Abstracts of the Scientific Program Joint Meeting of Association of Field Ornithologists (AFO) and Wilson Ornithological Society (WOS) October 27 to 30, 2019 Cape May, NJ Monday morning plenary address: Wilson Ornithological Society Margaret Morse Nice Lecture Dr. Robert Curry, Villanova University Transformation of familiar birds into model organisms: what chickadees can teach us. Much like the Song Sparrows that captivated Margaret Morse Nice, chickadees are charismatic backyard birds that we easily take for granted. Research concerning several North American chickadee species has burgeoned in recent decades, yielding insights about fundamental problems in ornithology –– approaching what we have learned from their European relatives. The role of vocal behavior in chickadee mating systems has been examined thoroughly. "Our" chickadees are currently central among studies of social networks using technological tools that allow us to track movements and associations in space and time. Chickadees have contributed important insights concerning cognitive ecology and neuroethology. Long-term research within the northward-moving hybrid zone between Black-capped and Carolina Chickadees combines many of these elements, while also employing genomic approaches and Citizen Science data; this work has revealed influences of ongoing climate change and behavioral mechanisms on the dynamics of songbird hybridization. There is still much to learn from these familiar birds. Tuesday morning plenary address: Association of Field Ornithologists Dr. Christina Riehl, Princeton University Cooperative breeding in the Neotropics: important lessons from obscure players. The study of cooperative breeding in birds has a long history in the New World tropics, beginning with Alexander Skutch's seminal observations of helpers at the nest. Recent studies of Neotropical birds have revealed a diversity of cooperative systems, ranging from small family groups to complex societies composed of relatives and immigrants. This talk will briefly review recent studies on these systems, which form our current understanding of the different evolutionary pathways leading to various forms of cooperative breeding. We'll then focus on the communally breeding cuckoos – the anis and their allies – which breed in social groups with several unrelated co- breeders. Although this breeding system is unusual among birds, the study of communal nesting can lend important insights into fundamental reproductive trade-offs in birds. Data from a long-term field project on Greater Anis in Panama has shed light on the selective pressures favoring (and constraining) sociality, including effects of group size on reproductive fitness, mating and parental care patterns, and alternative strategies such as conspecific brood parasitism. Oral Presentations C1 Samantha Apgar (S) and Chris Elphick. Department of Ecology and Evolutionary Biology, The University of Connecticut, Storrs, CT 06268. Tidal marsh bird behavioral plasticity in response to nest flooding events. As anthropogenic stressors threaten species with extinction, phenotypic plasticity and natural selection are two potential mechanisms for species persistence. Specialist species are especially vulnerable during times of environmental change, necessitating fine scale study of their potential to respond. We are studying behavioral plasticity of four sympatric tidal marsh bird species – Saltmarsh Sparrow Ammospiza caudacuta, Seaside Sparrow Ammospiza maritima, Clapper Rail Rallus crepitans, Willet Tringa semipalmata. These species nest near the ground in tidal marshes and are vulnerable to nest failure from high spring tides. Limited evidence suggests that Saltmarsh Sparrow chicks can climb up vegetation to avoid drowning and that Clapper Rails can manipulate nest structure during floods and retrieve eggs that have flooded out. To assess the frequency and conditions under which species engage in behaviors used to mitigate nest failure during flooding, we used infrared radiation cameras to film nests during nightly high tides occurring around the full and new moons. Preliminary data confirms existing literature on what behaviors each species employs and demonstrates that rails are most frequently at nests during flooding events, whereas adult Saltmarsh Sparrow, Seaside Sparrow, and Willets are largely absent. Chicks of both Saltmarsh Sparrows and Seaside Sparrows are able to climb once they reach a certain age. This ongoing project aims to determine how much flexibility there is in the frequency and conditions under which individuals employ behaviors to combat failure from nest flooding, in order to improve the understanding of each species’ status in the face of sea-level rise. H2 Ian