"The principal factor that reduces the populations is always sooner or later the deterioration of habitat," said University of Costa Rica researcher Gustavo Gutierrez. A growing number of developers are taking over their jungle habitat, isolating them in small communities by fragmenting their habitat. This also inhibits the genetic diversity needed to keep them healthy, according to Gutierrez. "What we have is 25 percent of the country in islands, without genetic contact between one island and another," Gutierrez said.
According to Sanchez, in order to restore the populations, protected areas will have to be increased, and corridors will have to be created to reconnect the ioslated areas.
Source: http://www.explorecostarica.com/newsmanager/publish/Costa_Rica_Monkey_Population_Decreasing.shtml
Time is passing. And in addition to loss of habitat, spider monkeys are still being hunted. Both Chiquito and Lolita were orphaned when their mothers were killed for bush meat. Throw the illegal pet trade into the equation. And the question becomes: "Will there be any spider monkeys left to re-populate with?"