Recent trends in renewable energy development in the United States (U.S.) show that new installed capacity of utility-scale solar energy has exceeded 30% of total installed capacity of all sources per year since 2013. Photovoltaic solar energy provides benefits in that no emissions are produced; however, there are potential impacts from photovoltaic solar development on birds that include habitat loss and potential for collision mortality. Only 2 papers in the peer-reviewed literature present fatality information from fatality monitoring studies at a photovoltaic utility-scale solar energy facility; however, more data exists in unpublished reports. To provide a more comprehensive overview of bird mortality patterns, we synthesized results from fatality monitoring studies at 10 photovoltaic solar facilities across 13 siteyears in California and Nevada. We found variability in the distribution of avian orders and species among and within Bird Conservation Regions, and found that water-obligate birds, which rely on water for takeoff and landing, occurred at 90% (9/10) of site-years in the Sonoran and Mojave Deserts Bird Conservation Region. We found that a cause of mortality could not be determined for approximately 61% of intact carcasses, and that approximately 54% of all carcasses were feather spots, introducing uncertainty into the interpretation of the fatality estimates. The average annual fatality estimate we calculated for photovoltaic solar (high-end estimate of 2.49 birds per megawatt per year) is lower than that reported by another study (9.9 birds per megawatt per year) that included one photovoltaic facility. Our results provide a summary of fatalities in bird conservation regions where the facilities are located, but expanding our conclusions to new regions is limited by the location of facilities with fatality monitoring data.

Bird strikes in aviation are an increasing threat to both aircraft and human safety. Management efforts have focused largely on the immediate airport environment. Avian radar systems could potentially be useful in assessing bird strike threats at greater distances from the airport, at higher altitudes, and at night, but few studies have been conducted to assess the capabilities of avian radar systems. Thus, our goal was to assess the detection and tracking abilities of a commercially available avian radar system in an airport environment in Indiana, USA, during October 2011-March 2012. Transits by free-flying birds allowed us to assess radar tracking performance as influenced by flock size, altitude, and distance from the radar unit. Most of the single large-bird targets (raptors) observed within 2 nautical miles (NM) of the radar were tracked !1 time, but such targets were generally tracked <30% of the time observed. Flocks of large birds such as geese (Branta canadensis) and cranes (Grus canadensis) were nearly always tracked !1 time, and were generally tracked approximately 40-80% of the time observed, even those several NMs away from the radar unit. Our results suggest that avian radar can be a useful tool for monitoring bird flock activity at airports, but less so for monitoring single large-bird targets such as thermalling raptors. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.KEY WORDS airport, airport wildlife management, avian radar, bird strike, human-wildlife conflict.

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