No abstract

Translocation of problematic individual animals is commonly used to reduce human-wildlife conflicts, especially to reduce the presence or abundance of raptors within airport environments, where they pose a risk to safe aircraft operations. Although this method has strong public support, there have been no scientific evaluations of its efficacy or to determine which factors might influence the return of translocated birds to the airport. We conducted a study to determine which biological and logistical factors might influence the return of red-tailed hawks (Buteo jamaicensis) translocated from Chicago's O'Hare International Airport (ORD) during 2010-2013. We live-captured and translocated red-tailed hawks various distances from the ORD airfield and monitored for returning birds. We found the odds of hawk return increased by 2.36 (95% CI ¼ 0.99-5.70) times for older birds (>1 yr of age) relative to younger birds ( 1 yr of age). Odds of hawk return went up 4.10 (95% CI ¼ 0.75-22.2) times when translocations were conducted during the breeding season relative to the non-breeding season. The odds of hawk return increased 11.94 (95% CI ¼ 3.29-43.38) times for each subsequent translocation event involving the same hawk. The cost of 1 translocation event to the release sites that were 81, 121, 181, and 204 km from ORD was $213, $284, $362, and $426, respectively. Management programs that use release sites 80 km from the airport minimize translocation events to include only younger birds during the non-breeding season, and undertake only 1 translocation event for an individual hawk would increase program efficacy and greatly reduce program implementation costs. The decision matrix regarding the use of a raptor trapping and translocation program involves a variety of biological, logistical, economic, and sociopolitical variables. This study represents an important first step in providing a scientific foundation for informing such management decisions. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Avian radar technologies have the potential to serve an important role in the quantification of bird movements and determining patterns of bird use in areas where human–wildlife conflicts might occur (e.g., airports, wind‐energy facilities). However, capabilities and limitations of these technologies are relatively unknown and ground‐truthing studies are needed to help wildlife managers understand the biological meaning of radar information. We evaluated the efficacy of 3 X‐band marine radar sensors for tracking birds and flocks of birds observed on the airfield at Chicago's O'Hare International Airport, USA, during March 2011–November 2012. We used specific information regarding field observations of birds or flocks to determine how frequently the 3 radar sensors provided corresponding tracks of these avian targets. In addition, we examined various factors to determine if they had any influence on the frequency of correspondence between visual observations and radar tracks. Of the 972 sightings of individual birds (49%) or flocks of birds (51%) by observers on the airfield that had the potential to be observed by the radar, 143 (15%) were tracked by ≥1 radar sensor. All confirmed tracks of individual birds or flocks were ≤4.8 km from these radars. Among the 3 radar sensors, larger bodied bird species, bird/flocks flying at higher altitudes, and bird/flocks closer to the radars increased the ability of those units to track avian targets. This study provides new information regarding the performance of radar systems for tracking birds on the airfield of one of the largest and busiest airports in the world. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Avian radar technologies have the potential to serve an important role in the quantification of bird movements and determining patterns of bird use in areas where human–wildlife conflicts might occur (e.g., airports, wind energy facilities). Ground-truthing studies are needed to help wildlife managers understand the biological meaning of radar information, as the capabilities and limitations of these technologies are relatively unknown. We conducted a study to evaluate the efficacy of three X-band marine radar sensors for tracking red-tailed hawks (Buteo jamaicensis) on or near the airfield at Chicago’s O’Hare International Airport from September 2010 to May 2014. Specific information regarding red-tailed hawk locations derived from satellite telemetry was used to determine how frequently the three radar sensors provided corresponding tracks of these avian targets (i.e., synchronized monitoring). We examined various factors (e.g., bird altitude and distance to the radar) to determine if they had any influence on the frequency of synchronicity between satellite telemetry locations and radar tracks. We found evidence that as the distance between a hawk and the radars increased, the radars’ ability to detect and track known avian targets decreased. Overall, the frequency of synchronization events for red-tailed hawks was low. Of the 1977 red-tailed hawk locations that should have been visible to the radar sensors, 51 of these bird movements were tracked by at least one of the radar sensors (2.6%). This study provides a new methodology for evaluating the performance of radar systems for tracking birds and determining what factors might influence overall performance.