Correction to: Far eastern curlew and whimbrel prefer flying low - wind support and good visibility appear only secondary factors in determining migratory flight altitude

Abstract

Following publication of the original article [1], errors were identified in the presentation of some of the reference citations in the Background section (page 2 of the PDF) and the Conclusion section (page 10 of the PDF) due to a typesetting mistake.

Geese migrating over the Pacific Ocean select altitudes coinciding with offshore wind turbine blades

“…Our finding that geese strongly selected low altitudes aligns with previous work showing that migrating birds often select altitude itself over other covariates. Flying at higher altitudes incurs inherent costs such as the energetic expense of climbing, reduced air density (reducing lift) or higher water loss (Galtbalt et al, 2021;Klaassen, 2004). These costs would be affected by body mass and relative wing-loading (Norberg, 1990), and so could be particularly pronounced in geese, though strong altitude selection has also been −2 SD, mean, and +2 SD, as calculated across all available points in the dataset; or two lines for day versus night for the binary daylight covariate.…”

“…A similar analysis has previously been applied to altitude selection in a conditional logistic mixed-effects model (Galtbalt et al, 2021), but we used a conditional Poisson mixed-effects model, as Muff et al (2020) found that to be analytically equivalent but better able to handle a large dataset like ours (thousands of locations).…”

“…Avian collision risk depends on frequency of encountering a windfarm, altitudes at which birds fly (highest risk at an altitude coinciding with the turbine blades, i.e., the rotor-swept zone), turbine characteristics such as blade length and speed and any behavioural avoidance of turbines and blades (Desholm & Kahlert, 2005;Furness et al, 2013;Masden & Cook, 2016). Migrating birds often fly at higher altitudes than those making local movements (Hüppop et al, 2006;Sugimoto & Matsuda, 2011;Zehtindjiev & Whitfield, 2011), but migrating birds may fly at lower altitudes with headwinds, precipitation, cloud cover, twilight or night (or, in other cases, during the day) and cooler air temperatures (Galtbalt et al, 2021;Hüppop et al, 2006;Lindström et al, 2021;Marcelino et al, 2021). Wind speed and direction can vary with altitude, so migrants may also seek altitudes that provide the best wind support, where wind support is defined as the amount of assistance (or resistance) provided by the wind in the intended direction of flight (Senner et al, 2018).…”

“…A more robust approach is an altitude-selection framework, which is similar to a step-selection framework (Thurfjell et al, 2014) in that ambient conditions at both used and available locations (altitudes) are considered. Application of this altitude-selection framework has been rare thus far, with only one published example that we are aware of (Galtbalt et al, 2021). That study found that favourable wind conditions were less important than previously thought; curlews first selected a flight altitude due to the inherent costs versus benefits of that altitude, such as energetic cost of climbing, air density and thus flight efficiency, and water loss (Klaassen, 2004;Klaassen et al, 1999;Pennycuick, 1989), before selecting for any other ambient conditions.…”

“…smaller species (curlews;Galtbalt et al, 2021). Evaluating other species in an altitude-selection framework would reveal the extent to which flight behaviour reflects strategies to minimize energetic and physiological costs.The relationships we found between altitude selection and other covariates also revealed behavioural strategies and associated possibility of collision with future windfarms.…”