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[HawkGoose61fWMS.gif]

Figure SI 1. The experimental set-up for testing free-ranging geese, ducks, and turkeys under semi-natural conditions with various types of “flying objects” during spring of 1961 (Schleidt 1961b). The test pen (6 by 7 m) was located between a small building (the “Gänsehaus”, centre of fowl research at the Institute in the sixties) and the edge of a spruce forest. The ropeway consisted of a Perlon monofilament loop between two wheels, mounted at a distance of about 20 m at the chimney of the Gänsehaus and a distant tree, respectively. The “operator” (W. M. Schleidt) was sitting on the roof, invisible to the experimental animals, but in eye contact with the “observer” (Margret Schleidt or Monica Magg, respectively), fastened a dummy and moved it at different speeds (0 to 0.5 m/s) by slowly and steadily turning the crank on the pulley above the experimental subjects toward the distant tree, where it disappeared behind a blind.

[SS&M SI fig2a WMS.gif]

Figure SI 2. In response to raptors, turkeys, like many other species of fowl, emit two different types of alarm call: “prr” and “singing”. Prr (a loud, rattling call, a rhythmical form of “clucking”) is given in response to sudden disturbance, as an approaching predator, and singing (a soft, long out-drawn call) in response to slight disturbance, as a high-flying raptor or distant ground predator. After Hale, Schleidt & Schein 1969, Fig. 102.

[SI3-HawkGoose61aWMS.gif]

Figure SI 3. The experimental set-up for testing turkey poults which had no prior experience with “flying objects” during spring of 1961 (Schleidt 1961a, Schleidt 1961b). The experimental cage (1 by 2.5 m, located in the Gänsehaus), featured a built in ropeway (height of the Perlon monofilament 2.30 m above ground level. During the experiments, the “operator” (W. M. Schleidt) was standing behind a curtain, invisible to the experimental animals, fastened the dummies and operated the electro motor which moved the dummy at a constant speed (0.25m/s) across the ceiling of the experimental cage (illuminated by three 150W reflector bulbs) until it disappeared behind a curtain. The “observer” (M. Schleidt or M. Magg, respectively) was seated in front of the experimental cage.

COM 0403 Supporting Information.doc