes to providing food for insects, birds and other animals. The non-native butterfly bush is another case in point. People plant butterfly bushes in the mistaken idea that they are helping nature. The bush does attract butterflies for its flower nectar, but they will not lay their eggs on these leaves, because the foliage offers no nutrition to the hatching larvae. Planting a native species, such as viburnum, milkweed, Joe Pye weed or purple coneflower for every butterfly bush - now that would really help nature. I am optimistic that the data we have collected will attract the attention of birders, who may be able to influence the garden marketplace. And I hope the scientific evidence gathered in this study will help spur home gardeners into action. Just imagine the future impact on bird populations and our natural heritage here in the Delaware Valley if homeowners replaced the non-native ornamental plants on their property with plant species historically native to the area. - Copyright 2001 Doug Tallamy Dr. Doug Tallamy Professor of Entomology and Applied Ecology University of Delaware Junk Food for Insects Foods Insects Like Multiflora rose Virburnam Oriental bittersweet Hickory Japanese honeysuckle Oak Autumn olive Black walnut Mile-a-minute weed Black willow Garlic mustard Elderberry Norway maple Goldenrod Ox-eye daisy Black cherry Red clover Red maple Karin H. Grosz, Conservation Planner CCA 28245/ MDNutMgt 1456 Sussex Cons District , DE 302/856.3990x116 Fax 302/856.4381 To unsubscribe from this group, send an email to: VA-MD-DE-Bugs-unsubscribe@yahoogroups.com ======================================================================= To leave the MDOsprey list, send e-mail to listserv@home.ease.lsoft.com with the following message in line 1: signoff mdosprey ======================================================================= =========================================================================