Evaluating Digital VHF Technology to Monitor Shorebird and Seabird Use of Offshore Wind Energy Areas in the Western North Atlantic

Information on offshore movements of high priority bird species is needed for monitoring and managing adverse effects of offshore wind energy development in the western North Atlantic Ocean. This information is particularly important at night and during periods of inclement weather when risks of collision with offshore wind turbines may be elevated. For small-bodied avian taxa, technologies for monitoring movements of individually-marked birds are limited since satellite-based devices are still too heavy (\u3e 5 g) for use on birds weighing \u3c 150 g. In this dissertation, I evaluate the use of light-weight (1 to 1.5 g) digital VHF transmitters and a network of automated radio telemetry stations for tracking shorebirds and seabirds in offshore areas. In Chapter One, I compare digital VHF telemetry with satellite telemetry for tracking a shorebird, the American Oystercatcher (Haematopus palliatus), at nesting areas in coastal Massachusetts. In Chapter Two, I evaluate possible adverse effects and retention time of using a glue and suture method for attaching digital VHF transmitters to the inter-scapular region of Common Terns (Sterna hirundo), a small-bodied seabird. In Chapter Three, I analyze data on the movements of digital VHF-tagged Common Terns and Arctic terns (Sterna paradisaea) from four colonies throughout the western North Atlantic Ocean to assess the utility of this technology for tracking birds at regional scales. In Chapter Four, I examine movements of digital VHF-tagged Common Terns from two colonies in southern New England shelf region of the U.S. Atlantic relative to Wind Energy Areas in state and federal waters. The aim of this chapter is to evaluate the use digital VHF telemetry for tracking terns across offshore Wind Energy Areas and to relate offshore movement events to temporal (time of day, calendar date), atmospheric (wind speed, precipitation rate, visibility) and demographic (sex, nesting colony) covariates associated with assessments of collision risk. Through these studies, I evaluate the safety and effectiveness of using digital VHF transmitter technology on non-Endangered Species Act listed shorebird and seabirds with the aim of informing future studies on two species of high conservation concern, the federally threatened Piping Plover (Charadrius melodus) and the federally endangered Roseate Tern (Sterna dougallii)

Distributing transmitters to maximize population-level representativeness in automated radio telemetry studies of animal movement

Telemetry is a powerful and indispensable tool for evaluating wildlife movement and distribution patterns, particularly in systems where opportunities for direct observation are limited. However, the effort and expense required to track individuals often results in small sample sizes, which can lead to biased results if the sample of tracked individuals does not fully capture spatial, temporal, and individual variability within the target population. To better understand the influence of sampling design on results of automated radio telemetry studies, we conducted a retrospective power analysis of very high frequency (VHF) radio telemetry data from the Motus Wildlife Tracking System for two species of birds along the United States Atlantic coast: a shorebird, the piping plover (Charadrius melodus), and a nearshore seabird, the common tern (Sterna hirundo). We found that ~ 100–150 tracked individuals were required to identify 90% of locations known to be used by the tracked population, with 40–50 additional individuals required to include 95% of used locations. For any number of individuals, the percentage of stations included in the sample was higher for common terns than for piping plovers when tags were deployed within a single site and year. Percentages of stations included increased for piping plovers when birds were tagged over multiple sites and, to a lesser extent, years, and increased with average length of the tracking period. The probability that any given receiver station used by the population would be included in a subsample increased with the number of birds tracked, station proximity to a migratory stopover or staging site, number of receiving antennas per station, and percentage of the tracked population present. Our results provide general guidance for the number and distribution of tagged birds required to obtain representative VHF telemetry data, while also highlighting the importance of accounting for station network configuration and species-specific differences in behavior when designing automated radio telemetry studies to address specific research questions. Our results have broad applications to remotely track movements of small-bodied migratory wildlife in inaccessible habitats, including predicting and monitoring effects of offshore wind energy development

