As every birder knows, a “Big Day” doesn’t refer to some sort of sales scheme, the Super Bowl, or the day when an expectant mother gives birth. Depending on who you talk to, yes, those dates are certainly auspicious BUT when it comes to birding, there is only one “Big Day”. This is a 24 hour period when a small team of diehard (or perhaps obsessive-cumpulsive) birders take to the field and attempt to identify as many species as they can. The usual goal is to break the standing Big Day record for a given region. Said region can be anything from your own backyard to the entire world. Since humans are extremely far from developing any sort of teleportation device, you can’t really do a Big Day that encompasses the “entire world”. Nevertheless, that doesn’t change the fact that there is a world record for a Big Day. It stands at 331 species that were recorded by Ted Parker and Scott Robinson in Manu National Park, Peru.
Birders in Costa Rica can’t really hope to get more than 331 species in one lowland rainforest but the large number of distinct habitats that can be accessed in one fell day certainly makes the record an attainable one. If I’m not mistaken, the second biggest of Big Days actually took place in Costa Rica and resulted in 304 species (!). I’m not sure which route was taken by Jim Zook and Jay Vendergast but it probably included the mix of habitats around Carara National Park and the wonderful diversity around La Selva. This past Sunday, Susan Blank, Juan Diego Vargas, and yours truly followed a similar route in an attempt to at least break the Costa Rican record.
During spare time over the past couple of months, I slowly formulated a plan that took into account different routes, sites, and various factors (such as dawn chorus and traffic avoidance) that would maximize our chances of getting the highest possible number of bird species. I constructed bird lists and amount of time to be spent at each site, thought about expected species and those that could easily escape detection. I listened to obscure calls of nocturnal migrants in the hopes of hearing and identifying the birds that make faint burry notes, odd chuckles, and weird rattles that descend from a night sky. Once I came up with that plan and was sure of the possibilities, I realized that we actually had a chance at getting the world record (!) but that there were also factors beyond our control that could hold us back like a teflon, super-glue barricade. These factors were:
1. Dawn chorus: There are so many darn bird species in tropical habitats that their natural rarity makes seeing all 400 species recorded at a site in one day an impossibility. There’s only so much time for each bird and you can’t be everywhere at once so you can’t see everything even during a week of solid birding. However, sound waves are much easier to perceive than a bird hiding in some dense rainforest. This means that you have to identify as much as possible by sound during the first hour after dawn (when the birds are singing) because your chances at seeing many of those same species later in the day falls like the water at Niagara ( I should know as I hail from the cataract city). We actually had a lot more control over this factor than other considerations but we still depended on the birds to vocalize and make themselves known.
2. Migrants- I chose Sunday, April first, to do the Big Day to increase our chances of getting a dozen or so species that are passing through Costa Rica on their way north. By definition, migrants come and go so this was a real crapshoot. Nevertheless, migration is happening in Costa Rica so Sunday seemed like a good day to go for gold.
3. Waterbirds: Despite hundreds of species occurring in the forested habitats of Costa Rica, making time for a site that holds shorebirds, egrets, herons, and the like is essential. If such birds are present, you can easily add 30 species to your total and at least 10 other common species associated with wetlands (like Osprey and Anhinga) will also be found.
4. Weather: It can’t rain at dawn or you lose a huge chunk of birds. In fact, it can’t rain anywhere except the waterbird site or you lose a chunk of birds. This can be a major point of contention when doing a Big Day in rain-soaked Costa Rica and is why you have to do the Big Day during the dry season.
5. Traffic: What? Traffic in Costa Rica?! Unfortunately, yes and it can devour time like the Cookie Monster let loose in a “Chips Ahoy” factory.
6. The birds of course: Who says those tinamous are going to sing? How do you know if the White Hawks are going to be flying right in front of your face like they did the previous week? The large territories held by any tropical bird species means that you simply don’t know if they are going to be in the same spot as the day before. In fact, many times, they aren’t and this is what makes tropical birding so unpredictable. All you can do is increase your chances of identifying the birds by putting yourself in the right habitat at the right time, knowing how to look for them, and being extremely attentive to every chirp, whistle, and rattle that issues from the underbrush.
To cut to the chase, although traffic worked out wonderfully in our favor, we fell far short of either record by not having enough time to check for waterbirds, being confronted with pouring rain at our high elevation site on Poas Volcano, and getting almost no migrants. I figure that eliminated at least 50 bird species but since we ended up with 260 for the day, that means that the Costa Rica Big day record was certainly attainable. If those factors had been in our favor along with a better site for the dawn chorus, I figure that close to 80 more species is also a definite possibility. That would get the world record so I’m sorely tempted to try another Big Day next week. Nevertheless, I’m pretty sure my wife would protest, so I’ll be happy to stick with a morning or two of more relaxed birding.
What birds did we get? Which birds did we amazingly miss? Stay tuned for part two...