Here’s a list of possible mammals you might spot during the birdwatching tour in Costa Rica, categorized by each location:

San José and Surroundings:

• White-faced Capuchin Monkey – Common in the forests around San José.
• Central American Squirrel Monkey – Sometimes seen in nearby reserves.

Tortuguero National Park:

• Howler Monkey – Easily spotted by their distinctive calls.
• Spider Monkey – Often seen swinging through the trees.
• Peccary – These wild pigs are often spotted in the park.
• River Otter – Frequently seen in the waterways.

Arenal Volcano Area:

• White-throated Capuchin Monkey – Common in the forests around Arenal.
• Coati – Often seen foraging on the forest floor.
• Kinkajou – A nocturnal mammal, sometimes seen during night tours.
• Paca – A large rodent found in the forest.

Monteverde Cloud Forest:

• Monteverde’s Spider Monkey – Occasionally spotted in the cloud forest.
• Howler Monkey – Common in the Monteverde area.
• Agouti – These rodents are often seen in the undergrowth.
• Baird’s Tapir – Rare, but sometimes spotted in the forested areas.

Manuel Antonio National Park:

• Capuchin Monkey – Frequently seen in the park.
• Mantled Howler Monkey – Common and vocal in the park’s forests.
• Squirrel Monkey – Often found in the park.
• Two-toed Sloth – Frequently seen hanging in the trees.

This list highlights a variety of mammals you might encounter during your birdwatching tour across Costa Rica. The actual sightings can vary based on weather, time of day, and specific locations within each reserve.