The Peru-Chile Pacific slope (including the 2 northern provinces of Chile) is considered by BirdLife International to be one of South America's endemic bird areas with a priority for biodiversity conservation.  From sea level to 4,000m, the portion of this endemic bird area which lies from Arica eastward is home to several of BirdLife's "restricted range species" among them the Chilean Woodstar, White-throated Earth-creeper, Slender-billed Finch, and Tamarugo Conebill (Endemic Bird Areas of the World, BirdLife Conservation Series No 7, 1998). 

The Province of Arica which bumps up against Peru contains rocky and sandy beaches, transverse agricultural valleys, and a slice of the Atacama Desert. Some other interesting birds in the province are the Oasis Hummingbird, Peruvian Sheartail,  Slender-billed Finch, Peruvian Thick-knee, Groove-billed Ani, Blue-black Grassquit, Chestnut-throated Seedeater, Croaking Ground-dove (no, that wasn't a frog you just heard), Yellowish Pipit, Bran-colored Flycatcher, Peruvian Pygmy Owl,  and of course the Humboldt Current birds like Hornby's Storm-petrel, Markham's Storm-petrel, and other seabirds.  

Province of Parinacota:  Lying above the Atacama Desert is the precordillera of the Andes, similar to foothills.  At these mid-elevations of roughly 3,000 to 4,000 masl, the diversity of birds is remarkable, with Putre being described frequently as a very "birdy" place.  Some interesting birds which are resident in the precordillera  include the White-throated Earthcreeper, Black-throated Flowerpiercer, White-tailed Shrike-tyrant, Golden-billed Saltator, Blue-and-Yellow Tanager, Canyon Canastero, White-browed and D'Orbigny's Chat-tyrants, Ornate Tinamou, the ground doves, and of course the regularly-present "foothill" hummers -- Andean Hillstar, Giant Hummingbird, and Sparkling Violet-ear. Many of these birds do not cross the Atacama Desert south of the Region of Arica y Parinacota, and can't be found further south in Chile. 

Altiplano:  Sharing its border with both Peru and Bolivia, the Province of Parinacota also includes the and 3 altiplano nature reserves: Lauca National Park, National Vicuñas Reserve and Natural Monument and Ramsar Site Salar de Surire.  A sampling of highland species include 2 coots, 5 ducks, Andean "Goose", Andean Gull, Andean Flicker, 2 grebes, condors, caracaras and other raptors, Puna Tinamou, Rufous-bellied Seedsnipe, White-tailed Shrike-tyrant, Puna Plover, 3 owls, Puna Rhea, Giant Conebill, 3 flamingos, a slew of interesting brownish passerines ----  and everyone's favorite target bird, the Diademed Sandpiper-plover.   

Depending on the rainfall and the resultant vegetation, some of the birds migrate altitudinally following the watered valleys from Arica or Putre to the highlands and vice versa. Some birds ascend to the precordillera for the nesting season, some of the hummingbirds (Oasis, Peruvian Sheartail) ascend to take advantage of flowering cacti, and some birds descend from the altiplano to avoid bad weather or in the case of the Mountain Parakeet to feast on pear trees. This provides an interesting conglomeration of migration routes, not to mention austral migration from the south and "neotropical" migration from the north. To observe as many species as possible the trick of birding this region is to know which birds will be found at what elevation at any given time of the year, and in what microhabitat.