Fig. 1

Fully assembled drill attachment prototype fastened to a commercially 20V cordless 2-speed drill driver. A Left lateral, B anterior, and C posterior view of the setup used in this study. The drill attachment is connected to the drill driver via the center drive shaft fastened within the drill driver head and the gear box is kept from rotating via the bar secured to the battery of the drill driver using a nylon strap. By removing the two drill bits on either the left or right side of the attachment, one can also use the drill attachment to drill two holes simultaneously for the deployment of the SPOT-380 tag, which shares the same vertical spacing between the bolts as the SPOT-364 tag. The figure shows the prototype of the drill attachment used for the in-field validation. The details of the refined attachment are shown in the Technical Drawings in the Additional file 1