Hummingbirds have been a continuous feature of my travels around south-east Brazil since day one when I ticked off the Sword-tailed hummingbird from my list at FUNCAMP. Since then I’ve kept a special ear and eye out for their whirring wing beats and rapid, darting movements, partly because they are significant pollinators in these Neotropical plant communities, but also because members of our research group have a long-standing interest in their ecology. Stella Watts for example has worked on hummingbird-flower interactions in Peru, and our friend and colleague Bo Dalsgaard spent a year in Northampton during his PhD research on Caribbean hummingbirds, and we now collaborate on some macroecological questions about hummingbird specialization in relation to current and past climates. And I did some work on their role as (probable) pollinators of some forest Apocynaceae in Guyana during field work in the late 1990s, which remains unpublished. Must write up those data one day…
The bird guide I’m using for this trip lists more than 80 hummingbird species for Brazil, many of which are found within the Atlantic Forest system. Over the last few days we’ve seen several of them in the lowland rainforest around Ubatuba, which proved to be a lot drier and warmer than the montane forest I described last time. It’s been good to have Pietro Maruyama on hand to identify the birds as they flash past. Pietro’s been studying the interactions between these birds and the flowers on which they feed as part of his PhD work, and has recently published a great paper on the subject.
On most days of field work we might see two or three species, but the day before yesterday we saw 11 species in just an hour. We were visiting a private garden belonging to a retired gentleman named Jonas who has been feeding the hummingbirds in and around his property constantly for about 12 years. The day we visited, Jonas had 13 bottles of sugar solution hung up around the house and we estimated that over 100 individual birds were using them. It’s hard to be more accurate as these birds move so fast, disappearing and re-appearing without warning, like hyperactive kids on a outing to a chocolate factory. It’s a quite stunning sight.
The 11 species we observed are about half of the total number Jonas has recorded since he began feeding the birds and there’s a regular annual rhythm to their appearance, presumably in response to temperature and plant flowering in other parts of the country. The density and richness of birds in this one small property is clearly artificial and we saw nothing like it out in the forest. Jonas is concerned that by feeding the birds so frequently (he uses 5kg of sugar a day and replenishes each feeder several times) he might be negatively affecting plant pollination in the surrounding forest. I doubt that this is the case and reassured him that his efforts were probably positive, certainly compared to some of the other activities that go on around the area, such as building, clearing forest, agriculture, and so on. Assuming that food availability limits the population size of these birds (which may or may not be the case) then feeding the hummingbirds should result in a population increase in that area which will spill out into the wider forest. Similar arguments apply to feeding garden birds in the UK, particularly in the winter.
As I watched the birds crowd and jostle around the feeders, frequently erupting into conflict and chase, I reflected that my trip to Brazil was passing as swiftly as the waft from a hummingbird’s wing on my skin. These last few days in lowland rainforest and restinga vegetation were spent conducting another two surveys of wind versus animal pollination, to add to the previous ones. This lowland forest is very similar in structure to the montane forest 1000 m higher, whilst the coastal restinga forest has rather shorter trees and is also drier. The coastline is stunningly beautiful but there’s a clear tension between its roles as a tourist destination and as an area of rich biodiversity. Humans are often drawn to such places and may unintentionally destroy what they so value, one of the ironic aspects to ecotourism as an ecosystem service.
Over the last few days I’ve been talking a lot with the students who are accompanying us, about their research data and what it means. One of our ongoing themes is the idea of flower colour, shape, smell, etc., as hypotheses about the likely pollinators of those flowers, a notion captured in the idea of “pollination syndromes”. For some flowers the syndromes are probably good predictors, for example the red tubular hummingbird-pollinated species of Fuchsia, Aeschynanthus and other Atlantic Forest plants. But there are also lots of examples of plants with flowers that don’t fit the conventional, “classic” syndromes. Yesterday on a 6km hike we encountered a species of Piper with very oddly smelling flowers, which by general agreement we described as “cockroach with a hint of lemon”. We have no idea what pollinates this plant, though we have some predictions. The genus Piper with its deceptively simple flowers has long fascinated me, ever since I undertook a short postdoctoral project on some Australian species in 1993-94. Hopefully Andre and Coquinho will spend some time observing the plants with their digital movie camera when they are in the forest next month; the results could be fascinating.
The Brazilian students I have met are a committed, passionate bunch who believe strongly in the importance of the natural heritage they are studying and trying to conserve. Though I’ve come and gone from their country like a hummingbird to a feeder, I hope I’ve made some impression on them. They’ve certainly impressed me and I’ve learned a lot from them, from their professors, and from the places we’ve visited. It’s been an amazing adventure but it’s time to come home now and see my family and friends, and colleagues. Over-and-out from Brazil.