104 JOURNAL OF THE 



[vol. u 



history 



and their flora it is not, of course, intended to imply that they are to be con- 

 sidered in terms of a few years or even centuries. Some of the Juniper trees 

 in the Paloduro Canyon are probably not less than one to two hundred years 

 old, and we have no reason to assume that in them we are looking upon the 

 original patriarchs of their race; but in comparison with some of the adja- 

 cent physiographic regions and as measured by the standards of geologic 

 time and biologic evolution both appear extremely modern. Some of the 

 plants, on the other hand, may have appeared only in the last few years and 

 other emigrants may be expected from time to time, some of which will be 

 only transient while others will establish themselves and become in time 

 conspicuous and important additions to the flora. 



Probably the two principal agents in introducing new plants into the 

 canyons are at present, as they have been in the past, wind and migratory 

 birds. The large proportion of southwestern species and the absence or 

 comparative paucity of those from the contiguous regions to the east and 

 northeast is doubtless due to the circumstance that during the season when 

 seeds of most i)Iants ripen and can be transported and successfully sown the 

 direction of both of these agencies is from the south or southwest northward. 

 Some of the lighter seeds, with special provisions for transportation througli 

 the air, may be carried almost incredible distances by such strong and per- 

 sistent winds as prevail upon the plains. As there are few inequalities on 

 the surface to arrest their progress, they would in many cases find lodgment 

 only, at least in situations where there would be any chance for them to ger- 

 minate and survive, when swept into the canyons that lie across their 

 northward cuurse. 



Many birds breed in the canyons and others in their passage northward, 

 doubtless, stop for a time in its protection. It is to be regretted that no 

 definite data can be given either as to the meteorology or ornithologj' of the 

 canyons to determine their relative and absolute importance as agencies in 

 plant introduction. Their investigation, however, would prove a most 

 interesting and fruitful field for a local observer with the taste and oppor- 



tunity for i)ursulng it. Amongst the birds noted in the Paloduro Canyon, 

 which are persistent seed eaters and probable agents in plant introduction 

 are the Western Mockingbird, Texas Quail, Texas Jay and species of Wood- 

 pecker, Vireo and Oreole. Other birds seen were the Canyon Wren, Horned 

 Lark, Poor Will, Cliff Swallow and Western Chipping Sparrow, and I was 

 reliably informed that both the Mexican and Bald Eagle are found. 



An analysis of the list of forty-five woody species given for the Paloduro 

 Canyon reveals the fact that no less than twenty-three, or more than half, 

 produce fruit attractive to ordinary seed-eating birds; while the seeds of 

 the Shin Oak and most of the Legumes might have been transported by 

 larger birds or mammals. Fifteen, including the Willows, Cottonwood, 

 Wafer Ash, Button Bush, Virgin's Bower and the Composits are more or 

 less perfectly adapted to wind transportation. In view of the inference that 

 birds have probablv been one of the chief a^encif^s in hrintrincr ti#^w r»lanto 



