Signs of Spring: Rainfall, Returning Migrants, and the Colours of Plumage – Londolozi Blog

There is always a sense of anticipation as September arrives. At Londolozi, this date doesn’t just mark the turning of the calendar, but also the beginning of a new rainfall year. We measure rain from September to September because it follows the rhythm of our seasons — winter is typically dry, and by the time September arrives, the land is at its thirstiest, waiting for relief. Starting here allows us to capture an entire wet season, from the very first spring showers through the height of summer storms, and see how that full cycle shapes the landscape. Fittingly, this new year began with a dramatic downpour — some areas of the reserve received as much as 40 millimetres in a single storm. The smell of wet earth lingered in the air, the dust settled, and the first flush of green began to break through.

This rain is more than just relief for thirsty soil; it is also a signal. Spring has arrived, and with it, the first shifts in the rhythm of the bush.

The First Migrants Return

With warmer days and fresh growth, the sky soon becomes animated by returning travellers. Migratory birds that have spent the winter months further north are on their way back to Southern Africa. The first Wahlberg’s Eagles have already returned, circling on rising thermals and reclaiming nest sites they have used for generations. Shortly behind them, the unmistakable forked tails of Yellow-billed Kites drift across the sky, returning to their familiar territories.

The return of the migrant Wahlberg’s eagle is also an exciting time in the summer months as breeding pairs return to previous nesting sites to raise offspring once more.

These birds are early signals of the great seasonal movement that is still to come. As the weeks progress and insect life explodes with the rains, more migrants will arrive,  swallows skimming the grasslands, cuckoos calling from the thickets, and later still, the jewel-bright kingfishers. For now, though, the Wahlberg’s and Yellow-billed Kites are the first messengers of change.

Breeding Plumage: The Colours Return

While some birds make their journey across continents, others have been here all along, simply waiting for the right moment to show a different side of themselves. As the rains begin and daylight hours stretch, we start to see familiar species take on a new brilliance.

The Pin-tailed Whydah, which through the winter months appears rather unassuming, transforms into a striking figure. Males don jet-black and white plumage, with elongated tails that flutter dramatically as they display. The Red-billed Queleas begin to show crimson masks across their faces, while the Village Weavers regain their vivid yellow and black hoods, busily constructing woven nests that swing from the branches. Even the male Widowbirds, often overlooked in their drab winter attire, become almost unrecognisable as their breeding plumage develops — velvety black feathers and streaming tails catching the light above the grasslands.

Why Birds Change Plumage

These seasonal changes are not random; they are tied to one of the most important questions in bird biology: why do birds have different plumages at all?

The answer lies in a balance between survival and reproduction.

During the non-breeding season, often the dry, resource-scarce months, camouflage is key. Drab, earthy plumage helps individuals avoid predators. Birds benefit from being more inconspicuous. A sparrow-coloured whydah or quelea can blend into the dry grass and avoid the attention of predators. Less energy is also required to maintain extravagant plumage at a time when food may be harder to come by.

Summer means breeding time for many different animals, particularly birds. For several species, the males will develop some extravagant plumages in an effort to court the females.

But as soon as the rains return and resources become plentiful, priorities shift. Males in particular need to stand out. Bright colours, elaborate tails, or striking head patterns signal health and vitality to potential mates. These features are honest advertisements; only individuals strong enough to find food, avoid predators, and resist parasites can afford to produce and maintain them. In this way, plumage becomes both a courtship tool and a form of natural selection.

What Causes the Colour Change?

The colour change is triggered primarily by hormones, which respond to shifts in day length and environmental cues like rainfall. Increased testosterone in males stimulates the growth of brighter or more elaborate feathers. These hormonal shifts initiate moulting, during which old feathers are replaced by new, brightly coloured ones.

The colours themselves come from different sources:

• Pigments such as Carotenoids, obtained through diet, produce reds, oranges, and yellows.

• Melanin is responsible for blacks and browns, and also strengthens feathers.

• In some cases, microscopic feather structures refract light to produce the iridescent blues and greens we see in birds like starlings and kingfishers.

Essentially, the landscape and the season tell the birds it is time. The cycle of rain and sun unlocks the cues that shift them from subtle to spectacular.

A Season of Transformation

The first rains bring a sudden shift in the season. Fresh green shoots and leaves begin to appear, wallows fill with water, and the first returning migrants start to appear overhead. At the same time, resident birds regain their breeding colours, adding flashes of yellow, red, and black across the bush. Together, these signs mark the clear arrival of spring at Londolozi.