Michael P. Guilfoyle

Bird Community Response to Vegetation Cover and Composition in Riparian Habitats Dominated by Russian Olive (Elaeagnus angustifolia)

Abstract Riparian systems in the western United States provide important habitat for bird communities during all times of the year. In recent decades, invasive plants, such as Russian olive (Elaeagnus angustifolia), have achieved broad distribution and local dominance in many western riparian areas, raising concerns over the loss of ecological function within these systems. In 2005 and 2006 we conducted avian point counts and surveyed vegetation cover at 95 points along the Snake and Columbia Rivers in southeastern Washington to investigate the effects of total woody vegetation cover and the relative proportion of Russian olive cover on breeding and wintering riparian bird communities. Our results indicated that riparian habitats dominated by Russian olive can support diverse and abundant bird communities, though cavity nesting species were noticeably sparse. Bird density and species richness were best explained by a quadratic relationship to total woody vegetation cover in both seasons, as was breeding bird community composition, with greatest density and richness in intermediate cover levels. We found no indication that the proportion of the woody vegetation comprised of Russian olive strongly influenced any of these bird community metrics. Given that Russian olive comprised 81.6% of the riparian vegetation in our study area, it is unclear from our results how Russian olive would affect bird communities in regions where native vegetation is more abundant. Regardless, complete eradication of Russian olive from riparian systems where the plant is a major component will reduce the overall habitat value for birds by eliminating significant structural complexity.

Ordination of breeding birds in relation to environmental gradients in three southeastern United States floodplain forests

We used an ordination approach to identify factors important to the organization of breeding bird communities in three floodplains: Cache River, Arkansas (AR), Iatt Creek, Louisiana (LA), and the Coosawhatchie River, South Carolina (SC), USA. We used 5-min point counts to sample birds in each study area each spring from 1995 to 1998, and measured ground-surface elevations and a suite of other habitat variables to investigate bird distributions and community characteristics in relation to important environmental gradients. In both AR and SC, the average number of Neotropical migrant species detected was lowest in semipermanently flooded Nyssa aquatica Linnaeus habitats and greatest in the highest elevation floodplain zone. Melanerpes carolinus Linnaeus, Protonotaria citrea Boddaert, Quiscalus quiscula Linnaeus, and other species were more abundant in N. aquatica habitats, whereas Wilsonia citrina Boddaert, Oporornis formosus Wilson, Vireo griseus Boddaert, and others were more abundant in drier floodplain zones. In LA, there were no significant differences in community metrics or bird species abundances among forest types. Canonical correspondence analyses revealed that structural development of understory vegetation was the most important factor affecting bird distributions in all three study areas; however, potential causes of these structural gradients differed. In AR and SC, differences in habitat structure were related to the hydrologic gradient, as indexed by ground-surface elevation. In LA, structural variations were related mainly to the frequency of canopy gaps. Thus, bird communities in all three areas appeared to be organized primarily in response to repeated localized disturbance. Our results suggest that regular disturbance due to flooding plays an important role in structuring breeding bird communities in floodplains subject to prolonged inundation, whereas other agents of disturbance (e.g., canopy gaps) may be more important in headwater systems subject to only short-duration flooding. Management for avian community integrity in these systems should strive to maintain forest zonation and natural disturbance regimes.

PERCH CHARACTERISTICS OF ACADIAN FLYCATCHERS (EMPIDONAX VIRESCENS) IN SOUTHERN BOTTOMLAND HARDWOOD FORESTS

Abstract Perch-site selection is thought to be an important component of foraging success for sit-and-wait avian predators, such as flycatchers. Perch selection has further consequences for territorial advertisement and display. We quantified perch characteristics of Acadian Flycatchers in three bottomland hardwood forests in Arkansas, Louisiana, and South Carolina. We compared measurements made at flycatcher perches with those made at randomly selected trees and branches. In two of our study areas, flycatchers perched on dead limbs more often than expected by chance, and foliage volume was less around flycatcher perches than at randomly selected branches. Both of these results suggest a preference for foraging and displaying sites that provide a relatively unobstructed view. Discriminant function analysis revealed substantial overlap in perch-site characteristics among study areas, indicating that species-wide preferences were at least as important as local conditions in perch-site selection by Acadian Flycatchers.

SPRING MIGRANT USE OF NATIVE AND SALTCEDAR-DOMINATED RIPARIAN AREAS ALONG THE LOWER COLORADO RIVER IN ARIZONA

Abstract Riparian systems in the western United States provide essential stopover habitat to en-route migrant birds, and there is concern that the invasion and dominance of saltcedar (Tamarix) in many areas may inhibit use by some species. However, evidence from recent studies is challenging the widely held belief that invasive plants universally reduce habitat quality. Moreover, where many studies have compared avian use of riparian habitats dominated by saltcedar with those comprised primarily of native trees, few have investigated how birds use shrub communities, which are becoming more prevalent in western riparian zones because of widespread hydrologic modifications. We compared spring migrant use of 125-m sections of riparian habitat dominated by five different habitat types in southwestern Arizona in 2006 and 2007. We found that migrant abundance, species richness, and community assemblages were all influenced by the composition of riparian vegetation. Habitats completely dominated by saltcedar supported fewer migrants and migrant species than any other habitat type, but the presence of small amounts of native vegetation as a part of the overall riparian plant community greatly bolstered habitat use. Habitats dominated by native shrubs tended to support the greatest total migrant abundance, total species richness, and abundance of many individual species. Our findings suggest that riparian areas dominated by saltcedar are avoided by many western migrant species and have relatively low value as stopover habitat. In places where this species is a predominant component of the riparian plant community, restoration of at least a portion of native riparian vegetation may be effective for encouraging use by stopover migrants.

