TRAVELS OF WATERFOWL 

 to the lake by the shortest route. Instead they bend their flight east or west 

 toward one of the passes where they cross over the trees to the lake. In 

 August and through autumn Mallards and Pintails that loaf on the lakeshore 

 move over these same passes in their journeys to the stubble fields. Many 

 times I have watched a flock of Lesser Scaup, Redhead, or Canvasback cruise 

 along the lakeshore for a mile or more, then suddenly swing south to cross 

 over a pass to the marsh. One July a band of pre-eclipse Redhead drakes fed 

 daily in a bay east of the village. A quarter-mile flight due north would have 

 given them a direct route; but instead of taking the short cut, they usually 

 moved west a mile to cross at a favored pass. 



In general, the width of the lakeshore passes at Delta is 100 to 400 yards, 

 although the core of a pass, through which goes the major flight line, often 

 is narrower than this. The main passage of birds through the pass may vary 

 from day to day, the travel within the boundaries apparently being dictated 

 by the wind's direction. It is not true that all trading is confined to passes ; 

 now and then a flock makes a crossing well to one side or the other. On 

 days of heavy traffic, however, hundreds of ducks fly over the pass for every 

 dozen going elsewhere. So closely does the great majority hold to the cross- 

 ings that these lanes of travel are well-known to guides and hunters. 



I have watched the flights over the lakeshore through sixteen years. The 

 pathways have been the same as long as the oldest guides can remember. 

 Dr. Fred Cadham, who has hunted the Delta Marsh since boyhood, tells 

 me that the pass over his cottage has been the same since 1898. For at least 

 fifty-six years — many generations in the life of waterfowl — ducks have 

 moved between marsh and lake on this same path. I suspect the history of 

 Cadham's Pass is much older than this. 



The gunner's eye detects little reason for this regularity as he watches 

 from marsh level. But a bird's-eye view from an aircraft reveals a sharp rela- 

 tion between the flight lines and the pattern of the terrain (Figure 1). Most 

 passes are at narrows where marsh water comes close to the lake ridge. Others 

 are at channels flowing near the ridge or cutting through to enter the lake. 

 Some are at old creek beds, long dry and overgrown, yet clearly defined 

 from the air. In short, the pass is where there is the shortest distance be- 

 tween marsh and lake. 



Such trailways are not confined to the lakeshore. These are doorways to 

 the north, but the marsh itself is a pattern of aerial lanes as well marked by 

 the flights of waterfowl as the roads on a highway map. In the marsh the 

 travel follows the path of least resistance; that is to say, the trails take the 



