Carriker : List of the Birds of Costa Rica. 321 



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Irazu and Turrialba the birds characteristic of it are seldom met with 

 below 8,500 feet, while on Poas, Barba, and on the Dota Mountains 

 and the Talamanca Cordillera, wherever the summits reach the height 

 of about 7,500 feet, some, but not all, of the characteristic forms are 

 found. The following species, all of which I believe are related to the 

 Sonoran and not to the Tropical, are rarely to be met with outside of 

 this belt: Catharus frantzii, C. graciliroslris gracilirostris, Planesticus 

 nigrescens, Troglodytes ochraceus, Oreothlypis gutturalis ■, Myioborus tor- 

 quatus, Vireo carmioli, Ptilogonys caudatus, Phai?wpiila melanoxantlia, 

 Empidonax atriceps, Selasphorus flammula, Melanerpes formicivorus 

 striatipectus, Dryob cites villosus extinuts. 



Upper Plateau (5,000 to 8,000 feet). 



This zone is in many ways similar to the Sub-Timberline, except 

 that it is warmer, less humid, and has a larger and more varied fauna. 

 It contains many species also found in the Lower Plateau belt, but 

 nevertheless has some forms characteristic of it. 



Catharus fuscater liellmayri, Planesticus plebejus, Myiadestes melan- 

 ops, Pheucticns tibialis, and perhaps other forms, the origin of which 

 is rather obscure, may be referred to this belt. 



Lower Plateau (2,500 to 5,000 feet). 



The Lower Plateau belt includes the whole of what is commonly 

 known as the central plateau region or the Highlands of Costa Rica, 

 and is characterized by several large valleys and plateau areas, all 

 originally forested, but long since cleared in many parts and devoted 

 to agriculture, pastures, etc. This belt extends much lower on the 

 Pacific slope than on the Caribbean, as do all the Sonoran zones, while 

 with those of the Tropical Area, the reverse is the case. Some of the 

 characteristic species of the zone are : Catharus nielponiene costaricensis, 

 Planesticus trisiis leucauchen, Vireo josephoz costaricensis, Piranga 

 testacea testacea, Melozone leucotis, M. cabanisi, Psilorhinus mexicanus 

 cyanogenys, Myiodynastes luteiventris, Legatus albicollis, Empidonax 

 flavescens, JVomonyx dominicus. 



Plains Region (100 to 2,500 feet). 



The Sonoran Plains Region fauna is practically confined to the 

 Pacific slope, there being but few species of true Sonoran origin which 

 are found on the Caribbean below 2,500 feet. It is also confined al- 