Supportive Wind Conditions Influence Offshore Movements of Atlantic Coast Piping Plovers during Fall Migration

In advance of large-scale development of offshore wind energy facilities throughout the U.S. Atlantic Outer Continental Shelf (OCS), information on the migratory ecology and routes of federally threatened Atlantic Coast Piping Plovers (Charadrius melodus melodus) is needed to conduct risk assessments pursuant to the Endangered Species Act. We tagged adult Piping Plovers (n = 150) with digitally coded VHF transmitters at 2 breeding areas within the southern New England region of the U.S. Atlantic coast from 2015 to 2017. We tracked their migratory departure flights using a regional automated telemetry network (n = 30 stations) extending across a portion of the U.S. Atlantic Bight region, a section of the U.S. Atlantic coast, and adjacent waters of the Atlantic Ocean extending from Cape Cod, Massachusetts, to Cape Hatteras, North Carolina. Most adults departed within a 10-day window from July 19 to July 29, migrated nocturnally, and over 75% of individuals departed within 3 hr of local sunset on evenings with supportive winds. Piping Plovers migrated offshore directly across the mid-Atlantic Bight, from breeding areas in southern New England to stopover sites spanning from New York to North Carolina, USA, over 800 km away. During offshore migratory flights, Piping Plovers flew at estimated mean speeds of 42 km hr−1 and altitudes of 288 m (range of model uncertainty: 36–1,031 m). This study provides new information on the timing, weather conditions, routes, and altitudes of Piping Plovers during fall migration. This information can be used in estimations of collision risk that could potentially result from the construction of offshore wind turbines under consideration across large areas of the U.S. Atlantic OCS

Radio Transmitters did not Affect Apparent Survival Rates of Adult Piping Plovers (Charadrius melodus)

Assessments of possible adverse effects of transmitters on marked individuals is an important component of individual-based tracking studies, particularly for species that are listed under the U.S. Endangered Species Act. The breeding and post-breeding movements of adult Piping Plovers (Charadrius melodus) from the federally-threatened Atlantic Coast Population were studied by gluing miniature, 1.0-g, digital VHF radio-transmitters on their interscapular region. Mark-resighting data from 2015-2018 was used to estimate apparent survival rates for 289 adult Piping Plovers in Massachusetts, Rhode Island, and New Jersey in order to compare survival estimates between individuals with a transmitter attached and control individuals without a transmitter. Cormack-Jolly-Seber models were used for live-encounter data in a Bayesian framework to estimate apparent survival rates based on resightings of uniquely marked individuals. There was no evidence that mean apparent survival rates differed between adults with transmitters (0.756; 95% CI = 0.611 - 0.877) and without transmitters (0.673; 95% CI = 0.607 - 0.740). In addition, there was no evidence of differences in apparent survival rates between breeding location (state) or years. This study provides further evidence that radio transmitters glued temporarily to the inter-scapular region can be an effective tool to monitor local and regional movements of sensitive shorebirds, such as Piping Plovers

Postbreeding dispersal and staging of Common and Arctic Terns throughout the western North Atlantic

