Birds, birds, birds!

Chhaya and I went birding with Ioana (our bird-studying teaching assistant) the other day. She was wonderfully patient with all of our questions and helped us identify all the birds. We say at least twenty species of birds including...

Black Orapendula (Psarocolius guatimozinus). It has distinctive yellow tail feathers which splay out when it flies.

Chachalaca (Ortalis cinereiceps).

Chachalaca silhouette. Apparently Chacalacas display rather like turkeys, but I haven't seen it.

Blue-crowned Motmot (Momotus momota), remember the myth about their remarkable tail feathers?
Also see the avocados?

The avocados are different here. They don't taste as good by themselves, but they are yummy mixed in with beans and rice, as I had for dinner today.

Close up of the Motmot. See the blue head?

We saw this nest in the process of being built...

...by this bird, the Yellow-bellied Elaenia (Elaenia flavogaster).

Panamanian Flycatcher (Myiarchus panamensis)

The more dully colored, but very cute Streaked Flycatcher (Myiodynastes maculatus).

Tropical Kingbird (Tyrannus melancholicus).

Orange-chinned Parakeet (Brotogeris jugularis).

They blend in remarkably well; although they are flashily colored, the sun shines through the leaves and illuminates them to a similarly brilliant green.

Grooming time! This involved a careful chewing of feet as well as ruffling of feathers.

Red-legged honeycreeper (Cyanerpes cyaneus). I wish I could have seen it from the side as it's a flashy blue.

Common Tody-flycatcher (Todirostrum cinereum).

Yellow warbler (Setophaga petechia).

Blue-gray tanager (Thraupis episcopus)

Crimson-backed Tanager (Ramphocelus dimidiatus).

And my favourite...

Golden-hooded tanager (Tangara larvata).

Here you can really see the golden hood.

I also loved this impressive tree covered with epiphytes (plants that grow on other plants)...

And this gorgeous orchid...

Back to the Stone Age

It was once thought that the earliest people in the Americas arrived 13,500-11,500 years ago. This culture was called "Clovis" and was characterized by remarkable "points" (arrowheads) with pressuring plating--which produces strong but sharp edges--and fluting--shaping at the base that forms a hollow where a shaft could be bound to produce a spear. Although some scholars argued that there were earlier settlements, the stone tools used as justification for this theory were so much simpler than Clovis tools that many archaeologists disagreed over whether or not they were actually stone tools as opposed to natural rocks. Even when more complex artifacts and features were found, the dating was often controversial. A site in Monte Verde, Chile, however, finally provided convincing evidence of a "pre-Clovis" settlement dating to 14,800 years ago (using radiocarbon dating of bones and charcoal). The site was particularly well preserved because it had become a bog soon after occupation which provided anoxic conditions in which even wood structures were preserved (since degrading bacteria could not live there). Current consensus--as much as there is one--among archaeologists now, is therefore that humans crossed the Bering Land Bridge into North America at least 16,000 years ago and the Neotropics (New World tropics) by at least 15,000 years ago. Some even argue for earlier dates (as far back as 35,000 years ago), but that is still extremely controversial.

This means that humans have been in the Neotropics for a long time. How did they live? It has long been thought that early prehistoric peoples relied mostly on large game animals for sustenance. While they undoubtedly hunted for meat, more evidence is emerging regarding the use of plants in prehistoric times.  Although archaeology has long been limited to the examination of pottery, bones, and stone remains, more recent paleobotany techniques have allowed us a glimpse into past ecology and agriculture.

Our professor for the first half of the class is a pioneer of some of this research. She uses phytoliths (formed by plants taking up water with soluble silica which crystallizes within the plant) and starch granules (the remains of plant cell organelles called amyloplasts which store starch)--all of which can be, but are not always, diagnostic of certain species or general types of plants. By looking for these signatures on stone tools she can reconstruct an approximate timeline for the development of agriculture. For example, she has found starch grains of corn and other crops on the grinding surfaces of stone tools in much higher concentrations than on other surfaces or in the surrounding soil. Starch granule analysis can even be done on teeth, giving us a direct indication of ancient peoples' diets. In some cases the domestic and wild versions of a plant have different phytoliths and/or starch grains, which allows us to check when signs of domestication become present in the archaeological record at different sites.

