Soaring Migratory Birds Avoid Wind Farm in the Isthmus of Tehuantepec, Southern Mexico

Abstract

The number of wind farms operating in the Isthmus of Tehuantepec, southern Mexico, has rapidly increased in recent years; yet, this region serves as a major migration route for various soaring birds, including Turkey Vultures (Cathartes aura) and Swainson's Hawks (Buteo swainsoni). We analyzed the flight trajectories of soaring migrant birds passing the La Venta II wind farm during the two migratory seasons of 2011, to determine whether an avoidance pattern existed or not. We recorded three polar coordinates for the flight path of migrating soaring birds that were detected using marine radar, plotted the flight trajectories and estimated the number of trajectories that intersected the polygon defined by the wind turbines of La Venta II. Finally, we estimated the actual number of intersections per kilometer and compared this value with the null distributions obtained by running 10,000 simulations of our datasets. The observed number of intersections per kilometer fell within or beyond the lower end of the null distributions in the five models proposed for the fall season and in three of the four models proposed for the spring season. Flight trajectories had a non-random distribution around La Venta II, suggesting a strong avoidance pattern during fall and a possible avoidance pattern during spring. We suggest that a nearby ridgeline plays an important role in this pattern, an issue that may be incorporated into strategies to minimize the potential negative impacts of future wind farms on soaring birds. Studies evaluating these issues in the Isthmus of Tehuantepec have not been previously published; hence this work contributes important baseline information about the movement patterns of soaring birds and its relationship to wind farms in the region.

A bridge between oceans: overland migration of marine birds in a wind energy corridor

“…Establishing macro-scale interaction represents only an initial step in identifying locations and extent of potential conflict, with further targeted research needed to determine whether micro-scale interaction is likely. Furthermore, migratory birds in the Tehuantepec region may adjust their routes to avoid turbines (Villegas-Patraca et al 2014, Cabrera-Cruz andVillegas-Patraca 2016), incurring energetic costs even in the absence of direct interaction (Masden et al 2010).…”

“…Recent work using marine radar has improved understanding of nocturnal migration in the region (Villegas-Patraca et al 2014); however, unlike diurnal observations, radar data cannot identify nocturnal migrants to species. In addition, coastal marine birds remained resident in the Tehuantepec Isthmus for long periods of time (up to six months), placing them at greater risk of collision-related mortality than passage migrants with shorter occupancy times (Krijgsveld et al 2009, Villegas-Patraca et al 2014. Local observations and short-term tracking of overwintering waterbirds in the Lagunas del Istmo would help to clarify how resident habitat use affects collision risk in these species.…”

Perspectives and challenges for the use of radar in biological conservation

“…In general, radar studies are particularly useful in estimating numbers of birds and bats and their behaviour near wind farm infrastructure (Johnson et al 2002, Desholm et al 2006, Kunz et al 2007, Ahlén et al 2009, Villegas-Patraca et al 2014, Hein 2017, Smallwood 2017, Hüppop et al 2019, Molis et al 2019. Bird detection radar was used to monitor behavioural responses and flight changes of migrating common eider Somateria mollissima and geese in relation to offshore wind farms and helped to evaluate wind farm avoidance rates (Desholm andKahlert 2005, Plonczkier andSimms 2012).…”

Detecting bird movements with L‐band avian radar and S‐band dual‐polarization Doppler weather radar

“…; Villegas‐Patraca et al. ; Tomé et al. ) and powerlines and towers (Gauthreaux ; Deng and Frederick ) and incineration at solar energy plants (Diehl et al.…”

“…Long-range weather radars have been used to monitor the seasonal movements and roosting departures of birds since the early 1950s in Britain (Harper 1958) and the early 1960s in the United States (Gauthreaux 1970). Small mobile radar units have been used to monitor bird movements at renewable energy sites in an effort to minimize bird injury and mortality from collisions with wind turbines (Kunz et al 2007;Villegas-Patraca et al 2014;Tom e et al 2017) and powerlines and towers (Gauthreaux 1985;Deng and Frederick 2001) and incineration at solar energy plants (Diehl et al 2016). The radars have also been placed at many airports throughout the world to monitor, warn and alert airport personnel of bird movements that pose a bird-aircraft collision risk (Chen et al 2012;Beason et al 2013;Gauthreaux and Schmidt 2013).…”