In the western North Atlantic, Common (Sterna hirundo) and Arctic (S. paradisaea) Terns are sympatric at breeding colonies but show divergent migration strategies to coastal areas of South America and pelagic regions of the Antarctic, respectively. During 2013, we studied postbreeding movements of adult Common (n = 130) and Arctic (n = 52) Terns from four breeding colonies in the eastern USA and Canada using digital very high frequency (VHF) transmitters and an array of 62 automated radio telemetry towers. Relative to hatch dates at respective colonies, Arctic Terns departed breeding sites an average of eight days later than Common Terns. Common Terns were detected during the postbreeding period by coastal towers upward of 850 km south of their original nesting sites. The telemetry array detected postbreeding movements of Arctic Terns from the Petit Manan Island colony in the Gulf of Maine as they traveled eastward past Nova Scotia, Canada, mostly during the night. Nantucket Sound, Massachusetts, USA was identified as an important staging area for Common Terns from all colonies, whereby 26% of 53 tagged Common Terns from colonies in the Gulf of Maine and Canada were detected for up to three weeks. Common Terns typically arrived at Nantucket Sound within 2 h of sunset, 2 to 10 days after their last detection at Gulf of Maine and Canadian colonies, suggesting rapid postbreeding dispersal. Postbreeding dispersal of Arctic Terns was poorly documented with the telemetry array, suggesting that this species is not using coastal sites for staging, and is instead departing directly from colonies to offshore staging areas prior to long-distance migrations. We conclude that digital VHF telemetry is a useful method for monitoring regional movements of Common Terns, but additional offshore receiving stations are needed to effectively monitor movements of Arctic Terns away from their nesting colonies

Densities of wintering scoters in relation to benthic prey assemblages in a north atlantic estuary

During winter, molluscivorous sea ducks often form high density feeding flocks in association with patchily distributed prey, although few studies have documented the substrate and prey characteristics where sea ducks (tribe: Mergini) aggregate and thus what constitutes high-value sea duck foraging habitat. Sea duck surveys were conducted and benthic grab samples collected at sites with different benthic substrate characteristics to compare macroinvertebrate community assemblages in relation to densities of three species of sea ducks: (Surf (Melanitta peispicillata), Black (M. americana), and White-winged (M. fusca) scoters (hereafter oscoters when combined) during winter (2010-2011) in Narragansett Bay, Rhode Island, an urbanized estuary in the Northwest Atlantic. Overall, the highest densities of scoters (104 ± 17 per 0.5 km2) were found over sand substrates with homogeneous assemblages of infaunal prey. Significantly lower densities of scoters (21 ± 4 per 0.5 km2) were associated with mixed sand-gravel-mud substrates that supported epifaunal assemblages and patchily distributed infauna. Mean energy densities (kcal/g) were higher among infaunal (0.64-4.49) vs. epifaunal (0.17-0.53) prey. Overall biomass (g/m2) of polychaetes was higher in mixed substrates, and biomass of infaunal bivalves did not significantly differ among habitat type. However, infaunal prey may have been less accessible to scoters at sites with mixed substrates due to a barrier effect created by high-densities of epifauna with low energetic value. Thus, sand-substrate sites supporting infaunal benthic communities may provide high-quality feeding habitat for scoters wintering in the Northwest Atlantic. Understanding the influences of benthic habitat characteristics and macroinvertebrate prey assemblages on distribution of feeding scoters is particularly important for managing sea ducks in areas with increasing anthropogenic development in the coastal zone

Fate of Common (Sterna hirundo) and Roseate Terns (S. dougallii) with Satellite Transmitters Attached with Backpack Harnesses

Miniature transmitters now permit ornithologists to track the annual cycle of smaller (\u3c 150 g) marine birds. To assess annual movements of Common Terns (Sterna hirundo) and endangered Roseate Terns (S. dougallii), 2.5 g satellite transmitters were attached with backpack harnesses. Using the same capture techniques and investigator to fit harnesses, five Common Terns were tagged in Maine in 2017, and 10 Roseate Terns in New York, USA in 2018. Common Terns were tracked from 102-652 days to destinations as far as Brazil with no documented adverse impacts. Three of five Common Terns returned to Maine, USA one year after tagging, and non-functioning tags were recovered from two Common Terns in 2018 and 2019. In contrast, Roseate Terns were tracked for only 1-72 days before transmissions ceased, with only two birds tracked for \u3e 7 days. We detected three Roseate Terns with their bill stuck in the harness material, with one documented mortality. Common Terns tolerated the tags and provided useful data on annual movements but were not a suitable surrogate for predicting the effects of backpack mounted transmitters on Roseate Terns. Researchers considering tracking Roseate Terns should avoid using backpack harnesses

