By Matt Betts
2016 marks our 8th year at Las Cruces Biological Station in the pursuit of hummingbirds, pollination, life, the universe and everything (apologies to Douglas Adams). This year is a milestone as is the first full field season of our work on the importance of ‘hub’ species to pollination networks; over the years we’ve found that a remarkable number of hummingbird species (at least 9) use Heliconia tortuosa as a resource during the dry season. We now also know that tropical forest fragmentation is causing a decline in this plant species (evidence lies in much reduced densities of ‘baby’ heliconias in small forest patches). So what will be the ecological impact of these declines? What happens when you remove a critical ‘hub’ from a network? (e.g., a key ‘friend’ in a social network, a key individual in a terrorist network, a key neuron in the brain, or in our case…a keystone plant from a pollination network).
It turns out very little is known about the properties of pollination networks when species are removed.
One possibility is that the network collapses; dependent birds depart from locations where heliconia no longer exist and as a result pollination of many other flower species suffers. An alternative is that “re-wiring” occurs; birds just change their foraging habits a bit (e.g., Big Macs versus steak) and keep up their pollination services to remaining plants. So, over the coming 3 years we intend to test these ideas using various experiments and methods that you’ll hear about in more detail as the months roll by.
I should mention that we’ve added several key members to our team: Prof Andy Jones (Oregon State Botany) is working with us on genetics and plant ecology. Kara Leimberger is visiting this season before starting her PhD in my lab in the fall. Jessica Greer (OSU graduate) has worked with us for three years as an integral part of our citizen science project and pollen identification effort but until now had not seen our study site (or the tropics for that matter). Finally, Luis Arias, a PhD student from University of Toronto under the supervision of Prof. Helene Wagner is here to work on H. tortuosa demography and seed dispersal.