Since Argentina is in the Southern Hemisphere, the seasons are the opposite of those in the US. When it is winter in the US, it is summer in Argentina, etc. The seasons vary for the array of sporting species available in Argentina and Uruguay.
Dove: Year round
Duck: May through August
Perdiz: May through August
Pigeon: typically, April through August depending on the destination
Brown, Rainbow and Sea Run Brown Trout: typically November 15th through April 31st depending on the river
Free Range Red Stag: March 1st through April 15th