We are reaching that time of the year again where we say goodbye to a number of our avian friends that have become such a constant feature on game drives during the Londolozi summer.
They start arriving in August, with the Wahlberg’s Eagle usually the first we welcome back, and as spring rolls by into summer we see kites and cuckoos, swallows and starlings, bee-eaters and buzzards all arriving at slightly different times. One of our last arrivals is the Woodland Kingfisher, who usually only gets here a week or two into November.
With summer months usually providing a greater opportunity for food, these bird families spend Northern Hemisphere summers scattered all over Asia, Europe, Russia and North Africa and then when it starts to get colder they migrate south into Southern Africa following the favourable conditions brought on by the change in seasons.
All of this begs the question as to why don’t all birds need to migrate then?
Even though a large number of bird species migrate north in our winter we are still left with a number of beautiful birds that reside here all year round. They seem to survive just fine without undertaking a journey of thousands of kilometres in search of more food and there are a couple of reasons why and how they have adapted to the tougher winter conditions.
Diet: Birds that remain here all year round usually have a diet that is quite varied.
Yellow Billed Hornbills for example will eat a whole variety of insects, small animals and rodents, as well as fruit and seeds. Some of these birds may adapt their feeding preferences as the seasons change and favour the readily available fruit and seeds in summer and then during winter focus on foraging under the bark of trees or in any crevice for whatever insects may be found there. With food sources being a major factor for migration, the benefit of having a constant food source even under harsher climatic conditions means that these birds do not need to undertake the perilous journey in search of more food.
Moulting: Summer time here is when a lot of our resident bird species breed, and you will see a vast array of bright and beautiful feathers on display as they moult into their breeding plumage in order to attract a mate. As winter approaches however, birds like the Pin-Tailed Whydah will lose their bright colours and long tail streamers as they moult into their non-breeding plumage. As this usually coincides with the cold winter months these moults will usually include a protective layer of insulated down feathers to help them retain their body heat which helps them survive the cold winter.
A decrease in food availability in winter also means there just won’t be enough energy available to maintain breeding plumage and courtship activity, so the birds revert to a more energy-friendly plumage.
Stockpiling: Feeding habits can also play a very helpful role in survival. The Common Fiscal, after catching food such as lizards and mice, will often find a tree with large thorns and hang its food on those thorns. In some cases I have seen multiple lizards being hung up in this fashion and although they do risk losing their food to other predators it does mean they have a constant food source at least for a few days.
The Fiscal itself is not found at Londolozi but lots of other members of the shrike family are known to do this, including the red-backed shrike pictured below, which is actually migratory.
Bird Parties: When you have a lot of different bird species flocking together in a particular area and all feeding, it’s called a bird party. They’re not all dancing and having a good time. No, the benefit of these parties is that with a lot of different birds together they can find food a bit easier with more eyes to search. The downside to this is that it does mean that competition for food increases. However, often all these different species will have slightly different food preferences and feeding habits and you will see them feeding in their own niche i.e. on the ground, in tree cavities, high or low foliage etc. More eyes also means more lookouts for danger.
Communal Roosting: One of my best sights on a cold winters morning is a branch full of Little Bee-Eaters all huddled up in a row. The benefit of this is that they will stay warm for longer by making use of each other’s body heat in case there is a cold snap during the night. A number of different birds will employ the same technique. Some Owls, such as the African Scops Owl will huddle together in a hole in a tree.
With all of these adaptations the benefits of staying in one area all year round outweigh the benefits of undertaking a dangerous migration and together with the amount of energy that these resident birds have saved by not migrating their survival prospects are a lot higher. The saved energy will be put to great use whist foraging for food, protecting their nests and defending their territories.
Nature is dynamic and ever-evolving and being able to witness this instinctive behaviour shown by these various bird families is one of the reasons I love heading out on game drives everyday.