MOSCOW — Answering a protest call issued from behind bars by the jailed Russian opposition leader Aleksei A. Navalny, small crowds of mostly young people gathered in towns across Russia on Saturday in a wave of nationwide demonstrations. The protests were timed to coincide with the 65th birthday of President Vladimir V. Putin.

The turnout for the protests, which began in Vladivostok in Russia’s Far East and then rolled westward throughout the day, was considerably smaller than in two previous days of nationwide rallies called by Mr. Navalny in March and June.