Birding in the tropics is substantially different from the temperate zone, and the diversity of faunal species in tropical environments is a direct result of habitat complexity. Habitat complexity has arisen through fierce competition for resources (light, water, nutrients) and the tradeoffs that species make between ensuring propagation (survival of the species) and defending themselves against excessive predation (consumption) and disease. In Panama there are more than 1,000 tree species, 10,000 species of vascular plant (including more than 1,000 species of orchid), and an unknown number of vines, lianas, ferns, mosses, and bryophytes. This diversity has arisen by way of competetion for resources, which drives the process of speciation or niche segregation.
There are 976 bird species known to occur in Panama, and thus, in the strictest sense, means there are 976 possible habitat niches. Defining niches however is not a simple task, because it is not often possible to include all of the spatial and temporal attributes that conribute to the complexity of multi-dimensional systems. Generally speaking though, you really only need to know the 4 C's: Complete Competition Cannot Coexist.
Through competion and diversification, tropical forests are very dense, both horizontally and vertically. Unlike simple two-story or three-story forests in North America, tropical forests have the appearance of a green wall with a green ceiling. Only when a tree falls does a substantial amount of light reach the forest floor, and consequently most forest-dwelling birds tend to be in the shade. Additionally, most species are often well-hidden from human eyes by the vegetation; even the deep layer of leaf litter is capable of concealing species such as Leaftossers. Another factor that makes birding in the tropics difficult is sound. Species living in dense forests tend to have deeper sounds than species living in less dense forests, and deeper (shallower) sound waves are decidedly deceptive when it comes to pin-pointing a species location. It is both a challenge to determine how far away a species is, and from which direction it is calling due to sound waves bouncing from the dense vegetation. I learned a great deal about birding in the tropics with Guido, and today was my first opportunity to put into practice my new found skills.
24 February, 2008
Today was my second trip to Metropolitan Park, and this time I decided to take a taxi, which admittedly I was a bit nervous about given that I don't speak Spanish. I left the hotel at 7:45am and attempted to signal a taxi; that took about 1 second. I communicated my destination and price (it is recommended that you establish the price first) as "Parque Natural Metropolitano, Dos dolares". The driver was puzzled, not about the price, but about the destination. I repeated it several times, and it was hopeless. Subsequently, I resorted to a variety of early-ancestral hand signals, indicating that he should just drive and I will lead the way. Fortunately, I had memorized the route from my first trip.
We arrived at the park at 8:00am, and the driver appeared pleased that he had driven to a new destination. My goal for this trip was to complete the trail loop that I had initially planned to do on 22 February: El Roble (0.7 km), Mono Titi (1.1 km), and La Cienaguita (1.1 km). I paid the $2 entry fee and began birding behind the visitor centre. Within minutes things were looking better than my first visit, as two of the first four birds I saw were lifers: Streaked Flycatcher and Yellow-bellied Elaenia. I birded the grassy area and forest margins extensively for about 30 minutes before entering the nearby forest. Immediately I spotted a bird flitting in the deep shade about 10 feet away - it was a pair of Lance-tailed Manakins - spectacular! I continued along the trail to a small opening where an artificial pond, and nursery, was present. Rufous-tailed Hummingbirds were omnipresent, as were a variety of tanager species, including Crimson-backed Tanager. On the small pond were several Red-eared Sliders (a type of turtle) and Jesus Christ Lizards (Basiliscus basiliscus), so-named for the ability to run on water.
As I continued along the trail I found that I was much better at being able to spot birds in the dense greenery compared to just two days ago. I was afforded great views of Red-throated Ant-Tanager, White-bellied Antbird, Lesser Greenlet, and Checker-throated Antwren. I also found several new lifers, including Rufous-breasted Wren, Olivaceous Woodcreeper, Long-billed Gnatwren, Blue-black Grosbeak, and Plain-brown Woodcreeeper. Eventually I arrived at the Mirador (viewpoint), where I gained a truer appreciation of the significance of the park in an urban environment.
