Bird monitoring at Effigy Mounds National Monument, Iowa: Status report 2009–2022

In 2009, the Heartland Inventory and Monitoring Network initiated bird surveys on Effigy Mounds National Monument to monitor changes in bird community composition and abundance and improve our understanding of relationships between breeding birds and their habitat and the effects of management actions on those relationships. This information helps park staff plan management objectives and assess the effectiveness of management alternatives. We evaluated park breeding bird trends in the context of trends observed within the North American Bird Conservation Initiative’s Prairie Hardwood Transition Bird Conservation Region where the park is located. This allows us to assess the influence of park habitat management on bird populations with an understanding of regional population trends that are outside the influence of natural resource management activities at the park. In 14 years (2009–2022) of monitoring, 111 bird species have been recorded on the park, 93 of which are considered breeding species (permanent or summer residents). Eight of these are species of concern for the Prairie Hardwood Transition Bird Conservation Region. Thirty-eight species were observed in sufficient numbers to calculate annual abundances and trends with some degree of statistical confidence. The American Redstart, American Robin, Baltimore Oriole, Eastern Wood-pewee, and Red-eyed Vireo were the most abundant and widespread species on the park. Regional trends (2009–2019; Sauer et al. 2020) were similar to those seen on the park with a few exceptions. American Robin, Brown-headed Cowbird, Common Grackle, and White-breasted Nuthatch were declining within the region but increasing within the park. Diversity, richness, and evenness in distribution of individuals across species in the breeding bird community on the park were unchanged over the 14 years. When sampled, habitats on the plots at Effigy Mounds National Monument consisted primarily of the woodland type, with lesser amounts of other types present. Canopy cover averaged 61 to 89% on plots with cover provided exclusively by hard¬wood trees. Basal area of hardwood trees averaged between 12 and 22 m2/ha, and canopy height averaged between 20 and 23 m. Tree species from 14 different families contrib¬uted to the canopy cover and basal area of plots. Plots were primarily unvegetated at ground level, with deciduous litter and woody debris common and bare soil exposed. Total foliar cover at ground level on plots consisted primarily of forbs.