SURVIVAL AND BREEDING SUCCESS OF REARED AND WILD RING-NECKED PHEASANTS IN SWEDEN

Little research compares the reproductive performance of game birds reared and released in different ways. Consequently, we studied survival and breeding success of 307 female ring-necked pheasants (Phasianus colchicus) by radio-tracking in Oster-Malma (O-M) and Gotland, Sweden, during 1983-86. All pheasants at O-M were released during spring after they had been reared (fostered) by domestic chickens (n = 46) or under lamps (n = 78; machine-reared). On Gotland, 114 machine-reared pheasants were released for comparison with 69 radio-tagged wild pheasants. When released in late May, survival was similar (P > 0.2) for fostered females (43 +/- 8%; xBAR +/- SE) and machine-reared females (44 +/- 9%). However, fostered pheasants had higher clutch survival (P = 0.034) and higher brood survival (P = 0.023) than machine-reared pheasants. Three-month survival of machine-reared birds released in early May at O-M was lower (21 +/- 7%; P = 0.002) than in similar releases on Gotland (53 +/- 7%). Wild pheasants on Gotland had 3-month survival rates (74 +/- 6%) higher (P = 0.01) than for pheasants released there, and their brood survival was higher (P = 0.043) than for birds released in 1985. First-year wild birds also lost more (P = 0.05) broods than older pheasants but had similar survival (P = 0.72) and hatching success (P = 0.38) to that of adults. Three-month survival varied from 6 +/- 6% to 67 +/- 14% for 60 juvenile females released in September on Gotland, and only 1 bird reared young the next summer. Lower survival and breeding success (P < 0.02) of similarly released birds at O-M was associated with severe red fox (Vulpes vulpes) predation. To augment wild pheasant stocks, we suggest releasing adults late in spring, in areas where predator pressure is low, and using birds that have been reared by foster parents.