Birds of a feather do not flock together

Sunbirds and sugar birds play an integral role in pollinating fynbos. Despite their obvious similarities, recent research conducted in Nature’s Valley in the Garden Route National Park has highlighted substantial differences in their behaviour.

Surprisingly, sunbirds feed on the nectar of resident fynbos species blooming all year round, while sugar birds are the opposite.

They target species that flower at different intervals, forcing them to travel further afield to fulfil their role.

This highlights the importance of protecting fragmented areas of fynbos, integral to the birds’ survival. If they disappear, it will, in turn, have devastating effects on the biodiversity of this world-renowned biome.

Fynbos, one of only six plant kingdoms found globally, is endemic to South Africa. Yet, its future is not guaranteed. “With a level of biodiversity comparable to tropical rainforests, there is surprisingly little research being done,” says Dr Mark Brown, programme director at the Nature’s Valley Trust.

It is also believed that climate change may have a negative effect on this biome as it could cause changes, or loss, of plant species. Most of the fauna and flora in this landscape co-exist, depending on close relationships. Most plants in the study rely solely on birds for pollination, a massive risk in terms of potential climate change effects, says Brown.

The research project will run for five years, of which the first has been completed. Random birds were caught with special nets, and freed again after being ringed.

Counts included over 100 Cape sugar birds, 30 orange-breasted sunbirds, 150 southern double-collared sun birds and 325 Cape white-eyes, which are all important pollinator species for fynbos.

About 1 000 birds of 30 different species were caught and ringed with only a few returning to the nets to be recorded a second time.

The recapture rate is what resulted in the surprising sugar-bird findings. “Only two per cent of Cape sugar birds were caught again, reflecting their nomadic nature. In contrast, we retrapped 24% of the orange-breasted sunbirds, suggesting a higher resident population of this species,” says Brown.

Sugar birds rely on proteas and therefore migrate over large distances to find flowering species. Sunbirds, with their main focus on flowering ericas, are resident as these species bloom throughout the year.

“These results prove that we can’t just look at conservation inside the park, but have to include fragmented areas as well. Brown said that one of their sugar birds was recaptured in Baviaanskloof after travelling 43km. It is the second-longest recorded movement for the species and shows how these birds move in fragmented landscapes.
Another surprise was that they caught a white-browed schrub robin.

The Western Cape is not part of its range at all but, says Brown, human influence and climate change have an effect on populations. There have only ever been two records in the area.

The project is funded by the Natures Valley Trust and affiliated to Sanbi and Birdlife Plettenberg Bay.