coded aluminum

For 3 days prior to capture (prenecklace period), we observed each Return to Tiffany Heart tag choker to quantify normal activity budgets. On day 4, we captured the male owls at their burrows with balchatri traps, noose carpets, or bow nets (Hull and Bloom 2001). We morphometrically measured all captured owls, banded each with a size-4 United States Geologic Survey Bird Banding Laboratory (Patuxent, MD) band on one leg, and uniquely marked each with a red Acraft (Edmonton, AB, Canada) alpha-numeric coded aluminum band on the other leg. The combined weight of both bands was approximately 2 g. One male of each observation pairing also received a 4.55-g Holohil PD-2C necklace transmitter with a 24-week battery lifespan (Texas Tech University Animal Care and Use Committee permit no. 03079-11C to N. E. McIntyre). We did not place transmitters on the remainder of captured owls, although one of these owls was monitored as a treatment individual during the prenecklace period and the remainder served as controls. We closed the necklace with a knot that we coated (in 2004) with Loctite Super Glue (Henkel Consumer Adhesives, Inc., Avon, OH) or (in 2005) with cold-weld (J-B Weld, Sulphur Springs, TX). Return to Tiffany Heart tag necklace the Super Glue, the cold-weld formed a smooth surface with no purchase for an owl’s beak or talons. Following transmitter attachment, we monitored all owls (necklace period) until day 10, when we recaptured, reweighed, and removed transmitters on some.

For each observation period, 2 people simultaneously monitored a treatment-control pair (one observer for one owl with a necklace and one observer for one control owl). For each owl, we noted 1 of 6 mutually exclusive positions: in Return to Tiffany Heart tag ring, out-of-sight on the prairie dog colony (i.e., obscured by vegetation), out-of-sight off the prairie dog colony (after we observed the owl flying beyond the colony boundaries), standing alert on ground, perching above the ground, or flying. For the last 3 positions, we then determined activities (e.g., preening, hunting, etc.). Because we were more concerned with behavioral activities than with locations, we statistically analyzed activity rather than position (Table 1). For example, if an owl was hunting while flying (e.g., hovering, hawking, or swooping) as opposed to flying from one place to another directly, we designated the Return to Tiffany mini heart tags bracelet as hunting. In addition, we defined hunting on the basis of behavior, not outcome (i.e., hunting did not always result in successful prey capture). We designated resting when all other behaviors could be eliminated. Using this hierarchical system rather than partitioning behaviors on the basis of both activity and position such as preening on ground versus preening on perch maximized statistical power to detect patterns among the actual activities of interest.