BIKD LIFE IN THE URUBAMBA VALLEY OF PERU. 35 



No doubt, however, can exist as to the origin of the Puna avifauna. 

 Suited only for the needs of plain, marsh, and water-inhabiting 

 species. Puna bird life has been largely derived from the vast area 

 of plains, marsh, and lakes which, without topographic barrier, 

 bounds it on the south and extends nearly to the southern limits of 

 the continent. 



The South Temperate Zone ducks and grebes find a suitable 

 home on the Puna lakes, where they are represented by permanently 

 resident races, while the oven-birds (Furnariidae) and finches of 

 Patagonia find congenial haunts and climatic conditions on the high 

 Andean table-land.*' 



Subtracting from the 58 genera found by us on the Puna, 27 of 

 general distribution (as Spatula, Phalacrocorax, F'alco, Anthus, etc.), 

 and we have left 31 genera, of which 19 are of the South Temperate 

 Zone, while only 7 are peculiar to the Puna. Comj^are these figures 

 with those given for the Temperate Zone and it is seen that the latter 

 owes practically nothing to the South Temperate Zone, while it has 

 a far larger proportion of endemic genera. Thus, of the genera found 

 by us in the Puna Zone, slightly more, than 7 per cent are endemic, 

 while of those found m the Temperate Zone 55 per cent are endemic. 



Continuing the comparison with the species found in the two zones, 

 it is seen that somewhat more than 57 per cent of Puna Zone species 

 are endemic, while of Temperate Zone species 80 per cent are endemic. 



The most obvious reason for the much greater differentiation of 

 the life of the Temperate Zone as compared with that of the Puna 

 Zone is apparently to be found in the geographic origin of their 

 respective faunas. That of the Temperate Zone, as we have seen, 

 presumablj^ origmated in the Tropical Zone, that of the Puna in the 

 South Temperate Zone, The former has consequently been sub- 

 jected to the influences of the wide climatic differences lying between 

 the Tropical and Temperate Zones, the latter has found in the Puna 

 Zone a climate not radically different from that in which we assume 

 it originated. 



It is probable that the life of the Temperate Zone, having doubt- 

 less passed through a Subtropical Zone stage, is older than that of 

 the Puna. This, however, is one of the many problems connected 

 with the origin of Andean life which we are not as yet in a position 

 to attack. I restrict myself therefore to the comparison which 

 clearly reveals the great distinctness of Temperate Zone bird life, 

 and repeat my belief that this distinctness is not primarily dependent 

 upon the age of the fauna, but mainly to the influence of the marked 

 climatic differences existing between the Tropical and Temperate 

 Zones. 



!' If the entire known avifauna of Peru were bare under review due consideration would of course be 

 given the Limicolae, Flamingoe,*!, Rheas, and other Puna birds of which we secured no specimens. 