Just below the Mirador and along the main trail is a steep hill that descends to the west. The steepness means that as an observer, you are in relatively close proximity to the forest canopy, a particularly broad niche where several bird species spend most of their lives. Guido had indicated yesterday that he had heard a Green Shrike-Vireo, but noted they are notoriously difficult to see because they spend the majority of their time in the canopy, often on the upper sides of leaves. They are also hard to see because, as their name implies, they're green. But as luck would have it, it was at this very spot, just below the Mirador, where I spotted my first Green Shrike-Vireo. What a magnificent bird.
I continued along down the hill and flushed a pair of Blue-crowned Motmots that were feeding at the edge of the trail. I also discovered my first ultra-obscure Orange-billed Sparrow that was so well-hidden in the leaf litter that I could only see its head. I completed the hike at 1:00pm, by which time it was very hot and humid. I flagged a taxi from the main road in front of the visitor centre and returned to the hotel for a cool shower and some lunch. At 3:00pm I met up with Fred and his wife Anthea, who had just arrived for the conference that was to begin tomorrow. I compiled my daily observations in my field notebook during supper and went to bed early so that I could squeeze in some early birding before the welcoming address of the conference at 2:00pm.
Total number of species seen today = 49
Total number of lifers seen today = 12
Total cumulative species seen for trip = 117
Total cumulative lifers seen for trip = 89
Total number of species seen at Metropolitan Park today = 44
Total cumulative species seen at Metropolitan Park = 52
25 February, 2008
I awoke at 6:00am and went through the same routine as yesterday, only this time my taxi driver understood the destination - Metropolitan Park. This was going to be a short trip, as the scheduled shuttle that would take guests to the conference was set to depart at 1:00pm. Upon arrival at the park at 6:45am I paid the usual entry fee and began birding behind the visitor centre. My plan today was to walk the El Roble trail to the junction of La Cienaguita, and then backtrack to the visitor centre via Los Caobos trail. I didn't see any lifers in the grassy area or along the forest margins, but I did spot some species familiar to be from Canada's Boreal Forest, namely Yellow Warbler, Bay-breasted Warbler, and Tennessee Warbler. My first lifer of the day was at the pond near the nursery - a Buff-breasted Wren. I continued walking to the information kiosk where a few picnic tables and some old decommisioned buildings are located. In this relatively open area I found Yellow-crowned Euphonia, and a Two-toed Sloth curled up amongst the lower branches of a tree overhanging one of the tables.
From the information Kiosk I began backtracking, but right where La Cienaguita trial joined El Roble I could here something rustling in the undergrowth. With a bit of patience, and a slow approach, I was rewarded when a Thrush-like Schifornis (previously Thrush-like Mourner) popped out onto a branch and provided an exquisite view. I continued back along El Roble and completed Los Caobos rather quickly and without seeing any new species. I returned to the visitor centre and found two more familiar Canadian breeders - Northern Waterthrush and Rose-breasted Grosbeak.
I checked the time and found that I still had 30 minutes to spare. I decided to walk Los Momotides, a 900m long trail rated as easy. The forest was notably different in this region, but the sound of traffic was almost unbearable for birding. I moved rather quickly along the trail as it seemed rather quite, but nonetheless I did manage to find three new lifers: Rufous-and-White Wren, Black-bellied Wren, and Yellow-olive Flycatcher.
It was now just after 11:00am, so I caught a taxi back to the hotel, had a quick shower, and grabbed my camera, notepad, and a pen for the conference. The conference was held at the Smithsonian Tropical Research Institute and the welcoming comments were well-received. Afterward, at 4:30pm, there was an outdoor social gathering with food, music, and featured local dancers. It was a gorgeous late afternoon, and although I didn't spot any new species among the campus gardens, I did manage to tally 14 species. At about 7:00pm we returned to the hotel where I compiled the remainder of my notes for the day.
Total number of species seen today = 43
Total number of lifers seen today = 6
Total cumulative species seen for trip = 125
Total cumulative lifers seen for trip = 95
Total number of species seen at Metropolitan Park today = 34
Total cumulative species seen at Metropolitan Park = 64