[Secret] The Magpies Robin and other animals in my garden

The migratory species tend to lay larger clutches of eggs, typically up to six, since the hazards of their journeys mean that many individuals will have only one chance to breed. In contrast, the laying of two eggs is typical for many tropical species, since the chicks can be provided with better care, and the adults are likely to have further opportunities for reproduction.

This group likely originated in northern Central America, where the greatest number of species and diversity between them is found. From there, they spread north during the interglacial periods, mainly as migrants, returning to the ancestral region in winter.

Two genera, Myioborus and Basileuterus, seem to have colonized South America early, perhaps before the two continents were linked, and together constitute most warbler species of that region.