Wildlife in Airport Environments: Preventing Animal–Aircraft Collisions through Science-Based Management

14: Avian Survey Methods for Use at Airports

Adverse effects and damage caused by interactions between humans and wildlife are increasing (DeStephano and DeGraaf 2003). To manage wildlife effectively —whether to mitigate damage, to enhance safety, or to reach conservation goals—wildlife biologists must identify hazards posed by or to members of a particular species (i.e., a population) or guild, and then prioritize management goals and specific actions. We examine the special problem of managing birds to reduce hazards to aviation, particularly those species known to cause structural damage to aircraft when struck and that pose problems to airport facilities (Dolbeer et al. 2000, Cleary and Dolbeer 2005, DeVault et al. 2011). Effective management of hazardous species at airports requires knowledge of species abundance and how abundance varies over time. In this context, the quality of the sampling methodology used will influence a biologist’s ability to accurately quantify avian hazards and to understand the ecological interactions of populations or guilds using airport environments. Accurate quantification of avian hazards allows biologists to calculate the relative risk presented by each population or guild for a period and habitat, and relative to management actions. A hazard (whether a resource contributing to bird use or simply incidental use of the airport by a population or guild) represents a particular state or condition within the airport environment that can affect the probability of bird strikes. In contrast, we define risk as the relative conditional probability of damage to an aircraft posed by a species, if struck, and the probability of the strike occurring (Schafer et al. 2007, Blackwell et al. 2009). Avian survey data form the foundation for identifying management priorities, reducing risks associated with avian hazards to aviation safety, and evaluating the effectiveness of management actions. Defensibledatacollection,analysis,andaccuratefindingsareimperativetojustifymanagementoptionstoother agencies and, increasingly, to a critical public (Anderson 2001). Lethal control of birds, although regulated, is an integral component of wildlife hazard reduction to mitigate strike risk at airports (see Cleary and Dolbeer 2005; Chapter7).Despitethisimportance,publicsupportforlethal control measures in wildlife management, regardless of the justification for their use, is declining. As a result, increased documentation is required to receive necessary permits, and there is need to directly demonstrate the efficacy of lethal control measures when used (Blackwell et al. 2002, 2009; Engeman et al. 2009; Runge et al. 2009). However, the union between direct management, particularly lethal control, and scientifically rigorous data collectionhasprovenusefulfordemonstratingandjustifying lethal control for endangered species recovery (Engeman et al. 2005, 2009), as well as for enhancing aviation safety (e.g., Dolbeer et al. 1993, Seamans et al. 2009). A demonstration of scientifically sound methods in the collection of survey data is increasingly necessary to justify andlegallydefendvariousmanagementactions—particularly lethal control—even in situations involving human health and safety (Messmer et al. 1997, Reiter et al. 1999, Conover 2002). Despite the need for scientific rigor, resource limitations often require that biologists base management Bradley F. Blackwell Paige M. Schmidt James A. Martin Avian Survey Methods for Use at Airports 14 154 wildlife monitoring decisions on brief samples or “snapshots” of target populations. The process used to take these snapshots, if based on sound sampling theory, will yield accurate inference as to population abundance or trends, habitat influences, seasonal dynamics, and response to management actions (Morrison et al. 2008). As outlined by Cochran (1977) and adapted here for application to the airport environment, the sample survey should be based on six primary steps: (1) define the objective, (2) delineate the target population, (3) determine the data necessary to address the objective, (4) identify and correct for factors that influence accuracy of the estimate , (5) select appropriate methods of measurement, and (6) select appropriate data management and analysis procedures. The survey objective will dictate aspects of the subsequent steps, as will available resources. In this chapter we use published sampling theory and methods to provide airport biologists with (1) the means to design and implement an avian survey at an airport that will maximize accuracy in quantifying avian hazards; (2) an understanding of bias and precision , and their influences on the quantification of avian hazards; (3) suggestions on how to quantify avian hazards and how to use these data to estimate relative risk to aviation safety posed by a particular species or guild by time period and habitat type; and (4) knowledge of how data can be used to prioritize management goals. Our recommendations are intended to compliment Federal Aviation Administration (FAA) procedures for Wildlife Hazard...