Habitat use and selection of black scoters in southern New England and siting of offshore wind energy facilities

The southern New England continental shelf is an important region for black scoters (Melanitta americana) during winter and migratory staging periods and a priority area for developing offshore wind energy facilities. However, little is known about the migration phenology and habitat use of black scoters in this portion of their range and this information is necessary to assess potential risks to black scoters during the marine spatial planning process. In this regional black scoter study over 2 winters, we used satellite telemetry and spatial modeling techniques to estimate migratory timing and length of stay, quantify winter home range size and site fidelity between winters, examine key habitat characteristics associated with core-use areas, and map relative probabilities of use across a 3,800-km2 marine spatial planning area for 2 proposed offshore renewable energy facilities. Black scoters spent nearly 5 months in southern New England, with wide variation among individuals in the size of winter utilization distributions (range 16-12,367 km2). Approximately 50% of the tagged birds returned to southern New England during the subsequent winter and had variable fidelity to core-use areas occupied the previous winter. During both winters, black scoter core-use areas were located closer to shore, at shallower water depths, with coarser sediment grain size and higher probability of hard-bottom occurrence relative to available areas. Resource selection functions classified the majority of a nearshore 5-turbine, 34-km2 renewable energy zone off Block Island as high probability of use by black scoters, whereas an offshore 200-turbine, 667-km2 federal lease block zone was classified as low to medium-low probability of selection. Wind energy facilities, such as the Block Island site, constructed in relatively shallow (\u3c20 m deep), nearshore habitats (\u3c5 km) over hard-bottomed or coarse-sand substrate could displace some foraging black scoters wintering in this region, whereas the larger federal lease block zone located farther offshore is more likely to affect scoters dispersing among core-use areas and during migration between wintering and breeding grounds. © 2014 The Wildlife Society

Annual-Cycle Movements and Phenology of Black Scoters in Eastern North America

Sea ducks exhibit complex movement patterns throughout their annual cycle; most species use distinct molting and staging sites during migration and disjunct breeding and wintering sites. Although research on black scoters (Melanitta americana) has investigated movements and habitat selection during winter, little is known about their annual-cycle movements. We used satellite telemetry to identify individual variation in migratory routes and breeding areas for black scoters wintering along the Atlantic Coast, to assess migratory connectivity among wintering, staging, breeding, and molt sites, and to examine effects of breeding site attendance on movement patterns and phenology. Black scoters occupied wintering areas from Canadian Maritime provinces to the southeastern United States. Males used an average of 2.5 distinct winter areas compared to 1.1 areas for females, and within-winter movements averaged 1,256 km/individual. Individuals used an average of 2.1 staging sites during the 45-day pre-breeding migration period, and almost all were detected in the Gulf of St. Lawrence. Males spent less time at breeding sites and departed them earlier than females. During post-breeding migration, females took approximately 25 fewer days than males to migrate from breeding sites to molt and staging sites, and then wintering areas. Most individuals used molt sites in James and Hudson bays before migrating directly to coastal wintering sites, which took approximately 11 days and covered 1,524 km. Males tended to arrive at wintering areas 10 days earlier than females. Individuals wintering near one another did not breed closer together than expected by chance, suggesting weak spatial structuring of the Atlantic population. Females exhibited greater fidelity (4.5 km) to previously used breeding sites compared to males (60 km). A substantial number of birds bred west of Hudson Bay in the Barrenlands, suggesting this area is used more widely than believed previously. Hudson and James bays provided key habitat for black scoters that winter along the Atlantic Coast, with most individuals residing for \u3e30% of their annual cycle in these bays. Relative to other species of sea duck along the Atlantic Coast, the Atlantic population of black scoter is more dispersed and mobile during winter but is more concentrated during migration. These results could have implications for future survey efforts designed to assess population trends of black scoters. © 2021 The Wildlife Society