Gray partridge habitat use and nesting biology in north-central Iowa

Gray partridge (Perdix perdix) movements, habitat use, and nesting were studied from 1975 to 1977 in north-central Iowa, a region of intensive row-crop agriculture. Use of 4 habitat classes by 9 birds monitored by radio telemetry was compared with habitat availability over 4 seasonal periods. Strip cover was used at higher than expected frequencies in all periods. Partridge utilized the periphery of fields at a relatively high frequency while use of the central portion was less than expected. Three partridge broods utilized soybeans at a high frequency and corn at a relatively low frequency through the 1st 4 weeks of life, but use of corn increased from 5 to 8 weeks of age. Hay and strip cover were used at a relatively high frequency through 2 weeks of age as were the edges of fields. Average overall activity range for 6 mated birds that were monitored over 4 or more months was 1.93 km('2) (range = 0.84 to 3.66 km('2)). Paired partridge occupied relatively restricted ranges from the prenesting through the nesting period, but activity ranges increased in late summer. An unmated male followed a different pattern of range size distribution with extensive wandering in the spring and a large activity range followed by a general reduction in range size through the summer. Birds occupying habitat with relatively high interspersion of cover types tended to have smaller overall activity ranges;Over all years, 23 partridge nests and 29 ring-necked pheasant (Phasianus colchicus) nests were found. Rates of nest success were 0.26 for partridge and 0.41 for pheasants. Mean clutch size for 9 completed partridge nests was 14.9 eggs. In contrast to pheasants, partridge made little use of drainage ditchbank, railroad right-of-way, or grass waterway cover for nesting; 83% of the partridge nests were found in roadside and fenceline cover. Only 2 pheasant nests and no partridge nests were found in hayfields. Spring-to-fall gain was more closely associated with an index to pair success than with mean brood size. Low pair success was affected by weather, renesting effort, and the scarcity of stable and protected nesting cover. Protection of roadside nesting cover from disturbance should benefit partridge populations in northern Iowa.