Estimating flight height and flight speed of breeding Piping Plovers

Abstract

ABSTRACT. Collisions with wind turbines are an increasing conservation concern for migratory birds that already face many threats. Existing collision-risk models take into account parameters of wind turbines and bird flight behavior to estimate collision probability and mortality rates. Two behavioral characteristics these models require are the proportion of birds flying at the height of the rotor swept-zone and the flight speed of birds passing through the rotor swept-zone. In recent studies, investigators have measured flight height and flight speed of migrating birds using fixed-beam radar and thermal imaging. These techniques work well for fixed areas where migrants commonly pass over, but they cannot readily provide species-specific information. We measured flight heights of a nesting shorebird, the federally threatened Piping Plover (Charadrius melodus), using optical range finding and measured flight speed using videography. Several single-turbine wind projects have been proposed for the Atlantic coast of the United States where they may pose a potential threat to these plovers. We studied Piping Plovers in New Jersey and Massachusetts during the breeding seasons of 2012 and 2013. Measured flight heights ranged from 0.7 to 10.5 m with a mean of 2.6 m (N = 19). Concurrent visually estimated flight heights were all within 2 m of measured heights and most within 1 m. In separate surveys, average visually estimated flight height was 2.6 m (N = 1674) and ranged from 0.25 m to 40 m. Average calculated flight speed was 9.30 m/s (N = 17). Optical range finding was challenging, but provided a useful way to calibrate visual estimates where frames of reference were lacking in the environment. Our techniques provide comparatively inexpensive, replicable procedures for estimating turbine collision-risk parameters where the focus is on discrete nesting areas of specific species where birds follow predictable flight paths. RESUMEN. Estimación de altura y velocidad de vuelo de Charadrius melodus en reproducciónLas colisiones con turbinas de viento son un motivo de preocupación para la conservación de aves migratorias, las cuales ya tienen muchas amenazas. Los modelos de riesgo de colisión existentes tienen en cuenta parámetros de turbinas de viento y comportamiento de vuelo de las aves, para estimar la probabilidad de colisión y las tasas de mortalidad. Dos características comportamentales que estos modelos requieren, son la proporción de aves volando a la altura de la zona de barrido del rotor y la velocidad de vuelo de las aves pasando a través de la zona de barrido del rotor. En estudios recientes, investigadores han medidos la altura y velocidad de las aves en migración usando radares de haz fijo e imágenes térmicas. Estas técnicas tienen buen desempeño enáreas fijas donde las aves migrantes comúnmente pasan, pero no proveen información especifica para cada especie. Medimos la altura de vuelo de un ave playera en anidación que están federalmente amenazada, Charadrius melodus, usando buscadores de rangoópticos y medim...

Breeding sites and winter site fidelity of Piping Plovers wintering in The Bahamas, a previously unknown major wintering area

“…Previous re‐sighting data from birds banded in breeding areas also support our conclusion that most Piping Plovers wintering in The Bahamas breed on the Atlantic coast (Stantial , M. L. Stantial and J. B. Cohen, unpubl.…”

“…), and birds wintering in The Bahamas were often seen at staging sites on the Atlantic coast during both spring and fall migration. This has conservation implications to plovers wintering in The Bahamas because coastal development in the Atlantic continues, including potential proliferation of coastal wind turbines (USFWS , Stantial ).…”

Use of an optical rangefinder to assess the reliability of seabird flight heights from boat‐based surveyors: implications for collision risk at offshore wind farms

“…, Bouten et al. , Corman and Garthe , Stantial and Cohen , Thaxter et al. , Johnston and Cook , Borkenhagen et al.…”

“…The use of rangefinders in combination with visual observations is often advocated for onshore monitoring to provide height and distance estimates for collision risk assessments (Madders and Whitfield , Stantial and Cohen , Wulff et al. ).…”

“…Indeed, notwithstanding training and experience, there may be considerable uncertainty in subjective estimates of flight heights at sea due to a lack of reference structures, parallax effects, variation in bird morphology, and rapid changes in altitude and speed (Garvin et al. , Stantial and Cohen ).…”