Question: When do purple martins migrate to the continent where São Lourenço River is located?

full_context: Document 1: Bird migration: The typical image of migration is of northern landbirds, such as swallows (Hirundinidae) and birds of prey, making long flights to the tropics. However, many Holarctic wildfowl and finch (Fringillidae) species winter in the North Temperate Zone, in regions with milder winters than their summer breeding grounds. For example, the pink-footed goose Anser brachyrhynchus migrates from Iceland to Britain and neighbouring countries, whilst the dark-eyed junco Junco hyemalis migrates from subarctic and arctic climates to the contiguous United States and the American goldfinch from taiga to wintering grounds extending from the American South northwestward to Western Oregon. Migratory routes and wintering grounds are traditional and learned by young during their first migration with their parents. Some ducks, such as the garganey Anas querquedula, move completely or partially into the tropics. The European pied flycatcher Ficedula hypoleuca also follows this migratory trend, breeding in Asia and Europe and wintering in Africa.
Document 2: Guaíra, Paraná: Guaíra is a municipality in the state of Paraná in the Southern Region of Brazil. The population is 32,591 (2015 est.) in an area of 560 km². The elevation is 517 m. This place name comes from the Tupi language and means "place difficult to access". The city is served by Guaíra Airport.
Document 3: Bird migration: Within a species not all populations may be migratory; this is known as "partial migration". Partial migration is very common in the southern continents; in Australia, 44% of non-passerine birds and 32% of passerine species are partially migratory. In some species, the population at higher latitudes tends to be migratory and will often winter at lower latitude. The migrating birds bypass the latitudes where other populations may be sedentary, where suitable wintering habitats may already be occupied. This is an example of leap-frog migration. Many fully migratory species show leap-frog migration (birds that nest at higher latitudes spend the winter at lower latitudes), and many show the alternative, chain migration, where populations 'slide' more evenly north and south without reversing order.
Document 4: Solimões River: Solimões () is the name often given to upper stretches of the Amazon River in Brazil from its confluence with the Rio Negro upstream to the border of Peru. At the confluence, the river is already by far the largest river in the world, even though its two largest tributaries have not yet entered (the Negro and the Madeira River). The Solimões portion of the Amazon river lies entirely in the State of Amazonas, Brazil, and some portion of the state is often referred to as the "Solimões region". The ecoregion of the Solimões river drainage basin is entirely tropical rainforest.
Document 5: Paraná Valles: Paraná Valles is a valley in the Margaritifer Sinus quadrangle (MC-19) region of Mars, located at approximately 23.1° South and 10.2° West. It is 350 km long and was named after an ancient and modern name for a South American river (Brazil, Argentina). A low area between Paraná Valles and Loire Valles is believed to have once held a lake.
Document 6: São Lourenço River (Mato Grosso): The São Lourenço River is a tributary of the Paraguay River within the Pantanal, an alluvial plain that spans portions of Brazil, Bolivia and Paraguay.
Document 7: Paraguay River: The Paraguay River (Río Paraguay in Spanish, Rio Paraguai in Portuguese, Ysyry Paraguái in Guarani) is a major river in south-central South America, running through Brazil, Bolivia, Paraguay and Argentina. It flows about from its headwaters in the Brazilian state of Mato Grosso to its confluence with the Paraná River north of Corrientes and Resistencia.
Document 8: Bird migration: Many of the smaller insectivorous birds including the warblers, hummingbirds and flycatchers migrate large distances, usually at night. They land in the morning and may feed for a few days before resuming their migration. The birds are referred to as passage migrants in the regions where they occur for short durations between the origin and destination.
Document 9: Paraguay: Paraguay (; ; , ), officially the Republic of Paraguay (; ), is a country in South America. It is bordered by Argentina to the south and southwest, Brazil to the east and northeast, and Bolivia to the northwest. Although it is one of only two landlocked countries in South America (the other is Bolivia), the country has coasts, beaches and ports on the Paraguay and Paraná rivers that give exit to the Atlantic Ocean through the . Due to its central location in South America, it is sometimes referred to as "Corazón de Sudamérica" ("Heart of South America").
Document 10: Guaporé River: Guaporé River (Portuguese: Rio Guaporé) is a river in western Brazil and northeastern Bolivia. Its Bolivian name is Río Iténez. It is 1,530 km (950 mi) long; 970 km (600 mi) of the river forms the border between Brazil and Bolivia.
Document 11: Tebicuary River: The Tebicuary River (Spanish: Río Tebicuary), a tributary of Paraguay River is a river in Paraguay. Located in the southwestern part of that country, it flows eastwards discharging to Paraguay River about 45 km south of Formosa and 30 km north of Pilar.
Document 12: San Ignacio de Loyola International Bridge: The San Ignacio de Loyola International Bridge (Spanish: Puente Internacional San Ignacio de Loyola) is a road bridge that crosses the border between Argentina and Paraguay over the Pilcomayo River, from the Argentine city of Clorinda, to José Falcón, near Asunción, Paraguay's capital.
Document 13: Bermejo River: The Bermejo River (Spanish, Río Bermejo) is a river in South America that flows from Bolivia to the Paraguay River in Argentina. The river is generally called Bermejo in spite of its different names along its way, but it also has its own Native American names; in Wichí it is called Teuco, and in Guaraní it is called Ypitá. In the plains of Argentina's Gran Chaco the Bermejo forms wetlands and splits into two branches. The southern branch is the bed of the old Bermejo River, now an intermittent stream called Río Bermejito. The northern branch is now the main stem of the Bermejo and is called the Teuco River ("Río Teuco"), Bermejo Nuevo, or simply the Bermejo River. The two branches rejoin at , near Villa Río Bermejito, forming the Lower Bermejo River.
Document 14: Purple martin: Wintering in South America, purple martins migrate to North America in spring to breed. Spring migration is somewhat staggered, with arrivals in southern areas such as Florida and Texas in January, but showing up in the northern United States in April and in Canada as late as May. Males usually arrive at a site before females.
Document 15: Purple martin: The purple martin migrates to the Amazon basin in winter. Its winter range extends into Ecuador but does not seem to ascend far up the Andean foothills.
ground_truth: winter
sub_queries: São Lourenço River >> mouth of the watercourse Answer: Paraguay River
Which continent is Paraguay River on? Answer: South America
when do purple martins migrate to South America Answer: winter