When did howler monkeys become endangered?

There isn't a single, specific date when howler monkeys became endangered. It's a complex issue with a gradual progression. Here's why:

* Endangerment is a process: It's not a sudden event. Species become endangered due to various factors like habitat loss, hunting, disease, and climate change. These factors act over time, gradually reducing populations.

* Different species, different timelines: There are several species of howler monkeys, each with unique threats and population trends. Some species might have faced more severe threats and reached endangered status earlier than others.

* Changing classifications: The conservation status of species isn't static. It can be updated as more research and data become available. A species may be classified as "vulnerable" one year and "endangered" the next.

Here's what we can say:

* Most howler monkey species are currently considered either "Vulnerable" or "Endangered" by the IUCN (International Union for Conservation of Nature). This indicates that they are facing a high risk of extinction.

* The decline of howler monkey populations has been accelerating in recent decades. This is largely due to habitat loss from deforestation and the illegal pet trade.

Instead of seeking a specific date, it's more important to understand the ongoing threats and the urgent need for conservation efforts to protect these magnificent creatures.