How safe is mist netting? evaluating the risk of injury and mortality to birds

Abstract

Summary1. The capture of birds using mist nets is a widely utilized technique for monitoring avian populations. While the method is assumed to be safe, very few studies have addressed how frequently injuries and mortalities occur and the associated risks have not been formally evaluated. 2. We quantified the rates of mortality and injury at 22 banding organizations in the United States and Canada and used capture data from five organizations to determine what kinds of incidents occur most frequently. Analyses focused on passerines and near-passerines, but other groups were included. We evaluated whether body mass, age, sex, mist net mesh size, month and time of day or frequency of capture are related to the risk or type of incident. We also compared the recapture histories over time between birds that were injured and those that were never injured for 16 species. 3. The average rate of injury was 0AE59%, while mortality was 0AE23%. Birds captured frequently were less at risk to incident. Body mass was positively correlated with incident and larger birds were at greater risk to predation, leg injuries, broken legs, internal bleeding and cuts, while smaller birds were more prone to stress, tangling-related injuries and wing strain. Rates of incident varied among species, with some at greater risk than others. We found no evidence for increased mortality over time of injured birds compared with uninjured birds. 4. We provide the first comprehensive evaluation of the risks associated with mist netting. Our results indicate that (1) injury and mortality rates below one percent can be achieved during mist netting and (2) injured birds are likely to survive in comparable numbers to uninjured birds after release. While overall risks are low, this study identified vulnerable species and traits that may increase a bird's susceptibility to incident that should be considered in banding protocols aimed at minimizing injury and mortality. Projects using mist nets should monitor their performance and compare their results to those of other organizations.

Does the stress response predict the ability of wild birds to adjust to short-term captivity? A study of the rock pigeon ( Columbia livia )

“…However, the first hours or days of captivity are probably crucial to consider, because individuals are confronted with a totally novel confined environment that is certainly stressful. Thus, body mass loss is especially pronounced during the first days of captivity [6], and, as a result of acute stress or/and energetic stress, mortality may even occur at capture or in the first hours/days of captivity [2,7]. …”

Immediate effects of capture on nest visits of breeding blue tits, Cyanistes caeruleus, are substantial

“…First, many studies have examined longterm fitness consequences of CHMS, i.e. changes in (1) reproduction (breeding cycle, territory residency, nest desertion, brood size, fledging success, reproductive success), (2) survival (mortality, recruitment, return, recapture and resighting rates), (3) condition (deterioration, injuries, body mass changes, energetic expenditure) or (4) behaviour (impairment of flight, swimming, migration, foraging, display, dominance, mating, communication, recognition) (Calvo & Furness, 1992;Duarte, 2013;Fair, Paul, & Jones, 2010;Griesser et al, 2012;Murray & Fuller, 2000;Owen, 2011;Spotswood et al, 2012). These studies typically aim to understand whether and to what extent specific CHMS procedures (trapping, marking, tagging, sampling) may permanently affect individuals, impact negatively on the study population or bias measurements relevant to the study.…”

Daytime sleeping behavior observed in a Black-and-white Warbler during spring stopover

“…Therefore we do not believe that our obtaining a blood sample comprising approximately 0.65% of the bird's body mass influenced its behavior. Additionally, while it has been documented that banding and handling of birds causes some levels of stress [13], given our anecdotal observations that BAWW resume typical behaviors within a few minutes of release, we do not believe the effects of banding influenced our observation. By all accounts, this individual was in good condition at the time of capture and we do not believe condition contributed to our observance of the sleeping behavior.…”