Pollinators are Sweet

Brunsvigia litoralis (top)
Nectarina famosa (middle right)

Despite the fact that hummingbirds are among the most beautiful creatures, a special interest has developed on a small guild of necarivorous birds and their response to urban habitat due to their great ecological role in South Africa (they pollinate about 4% of flora or 320 plant species). Generally, pollinators have been known to do many things: link separated landscapes, maintain gene flow, prevent small isolated plant species from obtaining inbreeding depression, and contribute to the resilience of small ecosystems within a metapopulation.

However, a recent study showed that urbanization in the city of Cape Town was rapidly expanding and engulfing conservation areas. This raised concern for the small guild of birds and how they would react to their changing environment. They observed low levels of functional redundancy and low levels of response diversity in this bird guild, thus they noticed that all the species in this functional guild could respond to urbanization in the same way. This is especially worrisome for certain plant species that are relying on specific bird species for pollination, but there is an even greater concern of potentially losing the ecological function that these birds serve entirely.

A great example presented in this paper showed the importance of these pollinators to the endangered plant species, Brunsvigia litoralis, which depends entirely on the bird species, Nectarinia famosa for pollination. Because N. famosa has the longest of bills, it is the only one that can properly pollinate floral tubes longer than 35mm, whereas other birds with shorter bills simply rob the nectar by poking holes at the base. Going back to previous lectures, this demonstrates why it is so crucial to have functional diversity in ecosystems. If these birds were somehow unable to move through urban land to get between the natural populations, they would be unable to reach the patches of this endangered plant, and there would not be another species ready to take its place.

Thankfully, conservation efforts to help facilitate the formation of links between different sections of natural land are already being formulated. Since one possible issue with urbanization is decreased nectar availability, two methods being considered for restoration are using bird feeders and planting appropriate nectar plants. This paper seemed to favor the idea of selecting schools to start special gardens that would create links between conservation areas. If done carefully, this would not only benefit the guild of necrarivores, but the schools, students, and other pollinators as well.

For more information on this study please see Urbanization Drives a Reduction in Functional Diversity in a Guild of Nectar-Feeding Birds