Module 4

Pollinator Friendly Habitat in Your Area

Purpose:

• To understand the habitat requirements of native pollinators.
• To become familiar with native pollinators and the native and introduced plants they pollinate.
• To learn the areas in the community that are suitable habitat for pollinators and what is being done to preserve or improve them.
• To consider ways to raise public awareness of the importance of pollinators and the need to protect their environment.
• To learn how to conduct a survey or a census.

Background:

Importance of Pollinator-Friendly Habitat

Pollinators, like other animals, require food, shelter and water, space, a place to reproduce, and materials for nesting in order to survive and flourish. These needs are usually met for native pollinators when the natural environment is not disturbed.

Black swallowtail larva feed on dill-family plants.
Photo by Suzanne DeJohn/NGA.

Pollinators play an important role in maintaining the balance and biodiversity necessary for a healthy ecosystem. There has been a global decline in biodiversity due to habitat loss, introduced species, pollution, population growth, and the overconsumption of resources. By applying sound ecological principles to our use of land and water, we can help to reverse this loss of biodiversity while making a healthier environment for all, including the animals that provide the essential eco-service of pollination. (From Saving Pollinators; see reference list at bottom of page.)

The following community services or organizations may be able to direct you to local groups or individuals that are knowledgeable about native plants and pollinators:

• Cooperative Extension Service (See listing in County Government pages in phone book.)
• Reference librarian at local library
• Local chapter of your state's native plant society (Do an Internet search by entering your state's name followed by "Native Plant Society.")
• Local plant nurseries
• The botany or biology department at your local high school or college
• U.S. Fish and Wildlife Service

Decline in the Pollinator Population

Monarch butterfly larvae feed only on milkweed
plants. Photos by Suzanne DeJohn/NGA.

Four reasons for the alarming decline in the pollinator population are:

1. Habitat loss and fragmentation. Habitat loss and fragmentation affect pollinators in two ways:

• Pollinators have basic food requirements. The availability of a variety of native plants is important because not all pollinators can access the nectar found in introduced flowers. Pollinators also depend on the availability of various flowering plants throughout a season. Habitat loss can negatively affect the timing and amount of food availability, thereby increasing competition for those limited resources.
  
• Loss of habitat can also disrupt the nesting requirements of certain pollinators. For example many species of bees nest in underground burrows and in hollowed-out logs. Decreases in suitable nesting areas can be attributed to natural disasters, such as fire, drought, or floods, and to the development of land for human use.

While habitat loss can seriously impact all pollinator organisms, increased fragmentation of habitats is particularly troublesome for those pollinators that travel great distances. Fragmentation of habitat increases the distance between suitable food and shelter sites along migratory routes, thereby disrupting the journey. Migratory pollinators, such as the monarch butterfly and the rufous hummingbird, travel thousands of miles each year as the season change. These trips require high levels of energy, making consistent food resources all along the way critical to survival. Some scientists believe that if fragmentation continues at its current rate, many migratory corridors will soon be closed.

2. Agricultural and grazing practices. Modern agricultural practices have made farms an increasingly poor habitat for wild pollinators. Single-crop farming has led to the elimination of fencing between smaller fields. Such fencing created buffer strips where native flowering plants could grow, providing suitable habitat for the native pollinator population. Removal of these buffer strips has a destabilizing effect on native pollinator habitat. At the same time, the use of hybrid crop seeds that require increased pollination make the farmer more dependent on costly managed honey bee colonies.

Use of land for grazing can result in diminished pollinator food resources and destruction of underground nests and potential nesting sites. Ironically, grazing animals are dependent on insect-pollinated legumes, such as alfalfa and clover, for forage.

3. Pesticides. Agricultural and residential use of broad-spectrum pesticides poses another major threat to all pollinators. Insecticides affect bees and other insect pollinators directly through unintentional poisonings, and herbicides affect them indirectly through destruction of insect forage and other wildflowers important in maintaining some insect populations.

4. Introduced species. Introduced species of plants and animals can have a serious effect on their new ecological system. Introduced pollinators can increase competition for floral resources, disrupt the reproduction of native plant species and facilitate the spread of invasive plants. Despite the negative impact they may have, some non-native pollinators also can be beneficial, the honey bee being an example. (From Ecological Society of America's Pollinator Tool Kit: Pollinators in Decline; see references below.)

References:

Buchmann, S.L. & Nabhan, G.P. (1999). Pollinators, Flowers, and Garden Ecology. Brochure for Contra Costa Clean Water Program and the Aquatic Outreach Institute. Life Garden, Walnut Creek, CA.

Butterfly World, Regional Garden Guidebook, Area 2. Bring Back the Butterflies Campaign

Emblidge, A and Schuster, E. (1999). Saving Pollinators. ZooGoer, Jan/Feb. http://natzoo.si.edu/Publications/ZooGoer/1999/1/savingpollinators.cfm

Shepherd, M. Backyard Conservation: Plants for Native Bees. The Xerces Society

The Ecological Society of America. Pollinators in Decline--Causes. Pollination Tool Kit. http://www.esa.org/ecoservices/poll/body.poll.scie.decl.html

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