I have been working with the Arquivo Regional da Madeira’s databases and was able to put together some stats on the most common first names of the da Silva family in Porto Santo.  The following table summarizes the top 5 names with the counts in parentheses:

Ranking Female Male
1 Maria (73) Manuel (55)
2 Júlia (14) João (41)
3 Rosa (7) José (29)
4 Catarina (6) António (22)
5 Luzia (6) Domingos (10)
All Others (119) All Others (90)

Maria is the most common female name of the da Silva of Porto Santo and Manuel is the most common male name.

There is also more variety in female name than in male names.  These top 5 names represent 64% of all male names and 47% of all female names.

I came to this conclusion by analyzing a database of baptismal records for children whose father has the surname of da Silva.  I assumed that records with a surname other than da Silva preceding the da Silva  (i.e. Simão de Melim da Silva) were not da Silva’s.  I classified the names into male and female categories.  I also counted records with two first names in the first of the two (i.e. Domingas Maria counted as Domingas not Maria).