A technique known as fladry was traditionally used to hunt wolves in Eastern Europe and Russia. It consists of driving wolves into an enclosure formed by 50 x 10 cm red flags hanging from ropes. The technique has been employed to livetrap wild wolves in Poland.

The aim of our pilot study was to see whether five captive wolves living in two enclosures (120 m2 and 850 m2) at the Rome Zoo were responsive to the device. In particular, we explored the effectiveness of variations in design attributes (between-flag distance; rope height; scent; flag movement and colour). We also tested the effectiveness of fladry to constrain wolf movement into portions of the enclosures and to prevent wolves from accessing food.

We found that avoidance was maximal when flags were less than 50 cm apart and their bottom edge was at ground level. With this design, wolves never crossed red flags (nor grey ones of the same brightness) intersecting their usual stereotyped routes (baseline: 4.08 +/- 3.11 SD crossings along the routes per min). Flags were not crossed even when the daily food ration was placed on the opposite side. In contrast, some crossing occurred when flag distances were 75 cm or more, or rope height was less than 25 cm or more than 75 cm, although wolves avoided these barriers and switched to less preferred routes (p < 0.0032, X2 > 8.67, df = 1). Disturbance (visual and/or related to scent) present when we dug holes in the ground, instead of setting a physical barrier, did not prevent movements along stereotyped routes (p = 0.1352, X2 = 2.20, df = 1). Behavioural reactions to flag movement were not noticed.

Our preliminary results indicate that fladry works effectively on captive wolves at least temporarily (1 hour test). Further experimental research is needed to evaluate the effectiveness of these barriers over repeated encounters. In these conditions, we will assess whether habituation, or other factors (such as wolves' motivation to cross them), decrease fladry's effectiveness. In addition to fladry, we will test the effectiveness of other traditional and new barriers (e.g., electric fences) to prevent captive wolves from accessing food sources. In case these experiments provide positive results, the next step should be to validate in the wild the effectiveness of these barriers to protect livestock (particularly in areas where conflicts between wolves and shepherds are arising) and to capture wolves.