154 GAME BIRDS OF CALIFOBNIA 



back in the nest of any other species. The eggs number six to ten. 

 They are grayish olive or greenish drab in color, of a darker shade 

 than the eggs of other species of ducks, and measure in inches, 2.36 

 to 2.57 by 1.68 to 1.80 and average 2.48 by 1.75. 



The Canvasback is an excellent diver, often descending to a depth 

 of twenty or thirty feet to obtain its food, and is said to use its wings 

 for propulsion when beneath the water. This species gathers in large 

 flocks on the bays where it sleeps during the day on open water, mov- 

 ing nearer the shore when wishing to feed. The Canvasback is a 

 strong, swift flier and makes a loud noise with its wings which is 

 clearly noticeable when a flock passes immediately overhead. The esti- 

 mated speed of the Canvasback is greater than that of any other 

 duck— 130 to 150 feet per second (Askins, 1911, pp. 556-560). When 

 coming to decoys in a pond the birds arrive with a rush of sound 

 like that made by the wind and they settle into the water with great 

 splashing. 



Canvasbacks decoy very readily. On the open water they are 

 usually wary and hard to approach. On the decoy pond, however, 

 they are said to be more easily obtained than teal or Mallard. By 

 carefully choosing the last one to dive each time, a whole flock can 

 sometimes be brought to bag. This duck is often hunted not only from 

 blinds on the marshes but also from brush blinds built up over the 

 shallow waters of the bays, and from brush-covered boats sculled near 

 the birds when they are at rest on the open water. 



In the east the Canvasback feeds almost exclusively on a plant 

 known as Vallisneria, often called wild celery or eel grass, hence the 

 specific name of the bird — -valisineria. Stomach examination has 

 shown that over twenty-three per cent of its food is made up of the 

 roots, leaves and seeds of this plant (McAtee, 1911&, p. 1). A much 

 larger per cent of pondweeds is also taken by this species than by any 

 other duck. It is also said to feed on fish, tadpoles, leeches, moUusks, 

 and insects, when these are available. In California the Canvasback 

 partakes of more animal food, for wild celery does not grow in this 

 state. On the shallow waters of the tidelands and marshes, it feeds 

 extensively on crustaceans and shellfish, thereby acquiring a "fishy" 

 taste and thus becoming undesirable as a table bird. The stomachs of 

 some Canvasbacks collected on San Pablo Bay contained clams {Mya 

 arenaria), and snails {Odostomia sp.) ; one stomach from Tia Juana 

 Slough, near San Diego, contained periwinkles (Cerithidea calif ar- 

 nica), and another from the same place contained grass-blades, stems 

 and roots. A stomach from Guadalupe, San Luis Obispo County, was 

 filled with barley, there being twenty-two whole kernels and many 

 hulls ; but there is a possibility that this was bait put out by hunters. 



