Not only does this species have the longest tail, the Long-tailed Meadowlark is by far the largest of the seven species of New World blackbird in the genus Sturnella. A small flock of these attractive meadowlarks was foraging in the grass. The upper birds are adult males; female is below. Unlike the polygynous North American meadowlarks in which the males and females look alike, their South American counterparts are sexually dimorphic and monogamous.
This species is sometimes placed in the genus Leistes (Howard & Moore). In the past it was lumped with the Red-breasted Blackbird (Leistes militaris) along with Peruvian and Pampas Meadowlarks The genus Pezites has also been appled to the combined species. Three subspecies are recognized by Clements. This is the larger S. l. falklandica restricted to the Falkland Islands. The nominate race is widespread on the mainland of southern South America. The paler S. l. catamarcana is restricted to northwest Argentina and a fourth subspecies S. l. obscura from the highlands of Central Argentina is recognized by Howard & Moore & HBW. It is darker with red more restricted. Canon PowerShot SX50 HS
References:
Fraga, R. (2018). Long-tailed Meadowlark (Leistes loyca). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/62328 on 23 May 2018).