In an Iowa Unit project, clucks were counted on specified areas as they flew to and from roosts at dawn and at dusk. 

 (Photo by Arnold O. Haugen) 



Rapid growth of ducklings in Arctic. — It has 

 long been assumed that the rapid growth of duek- 

 lings in arctic and subarctic regions accounted for 

 the high rearing success observed under conditions 

 induced by the short far-north summer. Actual 

 measurements of growth differences between tem- 

 perate and northern breeding areas has not pre- 

 viously been accomplished. In an Alaska Cooper- 

 ative Wildlife. Research Unit study, color-dyed 

 canvasback ducklings were found to attain flight 

 at -47 to 50 days, or 1 to 2 weeks earlier than in 

 southern Manitoba; arctic-born buffleheads were 



flying at 40 days; lesser scaup showed growth 

 rates comparable to those noted in South Dakota. 

 Wood duck roost, counts. — In evaluating the use- 

 fulness of roosting flights for determining wood 

 duck populations, an Iowa Unit fellow concen- 

 trated on pool 10 of the Upper Mississippi River 

 Wildlife and Fish Refuge, where he had access 

 to 530 pairs of nesting birds. About 35 percent 

 nested in the 50 square miles of bottomlands and 

 65 percent nested off the refuge along 5 miles of 

 tributaries or on adjacent bluffs. This pattern 

 represented no significant change from 1962, either 



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