A Utilitarian Argument for Sunbird Conservation

By Bill Newmark

Linked paper: African sunbirds predominantly pollinate plants useful to humans by W.D. Newmark, V.J. Mkongewa, D.L. Amundsen, C. Welch, The Condor: Ornithological Applications.

I have often wondered several years after I have written a paper what exactly was the initial inspiration for it. Fortunately, I can distinctly remember why I became interested in examining the number and relative frequency of food plants for African sunbirds that have useful properties to humans, because it occurred very recently.

In early 2018, I saw an announcement from the JRS Biodiversity Foundation requesting proposals assessing the impact of climate change on pollinators in sub-Saharan Africa. The over-arching objective of the funding program was to establish open-source databases focused on the distribution and abundance of pollinators in Sub-Saharan Africa for the purpose of enhancing their conservation.

My initial thought after reading the announcement was that the JRS Biodiversity Foundation was principally interested in supporting research focused on insects rather than birds (which, by the way, I think is terrific, given that insect conservation-oriented research has far fewer avenues of support than vertebrate conservation-oriented research in Africa). Nonetheless, I did inquire whether the JRS Biodiversity Foundation would consider a proposal focused on both butterflies and birds since birds, specifically sunbirds, sugar birds, and white-eyes, are the dominant vertebrate pollinators in Africa. JRS agreed to consider such a proposal and in May 2018, several Tanzanian colleagues and I submitted a proposal focused on assessing long-term changes in the elevational distribution of butterflies and birds, as well as the demographic response of flower-pollinating bird species to climate change in montane forests in Tanzania.

In writing the proposal, I wanted to say something about the importance of sunbirds as pollinators of plants that are useful to humans. Fortunately, an open-source database of useful tropical plants had recently been published. I was able therefore to quickly calculate the number and relative frequency of sunbird-pollinated useful plants — plants that are used by humans for medicine, food, building materials, or other uses — in the Usambara Mountains in Tanzania, a long-term study site of mine. A reviewer of the proposal, however, quite correctly asked about the source for the statement that I had made about the importance of sunbirds as pollinators of useful plants in the Usambara Mountains, because I had not cited any published literature.

Thus, in order to say something about the importance of sunbirds as pollinators not only in the Usambara Mountains in Tanzania but also across Africa, Debra Amundsen and Chad Welch, co-authors of our paper, compiled a database of known food plants for African sunbird species based on a detailed review of the literature. They also recorded whether the food plants were useful to humans, how they were used, and whether the plants were cultivated. To our surprise, this compilation indicate that more than two-thirds of all genera and nearly one-half of all species of food plants of African sunbirds are used by humans for medicine, food, building materials or other uses. However, most useful plants are pollinated by a small number of sunbird species. The median number of sunbird species that visit a useful genus and species of plant is 2 and 1, respectively. Somewhat less surprising, however, was that most genera and species of useful plants that are sunbird-pollinated are non-cultivated. In Africa, nearly all non-cultivated useful plants are collected, used, and traded locally rather than regionally or international, highlighting the important role that African sunbirds provide to communities at a local scale.

I must admit that I have often felt uncomfortable about making arguments for the conservation of biodiversity based strictly on utilitarian values of species, because such arguments can potentially be misconstrued to mean that species that do not provide direct benefits to human are less worthy of protection. However, over the last 50 to 150 years, more than 70% of many of the most important sunbird habitats in portions of Africa have been lost. For example, in the Eastern Arc Mountains of Tanzania and Kenya, a global biodiversity hotspot, 77% of the original forest has been lost, while in the Cape Floristic Region in South Africa, also a global biodiversity hotspot, more than 80% of the original habitat in the Agulhas Plain and in the Coastal Renosterveld Broad Habitat Unit has been lost. I believe that utilitarian arguments for species conservation can be important in convincing decision-makers and local communities about the immediate value and importance of conserving biodiversity.

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