People often congratulate us for the number of trees we've planted. Today, that number is well over 170,000 native trees across northern Colombia, and every one of them represents hope for the future of the critically endangered cotton-top tamarin. But whenever someone asks me, "How many trees have you planted?" My first thought isn't about planting at all. It's about monitoring. Because planting a tree is only the beginning. Over the years, I've learned that restoration isn't measured by how many seedlings go into the ground on planting day. It's measured years later, when those seedlings have survived droughts, competing vegetation, hungry insects, changing weather, and every other challenge that nature throws at them. A tree only matters if it becomes part of a forest. That philosophy has guided Proyecto Tití's restoration program from the very beginning.

This spring, our Tití Guardianes in Colosó reached an exciting milestone in the first phase of what will become our Great Corridor around the Serranía de Coraza in northern Colombia. Together, local farmers, nursery managers, and our restoration team planted 10,875 native trees representing 41 different species throughout degraded areas surrounding this protected landscape. Those trees have an important job to do, one day they will reconnect isolated patches of tropical dry forest, creating safer pathways for cotton-top tamarins and countless other species to move through the landscape. They will provide food, shelter, nesting sites, and shade. They will stabilize soils, improve water retention, and slowly help restore one of the world's most endangered ecosystems. But before we celebrate success, we have to answer a simple question. How many of those trees are actually surviving? That's where science comes in. Rather than simply hoping for the best, our restoration team selected approximately 30 percent of every species we planted for long-term monitoring.

In total, 3,264 individual trees were tagged with permanent identification plates. Every tree received its own code identifying the species and individual number, and every location was recorded with GPS so we can find that exact tree again in the months and years ahead. It may sound like a tremendous amount of work and it is. But good conservation depends on good data. Earlier this month, approximately four months after the first planting efforts, our team returned to the restoration sites to locate every one of those tagged trees. Walking through newly restored landscapes is very different from walking through mature forests. The seedlings are still small. Some disappear beneath grasses and shrubs. Others require careful searching before their identification tags finally come into view. One by one, our team found them. And the results gave us every reason to smile. Of the 3,264 monitored trees, only 88 trees had not survived. That translates into an early survival rate of 97.3 percent. Those numbers would be encouraging in any year.

They are even more remarkable this year. Colombia is currently experiencing unusual weather patterns associated with La Niña. In the Caribbean region, June and July are normally among the wettest months of the year, providing young seedlings with the rainfall they need to establish strong root systems. Instead, this year those rains have been inconsistent, with many areas receiving far less precipitation than expected. Young trees are especially vulnerable during their first few months after planting. Without consistent rainfall, they experience greater water stress at exactly the time they are trying to establish themselves. That makes our initial survival rate even more encouraging. While we still have many months—and several dry and rainy seasons—ahead before we can fully evaluate the success of this restoration effort, these early results suggest that both the careful species selection and the tremendous work of our nursery and restoration teams are giving these forests an excellent start.

Which brings me to another important lesson that monitoring teaches us. Not every species responds the same way. One of the reasons Proyecto Tití plants such a diversity of native species is because forests are diverse. Every tree plays a different ecological role, and every species has different requirements for successful establishment. Our initial monitoring already revealed that two valuable timber species—Brazilwood (Peltogyne purpurea) and Tolúa (Pachira quinata)—experienced higher early mortality than many of the other species we planted. At first glance, that might sound discouraging. To me, it's exactly why monitoring matters. The goal isn't simply to count dead trees. The goal is to understand why. Were the seedlings stressed during transport? Did their root systems develop differently in the nursery? Were soil conditions less favorable? Did rainfall vary between planting sites? Was competition from surrounding vegetation greater in certain areas? Without monitoring, we'd never know. 

Instead of guessing, we now have questions we can investigate. We'll compare nursery records, evaluate planting conditions, revisit each site, and continue collecting data over time. Every answer helps us improve how we grow seedlings, where we plant them, and how we care for them after they leave the nursery. In conservation, even setbacks become opportunities to learn. And learning is what makes future restoration more successful.

One of my favorite moments from this first monitoring effort wasn't recorded in a spreadsheet. As our team moved through the restoration sites, something wonderful happened. Groups of cotton-top tamarins appeared in the neighboring forest. Almost as if they had come to inspect our work. The trees we've planted are still much too small for tamarins to use. They won't be traveling through these new corridors anytime soon. But standing there, watching those tiny primates moving through the canopy just beyond the restoration sites, I couldn't help but imagine what these landscapes might look like twenty or thirty years from now. The seedlings we measured this month could become towering forest giants. Today's open pastures could become connected forests. And tomorrow's cotton-top tamarins may never realize there was once a gap between these fragments.

That's the beauty of restoration. We rarely plant trees for ourselves. We plant them for future generations—of people and wildlife alike. The first monitoring results remind me that restoration is much more than planting trees. It is science, it is patience, it is adapting when nature surprises us, it is working hand in hand with local communities who care deeply about the future of their forests and most of all, it is understanding that every living tree represents possibility.

The coming months will continue to test these young forests. Climate variability is becoming an increasingly important challenge for restoration projects across Colombia, making long-term monitoring more important than ever. Each visit back to these restoration sites helps us understand not only which trees survive, but which species are most resilient as weather patterns become less predictable. Those lessons will shape every future planting we undertake. We'll return to these forests again and again, measuring growth, recording survival, learning from every success and every challenge. Because that's how restoration succeeds. Not by planting thousands of trees in a single day.

But by making sure those trees are still standing many years from now—creating forests where cotton-top tamarins, and countless other species, can thrive for generations to come.