Tatie 1 
we carrie 

Area Adults Brooce No, Youns Per Prood Area Sampled 
San Luis Vajley 
Rio «rande River Sag Y1 no = .o6 76 eg. miles 
Hugseii Lakes aol lz BE 5,66 10.5 eg. miles 
Potholes 1,691 a? 165 6,86 75 fo. Miles 
San Luis Lakes aS 2 14 7.00 10 aq. miles 
Meadow and farm land 14] —=s _- 5.60 JStO eo. miles 
Total 2, 536 x? f4 6,0) 1,484.5 sq. miles 
Nerth Fark 
otreams 957 B 40 5 OO 46 aq. mlles 
Leires __ASlL _ 1? 2466 _9,5 eq. olles 
Total 1,608 il Sv 5.158 Died #g. miles 
lest) 
Northern Colorada 
Faro Land 121 g 47 5.87 (Undetermined) 


Ground Surrey 
ban Luis Valley: # total of 241 nesta were located on the study areas 
during the period from April 1 to September 1, 1949, Of this total, 226 were 
mailard neete. Table 2 gives the clutch size for mallard nests observed. 

Table 2, == Clutch Size of 226 Maliard Neets 
(Average clutch of 165 completed clutches - 8,1) 
Under €& egze when Hatched before 
Complete clutchee, gestroyed, deserted found, clutch 
known size as of last virit estimated 
Ko. of neste eo 28 46 3819 & 2 ] 47 L4 
Ko. of efza & ** 8&8 28 1011 le 14 = = 

No clutches under eix, ¢gg3 were known ta have hatched any young. 
During the season, 1,575 mallard egazs were under observation. Fate of 
996 egea is known, while the remaining 577 were not located again. The latter 
ezgea may have been destroyed by some decimating factor, although ln many 
ingtances nests were lost to the observer due to destruction of nest markers. 
Table &S summarizes the final data for mallard egen under obeervation. 
138 
