38 PHYSICAL FEATURES ETC. 
Tropical,—the first two coming down from the north, the last coming up from the 
south, and all meeting in the Republic of Costa Rica. He says, and truly, that 
the geographical position and meteorological peculiarities of the country make this 
enormous bird fauna within its confines explicable, but at the same time they greatly 
increase the difficulty of a satisfactory disposition of many of the species with respect 
to life zones. The continent decreases from 3000 miles in breadth to scarcely more 
than 60 at the narrowest part of Costa Rica, and within those 60 miles are crowded a 
diversity of climatic conditions, altitudes, etc., scarcely paralleled in the world. ‘The 
northern and southern forms of the Pacific and Atlantic lowlands meet here and 
overlap, a single remnant of the Canadian bird-fauna persists on some of the isolated 
peaks of the high mountains (Junco vulcani), while modified forms of this northern 
species are found on the high lands of Mexico and Guatemala. A very large number 
of North American migrants arrive during the winter months and distribute themselves 
widely as to altitude throughout the country. Mr. Carriker also observes that amongst 
certain species there is a seasonal migration from a higher to a lower altitude, 
doubtless for the sake of food, and Salvin and I noticed similar migrations of 
several species of birds in Guatemala; this was especially the case with humming- 
birds, which were very abundant at Duefias during the flowering season, but in the dry 
season, when the flowers failed, this district was entirely deserted and the birds 
migrated to the Pacific Coast, where the atmosphere was damper and the blossoms on 
which they fed were abundant. 
The cultivation of bananas, however, is having a marked effect on the birds, which 
are decreasing at an alarming rate, for in the few years since the establishment of the 
Fruit Company at Port Limon the forest has been completely cleared—not only there, 
but also southward towards the Talamanca district. Very few of the forest birds 
frequent the banana plantations, and with the destruction of the forest they recede 
or disappear altogether. 
Mr. Ridgway (‘ Condor,’ vii. 1905) gives an interesting account of Poas, which is 
the only active volcano in Costa Rica. After spending the night at San Pedro, 
he resumed his journey by bright moonlight at 4 o'clock the next morning. The 
‘lecheria’ or dairy farm at the upper edge of the cleared zone was reached soon after 
daybreak, and the primitive forest which covers the last thousand feet of the mountain 
was then entered. No pine trees were found here, as would have been the case at the 
same altitude in Mexico or Guatemala, as south of Nicaragua they cease to exist. 
The density of the forest was, however, such that it was impossible to leave the track 
without cutting a way with ‘machetes,’ and as the undergrowth consisted mostly of 
slender climbing bamboos, with exceedingly hard stems, which almost filled the 
spaces between the trees, the difficulty of making much headway may be imagined, 
‘Lhe variety of trees was very great, and all were laden with orchids, bromeliads, and 
mistletoes, the latter often conspicuously and brilliantly flowered and the bromeliads 
