of goose broods in their study areas, goose broods on the Yellowstone are not 

 believed to move long distances downstream after hatching. Two goslings 

 approximately two weeks of age when captured on the river near Kinsey in early 

 June were recaptured in subsequent banding trips 1 .5 to 3 km ( 1 to 2 mi . ) 

 upstream from where they were first encountered. Three goslings of a brood 

 dyed in a nest on the river 11 km (7 mi) southwest of Miles City exhibited 

 greater movement; they were captured at seven weeks of age on a reservoir 

 10 km (6 mi) overland from the island where they hatched. 



Hatching and Brood Rearing . Hatching dates were estimated to be 28 days 

 (Atwater 1959) plus 1.5 days per egg in the clutch (Kossack 1960) after the 

 date of nest initiation (figure 5). The peaks which occurred in the period 

 of nest initiation were followed approximately five weeks later by the 

 hatching peaks. 



Young were encountered in nests an estimated one to two days after 

 hatching. Brooding in the nest was also reported by Zicus (1975). After one 

 to two days, goose pairs moved their young away from the nesting islands to 

 brood-rearing areas, perhaps partially in response to crowding and territorial 

 disputes on some of the nesting islands. The areas where geese were observed 

 with young were highly diverse with respect to vegetation. The same areas were 

 used by broods of different ages. Many brood-rearing areas were characterized 

 by a semiopen understory with some sparse shrubbery and a cottonwood canopy. 

 Some consisted of streamside barley fields, grazed and cleared pastureland, 

 cornfields, alfalfa fields, and other agricultural and riparian vegetation 

 types. All brood-rearing areas adjoined the river which served as an escape 

 route for geese when threatened. 



Flightlessness . Shortly after the young leave the nests, the adult 

 geese begin to molt their flight feathers. The wide variation of hatching 

 dates resulted in the occurrence of flying and flightless birds on the river 

 at the same time. 



Early Fall Resident Period 



Geese Present . This portion of the goose resident period is characterized 

 by the presence of from 1,500 to 3,500 flying birds in the study area (figure 

 4), possibly including nonbreeding geese returning to the study area in early 

 fall from molt migrations to the north (Hanson 1965). Forty percent of all 

 geese observed during aerial censuses conducted during this and the flight- 

 less period (table 11) were recorded in the Bighorn-to-Rosebud reach of the 

 river, 20 percent of the area censused. This may reflect higher nesting density 

 in this section and attraction of nonbreeders and/or early migrants to the 

 area. 



Crops and Forage Utilized . During the early fall resident period, most 

 field-feeding birds were observed in fields containing barley and wheat stubble 

 and corn cut for silage (table 2). Bossenmaier and Marshall (1958) reported 

 similar goose utilization of wheat and barley fields in the Whitewater Lake 

 region of southwestern Manitoba. 



39 



