by Rebeka Mayhew

Today marks five weeks for me on the Smithsonian Tropical Research Institute’s Barro Colorado Island in Panama and surveying the bird communities in the Barro Colorado Nature Monument. I am one of Daisy Dent’s PhD students and I am currently in Panama to examine how bird species and their functional composition changes in regenerating forests. Barro Colorado Island (BCI) is located in the artificial Lake Gatun in the middle of the Panama Canal.

The Smithsonian has administered the island and five adjacent peninsulas, collectively known as the Barro Colorado Nature Monument (BCNM), since 1946. It is one of the most-studied areas of tropical forest in the world. BCI is an exciting place to live for a couple of months; it hosts up to 90 scientists at any one time. They are associated with various universities from around the world and are here to work on a range of short and long-term projects such as the effects of lightning strikes on trees, seedling dynamics, the herbivory rates of ants and seed dispersal by bats.

As always with fieldwork, and perhaps particularly when working overseas, there have been lots of ups and downs already! Bureaucracy kept me fairly busy for the first two weeks that I was out here in Panama, along with attempting (successfully!) to gain my Panama Canal Boat License. In order to achieve this you have to sit a theory test, a little like your driver’s theory test, in the Panama Canal Authority’s office in Panama City. No practical boat-driving test for some reason… This now means that while driving my small tin bath along the edge of the Panama Canal to access my sites, I know that the number one rule is to keep well clear of the big ships! As well as avoiding the big ships, once you leave the main canal you also have to battle with half submerged trees; the remnants of the forest that was flooded by the creation of Lake Gatun. Instead of rotting away, a century underwater has caused the stumps to petrify, ready to snag any unwary researchers passing by.

Attempting to avoid the big ships of the Panama Canal.

In order to assess the bird communities in regenerating forests I am making use of Daisy’s chronosequence of secondary forest plots within the BCNM. These consist of ten plots in five different age categories, 40-year old, 60-year old, 90-year old and 120-year old secondary-growth forest, as well as old-growth forest. In September I will also visit another site, Agua Salud, where the forest is even younger, only 10 – 20-years old. Daisy has documented the tree species and functional composition of these forest plots. I intend to identify how the diversity and composition of the bird communities relate to that of the tree communities, and how the functional composition of birds corresponds with that of trees across the successional gradient.

I have now found all ten of Daisy’s vegetation plots, which are located both on the island and the surrounding peninsulas, a bit of a tricky task in Daisy’s absence! However, surveying the birds is now well under way. I’m lucky enough to have two teams in the field. My assistants are Ovidio, a very knowledgeable local birder who has worked with many STRI ornithologists before, and Tom and Sam, who are enthusiastic ecologists from the UK.

Now that we’ve found our sites, fieldwork is settling into a routine. Our day begins at 4.30am, with either walking for an hour into the jungle if we are surveying a site on the island, or a short boat journey to one of the peninsula sites (rather scary as it involves driving along the Panama Canal in the dark!). We then battle our way through the jungle to nine different survey points and undertake the counts. This involves standing for 10 minutes and recording all the birds we see and hear. In a morning’s survey we might perhaps only see about three birds, the rest we have to identify from their call. I’m very glad to have Ovidio with us, as it’s a steep learning curve attempting to memorise all of the birdcalls! We’ve now recorded over 2000 observations and 95 species of birds.

A Rufous Motmot and a Rufous-tailed Hummingbird – some of the few birds we have been lucky enough to see!

I will be here for another month on BCI before moving on to the other site at Agua Salud for September. I’ve already had a fantastic time working here; each trip into the jungle offers a new wildlife experience. Along with the amazing birdlife I’ve been lucky enough to see a tamandua, armadillo, peccary and various species of monkey. However, whilst as an ecologist I believe all animals are equally interesting, I do have a preference for the coatis over the spiders…