Banner from left to right: Carolina Chickadee, Red Maple, Red bud Leaf Roller Caterpillar
Neighborhood Nestwatch Food Web Project
What is a Trophic Web?
The main objective of this study is to determine how non-native (exotic) plants are impacting higher trophic organisms. A trophic (or food web) refers to the way that energy flows through the ecosystem from producers (i.e. organisms that make food; plants) to consumers (organisms that consume food). Consumers can be low in the trophic web if they directly eat producers (like a caterpillar) or high if they eat other consumers. For example, a hawk would be the highest trophic organism because they eat consumers (birds and small mammals), and there are few or no organisms that eat them.
To protect themselves, plants have evolved special chemical defenses in their leaves to deter herbivory from insects. However, over time some caterpillars have evolved their own protection against these defenses, resulting in only a select few insect species able to feed on a particular species of plant. Caterpillar species tend to be either generalist (eating many different types of plants), or specialists (those that solely eat one plant species, or one group of plant species). Different tree species vary in the abundance and diversity of caterpillars that feed on their leaves. For example, oak trees (Quercus spp.) can support over 500 different species of caterpillar!
As areas become urbanized and developed, there are drastic changes in vegetation cover by way of forest loss and fragmentation. In addition, many homes are planted with ornamental varieties of trees, which homeowners may specifically landscape for either aesthetic and/or ecological properties. The loss of a particular species of tree, and/or replacement by a related non-native species, may result in changes to the community of organisms that rely on this food source. This suggests that insect eating birds (like chickadees) may in part be negatively effected by non-native plants, by way of reducing available food resources. This prediction however, has not yet been explicitly tested, so with the help of Neighborhood Nestwatch participants we will begin to address these questions.
The main objective of this study is to determine how non-native (exotic) plants are impacting higher trophic organisms. A trophic (or food web) refers to the way that energy flows through the ecosystem from producers (i.e. organisms that make food; plants) to consumers (organisms that consume food). Consumers can be low in the trophic web if they directly eat producers (like a caterpillar) or high if they eat other consumers. For example, a hawk would be the highest trophic organism because they eat consumers (birds and small mammals), and there are few or no organisms that eat them.
To protect themselves, plants have evolved special chemical defenses in their leaves to deter herbivory from insects. However, over time some caterpillars have evolved their own protection against these defenses, resulting in only a select few insect species able to feed on a particular species of plant. Caterpillar species tend to be either generalist (eating many different types of plants), or specialists (those that solely eat one plant species, or one group of plant species). Different tree species vary in the abundance and diversity of caterpillars that feed on their leaves. For example, oak trees (Quercus spp.) can support over 500 different species of caterpillar!
As areas become urbanized and developed, there are drastic changes in vegetation cover by way of forest loss and fragmentation. In addition, many homes are planted with ornamental varieties of trees, which homeowners may specifically landscape for either aesthetic and/or ecological properties. The loss of a particular species of tree, and/or replacement by a related non-native species, may result in changes to the community of organisms that rely on this food source. This suggests that insect eating birds (like chickadees) may in part be negatively effected by non-native plants, by way of reducing available food resources. This prediction however, has not yet been explicitly tested, so with the help of Neighborhood Nestwatch participants we will begin to address these questions.
For more information: Desiree L. Narango - PhD Student/Research Associate University of Delaware, Newark, DE Smithsonian Migratory Bird Center, Washington, DC Email: [email protected] |