I was digging through some old field notes yesterday, and came across an interesting entry from a research expedition to western Panama in 2005. The crew was led by the inimitable Adam Stein, followed by Kyle Elliott, Cory Neidig, and myself. The expedition was intended to gather data for Adam’s dissertation research, on the evolutionary dynamics of a unique avian hybrid zone, where Manacus candei meets and interbreeds with Manacus vitellinus), in the remote Changuinola river valley of northwestern Panama (see publication credits at the end of this post). Our study site was located in the environs of the indigenous Guaymi village of Changuinola Arriba, ten hours upriver in a motorized dugout canoe.
We located leks (i.e., courtship display sites) by sound, using machetes to build and maintain temporary access trails through the dense secondary growth along the riverbank. We trapped each of our target birds in mist-nets, color-banded the males and took various measurements; blood and semen samples were obtained and frozen in a portable liquid-nitrogen tank, photospectrometer readings were taken from the plumage of each male, and morphological measurements were taken with calipers. We studied aggressive interactions by presenting taxodermied mounts (both yellow & white) and non-manakin control mounts to a sample of males at both sites, and then recording their reactions.
I spent many days working alone, or paired with another member of the team. Our study sample was largely split between two riverside lekking sites, separated by a considerable distance of river, and we had only one canoe. Many days, due to limited transportation, I made my way back to camp via muddy jungle slope or swift jungle river, gear slung overhead in a waterproof dry-bag – often a two or three hour process.
Typically, each male manakin maintains its own court for display. Although courts can be placed in proximity to one another (resulting in a congregation of courts – a lek), most courts are occupied by a single territorial male who is not tolerant of other males within its immediate vicinity. However, on March 30, 2005, I had an interesting observation of two males (one yellow, one white) that were displaying together on the same court. I counted the number of cheers that each bird made during a 20-min (yellow) mount presentation, and then continued to observe them for 2 hours afterwards. Here is a transcript of my field notes:
The flagging says W but a yellow bird is hanging out. There is a white [bird] that is always with him. I watched them for 2+ hours. The 2 birds fly back and forth between 2 courts, always together. They even display together on one court. They both came in and cheered at the mount. Yellow seems to own Court B but shares it with White. White will follow Yellow into Court B; they hang out there and chirp together; and then White flies back to his court, and Yellow follows. Yellow then leads the way back to Court B, and White follows. Neither seemed too concerned with mount. The cheers they made seemed more directed at each other. They flew back and forth between both courts (always together) at least 20 times during 30 minute [mount] presentation. When they are in White’s court, they both cheer. Occasionally, they both left the area together, but always flying together. Eventually, Yellow would show up at Court B again, and White would arrive 2 seconds later. Literally no attention was paid to the mount by either bird. They cheered the same amount while they were in the other court as when they were in Court B.
Yellow spent slightly more time in Court B than White, although it was never more than 1 minute before White arrived. White was never in Court B alone. This is nuts. They even followed each other from perch to perch, and sitting next to each other on one perch. It was like a game of tag.
The research that we conducted in Panama was supported by J.A.C. Uy’s lab at Syracuse University, Smithsonian Tropical Research Institute, and a large number of people including A. Pineda Jr., R. Santos, A. Santos, H. Santos, F. Abrego, M. Leone, O. Orsomena, C. De Leo´n, U. Gonzalez, D. Santos and the community of Changuinola Arriba.
Concannon, M. R., Stein, A. C., and J. A. C. Uy. 2012. Kin selection may contribute to lek evolution and trait introgression across an avian hybrid zone. Molecular Ecology 21: 1477–1486.
Stein, A. C., and J. A. C. Uy. 2006. Unidirectional introgression of a sexually selected trait across an avian hybrid zone: a role for female choice? Evolution 60: 1476–1485.
Stein, A. C. 2009. Plumage evolution in bearded manakins (Manacus spps.). Ph.D. Dissertation, Syracuse University.
Uy, J. A. C., and A. C. Stein. 2007. Variable visual habitats may influence the spread of colorful plumage across an avian hybrid zone.Journal of Evolutionary Biology 20: 1847–1858.