3227^ 



In the State of Durango " the most important water units are Lakes Santia- 

 guillo and Conatlan in the Guadiana. Valley, the Laguna de Sanjuanera near 

 Madera, and some river channels, notably that of the Rio Nazas. El Palmito 

 Reservoir, with a superficial area of h5 square miles, and now under con- 

 struction on the headwaters of the Hio Nazas, will add materially to the 

 water storage resources of Durango and western Coahuila. In addition, there, 

 are numerous smaller reservoirs, lagoons, and. river channels which, with 

 flooded fields and overflows on waste lands from the irrigation canal systems, 

 and temporary rain-water lakes and ponds, add materially to : the aggregate . 

 of sui table habitat. They are not all good waterfowl nesting grounds as 

 many lack the stability of water levels necessary for the production of 

 extensive marsh areas with protective cover or adequate* feeding grounds. 



During the. early part of the season Mexican Black Ducks and Cinnamon 

 Teals were common in small flocks and in pairs. Little nesting activity was 

 detected and it was not until early July that the first female Black Duck was 

 flushed from her nest at; Lake Bustillos on July 2k, Nests of Cinnamon Teals 

 and Coots, with only partially filled complements of eggs, were found as late 

 as September 19 at La Colina Reservoir. 



During July some Baldpa.tes, Shovellers, and Pintails were seen and while 

 neither nests nor downy young were observed, there is a possibility that the 

 latter two species may breed. in limited numbers. Mere'presence of a species 

 during the breeding season cannot be accepted, however, as evidence of nesting. 

 It must be concluded that aside from the regular resident ducks, there is not a 

 large production of waterfowl in Mexico. 



By early September northern migrants were arriving in considerable numbers 

 and by the last of the month were present in force. Sandhill cranes were first 

 observed on September 3 and by the latter part of the month even Lesser Snow 

 Geese had reached the Ojo de Agua Lagoon. - In' addition to the species that had 

 been observed earlier in the sea-son, /Gadwa lis, Green-winged Teals, 31ue-winged 

 Teals, Redheads, Ring- necked Ducks, and White-fronted Geese came in September. 



Nesting Conditions in the United States 



Most of the waterfowl nesting refuges had more water and were generally 

 in better condition than ever before. Some of these had an abundance of water 

 for the. first time since ' their' establishment. The spring run-off not only filled 

 the water- areas of the refuges, but also countless thousands of pot-holes and 

 sloughs, some of which had been dry for several years. This again resulted in a 

 wide dispersal of the ducks and other water birds and, while it greatly increased 

 the magnitude of the job of appraising results of the breeding season, it also 

 served to prevent some of the heavy losses from disease that in the past have 

 occurred when ducks were heavily concentrated in infected areas. There were, how- 

 ever, a few locally serious outbreaks of botulism. Also afew areas seemed to have 

 a reduced number of birds, For example, a Service biologist with several years 

 experience on the Crescent Lake National Wildlife Refuge in Nebraska, reported that 

 in 19^2 it produced only about one-third as many ducks as in 1938. 



