15/10/2023
The second Saturday of October 2023 is World Migratory Bird Day. The point of this is to raise awareness for the conservation of migratory birds and their habitats. These species have significant ecological importance, and they are facing several threats, both in their summer and winter grounds as well as en route during their migrations.
South Africa is a popular destination for many migratory bird species that spend their northern winters here during our southern spring and summer. Many of these species are insect or seed eaters, and many of them travel thousands of kilometres, arriving exhausted from their long trips, relying on local food supplies to fatten them up for the return journeys as the southern autumn approaches.
Most migratory birds are waterbirds, raptors, and some land-birds.
Waterbirds are defined as those species ecologically dependant on wetlands or water bodies for at least part of their annual life-cycle. They generally feed on aquatic life, whether it be certain types of plants, aquatic invertebrates, or fish. Birds like herons, many of the waders, geese, gulls, cranes and even penguins, along with many other families fall into this group. The main threat these birds face is habitat degradation through pollution, loss of wetlands to agriculture and urbanisation, loss of food resources (because of many factors, including anthropogenic activities such as overfishing).
Raptors, also known as birds of prey, include eagles, owls, vultures, falcons, and kestrels etc. Many of these are apex predators within the ecosystems in which they live, and can also be indicator species, in that they are indicative of the health of an ecosystem, which when in good condition, is diverse enough to support enough species in the food chain (plants, herbivores, etc) to enable predators at the top to survive and breed.
Land-birds include species like swallows, bee-eaters, cuckoos, and songbirds, many species of which are in rapid decline worldwide. Most of these species are insectivorous, and the abundant misuse of agricultural chemicals and pesticides across the world, especially in developing nations where these species breed or migrate over means that food supplies are dwindling, and the effects of eating food with high levels of chemicals results in poor egg development, high rates of infertility and poor survival rates in those youngsters that do manage to hatch out, putting sever stress on population diversity.
Large numbers of birds are killed on migration through collisions with man-made structures such as powerlines and glass (reflective) buildings, or are killed illegally through poaching activities at places where they congregate en route to rest or feed, or are unable to find suitable places to rest and feed because of habitat destruction. Many raptors succumb to poisoning en route, either indirectly as the result of consuming other species that have been poisoned on a large scale such as locusts by farmers, or directly through the actions of poachers and farmers misguidedly “protecting” their commercial animals. Several of them are also captured for the illicit trade in traditional medicines.