Ausprey, Felicity Newell, and Scott Robinson. Florida Museum of Natural History, Department of Biology, University of Florida. Eye size predicts light microenvironment use, foraging niche, and sensitivity to habitat disturbance of Neotropical cloud forest birds. Eye size of terrestrial birds is often assumed to reflect interspecific variation in light microenvironment use and predicted to influence foraging behavior and sensitivity to habitat disturbance. However, no study has explicitly linked eye size to the actual light microenvironments used by wild birds. We hypothesized that eye size would predict (1) light intensity use, (2) foraging niche (stratum and maneuver), and (3) sensitivity to human-induced habitat modification. During 2016 – 2019 we placed light sensors on 15 species of cloud forest birds in northern Peru (N = 72 individuals), measured the lateral eye width for 135 species, and conducted point count surveys across a gradient of agricultural land use. Foraging behavior and eye size (phylogenetically corrected for body mass) predicted most of the variation in light intensity use (F4,10 = 8.312, p = 0.003, R2 = 0.84). Understory species had the largest eyes and used the darkest environments (<2% of total available sunlight) compared to canopy species with smaller eyes that used brighter environments (20-30% total available sunlight). Across the bird community 38% of the variation in eye size was explained by foraging stratum and behavior, with far-sighted foragers (sally/pouncers) in the understory having the largest eyes and near-sighted foragers (pick/gleaners) in the canopy having the smallest eyes. Average eye size was marginally higher for species sensitive to the two most brightly lit habitats in our system: fencerows and pasture trees. We argue that eye size is a novel functional trait contributing towards the fundamental niche of terrestrial bird species. G4 Daniel T. Baldassarre1,2, Leonardo Campagna3,4, Henri A. Thomassen5, Jonathan W. Atwell6, Miyoko Chu7, Lisa H. Crampton8, Robert C. Fleischer9, and Christina Riehl1. 1Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA, 2Current address: Department of Biological Sciences, SUNY Oswego, Oswego, NY, USA, 3Fuller Evolutionary Biology Program, Cornell Laboratory of Ornithology, Cornell University, Ithaca, NY, USA, 4Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA, 5Institute for Evolution and Ecology, University of Tübingen, Tübingen, Germany, 6Department of Biology, Indiana University, Bloomington, Indiana, USA, 7Communications Program, Cornell Laboratory of Ornithology, Ithaca, NY, USA, 8Kaua’i Forest Bird Recovery Project, University of Hawaii at Manoa, Hanapepe, HI, USA, 9Center for Conservation Genomics, Smithsonian Conservation Biology Institute, Washington, DC, USA. GPS tracking and population genomics suggest itinerant breeding across drastically different habitats in the Phainopepla. Migratory birds generally divide the annual cycle between discrete breeding and non-breeding ranges. Itinerant breeders, however, reproduce twice at different geographic locations, migrating between them. This unusual flexibility in movement ecology and breeding biology suggests that some species can rapidly modulate the conflicting physiological and behavioral traits required for migration and reproduction. The Phainopepla (Phainopepla nitens), a songbird of the southwestern USA, has long been suspected to breed first in desert habitats in spring, then migrate to woodland habitats to breed again in summer. However, direct evaluation of movement and gene flow among individuals breeding in different locations has previously been logistically intractable. We deployed GPS tags on free-flying Phainopeplas in southern California, all of which migrated to woodland breeding habitats after desert breeding (an average distance of 232 km). GPS data also revealed previously unknown fall and spring stopover sites. Population genomic analyses revealed no genetic differentiation among desert and woodland breeding populations, indicating significant movement and gene flow across the region. Finally, we used random forest analyses to quantify substantial environmental differences among temporal stages. Our results provide direct evidence that individual Phainopeplas do indeed move between two drastically different breeding habitats in the same year, representing a rare and extreme example of life-history flexibility. M2 Priti Bangal (1) (SP), Hari Sridhar (2), and Kartik Shanker (1). 1Centre for Ecological Sciences, Indian Institute of Science, Bengaluru, Karnataka, India, 2National Centre for Biological Sciences, Bengaluru, Karnataka, India. Phenotypic clumping reduces with flock size in heterospecific bird flocks. Mixed-species bird