Conservation Letter: Monitoring Raptor Populations – A Call for Increased Global Collaboration and Survey Standardization

A minimum of 159 bird species, including eight raptor species, have gone extinct since the year 1500 (BirdLife International 2021). Monitoring programs can help prevent extinction if they alert conservationists to population losses in time to take action (Martin et al. 2012, Lindenmayer et al. 2013, Woinarski et al. 2017). Indeed, monitoring, which is defined as ‘‘collecting and analyzing repeated observations or measurements to identify changes and evaluate progress of management towards stated aims’’ (Robinson et al. 2018) is essential for conservation (Wiens 1984, Nichols and Williams 2006, Lovett et al. 2007) and provides for the prioritization of taxa and places for conservation effort. Raptors tend to be long-lived and to reproduce slowly, making their populations susceptible to changes in adult survival (Newton 1979). Decreases in survival of adult raptors can therefore cause precipitous population declines (Pain et al. 2008, Ogada et al. 2016) that must be detected quickly to avert catastrophe. Importantly, these species tend to be wide-ranging and occur at relatively low densities (Newton 1979). Thus, a single scientist or program might not be able to cover sufficient area or attain the sample sizes necessary for inference of population dynamics, whereas a consortium of researchers could monitor raptors more effectively. Collaboration is therefore needed for global populations of most raptors to be properly monitored. This Conservation Letter provides the results of a survey of raptor researchers across the globe to identify current spatial, taxonomic, and topical gaps in raptor monitoring. The intent of the Raptor Research Foundation (RRF) is to provide readers with evidencebased recommendations for more impactful global raptor monitoring and greater collaboration among raptor researchers, and to provide readers with a better understanding of where and for which species gaps in raptor monitoring persist.