Goals and Objectives:

The specific objectives of this project were to:

• determine the potential of urban gardens and natural areas embedded in urban settings in central Iowa to serve as habitat for butterflies, and to compare their ability to do so;
• compare modified transect and point-count survey protocols to evaluate the suitability of these protocols for assessing butterflies in urban habitats; and
• conduct initial outreach at Reiman Gardens and Ames High School (with Environmental Science faculty and students), by developing maps of butterfly habitat use and engaging volunteers/students in ongoing monitoring efforts using uniform protocols.

Progress:

Sites were surveyed starting in June and ending in September, 2015. Surveys were conducted between 10:00 am and 6:30 pm on sunny days with wind speeds less than 10 mph and temperatures between 70˚ and 95˚ F (Ries et al. 2001; IDNR nd). We conducted Pollard Walk transects, purposive point-count and random point-count surveys during each site visit.

Conclusions and Recommendations:

Each site was surveyed six times from June through September. Frequency of sampling was limited by cool, wet, weather conditions early in the season and windy conditions late in the season.

Comparison of habitat types. The number and proportions of butterfly sightings was influenced somewhat by both habitat type and survey method, with the greatest number of sightings occurring for purposive point surveys conducted in public gardens. Fewer sightings were documented using purposive point surveys in restored prairie areas, and for the two other survey methods in both habitat types.

However, no statistically significant differences were detected for number of sightings according to habitat. Similarly, total number of taxa observed was greatest in public gardens, but not statistically different.

Comparison of survey methods. Among survey methods, the greatest number and proportion of sightings were detected with purposive point surveys compared to other methods; the number of sightings detected using random point-count surveys were intermediate between the other two. The difference between purposive point counts and Pollard Walk transects was marginally detectable statistically before correcting for sampling effort (p = 0.056) using pairwise comparisons with a Tukey-Kramer test; after sampling effort adjustment the difference was not significant (p = 0.096).

Taxa observed. Across all sites, survey methods, and sample dates 1,093 sightings representing 28 species were documented. The most commonly encountered taxa were seen in both site types and included primarily disturbance-tolerant species: cabbage white, monarch, clouded sulphur, red admiral, and eastern-tailed blue. Least common species that were observed occurred somewhat more frequently in public gardens than in natural areas and included checkered white, clouded skipper, cloudless sulphur, coral hairstreak, hackberry emperor, least skipper, and Peck’s skipper. Several habitat-sensitive species also were observed: regal fritillary, great spangled fritillary, tawny-edged skipper, gray copper, and silver-spotted skipper (species were categorized as per Ries et al. 2001, Shepherd and Debinski 2005, and Reeder et al. 2005).

Initial outreach. Project personnel have participated in one outreach event and one symposium to date. Additional outreach on site-specific results with project partners at most sites was delayed to allow completion of data collection and preliminary analysis, and is planned for spring and summer, 2016. These events will include on-site demonstrations of protocols, use of interactive “Story Maps” and distribution of fact sheets based on observations at each site.

Additional planned project activities. Because weather conditions limited data collection according to sampling criteria for ambient conditions during summer 2015, collection of four to six additional sample sets is planned for summer 2016.

Funding Organization: Iowa Department of Natural Resources (IDNR), Wildlife Diversity Small Grants Program

Duration: 04/15/2015 to 03/31/2016

Award Number: 15CRDWBKINK-0073