As the days are now growing longer and that winter chill is beginning to fade, it’s clear that the seasons are shifting here at Londolozi. The sun greets us earlier, and we’re staying out a little longer to enjoy the sunset with a drink in hand. The laters we wrap ourselves up in are now shed by the time we return to camp, as the warmth of spring has arrived. But the most telling signs of the changing season come not just from the lengthening days or the rising temperatures, but from the behaviour of the wildlife around us.

Grey Heron sitting on its nest.

One of these signs is the activity of the grey herons at the causeway. Just the other morning, we watched as a male heron meticulously gathered sticks and plant material, delivering them to his mate perched on the nest. With careful precision, she wove these pieces into the nest structure that will soon hold their eggs, signalling to us that they are preparing for the arrival of the spring rains. Yet, in contrast, the usually bustling weavers, known for their impressive nest-building above the causeway pool, are notably still absent.

Male village weaver hangs upside down in order to display, through song and flapping wings, to any passing females while showing off his newly completed nest.§

This observation led me to wonder: why do different birds choose to nest at different times of the year? What advantages—and perhaps challenges—does each season present to these nesting birds?

The Summer Advantage

Summer is often considered the prime time for breeding in many parts of the world, and for good reason. In these parts of Southern Africa, summer coincides with the rainy season. The rains bring a flush of green to the landscape, and with it comes an abundance of food. There are plenty of insects around, plants bear fruit, and small animals emerge from their winter slumber, providing ample resources for birds to raise and feed their young.

White Crested Helmetshrike chicks begging for food that hasn’t been provided on this trip back to the nest by the adult.

Weavers are among the most notable summer breeders at Londolozi. These social birds, such as the Southern Masked Weaver, are known for their intricate, hanging nests constructed from strips of grass and reeds. The summer rains provide an abundance of plant material for nest building, as well as a steady supply of insects to feed their growing chicks. The timing is perfect for ensuring that their young have the best chance of survival.

However, breeding in summer is not without its challenges. The increased competition for resources, both within and between species, can be intense. Predation pressure is also higher during this time, as predators take advantage of the abundance of young, inexperienced chicks. Additionally, the unpredictable nature of rainfall can sometimes lead to drought conditions even in summer, leaving birds struggling to find enough food and water.

The Winter Breeders

While summer breeding is common, some birds choose to nest during the cooler, drier months of winter. This strategy might seem counterintuitive at first, but for certain species, it offers distinct advantages. One of the main reasons some birds breed in winter is to avoid the intense competition for food and nesting sites that occurs during the summer months. By breeding in the off-season, these birds can access resources with less direct competition from other species.

Vultures are prime examples of winter breeders at Londolozi. Species such as the White-backed Vulture often choose to nest during the dry season. During this time, large herbivores like elephants and buffalo may succumb to the harsher, drier conditions, providing a more consistent supply of carcasses. This steady food source is crucial for vulture parents who need to feed their chicks regularly. Additionally, by nesting in the winter, vultures avoid the intense heat of summer, which can be challenging for chicks to survive, especially in large open nests at the top of a tree.

Winter breeding also offers the advantage of reduced predation pressure. With many predators focused on other prey that are more active during the cooler months and some predators being less active during the cooler months, such as snakes, the chances of eggs or chicks being predated upon may be lower.

However, winter breeding comes with its own set of challenges. The cooler temperatures mean that parents must invest more energy in keeping their eggs and chicks warm, which can be taxing. Food can also be scarcer, requiring parents to expend more effort in foraging. This can be particularly risky if unexpected cold spells or frosts further reduce food availability.

The Shoulder Season Specialists

Some birds at Londolozi are neither strictly summer nor winter breeders but instead, time their nesting to occur during the transitional periods between seasons—spring and autumn. These shoulder seasons can offer a balanced combination of the benefits seen in both summer and winter, with fewer extreme challenges.

Grey Herons are a good example of shoulder season breeders. They often begin their nesting activities in late winter or early spring, just before the rains fully arrive. This timing allows them to take advantage of the early abundance of fish and frogs in the drying pools before the heavy rains flood the landscape. Grey Herons can therefore provide a steady supply of food to their chicks without the intense competition that summer brings.

After capturing this grey heron standing over its pale blue eggs, I will be keeping an eye out to see when the chicks hatch! The incubation period is normally between 23-28 days.

In autumn, Spotted Eagle-owls may begin nesting as the heat of summer wanes, taking advantage of the late-season abundance of small mammals that are preparing for the cooler months. The milder temperatures and still-ample food resources make autumn an ideal time for these birds to raise their young, ensuring they are strong and well-fed by the time winter arrives.

This strategy of timing breeding to coincide with the shoulder seasons allows birds to take advantage of a relatively stable environment where resources are available, but competition and predation pressures are not as intense as in the peak of summer.

Flexible Breeding Strategies

Not all birds are strictly tied to a single breeding season. Some species are more flexible in their breeding strategies, adjusting their timing based on environmental conditions. This adaptability can be a crucial survival strategy in regions like Southern Africa, where weather patterns can be unpredictable.

Fork-tailed Drongo chicks huddled in a nest awaiting the return of the adults.

For example, if a particularly early or abundant rainy season brings a sudden increase in food resources, some birds may take the opportunity to breed earlier than usual. Conversely, in years of drought or poor conditions, these birds might delay breeding until conditions improve, or in some cases, skip breeding altogether to conserve energy and resources.

As the seasons change at Londolozi, so too do the behaviors of our birds, each uniquely adapting to the ever-shifting environment, carefully timing their nesting to maximize reproductive success.Whether it’s the Grey Herons building their nests in anticipation of the spring rains, the Weavers buzzing with activity in the heat of summer, or the Vultures nesting high in the trees during winter, each species has its own strategy for ensuring the survival of the next generation. Observing bird behavior reminds us that seasonal shifts are seen not only in the changing landscape but also in the intricate lives of all the creatures around us.