Bergeron, L.

Logan, C.

English

MPG.PuRe

Modifications to the bownet trapping method to increase safety for medium-sized, agile birdsLuisa Bergeron^ and Corina J. Logan*^Institute for Social, Behavioral and Economic Research, University of California Santa Barbara, U.S.*Comparative Behavioral Ecology Research Group, Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Germany, corina_logan@eva.mpg.deSee more about The Grackle Project at www.CorinaLogan.com and follow us on Twitter @LoganCorina @luisambergeron #TheGrackleProjectFig 3. Bownet before modifications with banded grackle (left) and taxidermic decoy grackle (right).IntroductionMany people aim to capture birds for research in a way thatmaximizes efficiency and safety. However, trapping methods oftenhave trade-offs that are not well known. For example, prioritizingsafety can reduce trap efficiency, and camouflage can reducefunctionality for traps with bulky parts. Researchers studying speciesthat are notoriously difficult to catch, or that live in more urbanenvironments, may not be able to use well-known and relatively safetrapping methods such as mist nets or walk-in traps. A less frequentlyused, but often more discreet option is a bownet. This method hasbeen used primarily for larger species such as raptors, or ducks on thenest1,2. However, we are not aware of documentation of the potentialhazards of this method, or how to modify it for consistently safedeployment, especially for smaller birds.AIM: to share the bownet safety modifications we developed to trapwild great-tailed grackles (Quiscalus mexicanus), a medium-sized,agile passerine. DiscussionWe found it necessary to modify the bownet and theprotocol for how it is used to prevent injury to grackles.These modifications resulted in reduced trappingefficiency and increased bird safety. No grackles havebeen injured since implementing these safety features,and as of May 2019 it is our most successful trappingmethod (28 birds caught vs. 26 birds with mistnets,0=carpet noose, 3=walk-in traps). The modifications didnot appear to require a rehabituation period, howeverit is rare for a single grackle to be in the ideal trappingposition (Fig 1).We believe it is important for researchers to considerincorporating these or similar modifications when usingthe bownet with smaller, agile birds. Broadly, weencourage more open publication of modifications toincrease trapping safety across research programs.Risks1. Bird gets struck by moving bow2. Other birds in the way3.  Human error in deploymentSolutions1. Add foam piping and trap bird at specific location in bow area (Fig 4)2. Trap one bird at a time with no other birds within 3ft of trap area3. Use only the remote trigger to deploy after extensive training, and follow a detailed protocol3Fig 4. Bownet after modifications (foam and trigger box) with grackle in the correct trapping position.References:1Stewart, Robert E., et al. 1945. Live Trapping of Hawks and Owls. J Wildlife Manage9(2):99-104.2Salyer, James W. 1962. A Bow-Net Trap for Ducks. J Wildlife Manage 26(2):219-221.3Our bownet deployment protocol and this poster are available at https://tinyurl.com/y496ppokPhoto credit: Zoe Johnson-Ulrich, Luisa Bergeron, Cameron MaloneFig 2. Proper bowl placement inside bow with netting clear of metal stakeholder (1) and trigger pin (2), and bowl as close to bow as possible without touching netting (3).Fig 1. Taxidermic decoy grackle in ideal trapping position: head down with feet ~1in from bowl (6.5in diameter).

Modifications to the bownet trapping method to increase safety for medium-sized, agile birds

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