Movement of Hypophthalmichthys DNA in the Illinois River Watershed by the Double-Crested Cormorant (Phalacrocorax auritus)

Abstract. Paired throat and cloacal swabs, along with feather samples, from nesting Double-crested Cormorants (Phalacrocorax auritus) at two sites in Illinois, USA, were tested for presence of invasive bigheaded carp (Hypophthalmichthys spp.) DNA. We also used DNA from the feather calamus to determine cormorant sex. Throat and cloacal swabs from cormorants at both locations tested positive for DNA from silver carp (H. molitrix), but none tested positive for bighead carp (H. nobilis). Hypophthalmichthys DNA was not detected on feathers. There were no significant differences among positive Hypophthalmichthys DNA detection frequencies between cormorant sexes. To our knowledge, this is the first demonstration of silver carp as part of the Double-crested Cormorant diet in North America. Hypophthalmichthys are major invasive species of concern in this region, the detection of water-borne environmental DNA of Hypophthalmichthys is an important monitoring tool, and the potential movement of DNA via piscivorous birds may have significant implications for interpreting environmental DNA monitoring data.

Rapid assessment of invasive riparian trees for planning and implementing USACE ecosystem restoration projects

PURPOSE: This Technical Note (TN) was developed by the U.S. Army Engineer Research and Development CenterEnvironmental Laboratory (ERDC-EL), to provide an introduction to rapid assessment methods that can be used to provide a quantitative index to the abundance and distribution of invasive riparian trees found on U.S. Army Corps of Engineers (USACE) project lands. The USACE Ecosystem Management and Restoration Research Program (EMRRP) is supporting a nationwide effort to address the impacts of invasive tree species that affect decision making and the ultimate success of ecosystem restoration efforts. This research project has four objectives: (1) identify the suite of invasive woody riparian trees that are most problematic to USACE ecosystem restoration efforts, (2) develop guidelines that suggest thresholds for when and where on the landscape funds should be spent to control invasive trees, (3) determine the most efficient and ecologically-effective spatial configuration for woody invasive riparian plant removal on Corps-managed lands, and (4) investigate how faunal communities respond to various spatial control methods for invasive tree removal in densely vegetated riparian habitats.

Creating nesting habitat for the Common tern (Sterna hirundo) on the repaired Ashtabula breakwater : lessons learned 2014 – 2016

PURPOSE: The U.S. Army Engineer Research and Development (ERDC), Environmental Laboratory (EL) developed this technical note to summarize data collected during avian monitoring efforts on a repaired breakwater in Ashtabula Harbor, Ashtabula, OH. The repaired breakwater included a modified design that provided nesting habitat for the state-listed (Ohio) Common Tern (Sterna hirundo). The purpose of the nesting structure was to demonstrate simple design changes, executed during repairs to an existing breakwater, that increases environmental benefits consistent with the Engineering With Nature (EWN) initiative (U.S. Army Corps of Engineers [USACE] 2012). The U.S. Environmental Protection Agency (USEPA), Great Lakes Restoration Initiative (GLRI), and the Dredging Operations and Environmental Research Program (DOER) funded this project. The Nature Conservancy (TNC), with expert consultation from the Ohio Department of Natural Resources (ODNR) and the New York Department of Natural Resources (NYDNR), assisted with the implementation of this project. Elements of this work included (1) specific features of the repaired breakwater utilized to attract terns to the structure, (2) development and implementation of a monitoring program to assess the use of the structure by terns, (3) description of media coverage of this effort, and (4) final results and lessons learned from the project and future efforts to monitor the breakwater.

Documenting Presence and Movements of Piscivorous Birds along the Illinois River and within the Chicago Area Waterway System

Abstract : This technical report summarizes research conducted on piscivorous birds along the Illinois River and in the Chicago Area Waterway System (CAWS) to assess the potential role of these birds as vectors of invasive carp (bighead carp (Hypophthalmichthys noblis) and silver carp (H. molitrix)) DNA (deoxyribonucleic acid). To prevent invasive carp from invading the Great Lakes, the U.S. Army Corps of Engineers has spent considerable time and resources constructing electrical barriers in the Chicago Sanitary and Ship Canal around Romeoville, IL, just south of the Chicago metropolitan area. Since the construction of these barriers, intensive monitoring of fish populations and invasive carp environmental DNA (eDNA) have been used to document the possible presence of carp above the barrier. The Asian Carp eDNA Calibration Study (ECALS) was designed to improve our understanding and interpretations of eDNA monitoring efforts in the Chicago Area Waterway System (CAWS). Existing online bird population data sources were analyzed, and 30 Double-Crested Cormorants (Phalacrocorax auritus) were captured and satellite-tagged. The results from these projects are evidence that piscivorous birds are likely contributingat least in partto the presence of invasive carp DNA in the Chicago Area Waterway System.