Migrating raptor counts: the need for sharing objectives and field protocols, and the benefits of using radar

Abstract

Capsule: Raptor migration attracts the interest for different reasons, but not all raptor counts achieve the goal of repeatability through the use of standardized field protocols, and this does not allow comparisons of data to be made across years and sites. Aims: We analysed migrating raptor count activities in Italy to verify the interest on this phenomenon by identifying organizers of such counts, and we ascertained the use of a minimum repeatable field protocol (MRFP), and the implications of using it or not. Moreover, we tested the use of radar to support field monitoring. Methods: We analysed 298 migrating raptor counts carried out between 1984 and 2016 by considering characteristics of raptor counts at migratory bottlenecks (number of years covered, use of MRFP, numbers of raptors counted, etc.). In addition, we analysed two case studies using radar to evaluate the effectiveness of raptor counts. Results: There is a growing interest in raptor migration, as well as an increasing use of a MRFP, although differences between counts emerged, probably due to the different aims of the promoting organizations. At sites not using MRFP, more raptors were counted than at other sites, probably because of a greater bias in the data collected. Radar is able to clarify the watercrossing behaviour of raptors at coastal sites, and allows the proportion of birds passing undetected by observers to be evaluated. It also provides data on the spatial density of migrants across a sample area. Conclusions: The use of MRFP is important to harmonize data collection and is necessary to allow comparisons across years and sites. Moreover, the use of radar can be recommended for optimizing raptor monitoring schemes.

Better utilisation and transparency of bird data collected by powerline companies

“…Most TSOs have some form of partnerships with NGOs, with some already collaborating in academic research through data collection, financial support and/or guidance, leading to peer-reviewed publication (e.g. Panuccio et al, 2018;D'Amico et al, 2019;Moreira, 2019), and this tends to be where the most intensive data are collected.…”

Perspectives and challenges for the use of radar in biological conservation

“…For example, traditional feeding or migratory flight corridors or airspaces proximal to large bat or bird roosts, may require preservation (no wind turbines, power lines, lit buildings or other man-made obstacles) or some other form of legal protection (Diehl 2013, Lambertucci et al 2015, Diehl et al 2018. Such reserves could benefit migratory birds and bats moving through geographic and seasonal bottlenecks (Rydell et al 2014, Bayly et al 2017, Panuccio et al 2018, Sherry 2018 or more locally, roosting birds and bats or foraging waterfowl and raptors that use the same airspaces on a recurring basis. Airspace protection does not need to be absolute: dynamic aerial reserves would offer protection at critical points in the season and allow human use at other times (Davy et al 2017).…”

“…These radars offer an unparalleled opportunity for objective, continuous, reliable, cost-effective large-scale data collection of aerial animal movements, which can assist in delineating and managing conservation areas, migratory bottlenecks (i.e. points where geography constrains migration, leading to significant concentrations of populations; Bayly et al 2017, Panuccio et al 2018, population monitoring, pest control, and many other aspects of biological conservation. Furthermore, many types of smaller (and often relatively mobile) radars have broad applications in environmental impact studies and monitoring of cryptic species (Table 1).…”

Groping in the Fog: Soaring Migrants Exhibit Wider Scatter in Flight Directions and Respond Differently to Wind Under Low Visibility Conditions

“…The aim of this study was to examine the effects of fog on orientation and response to wind in soaring migrants tracked by a marine radar over a migration bottleneck, The study was carried out at the Strait of Messina in Southern Italy, where Honey Buzzards (Pernis apivorous) comprise approximately 95% of the tracked migrants (Becciu et al, 2018;Panuccio et al, 2018). We analysed the distribution of flight directions and the effects of wind conditions (speed and direction) on buzzard ground-and airspeed when they fly in fog versus clear conditions.…”