AN INCREASINGLY URBANIZED WORLD REPRESENTS AN UNPRECEDENTED ALTERATION OF NATURAL ENVIRONMENTS WITH WIDE-RANGING EFFECTS ON BIODIVERSITY. URBANIZATION CAUSES THE SIMPLIFICATION OF ANIMAL COMMUNITIES DOMINATED BY EXOTIC AND INVASIVE SPECIES WITH FEW TOP PREDATORS. IN RECENT YEARS HOWEVER MANY ANIMAL PREDATORS (E.G. COYOTES COUGARS AND HAWKS) HAVE BECOME INCREASINGLY COMMON IN URBAN ENVIRONMENTS. AS PREDATOR RECOVERY IS CENTRAL TO THE MISSION OF CONSERVATION BIOLOGY THIS REWILDLING OF URBAN ENVIRONMENTS REPRESENTS A UNIQUE EXPERIMENT IN PREDATOR COLONIZATION AND ITS ASSOCIATED ECOLOGICAL CONSEQUENCES. ONE SUCH PREDATOR THAT IS RECOVERING FROM DECADES OF WIDESPREAD POPULATION DECLINES ARE ACCIPITER HAWKS. THESE WOODLAND HAWKS ARE WIDELY DISTRIBUTED THROUGHOUT NORTH AMERICA THAT ARE INCREASINGLY COMMON IN URBAN AND SUBURBAN LANDSCAPES. ACCIPITER HAWKS OFTEN HUNT AT BIRD FEEDERS AND THIS BEHAVIOR PROVIDES A UNIQUE OPPORTUNITY FOR MILLIONS OF PEOPLE TO OBSERVE THE ECOLOGY OF A PREDATOR RIGHT IN THEIR OWN BACKYARDS. OUR OVERARCHING GOAL IS TO INTEGRATE DATA FROM ESTABLISHED CITIZEN SCIENCE PROGRAMS WITH NASA SATELLITE OBSERVATIONS TO EXPLORE THE ENVIRONMENTAL CONTEXT AND ECOLOGICAL CONSEQUENCES OF COLONIZING ACCIPITER HAWKS IN URBAN AREAS THROUGHOUT THE UNITED STATES. TO DO SO WE WILL ADVANCE THE USE OF CITIZEN SCIENCE IN URBAN AREAS BY LEVERAGING OVER 25 YEARS (1990-PRESENT) OF DATA FROM PROJECT FEEDERWATCH (PFW) A WINTER-LONG SURVEY OF BIRDS THAT VISIT PEOPLE S FEEDERS AND BACKYARDS ACROSS NORTH AMERICA. EQUIPPED WITH A TIME-TESTED MODEL FOR PARTICIPANT RECRUITMENT AND DATA VALIDATION PFW REGULARLY ENLISTS MORE THAN 12 000 VOLUNTEERS EACH YEAR TO OBSERVE AND RECORD THE BIRDS IN THEIR OWN BACKYARDS. WE WILL USE THESE CITIZEN-SCIENCE OBSERVATIONS TO EXPLORE THE EFFECTS OF COLONIZING HAWK POPULATIONS IN A DIVERSITY OF URBAN ENVIRONMENTS SPANNING A WIDE RANGE OF LAND COVER RATES OF URBANIZATION AND GEOGRAPHIC DISTRIBUTION. SPECIFICALLY WE WILL 1) STUDY THE COLONIZATION PATTERNS OF ACCIPITER HAWKS IN CITIES ACROSS NORTH AMERICA 2) QUANTIFY HOW THESE RELATIONSHIPS ARE MODIFIED BY THE CHARACTERISTICS OF URBAN ENVIRONMENTS 3) EVALUATE THE ECOLOGICAL CONSEQUENCES OF INCREASING HAWK POPULATIONS ON URBAN BIRD COMMUNITIES AND 4) CONDUCT AN UNPRECEDENTED LARGE-SCALE BEHAVIORAL EXPERIMENT OF ANTIPREDATOR BEHAVIOR IN FOUR MAJOR METROPOLITAN AREAS. CITIZEN SCIENCE AND SATELLITE DATA WILL BE CLOSELY INTEGRATED. WE WILL BEGIN BY ANALYZING EXISTING SATELLITE DATA IN TWO METROPOLITAN AREAS (E.G. CHICAGO AND WASHINGTON D.C.) WHERE WE HAVE DOCUMENTED RISING POPULATIONS OF ACCIPITER HAWKS AND THEN QUICKLY EXPAND OUR SCOPE TO 25 CITIES ACROSS THE UNITED STATES. WE WILL INCORPORATE ADVANCED REMOTE-SENSING PRODUCTS DERIVED FROM THE FULL ARCHIVE OF LANDSAT TM/ETM+/OLI AND SENTINEL 2A/B IMAGERY TO IDENTIFY THE DYNAMIC FEATURES OF THE URBAN ENVIRONMENT (E.G. IMPERVIOUS SURFACES URBAN VEGETATION SURFACE TEMPERATURE) ASSOCIATED WITH HAWK COLONIZATION PATTERNS. WE HYPOTHESIZE THAT INCREASING POPULATIONS OF ACCIPITER HAWKS IN URBAN AREAS WILL INFLUENCE THE COMPOSITION AND BEHAVIOR OF URBAN BIRD COMMUNITIES BUT THESE EFFECTS WILL BE MEDIATED BY THE ENVIRONMENTAL CHARACTERISTICS AND CONTEXT OF URBAN ENVIRONMENTS. THE IMPLICATIONS OF RETURNING PREDATORS AND ALTERED ECOLOGICAL DYNAMICS IN URBAN ENVIRONMENTS IS OF CRITICAL IMPORTANCE TO CONSERVATION BIOLOGY AND INTEGRATING NASA SATELLITE OBSERVATIONS AND CITIZEN SCIENCE WILL ALLOW FOR AN UNPRECEDENTED INVESTIGATION OF THESE RELATIONSHIPS ACROSS THE CONTINENT. OUR PROPOSAL DIRECTLY ADDRESSES THE PRIMARY GOAL OF NASA S CITIZEN SCIENCE FOR EARTH SYSTEM PROGRAM TO DEVELOP AND IMPLEMENT CAPABILITIES TO HARNESS VOLUNTARY CONTRIBUTIONS FROM MEMBERS OF THE GENERAL PUBLIC TO ADVANCE UNDERSTANDING OF THE EARTH AS A SYSTEM. IN ADDITION OUR PROPOSED RESEARCH WILL CONTRIBUTE DIRECTLY TO NASA'S GOAL IN THE STUDY LAND USE CHANGE IN URBAN AREAS AND ITS BIOLOGICAL IMPACTS.