This type of evidence adds to pollen and charcoal data from lake sediments which show the increase of grass species (which invade cleared areas), decrease of woody tree species (mature, undisturbed forest), and increased charcoal levels which indicate the use of slash and burn agriculture in Panama at least 7,600-7,200 years ago. Altogether, the current evidence supports origins of crop domestication and agriculture in both Mexico and South America independently about 10,000-9,000 years ago. This is concurrent with the development of agriculture in both China and Southwest Asia, probably because global climate was transitioning from the last ice age (Pleistocene) into the current interglacial (Holocene) which changed the state of ecosystems such that farming became more energetically rewarding than hunting and gathering (though the reasons for the simultaneous emergence of agriculture throughout the world are also controversial, ranging from purely climatological to purely social reasons).

The exciting thing about starch grain analysis is that it allows for identification of different crop species being ground or eaten at different archaeological sites through time. (Phytoliths can also provide this information, but both phytoliths and starch grains are only distinctive for certain species, and are deposited in different amounts by different plants and processes, so this adds another tool to the toolkit, as it were.) The use of starch grains in archaeological work is still quite new, however, so there are many questions about how to interpret starch grain results. For instance, which crops and distinguishable and which look the same? Which are damaged by grinding and how? We did some exploratory work on these questions, grinding up corn, yam, beans, squash, and manioc (also called yuca or tapioca) to compare fresh and ground starch granules. We collected suitable stones from the Chagres River when we visited the Embera, brought them back to the lab, and started grinding!

Thanks to Chhaya for the photo!

As you can see, it's a rather messy process. Grinding releases the starch grains from the plant cells and some are left behind on the stones. We washed them off and looked at the resultant liquid under a light microscope and were able to observe some alterations due to grinding such as an increased occurrence of fractures on the starch grains.

Here are some photos taken through the microscope (thanks to Lee for these).

Bean, highly fractured.

Yam

Squash

The grinding stones also because smooth and sometimes striated from the grinding process, signs of human alteration. It's fascinating to get a glimpse of how such study and reconstruction of the lives of ancient peoples is done (though one can't help feeling a little silly banging rocks together for a grade...)!

Kitties! (Pumas, Margays, and an Ocelot): An afternoon at the zoo.

Chhaya, Simone, and I went to the zoo on Sunday. It's called Parque Municipal Summit and includes both a botanical garden and small zoo of rescued animals.

First, there was a pair of twin pumas, born January 2012, that had been rescued from poachers who had killed their mother.

Puma #1 stayed close to the fence on a nice elevated platform.

While Puma #2 walked around the pond and looked playful.

The King vulture (Sarcoramphus papa) has a rather startling head!

The Margay (Leopardus wiedii) was my favorite. It was small with long legs and very big eyes.

To the left was a caiman.

And to the left of that, an ocelot taking a nap.

The monkeys were in these nice enclosures with large trees for them to play in.

Howler monkey.

Spider monkey.

This painted train was parked next to a nice playground.

And there was another (I think) Margay. Either that or a small ocelot, it wasn't labeled.

As we stood watching, it started to rain.

First just a little, and then it was pouring.

A heavy afternoon rain is pretty much a daily affair during the rainy season, but we're only just transitioning from the dry season to the rainy season now, so we're not quite used to it yet. One of the best parts of the coming of the rainy season is that it is also mango time! We have nice, fresh mangoes in the schoolhouse many days now. It was rather nice to stand in the rain and cool off, but we didn't want our stuff to get wet, particularly the cameras, so we went over to where the toucans were which had a slightly overhanging roof.

Keel-billed Toucans (Ramphastos sulfuratus),  also sometimes called Rainbow-billed Toucan for obvious reasons.

Toucans are social creatures, often traveling in groups of 6-12. I think there were six or seven in the enclosure.

Doesn't it have the most gorgeous bill? It does give the bird a rather lopsided look, though, particularly when in flight!

Their bills are so beautiful that you rarely see pictures of toucans head-on...they look rather comical.

The bills are actually serrated, as you can see as soon as they open their mouths. 

It's unclear why toucans have such huge, brightly colored, and serrated bills. Possible explanations (not mutually exclusive) include easier access to fruits on branches too thin to support their weight, thermal regulation, species recognition, and sexual selection.
There were also Squirrel Monkeys and Geoffroy's Tamarins next to the toucans, but they were so small, active, and friendly--therefore right up against the fencing--that I couldn't get a good picture, especially given that I was by that time huddling under the roof  of the enclosure to keep my camera dry!

It was wonderful to get a chance to see some of the creatures I haven't gotten a chance to see in the forest...particularly the cats, of course.