Selecting Nectar Sources

Literature Review

Determining native nectar sources was accomplished through literature review by recommended and documented butterfly species to specific flower use from local and regional field guides and organizational websites.

Native Nectar Source Data

Determining which species of flowering plants were to be placed on the list was a combination of objective and subjective thinking. There are no guidelines to how lists of favored nectaring plants are compiled, so I devised a method of researching local butterfly recommended nectaring plants. Each time a flowering plant was cited on an organization’s list as good for a butterfly nectar source, I gave the plant a check mark, as the list of sources grew, plants that showed repeated occurrence as recommended nectar sources were given the according check marks. The number of local resources researched totaled six. Plants that appeared on all six separate sourced lists were given a rating of six out of six and were listed as a top nectar source. Each plant was given the same consideration and given the same check mark tally. 1. NABA

2. Salix & Associates

3. Heritage Seedling and Liners

4. Life Histories of Cascadia Butterflies (book) 5. Oregon State University

6. Self-observation in-field documentation

An arbitrary number of suggested nectaring plants was arrived to be at the number 50. Some plant lists stop at 20, some continue up to the top 100 recommended nectaring plants. I chose 50, as I felt it was enough of a list to be inclusive but not so much as to be overwhelming. Out of the top fifty nectaring plants, 44 occur as color plates. This choice was made due to the lower half of the list consisted

Methods

of plants that only occurred once out of the six sources and thus could be considered omissible from garden design despite being documented as a valid nectar source. However, experimentation is always recommended. Plants that occur on one list may not work for certain gardens. Use lists as a baseline but experiment and stick with what works.

Exotic Nectar Source Data

Because it is recognized that certain exotic flowering plants play a key role in providing high quality of nectar and that many of these flowering plants have shown to extend the nectaring season for adult butterflies, that the use of exotic flowers is warranted. Accordingly, I present a list of the top 50 exotic flowering plants favored by butterflies. This list was again compiled by the same methods used to compile native nectaring plants. This list used eight sources, both local and non-local plant lists. These plants however, do not appear as color plates, and the reader needs to further research web pages or gardening books for specific uses and cultural needs of those individual plants. This plant list was compiled from the following sources:

1. Butterfly Conservation Top 100 nectar sources

2. Nectar sources appendix: Mathew Tekulsky’s book The Butterfly Garden 3. NABA Southwest Oregon Top Butterfly Nectar Flowers Checklist 4. Oregon State University Butterfly Garden Nectar Source Checklist 5. Xerces Society Butterfly Gardening Appendix A, Nectar Plants for North American Butterflies

6. Missouri Botanical Garden Plant Finder web page

7. Sunset Western Garden Book, Butterfly Attracting Flowering Plants Checklist

8. Self-observation and documentation Observation

Observation played a key part in determining butterfly nectar fidelity within urban settings. There is good reason to conduct ground truthing surveys when it comes to nectar

source usage. An example: Many books recommend the Shasta Daisy and Black-Eyed Susan as top nectaring plants, however, within my study area of the urban neighborhood, Shasta Daisy and Black-Eyed Susan were rarely used as nectar sources and fell favor to English Lavender and Echinacea in the summer and Goldenrod and asters in the fall. By far the most utilized annual flowering plant was the zinnia. Gardens which had mass plantings of butterfly weed, lavender, asters, echinacea, tall verbena and mints were used almost exclusively over gardens which presented large patches of colorful Black-Eyed Susan’s, Shasta Daisy, cosmos, daylily, and coreopsis.

Building the Nectar Source to Habitat Quickguides

The same methods for building the nectar source to habitat quickguides were used with the building of the butterfly to habitat and host plant to habitat quickguides.

Methods

Once the nectar sources are selected based on habitat community, the reader needs to access the nectar source color plates to select a palette of flowering plants for the garden. A more detailed description of how to use the nectar source to habitat quickguides and color plates is described in chapter three.

Building the Native Nectar Source Color Plates

Over 1000 images of nectar sources both exotic and native were photographed and cataloged between April 2017 and March 2018. Photo documentation was key for the building of the nectar color plates. Color plates were formatted much the same as the host plant color plates with the omission of butterfly images, as butterflies as far less exclusive to flower choices than they are to host plant interactions (Fig. 2.14). Color plates are explained in greater detail in chapter three.