Avifauna and Butterfly (Lepidoptera) Recovery in Restored Wetland and Riparian Habitats
During 2011, FPC received over $100,000 from the Arizona Water Protection Fund (AWPF) to conduct research to determine the difference between breeding bird and butterfly community richness and abundance in restored verses control riparian and wetland habitats in the Yuma East Wetlands (YEW). Baseline research conducted by FPC biology staff during 2007-2008 indicated that butterflies and breeding birds warranted further research as restored habitats matured. Both bird and butterfly communities can quickly re-colonize restored sites as well as provide good indicators of ecological health. The objective of this project was to determine if bird and butterfly communities were similar between restored and control habitats in order to further refine restoration practices and evaluate restoration success.
Restored and control habitats were primarily located in the YEW with one restored riparian site in the Yuma West Wetlands. Riparian breeding birds were surveyed using intensive area searches, which included surveying five restored and five control plots (1-3 ha) six times during mid-April to June. Breeding evidence of all birds detected was recorded on a geo-referenced map. Marsh birds were surveyed using variable circular plots and the National Marsh Bird Monitoring Protocol (Conway 2005) three times during March- May. Butterflies were surveyed in riparian habitats during May, June, July and September. Transects were established down the center of the plot or around the periphery if vegetation was too dense to survey for butterflies. Timed searches were conducted by zigzagging across the transect in search of butterflies at a rate of one minute per 20 m (not including pursuit time). All butterfly species detected were recorded as well as their behavior (nectaring, basking, flying) and if nectaring the plant species. Vegetation characteristics such as total vegetation volume and cover estimates in 3m plots were recorded to evaluate bird habitat and butterfly host plants. Nectar resources and blooms were also evaluated every 10 m along the transect after every butterfly survey.
The results from this study indicated that both bird and butterfly species preferred restored riparian and wetland habitats over the control riparian and wetland habitats. A higher richness and density of resident birds was detected using the restored riparian habitats than the control riparian habitats, however the results were not statistically significant. No correlations were detected between resident or migratory riparian bird richness or abundance and environmental characteristics. Bird richness and abundance was significantly higher in restored wetland habitats as compared to the control wetland habitats, with yellow-headed blackbirds being the most common species detected. Eight endangered Yuma clapper rail were detected in the restored wetland habitats, which was higher than previous years. Butterfly species richness and abundance was significantly higher in the restored riparian habitats as compared to the control riparian habitats, which was likely due to the diversity of flowering plants detected in restored habitats. Butterfly species richness was correlated with flowering plant richness and abundance, vegetation species diversity and percent herbaceous cover. This indicates that in order to attract a variety of butterfly species, a diversity of flowering herbaceous vegetation should be planted at restoration sites. FPC has been contracted by the Yuma Crossing National Heritage Area as part of the Multi-Species Conservation Program (MSCP) of the Bureau of Reclamation agreement to continue the intensive bird surveys following the protocols established by the MSCP.